Field of Science

Showing posts with label evolution. Show all posts
Showing posts with label evolution. Show all posts

Daniel Dennett (1942-2024)


For a long time there's been a kind of Cold War with a slow moving front between philosophers and scientists, especially physicists. The scientists accuse the philosophers of being as useful to the theory and practice of science as "ornithologists are to birds", as a popular saying goes. The philosophers in turn emphasize to the scientists that their disciplines, especially in the 20th and 21st centuries, are so complex and abstract that they cannot be understood without the input of philosophy.

It is in the light of this debate, especially, that the death of Daniel Dennett hit so hard. Unlike most philosophers, Dennett was someone who tried to seriously grapple with the actual facts of science - in his case, evolutionary biology and neuroscience - as opposed to the fevered armchair speculation of philosophy. These facts were on full display in the many phenomenal books he wrote, of which my favorites are "Darwin's Dangerous Idea", "Breaking the Spell" and "From Bacteria to Bach and Back".

Dennett's writing was wonderful and brilliant - extremely witty, confident, bold, even stridently so. He was one of only a handful of writers who regularly elicited moments of "Aha!" in my mind. More than almost anyone else from his generation he was unafraid of taking on bold ideas, particularly ones which would make readers uncomfortable. Whether he was arguing that consciousness is a kind of useful delusion in "Consciousness Explained" or exhorting readers to take the scientific study of religion seriously, as in "Breaking the Spell", Dennett was always provocative. I do not remember a single time when I did not come away from a piece of Dennett's writing without ideas and questions swirling around in my head.

This was true irrespective of whether I agreed with him or not, and there was certainly enough in his work for spirited disagreement. But this is something that needs to be pointed out especially today when so many of us are being asked, explicitly or implicitly, to pick sides, to eschew shades of gray, to personify the "with us or against us" ethos. Dennett took his opponents' arguments seriously, before politely demolishing them. Even when he mocked shoddy thinking - and there was no dearth of that kind of incisive analysis in his writings - he did so after careful consideration of their positions. That quality is on full display in "Breaking the Spell" in which he takes on religious proponents with zeal and certainly, but also with careful analysis.

It was Dennett's critical take on religion that led him to be pegged as one of the four "horsemen" of the New Atheism movement, along with Richard Dawkins, Christopher Hitchens and Sam Harris. Part of what made him a member of that group was his sheer delight at the wonders of natural (as opposed to supernatural) evolution by natural selection. In fact, one of the most delightful and brilliant things he wrote showcasing the centrality of a mindless but highly creative process giving the illusion of intelligence was the following from "From Bacteria to Bach and Back":


I find that last sentence to be cleverness exemplified. But given his vast oeuvre of writings, I never thought membership in the brotherhood of the horsemen to be a particularly significant part of Dennett's intellectual identity, and from what I hear, neither did he. Instead it was just one among many facets of a life devoted to reason, understanding and debate. His books were packed with so many things apart from atheism that it would be a disservice to primarily identify him with that movement.

When I heard about Dennett's death I was about to spend some quality reading time in a coffee shop. I picked up "Breaking the Spell" and spent the next two hours engaging with that classic Dennettsian blend of provocativeness, wit and wisdom. At the end, just like when I had read his works before, I felt invigorated, as if I had just had a first-class workout in a mental gym. And as before I felt like a slight shift had taken place in my consciousness, my understanding of the world and myself. The core of Dan Dennett's identity was devoted to teaching us to question our deepest, most cherished beliefs and to encourage critical thinking, no matter where it led us. In the process he made us think and feel provoked, delighted and yes, uncomfortable. Because through discomfort, whether physical or mental, comes enlightenment.

Book Review: "The Rise and Reign of the Mammals: A New History, From the Shadows of the Dinosaurs to US", by Steve Brusatte

A terrific book by Edinburgh paleontologist Steve Brusatte on the rise of the mammals. Engaging, personal and packed with simple explanations and analogies. Brusatte tracks the evolution of mammals from about 325 million years ago when our reptilian answers split off into two groups - the synapsids and the diapsids. The diapsids gave rise to reptiles like crocodiles and snakes while the synapsids eventually gave rise to us. The synapsids evolved with a hole behind their eye socket: it’s now covered with a set of muscles which you can feel if you touch your cheek while chewing.

Much of the book is focused on how mammals evolved different anatomical and physiological functions against the backdrop of catastrophic and gentle climate change, including the shifting of the continents and major extinctions driven by volcanic eruptions, meteors (during the K-T extinction event that killed the dinosaurs) sea level rises and ice ages. That mammals survived these upheavals is partly a result of chance and partly a result of some remarkable adaptations which the author spends considerable time describing. These adaptations include milk production, temperature regulation, hair, bigger brains and stable locomotion, among others.
Some these changes were simple but significant - for instance, a law named Carrier’s law limits lung capacity in slithering reptiles because each lung alternately gets compressed during sidewinding motions. When mammalian ancestors were able to lift their body upward from the ground and able to install a set of bones that constrained the rib cage, it allowed their lungs to be able to breathe and expel oxygen during movement and when the animal was eating. Needless to say, the ability to breathe and move while eating was momentous for survival in an environment in which predators abounded.
Another adaptation was the development of a specialized set of teeth that mark all mammals including humans - the incisors, canines, pre-molars and molars. Because these teeth form a specialized, complex apparatus, they emerge only twice in mammals - once during infancy and one more time during adulthood. But out chewing apparatus gave rise to another remarkable adaptation - in an evolutionary migration spread out over millions of years, bones of the jaw became the bones of the ear. The ear bones are a set of finely orchestrated and sensitive sound detectors that gave mammals an acute sense of hearing and enabled them to seek out mates and avoid predators.
Quite naturally, the book spends a good amount of time describing the mystery of why mammals survived the great meteor extinction of dinosaurs and much of other life on the planet. Except that it’s no mystery. Dinosaurs were bulky and specialized cold-blooded eaters which were exposed. Mammals were furry, rodent-like warm-blooded omnivores which could hide out underground and eke out an existence on charred vegetation and dead flesh in the post-apocalyptic environment. After the K-T event, there was no turning back for mammals.
The rest of the book spends time discussing particular features of mammalian evolution like flight in bats and the odd monotremes like the duck-billed platypus which lay eggs. A particularly memorable discussion is of the whales, the biggest mammals which have ever lived, which actually evolved from land mammals that would occasionally take to water to escape predators and seek out new food. With their exceptionally big brains and bat-like echolocation, whales remain a wonder of nature.
Brusatte also spices up his account with adventurous stories of intrepid paleontologists and archeologists who have dup up pioneering fossils in extreme environments ranging from the blistering tropical forests of Africa to the Gobi desert of Mongolia. Paleontology comes across as a truly international endeavor, with Chinese paleontologists especially making significant contributions; they were among the first for instance to discover a feather dinosaur, attesting to the reptile to bird evolutionary transition. Unlike old times when Victorian men did most of the digging, women are now a healthy percentage of the field.
Human evolution occupies only a few chapters of Brusatte’s book, and for good reason. While humans occupy a unique niche because of their intelligence, evolutionarily they are no more special or fascinating than whales, bats, platypuses, elephants or indeed the earliest synapsids. What we can take heart from is the fact that we are part of an unbroken thread of evolution ranging across all these creatures. Mammals have survived catastrophic extinctions and climate change events. Humans are now being responsible for one. Whether they are responsible for their own extinction or show the kind of adaptability that their ancestors showed is a future state only they are responsible for.

If you want to improve AI, let it evolve toward emergence

One of my favorite quotes about artificial intelligence is often attributed to pioneering computer scientists Hans Moravec and Marvin Minsky. To paraphrase: “The most important thing we have learned from three decades of AI research is that the hard things are easy and the easy things are hard”. In other words, we have been hoodwinked for a long time. We thought that vision and locomotion and housework would be easy and language recognition and chess and driving would be hard. And yet it has turned out that we have made significant strides in tackling the latter while hardly making a dent in the former.
Why is this? Clearly one trivial reason is that we failed to define “easy” and “hard” properly, so in one sense it’s a question of semantics. But the question still persists: what makes the easy problems hard? We got fooled by the easy problems because we took them for granted. Things like facial recognition and locomotion come so easily to human beings, even human beings that are a few months old, that we thought they would be easy for computers too. But the biggest obstacle for an AI today is not the chess playing ability of a Gary Kasparov but the simple image recognition abilities of an average one year old.
What we forgot was that these things seem easy only because they are the sleek final façade of a four billion year process that progressed with countless fits and starts, wrong alleys and dead ends and random experimentation. We see the bare shining mountaintop but we don’t see the tortuous road leading to it. If you looked under the hood, both spatial and temporal, of a seemingly simple act like bipedal navigation over a slightly rocky surface, you would find a veritable mess of failed and successful experiments in the history of life. If the brain were an electrical box which presented an exterior of wondrous simplicity and efficiency, inside the box would be fused wires, wires leading nowhere, wires with the middles cut off, wires sprouting other wires, stillbirthed wires; a mélange of wired chaos with a thread of accident and opportunity poking through it. We see only that ascendant thread but not the field littered with dead cousins and ancestors it resides in.
Over the ages, much of AI tried to grasp the essence of this evolutionary circus by trying to reproduce the essential structure of the human brain. The culmination of these efforts was the neural network, a layered abstract model of virtual electronic neurons trying to capture different aspects of reality with adjustable weights on every layer and a feedback loop that optimized the difference between the model and reality. So far so good, but neural networks are only modeling the end product and not the process. For the longest time they were not allowed to deliberately make mistakes and mirror the contingent, error-ridden processes of evolution that are grounded in mutation and genetic recombination. They made the evolution of thinking seem far more deterministic than what it was, and if there’s anything we know about evolution by now, it’s that one cannot understand or reproduce it unless one understands the general process of clumsy, aimless progress intrinsic to its workings.
But apart from the propensity of evolution to make mistakes, there is another, much broader aspect of evolution that I believe neural nets or other models of AI must capture in order to be useful or credible or both. That aspect is emergence, a feature of the human brain that is directly the product of its messy evolution. Not only could emergence help AI approach the actual process of thinking better and realize its scientific and financial potential, but it could also lead to reconciliation between two fields that are often and unnecessarily at war with each other – science and philosophy.
The basic idea of emergence has been recognized for a long time, first by philosophers and then by scientists. Whether it’s a block of gold having color properties that cannot be ascribed to individual gold atoms, individual termites forming a giant anthill or thousands of starlings forming stunning, sweeping, transient geometric patterns that carpet the sky for miles, we have known that the whole is often very different from both the individual parts and the sum of the parts. Or as one of the philosophical fathers of emergence, the physicist Philip Anderson, wrote in a now-famous article, “More is different”. Anderson noted that the properties of a physical system cannot be directly derived from its individual constituents, and more components are not just quantitatively but qualitatively different from fewer ones. Part of the reason for this is that both physics and biology are, in the words of Anderson’s fellow physicist Murray Gell-Mann, the result of “a small number of laws and a great number of accidents”. In case of biological evolution the laws are the principles of natural selection and neutral drift; in case of physical evolution the laws are the principles of general relativity, quantum mechanics and thermodynamics.
Emergence is partly a function of the great number of accidents that these small numbers of laws have been subjected to. In case of biology the accidents come from random mutations leading to variation and selection; in case of physics they come from forces and fields causing matter to stick together in certain ways and not others to form stars, galaxies and planets. Evolution critically occurred while immersed in this sea of stochastic emergence, and that led to complex feedback loops between fundamental and emergent laws. The human brain in particular is the end product of the basic laws of chemistry and physics being subjected to a variety of other emergent laws imposed by things like group and sexual selection, tribalism, altruism, predation avoidance and prey seeking. Agriculture, cities, animal domestication, gossip, religion, empires, democracy, despotism; all of humanity’s special creations are emergent phenomena. Mind is the ultimate emergent product of the stochastic evolution of the brain. So is consciousness. It’s because of the universal feature of accidental emergence that even a supercomputer (or an omniscient God, if you will) that had all the laws of physics built into it and that could map every one of the countless trajectories that life would take into the future would be unable to predict the shape and function of the human brain in the year 2018.
The mind which itself is an emergent product of brain evolution is very good at modeling emergence. As just one example, our minds are quite competent at understanding both individual needs as well as societal ones. We are good at comprehending the behavior of matter on both a microscopic scale – although it did take some very determined and brilliant efforts to achieve this feat – and the macro scale. In fact, we have so completely assimilated the laws of emergent physics in our brains that implementing them – throwing a javelin or anticipating the speed of a charging elephant for instance – is instinctive and a matter of practice rather than active calculation. Our minds, which build constantly updated models of the world, can now take emergent behavior into account and can apply the right level of emergent detail in these models to address the right problem. Evolution has had a leisurely four billion years to experiment with its creations while buffeted by the winds of stochastic emergence, so it’s perhaps not surprising that it has now endowed one of its most successful species with the ability to intuitively grasp emergent reality.
And yet we are largely failing to take into account this emergent reality when imagining and building new AIs. Even now, most of our efforts at AI are highly reductionist. We are good at writing algorithms to model individual neurons as well as individual layers of them, but we ignore the higher-level emergent behavior that is expected to result from a real neural network in a real human brain. Through a process called backpropagation, the neural networks are getting better at optimizing the gap between reality and the models they represent by setting up feedback loops and optimizing the weights of individual neurons, but whether their models are trying to capture the right level of emergent detail is a question they don’t address. If your model is capturing the wrong emergent details, then you are optimizing the wrong model.
Even if your model does solve the right problem, it will be such a specialized solution that it won’t apply to other related problems, which means you will be unable to build an artificial general intelligence (AGI). Consider the example of image recognition, a problem that neural nets and their machine learning algorithms are supposed to especially excel at. It’s often observed that if you introduce a bit of noise into an image or make it slightly different from an existing similar image, the neural net starts making mistakes. And yet children do this kind of recognition of “different but similar” images effortlessly and all the time. When shown an elephant for instance, a child will be able to identify elephants in a variety of contexts; whether it’s a real elephant, a stuffed elephant toy, a silhouette of an elephant or a rock formation that traces out the outline of an elephant. Each one of these entities is radically different in its details, but they all say “elephant” to the mind of the child but not to the neural network.
Why is this? I believe that emergence is one of the key secret sauces accounting for the difference. The child recognizes both a real elephant and a rock formation as an elephant because its brain, instead of relying on low-level “elephant features” like the detailed texture of the skin and the black or gray colors, is instead relying on high-level “emergent elephant features” like the general shape and more abstract topological qualities. The right level of emergent abstraction makes the child succeed where the computer is failing. And yet the child can – with some practice – also switch between different levels of emergence and realize for instance that the rock formation is not going to charge her. Through practice and exploration, the child perfects this application of emergent recognition. Perhaps that’s why it’s important to heed Alan Turing’s prescription for building intelligent machines in which he told us to endow a machine with the curiosity of a child and let intelligence evolve.
Another emergent feature of living organisms is what we call “emotion” or “instinct”. For the longest time we used to believe that human beings make rational decisions when evaluating their complex social and physical environments. But pioneering work by psychologists and neuroscientists ranging from Daniel Kahneman to Antonio Damasio has now shown that emotion and logical thinking both play a role when deciding how to react to an environmental stimulus. Take again the example of the child recognizing an elephant; one reason why it is so good at recognizing elephant-like features is because the features trigger a certain kind of emotional reaction in her. Not only are the logical feature-selecting parts of her brain activated, but so are her hormonal systems, perhaps imperceptibly; not only does she start thinking, but even before this, her palms may turn sweaty and her heartbeat may increase. Research has now consistently shown that our instinctive systems make decisions before our logical systems even kick in. This behavior was honed in humans by millions of years of living and passing on their genes in the African savannah, where split second decisions had to made to ensure that you weren’t weeded out of the gene pool. This kind of emotional reaction is thus also a kind of emergent behavior. It comes about because of the interaction of lower-level entities (DNA sequences and hormone receptors) with environmental and cultural cues and learnings. If an AI does not take emotional responses into account, it will likely never be able to recognize the kinds of abstract features that scream out “elephant” in a child’s mind.
As the biologist Theodosius Dobzhansky famously quipped, “Nothing in biology makes sense except in the light of evolution”, and I would extend that principle to the construction of artificial intelligences. Human intelligence is indeed a result of a few universal laws combined with an enormous number of accidents. These accidents have evolved evolution to select for those brains which can take stochastic emergent reality into account and build generalized models that can switch between different levels of emergent abstraction. It seems to me that mimicking this central feature of evolution would not just lead to better AIs but would be an essential feature of any truly general AI. Perhaps then the easy problems would truly become easy to solve.

This is my latest column for 3 Quarks Daily.

Darwin Day: A personal offering


Two hundred and eight years ago this day, Charles Darwin was born. The vision of life that he created and expounded on transformed humanity's perception of its place in the universe. After Copernicus's great heliocentric discovery, it was Darwin's exposition of evolution and natural selection that usurped human beings from their favored place at the center of the universe. But far from trivializing them, it taught them about the vastness and value of life, underscored the great web of interactions that they are a part of, and reinforced their place as both actor and spectator in the grand game of the cosmos. Not only as a guiding scientific principle but as an all-encompassing element of understanding our place in the world, evolution through natural selection has become the dominant idea of our time. As the eminent biologist Theodosius Dobzhansky put it quite simply, nothing in biology makes sense except in the light of evolution. Evolution is a fact. Natural selection is a theory that is now as good as a fact. Both evolution and natural selection happen. And both of them owe their exalted place in our consciousness to a quiet, gentle and brilliant Englishman.

Today it is gratifying and redeeming to know how right Darwin was and how much his theory has been built upon, and frustrating to keep on realizing how those professing religious certainty threaten to undermine the value of his and others' careful and patient discoveries. Especially in the United States evolution has become a bizarre battleground of extreme opinions and mudslinging, a development that seems to be in step with the tradition of coloring any and every issue with a political hue. In this country, it seems today that you can hardly utter an opinion without attaching a label to it. You cannot simply have an opinion or take a position, no matter how grounded in fact it is; your position has to be Republican, Democrat, Libertarian, Neo-Conservative, Socialist or Atheist. If none of these, it has to be Centrist then.

When it comes to evolution, attaching the label of "Darwinism" has obscured the importance and power of the theory of natural selection. On one hand, those who defend the label sometimes make it sound as if Darwin was the beginning and end of everything to do with evolution. This is simply untrue; in his creation of the theory of natural selection, Darwin was a little like Martin Luther King. The Civil Rights movement owed an incalculable debt to King, but King was not the Civil Rights movement. On the other hand, those who oppose the Darwinist label make it sound like all of us who "believe" in evolution and natural selection have formed a cult and get together every weekend to worship some Darwin idol.
Unfortunately both these positions only serve to obfuscate the life and times of the man himself, a simple, gentle and brilliant soul who painfully struggled with reconciling his view of the world with prevailing religious sentiments and who thought it right to cast his religious views aside in the end for the simple reason that his findings agreed with the evidence while the others did not. Darwin Day should be a chance to celebrate the life of this remarkable individual, free from the burdens of religion and political context that his theory is embroiled in today. Because so much has been said and written about Darwin already, this will be more of a personal and selective exposition. Since I am a lover of both Darwin and books, I will tell my short story of Darwin as I discovered him through books.

When you read about his life for the first time, Charles Darwin does not evoke the label of "genius", and this superficial incongruence continues to beguile and amaze. His famous later photographs show a bearded face with deeply set eyes. His look is gloomy and boring and is not one which elicits the image of a sparkling, world-changing intellect and incendiary revolutionary taking on an establishment steeped in dogma. Darwin was not a prodigy by the standards of his English contemporaries William Hamilton or Lord Kelvin, nor did he particularly excel in school and college. He went to Cambridge, of course, but most well educated Englishmen went to Cambridge or Oxford. At Cambridge, although he studied religion, Darwin had one overriding quality: curiosity about the natural world. He consummately nurtured this quality in field trips and excursions; as one famous story goes, Darwin once held two beetles in two hands and popped one of them in his mouth so that he could free one hand for catching a third very attractive one which he had just noticed. He indulged in these interests much to the chagrin of his father who once said that he would not amount to anything and that he would be a disgrace to his family.

As is well-known, Darwin's story really begins with his voyage of the Beagle when he accepted a position on a ship whose melancholic, manic-depressive captain Robert Fitzroy wanted an educated, cultured man to keep him company on a long and dangerous voyage that circumnavigated the world. For Darwin this was a golden chance to observe and document the world's flora and fauna. One of the best illustrated expositions of Darwin's voyage is in Alan Moorhead's "The Voyage of the Beagle" which is beautifully illustrated with original drawings of the wondrous plants, animals and geological formations that Darwin saw on the voyage. Darwin's own account of the voyage is characteristically detailed and modest and depicts a man enthralled by the beauty of the natural world around him. By the time he set off on his historic journey, young Charles had already been inspired by his teacher Charles Lyell's book on geology that talked about geological changes over vast tracts of time: in time, “Principles of Geology” would become a seminal text and a touchstone of the Great Books program. As is also rather well known, evolutionary ideas had been in the air for quite some time by then (as marvelously documented in Rebecca Stott's recent book "Darwin's Ghosts", which traces evolutionary thinking back to Aristotle and even before), and Darwin certainly was not the first to note the rather simple fact that organisms seem to have changed over time, a view that nonetheless and naturally flew in the face of religious dogma. Most importantly, Darwin was well aware of Thomas Malthus's famous argument about the proliferation of species exceeding the resources available to them, an idea whose logical extension would be to conjecture a kind of competition between species and individuals for finite resources. The "struggle for survival", taught today in school textbooks, a phrase that became much maligned later, nonetheless would have been obvious to a man as intelligent and perceptive as Darwin when he set off on his voyage.

Biology, unlike mathematics or physics, is a science more akin to astronomy that relies on extensive tabulation and observation. Unlike a theoretical physicist, a biologist would be hard-pressed to divine truths about the world by armchair speculation. Thus, painstakingly collecting and classifying natural flora and fauna and making sense of its similarities and differences is a sine qua non of the biological sciences. Fortunately Darwin was the right man in the right place; endowed with a naturally curious mind with an excellent memory for assimilation and integration, he was also unique and fortunate to embark on a worldwide voyage that would enable him to put his outstanding faculties to optimum use. Everywhere he went he recorded meticulous details of geology, biology, anthropology and culture. His observation of earthquakes and rock formations in South America and his finding of fossils of giant mammals lend credence to his beliefs about organisms being born and getting extinguished by sometimes violent physical and planetary change. His observation of the Pacific and Atlantic islanders (especially the ones on Tierra del Fuego) and their peculiar customs underscored the diversity of human life along with other life in his mind. But perhaps his best known and most important stop came after several months of traveling, when the ship left Ecuador to dock at the Galapagos Islands.

Again, much has been written about the Galapagos Islands and about Darwin's Finches (most notably by Jonathan Weiner in his “The Beak of the Finch”). The truth is subtler, both simpler and more interesting than what it is made out to be. Darwin had mistaken his famous finches for other species of birds. It was only after coming back that his friend, the ornithologist John Gould, helped him to identify their correct lineage. But finches or not, the birds and the islands provided Darwin with a unique opportunity to study what we now know as natural selection. The islands were separated from each other by relatively small distances and yet differed significantly in their geography and flora and fauna. On each island Darwin observed similar plants and animals that were yet distinct from each other. As in other places, he also observed that species seemed to be adapted to their environment. Geographic isolation and speciation were prominent on those hot, sweaty and incredibly diverse landmasses.

After five years of exhaustive documentation and sailing Darwin finally returned home for good, much changed both in physical appearance and belief. His life following the voyage has been the subject of much psychological speculation since he settled down with his cousin Emma and never ever left the British Isles again. He also seemed to have been stricken with what today is noted by many authors as a kind of psychosomatic illness because of which he was constantly ill with abdominal and other kinds of pains. After living in London for some time, Darwin retired to Down's House in Kent where he peacefully lived the rest of his life with a kind and loving wife, playing with his children, taking walks along the path at the back of his house named the "Sandwalk", corresponding with intellectuals around the world and constantly interrupting his research with salutary visits to spas and resorts for "natural" treatments that were often of dubious value.

But peaceful as his life was, psychologically Charles Darwin was fomenting a maelstrom of revolution that was to have earth-shaking implications. Another fact that is frequently emphasized in contemporary discourse is his hesitation to not publish his ideas for another twenty-five years. Darwin was planning to write it for a while, but was finally jolted into writing it when he received a letter from an obscure young naturalist named Alfred Russell Wallace who was living a hard life of science and natural history exploration in Indonesia. Wallace had read some of Mr. Darwin's papers and manuscripts and had been struck by the similarity of his ideas to his own. Would Mr. Darwin comment on them? Darwin finally realized that he had to act to prevent getting scooped but characteristically credited Wallace in his published work.

In my mind however, Darwin's procrastination and its story sounds much simpler than the mystique and psychological speculation that sometimes envelop it. As we noted earlier, Darwin was a highly trained biologist and scientist of the first caliber. He knew that he would have to exhaustively document and classify the windfall of creatures, plant and rock specimens that he had collected on his voyage. Apart from thinking and writing about his Beagle collections, Darwin also maintained an astonishingly comprehensive and detailed research program on marine invertebrates and barnacles. More tellingly, he did experiments to find out if seeds are viable even when dispersed over long distances over salt-water. He visited gardens and zoos, and quizzed pigeon breeders about their profession. Much of this was in preparation for the grand act that was to follow. In case of the barnacles and marine creatures, Darwin's research was second to none. He published several extremely detailed books on the minutiae of these organisms; some of these had titles which would have put anyone to sleep.

And yet the level of detail in them reflects the extraordinary patience, power of observation and meticulous hard work that characterized the man, characteristics crucial for developing the theory of natural selection. Darwin was also very fortunate to have had several friends and colleagues who were experts in areas that he was not, who helped him classify and name all the material. Foremost among his correspondents were Charles Lyell and Joseph Hooker to whom he confided not just his scientific questions but also his emerging convictions about the interconnections and implications that were emerging from his research and writing. Also as noted above, John Gould accomplished the crucial task of reminding Darwin that his Galapagos birds were finches. With help from these collaborators and his own studies and thoughts on his observations, thoughts that filled literally dozens of rough drafts, scribblings and private diaries, Darwin finally began to glimpse the formation of a revolutionary chain of thought in his mind.

But Darwin did not rush forth to announce his ideas to the world, again for reasons that are obvious; Victorian England was a hotbed of controversy between science and religion, with many distinguished and famous scientists there and in other countries not just fervently believing in God, but writing elegant tomes that sought a supernatural explanation for the astounding diversity of life around us. Cambridge was filled with intellectuals who sought a rational framework for God's intervention. Darwin would have been quite aware of these controversies. Even though Darwin's grandfather (a more pugnacious character) himself had once propounded an evolutionary view, Darwin was finely attuned to the sensitive religious and social debate around him. Not only did he not want to upset this delicate intellectual and spiritual balance and get labeled as a crackpot, but he himself had not started his voyage as a complete non-believer. One can imagine the torment that he must have faced in those early days, when the evidence pointed to facts that flew in the face of deeply held or familiar religious beliefs. One of the factors that dispossessed Darwin of his religious beliefs was the stark contradiction between the observation of a cruel and ruthless race for survival that he had often witnessed first hand, and the image of an all-knowing and benign God who kindly reigned over his creations. As the evidence grew to suggest relationships between species and their evolution by the forces of natural selection that preserved beneficial characteristics, Darwin could no longer sustain two diametrically opposite viewpoints in his mind.

Opponents of evolution who want to battle the paradigm not from a scientific viewpoint (because they can't) but from a political one frequently raise a smokescreen and proclaim that evolution itself is too complex to be understood. The tricksters who propagate intelligent design further attest to the biochemical complexity of life and then simply give up and say that only an omniscient God (admittedly more complex than the systems whose complexity they are questioning) could have created such intricate beauty. The concept of a struggle for survival has also been hijacked by these armies of God who proclaim that it is this philosophy that would make evolution responsible for genocide, fascism and the worst excesses of humanity. This is a deeply hurtful insult to natural selection and evolution as only the most dogmatic believers can deliver.

One thing that constantly amazes you about evolution is its sheer simplicity. Stripped down to its essentials, the "theory" of evolution can be understood by any school child.
1. Organisms and species are ruthlessly engaged in a constant struggle for survival in which they compete for finite resources in a changing environment.
2. In this struggle, those individuals who are more adapted to the environment, no matter how slightly, win over other less adapted individuals and produce more offspring.
3. Since the slight adaptations are passed down to the offspring, the offspring are guaranteed to preserve these features and therefore are in a position to survive and multiply more fruitfully.
4. Such constant advantageous adaptive changes gradually build up and, aided by geological and geographical factors, lead to the emergence of new species.

It's almost like a simple three-step recipe that when followed keeps on churning out culinary wonders of staggering complexity and elegance. In my mind the beauty of evolution and natural selection is two-fold; firstly, as Darwin emphasized, the slightest adaptation leads to a reproductive advantage. Such slight adaptations are often subtle and therefore sometimes can sow confusion regarding their existence; notice the debate between driver and passenger mutations in fields ranging from evolutionary biology to oncology. But the confusion should be ameliorated by the second even more striking fact; that once a slight adaptation exists, it is guaranteed to be passed on to the offspring.

As Gregor Mendel hammered the mechanism for natural selection in place a few years after Darwin with his discovery of genetic inheritance, it became clear that not every one of the offspring may acquire the adaptation. The exact pattern may be complex. But even if some of the offspring acquire it, the adaptation is then guaranteed to confer reproductive fitness and will be passed on. This fact should demolish a belief that even serious students of evolution, and certainly laymen, have in the beginning; that there is something very uncertain about evolution, that it depends too much on "chance". The key to circumvent these misgivings is to realize the above fact, that while adaptations (later attributed to mutations) may arise by chance, once they arise, their proliferation into future generations is virtually certain. Natural selection will ensure it. That in my mind is perhaps Darwin's greatest achievement; he finally found a mechanism for evolution that guarantees its existence and progress. As for the struggle for survival, it certainly does not mean that it results in non-cooperation and purging of other individuals. As examples in the living world now document more than convincingly, the best reproductive fitness can indeed come about through altruistic leanings and cooperative behavior.

Every one of these factors and facts was detailed and explained by Darwin in "The Origin of Species", one of the very few original works of science which remain accessible to the layman and which contained truths that have not needed to be modified in their basic essence even after a hundred and fifty years. It was readable even when I picked it up as a callow young college student. No one who approaches it with an open mind can fail to be taken with its simplicity, elegance and beauty. One of the most extraordinary things about Darwin and something that continues to stupefy is how right the man was even when he lacked almost all the modern tools that have since reinforced basic evolutionary ideas. As one of Darwin's intellectual descendants, the biologist E O Wilson says, it is frustrating for a modern biologist to discover an evolutionary idea through his work, and then go back a hundred and fifty years and discover that the great man had hinted at it in his book.

And yet as Darwin himself would have acknowledged, there is much in the book that needed to be modified, there was much that he could not explain. Darwin had no inkling of genes and molecular biology, nor could he come up with a convincing mechanism that explained the sheer age of the earth required for evolutionary processes to work their charm (the mechanism was found later with the discovery of radioactivity). The exact mechanism of passing on adapted characteristics was unknown. Major fossils of primates and humanoid ancestors had yet to be discovered. Quite importantly, random genetic drift which is completely different from natural selection was later discovered as another process operating in evolution. The development of viral and bacterial resistance in causing diseases like AIDS finally brought evolution to the discomfort of the masses. It was only through the work of several evolutionary biologists and geneticists that Darwin finally became seamlessly integrated with the understanding of life in the middle twentieth century. Genomics has now proven beyond a shade of doubt that we truly are one with the biosphere. But in the absence of all these developments, it is perhaps even more remarkable how many of Darwin's ideas still ring true.

There is another factor that shines through in "The Origin"; Darwin's remarkable modesty. One would have to search very hard in history to find a scientist who was both as great and as modest. Newton may yet be the greatest scientist in history, but he was nothing if not a petty, bitter and difficult man. Darwin in contrast was a symbol of kindly disposition. He doted on his children and told them stories. He loved and respected his wife even though their religious views gradually grew more distanced. His written correspondence with her was voluminous and fond. His correspondence with his collaborators, even those who disagreed, was cordial and decent. Never one for contentious public debates, he let his "bulldog" Thomas Henry Huxley fight his battles; one of them with Bishop Samuel Wilberforce ended in a famous showdown when the Bishop inquired whether it was through his father or mother that Huxley had descended from an ape, and Huxley countered that he would rather descend from an ape than from the Bishop. Darwin stayed away from these entertaining confrontations; as far as he was concerned, his magisterial work was done and he had no need for public glory. To the end of his life this kind and gentle man remained a wellspring of modest and unassuming wonder. His sympathetic, humane and sweet personality continues to delight, amaze and inspire reverence to this day.

In the later stages of his life Darwin became what he himself labeled as an agnostic but what we today would probably call an atheist. His research into the progression of life and the ruthless struggle that it engenders made it impossible for him to justify a belief in a paternal and loving deity. He was also disillusioned by popular conceptions of hell as a place where non-believers go; Darwin's father was a non-believer and yet a good doctor who treated and helped hundreds of human beings. Darwin simply could not accept that a man as kind as his father would go to hell simply for not believing in a version of morality, creation and life trotted out in a holy book. Probably the last straw that convinced Darwin of the absurdity of blind faith was the untimely death of his young daughter Annie who was his favorite among all the children. According to some accounts, after this happened, Darwin stopped even his cursory Sunday trips to church and was satisfied to take a walk around it while not at all minding his wife and children's desire to worship inside.

The second fact is also in tune with Darwin's kind disposition; he admittedly had no problem reconciling the personal beliefs of other people with his conviction about their falsity. Darwin's tolerance of people's personal faith and his unwillingness to let his own work interfere in his personal life and friendships is instructive; to the end he supported his local parish and was close friends with a cleric, the Reverend John Innes. Darwin's example should keep reminding us that it is actually possible to sustain close human bonds while having radically different beliefs, even when one of these is distinctly true while the other one is fantasy. Nurturing these close bonds with radical scientific ideas that would change the world for ever, Charles Darwin died on April 19, 1882, a content and intellectually satisfied man.

To follow, nourish and sustain his legacy is our responsibility. In the end, evolution and Darwin are not only about scientific discovery and practical tools arising from them, but about a quest to understand who we are. Religions try to do this too, but they seem to be satisfied with explanations for which there is no palpable evidence and which seem to be often contradictory and divisive. It is far better to imbibe ourselves with explanations that come from ceaseless exploration and constant struggle; the very means that constitute these explorations are then much more alluring and quietly fulfilling than any number of divergent fantasies that can only promise false comfort. And these means promise us a far more humbling and yet grand picture of our place in this world. Especially in today's age when the forces of unreason threaten to undermine the importance of the beautiful simplicity in the fabric of life that Darwin and his descendants have unearthed, we owe it to Charles Darwin to continue to be amazed at the delightful wonder of the cosmos and life. We owe it to the countless shapes and forms of life around us with whom we form a profoundly deep and unspoken connection. And we owe it to each other and our children and grandchildren to keep rationality, constructive skepticism, freedom and questioning alive.

LITERATURE ON DARWIN:

I don't often write about Darwin and evolution here for a simple reason; there is literally an army of truly excellent authors and bloggers who pen eloquent thoughts about these subjects and the amount of stuff published about him will fill up entire rooms. You could probably put together a thousand-page encyclopedia simply listing works on Darwin. His original work as stated above is still very readable. Every aspect of his life and work - the scientific, the psychological, the social, the political and the personal - has been exhaustively analyzed. I have certainly not sampled more than a fraction of this wealth of knowledge, but based on my interest in Darwin and selected readings, I can recommend the following.

For what it's worth, if you want to have the best overview of Darwin's life after he came home from his voyage on the Beagle, I think nothing beats the elegance of language and wit of David Quammen's "The Reluctant Mr. Darwin". Quammen has exhaustively researched Darwin's post-Beagle life and work, and no one I have come across tells the story with such articulate enthusiasm, fondness and attention to detail in a modest sized book.

Janet Browne's magisterial biography of Darwin is definitely worth a look if you want to get all the details of his life. Browne pays more attention to the man than the science, but her work is considered the authoritative work, and there are nuggets of eloquence in it.
As a student in high school I was inspired by Alan Moorehead's "The Voyage of the Beagle" noted above which combines an account of Darwin's life and voyage with beautiful and full page illustrations.
Geting to evolution now, there's an even bigger plethora of writings. Several books have captured my attention in the last many years. I don't need to extol the great value of any (and indeed, all) of Richard Dawkins' books. If you ask me which ones I like best, I would suggest "The Selfish Gene", "The Extended Phenotype", "Climbing Mount Improbable" and "The Blind Watchmaker". For a journey into our ancestral history, Dawkins' strikingly illustrated "The Ancestor's Tale" is excellent. Speaking of ancestral history, Neil Shubin's "Our Inner Fish" charts a fascinating course that details how our body parts come from older body parts that were present in ancient organisms. So does his recent book "The Universe Within". Shubin provides scores of interesting tidbits; for instance he tells us how hernias are an evolutionary remnant. Another great general introduction to evolution is Carl Zimmer's "Evolution"; Zimmer has also recently written excellent books on bacteria and viruses in which evolution plays a central theme.

No biologist- not even Dawkins- has had the kind of enthralling command over the English language as Stephen Jay Gould. We lost a global treasure when Gould died at age sixty. His books are relatively difficult to read and for good reason. But with a little effort they provide the most sparkling synthesis of biology, history, culture and linguistic exposition that you can ever come across. And all of them are meticulously researched, although Gould’s political ideology sometimes has to be watched out for. Out of all these I personally would recommend "Wonderful Life", and if you want to challenge yourself with a really difficult unedited original manuscript written just before he died, "The Hedgehog, the Fox and The Magister's Pox". His collections of essays - "Full House" and "Eight Little Piggies" for instance - are also outstanding.

I don't want to really write about books which criticize creationism since I don't beat that horse much, but if you want to read one book about the controversy that rips apart intelligent design proponents' arguments, read Ken Miller's "Finding Darwin's God" which makes mincemeat out of the usual "arguments from complexity" trotted out by creationists which are actually "arguments from personal incredulity". He also has a book covering the Dover Trial. I have only browsed it but it seems to be equally good read. What makes Miller a tough target for creationists (and puzzling for evolutionists) is that he is a devout Christian.

This is an updated and revised version of a post originally written on Darwin's 200th birthday.

Physics and the search for fundamental laws: Is physics turning into biology?

The Standard Model of particle physics
contains many fundamental values which
may be a result of pure accident
Physics, unlike biology or geology, was not considered to be a historical science until now. Physicists have prided themselves on being able to derive the vast bulk of phenomena in the universe from first principles. Biology - and chemistry, as a matter of fact - are different. Chance and contingency play an important role in the evolution of chemical and biological phenomena, so beyond a point scientists in these disciplines have realized that it's pointless to ask questions about origins and first principles.

The overriding "fundamental law" in biology is that of evolution by natural selection. But while the law is fundamental on a macro scale, its details at a micro level don't lend themselves to real explanation in terms of origins. For instance the bacterial flagellum is a product of accident and time, a key structure involved in locomotion, feeding and flight that resulted from gene sharing, recombination and selective survival of certain species spread over billions of years. While one can speculate, it is impossible to know for certain all the details that led to the evolution of this marvelous molecular motor. Thus biologists have accepted history and accident as integral parts of their fundamental laws.

Physics was different until now. Almost everything in the universe could be explained in terms of fundamental laws like Einstein's theory of general relativity or the laws of quantum mechanics. If you wanted to explain the shape and structure of a galaxy you could seek the explanation in the precise motion of the various particles governed by the laws of gravity. If you wanted to explain why water is H20 and not H30 you could seek the explanation in the principles of quantum mechanics that in turn dictate the laws of chemical bonding.

But beyond this wildly successful level of explanation seems to lie an impasse. The problem arises when you try to explain one of the most profound facts of nature, the fact that the fundamental constants of nature are fine-tuned to a fault, that the universe as we know it would not exist if these constants had even slightly different values. For instance, it is impossible to imagine life existing had the strength of the strong force binding nuclei together been even a few percent smaller or larger. Scientists have struggled for decades to explain why other numbers like the value of Planck's constant or the electron's mass are what they are. In fact this is one of the biggest gaps in the Standard Model of physics, an otherwise spectacularly successful paradigm that nonetheless contains arbitrary constants that defy an origin story. It seems now that physicists are giving up trying to explain conundrums like these, or at least giving up trying to do it the way they always have.

Two books that I read recently drove the point home to me. One was Max Tegmark's "The Mathematical Universe". In the book Tegmark takes us on a dizzying journey through modern physics that ends in the fanciful realm of multiple universes. It's hardly the first book to do so. Multiple universes have been invoked to explain many problems in physics, but their most common use is try to explain (or explain away, as some seem to rightly think) the problem of the fundamental constants. The purported "solution" sounds simple; we can stop wondering why the fundamental constants have the precise values that they do if we assume the existence of a potentially infinite number of universes, each of which has a different set of values for the constants. Our universe just happens to have the right combination that allows sentient life to arise and ask such questions in the first place.

Leaving aside the fact that multiple universes still belong to speculation and science fiction rather than science, what is really striking about them to me is that they have finally transported physics into the realm of biology. What physicists are essentially saying is that there have been several universes in the past and there are likely several universes in the present, and our unique universe with its specific combination of fundamental constants is an accident. The multiple universe argument is very much similar to the argument establishing evolution by natural selection as the centerpiece of biology: there have been several species with several genotypic and phenotypic features, and our own human species is a result of contingency and historical accident. This is not so much an explanation as an admission of incomplete knowledge, but biologists are fine with this since it does not obviate any natural law and is still part of a satisfying overarching theory.

It looks like with the postulation of multiple universes physicists too have stepped over from the land of fundamental explanatory laws into the land of historical accident and contingency. This is a radical shift in the way physics has been done until now and a rather painful blow to the physicist's view of nature. One might also say that biology is having the last laugh. In the sixteenth and seventeenth century when biology was still doing the messy job of cataloging data and trying to make sense of the mess, physics was marching on, discovering precise regularities and generalities in nature's offerings. Since then several sciences including biology and economics have suffered from "physics envy". But now it ironically looks like physics' successful run at predicting everything from first principles might have become a victim of its own success. It may be the case that physicists' spectacular findings themselves have illuminated their own limitations. In his book "The Accidental Universe", physicist and writer Alan Lightman puts it thus:

"Dramatic developments in cosmological findings and thought have led some of the world's premier physicists to propose that our universe is only one of an enormous number of universes, with wildly varying properties, and that some of the most basic features of our particular universe are mere accidents - random throws of the cosmic dice. In which case, there is no hope of ever explaining these features in terms of fundamental causes and principles."

Lightman also quotes the doyen of physicists, Steven Weinberg, who recognizes this watershed in the history of his discipline:

"We now find ourselves at a historic fork in the road we travel to understand the laws of nature. If the multiverse idea is correct, the style of fundamental physics will be radically changed."

Although Weinberg does not say this, what's depressing about the multiverse is that its existence might always remain postulated and never proven. This is an ever worse scenario because the only thing that a scientist hates even more than an unpleasant answer to a question is no answer at all. It's not inaccurate to say that many physicists - and especially those like Weinberg who have been part of the spectacular revolution in physics during the 60s and 70s - are distressed by this fact.

The metamorphosis of physics into a historical science means that many of the facts that have troubled the field's foremost practitioners may be a product of chance and fundamentally unexplainable in terms of more basic laws. I must emphasize that this is not some kind of "end of physics" scenario that I am imagining here (unlike my colleague John Horgan); there are still plenty of very challenging questions dealing with the application of the fundamental laws that will keep physicists occupied for decades. Foremost among these may be the conundrum of emergent phenomena which themselves are very fundamental in fields like neuroscience and economics. I am also not implying that physicists should simply give up looking for fundamental laws. But their methodological take on finding these laws may have to change. As far as the deep question of why certain building blocks of the universe seem to exist within very narrow constraints is concerned, physicists might simply have to accept that there is no true causal explanation for the fact.

String theory, which at one point was considered a promising strategy to unify quantum mechanics and gravity and possibly explain such problems, has been severely floundering for the last few years. Bereft of testable predictions, some of its proponents have now resorted to thinking of the theory as a good example of “non-empirical” science. This kind of thinking seems to me to be an alarming cop-out. As the physicist Carlo Rovelli explained in a recent talk, many predictions like antimatter and the bending of starlight of gravity have started out as non-empirical predictions based on pure thought. But they were not regarded as a legitimate part of science until they were experimentally verified. In addition the predictions they made were testable in a very well defined manner. To consider a theoretical framework as perpetually being a legitimate part of science as a non-empirical framework would be contrary to all the science that we know and love.

Are physicists justified in feeling despondent because they seem to be tapping the bottom of the barrel in their search for fundamental laws and because their efforts to explain these laws at a truly basic level have not borne fruit? I don't think so. Biologists have known about contingency and accident ever since Darwin wrote his great book, but not only has this not made them emotionally unstable but it has also not kept them from making spectacular discoveries in their discipline. Just because a system of laws might have a historical origin based on accident does not mean that there are no great truths about the system still waiting to be discovered. But more importantly, perhaps physicists need to embrace contingency to be as much of a fundamental law as any other. Biologists know this; in fact they know that there would be no evolution in the first place without contingency, and they know that it is thanks to historical accident that they get to study the incredibly rich cornucopia of living structures that the earth has presented to them.

The best thing would be for physicists to realize that just because the ultimate laws of their discipline might have a fundamentally accidental origin, it does not mean that the manifestations of those laws are any less important or useful. The most important page they should lift out of the biologists' playbook is very simple; when ideas about a field evolve, it is best for the practitioners of the field to evolve too.

This is a revised and updated version of an older post.

Darwin's "endless forms most beautiful" quote...applied to chemistry

“Thus, from the ashes of alchemy, from war and peace, the most exalted object which we are capable of conceiving, namely, the production of new molecules that never existed before, directly follows. 

There is grandeur in this view of matter, with its several properties, having been originally breathed into a few elements or into one; and that, whilst this planet has gone cycling on according to the fixed laws of thermodynamics, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, synthesized.”

Darwin and his vision of life: A personal offering



"You care for nothing but shooting, dogs, and rat- catching, and you will be a disgrace to yourself and all your family."

- Robert Darwin, to his son Charles.

Two hundred and seven years ago this day, Charles Darwin was born. The vision of life that he created and expounded on transformed humanity's perception of its place in the universe. After Copernicus's great heliocentric discovery, it was Darwin's exposition of evolution and natural selection that usurped human beings from their favored place at the center of the universe. But far from trivializing them, it taught them about the vastness and value of life, underscored the great web of interactions that they are a part of, and reinforced their place as both actor and spectator in the grand game of the cosmos. Not only as a guiding scientific principle but as an all-encompassing element of understanding our place in the world, evolution through natural selection has become the dominant idea of our time. As the eminent biologist Theodosius Dobzhansky put it quite simply, nothing in biology makes sense except in the light of evolution. Evolution is a fact. Natural selection is a theory that is now as good as a fact. Both evolution and natural selection happen. And both of them owe their exalted place in our consciousness to a quiet, gentle and brilliant Englishman.

Today it is gratifying and redeeming to know how right Darwin was and how much his theory has been built upon, and frustrating to keep on realizing how those professing religious certainty threaten to undermine the value of his and others' careful and patient discoveries. Especially in the United States evolution has become a bizarre battleground of extreme opinions and mudslinging, a development that seems to be in step with the tradition of coloring any and every issue with a political hue. In this country, it seems today that you can hardly utter an opinion without attaching a label to it. You cannot simply have an opinion or take a position, no matter how grounded in fact it is; your position has to be Republican, Democrat, Libertarian, Neo-Conservative, Socialist or Atheist. if none of these, it has to be Centrist then.

When it comes to evolution, attaching the label of "Darwinism" has obscured the importance and power of the theory of natural selection. On one hand, those who defend the label sometimes make it sound as if Darwin was the beginning and end of everything to do with evolution. This is simply untrue; in his creation of the theory of natural selection, Darwin was a little like Martin Luther King. The Civil Rights movement owed an incalculable debt to King, but King was not the Civil Rights movement. On the other hand, those who oppose the Darwinist label make it sound like all of us who "believe" in evolution and natural selection have formed a cult and get together every weekend to worship some Darwin idol.

Unfortunately both these positions only serve to obfuscate the life and times of the man himself, a simple, gentle and brilliant soul who painfully struggled with reconciling his view of the world with prevailing religious sentiments and who thought it right to cast his religious views aside in the end for the simple reason that his findings agreed with the evidence while the others did not. Darwin Day should be a chance to celebrate the life of this remarkable individual, free from the burdens of religion and political context that his theory is embroiled in today. Because so much has been said and written about Darwin already, this will be more of a personal and selective exposition. Since I am a lover of both Darwin and books, I will tell my short story of Darwin as I discovered him through books.

When you read about his life for the first time, Charles Darwin does not evoke the label of "genius", and this superficial incongruence continues to beguile and amaze. His famous later photographs show a bearded face with deeply set eyes. His look is gloomy and boring and is not one which elicits the image of a sparkling, world-changing intellect and incendiary revolutionary taking on an establishment steeped in dogma. Darwin was not a prodigy by the standards of William Hamilton or Lord Kelvin, nor did he particularly excel in school and college. A Cambridge man who studied religion, Darwin had one overriding quality; curiosity about the natural world. He consummately nurtured this quality in field trips and excursions; as one famous story goes, Darwin once held two beetles in two hands and popped one of them in his mouth so that he could free one hand for catching a third very attractive one which he had just noticed. He indulged in these interests much to the chagrin of his father who once said that he would not amount to anything and that he would be a disgrace to his family.

As is well-known, Darwin's story really begins with his voyage of the Beagle when he accepted a position on a ship whose melancholic, manic-depressive captain Robert Fitzroy wanted an educated, cultured man to keep him company on a long and dangerous voyage that circumnavigated the world. For Darwin this was a golden chance to observe and document the world's flora and fauna. One of the best illustrated expositions of Darwin's voyage is in Alan Moorhead's "The Voyage of the Beagle" which is beautifully illustrated with original drawings of the wondrous plants, animals and geological formations that Darwin saw on the voyage. Darwin's own account of the voyage is characteristically detailed and modest and depicts a man enthralled by the beauty of the natural world around him. By the time he set off on his historic journey, young Charles had already been inspired by his teacher Charles Lyell's book on geology that talked about geological changes over vast tracts of time. 

As is also rather well-known, evolutionary ideas had been in the air for quite some time by then (as marvelously documented in Rebecca Stott's book"Darwin's Ghosts"), and Darwin certainly was not the first to note the rather simple fact that organisms seem to have changed over time, a view that nonetheless and naturally flew in the face of religious dogma. Most importantly, Darwin was well-aware of Thomas Malthus's famous argument about the proliferation of species exceeding the resources available to them, an idea whose logical extension would be to conjecture a kind of competition between species and individuals for finite resources. The "struggle for survival", taught today in school textbooks, a phrase that became much maligned later, nonetheless would have been obvious to a man as intelligent and perceptive as Darwin when he set off on his voyage.

Biology, unlike mathematics or physics, is a science more akin to astronomy that relies on extensive tabulation and observation. Like chemistry it is a synthetic rather than a purely analytical science. Unlike a theoretical physicist, a biologist would be hard-pressed to divine truths about the world by armchair speculation. Thus, painstakingly collecting and classifying natural flora and fauna and making sense of its similarities and differences is a sine qua non of the biological sciences. Fortunately Darwin was the right man in the right place; endowed with a naturally curious mind with an excellent memory for assimilation and integration, he was also unique and fortunate to embark on a worldwide voyage that would enable him to put his outstanding faculties to optimum use.

Everywhere he went he recorded meticulous details of geology, biology, anthropology and culture. His observation of earthquakes and rock formations in South America and his finding of fossils of giant mammals lend credence to his beliefs about organisms being born and getting extinguished by sometimes violent physical and planetary change. His observation of the Pacific and Atlantic islanders (especially the ones on Tierra del Fuego) and their peculiar customs underscored the diversity of human life along with other life in his mind. But perhaps his best known and most important stop came after several months of traveling, when the ship left Ecuador to dock at the Galapagos Islands.

Again, much has been written about the Galapagos Islands and about Darwin's Finches. The truth is more subtle, sometimes simpler and sometimes more interesting than what it is made out to be. Darwin had mistaken his famous finches for other species of birds. It was only after coming back that his friend, the ornithologist John Gould, helped him to identify their correct lineage. But finches or not, the birds and the islands provided Darwin with a unique opportunity to study what we now know as natural selection. The islands were separated from each other by relatively small distances and yet differed significantly in their geography and flora and fauna. On each island Darwin observed similar plants and animals that were yet distinct from each other. As in other places, he also observed that species seemed to be adapted to their environment. Geographic isolation and speciation were prominent on those hot, sweaty and incredibly diverse land masses.

After five years of exhaustive documentation and sailing Darwin finally returned home for good, much changed both in physical appearance and belief. His following life has been the subject of much psychological speculation since he settled down with his cousin Emma and never ever left the British Isles again. He also seemed to have been stricken with what today is noted by many authors as a kind of psychosomatic illness because of which he was constantly ill with abdominal and other kinds of pains. After living in London for some time, Darwin retired to Down's House in Kent where he peacefully lived the rest of his life with a kind and loving wife, playing with his children, taking walks along the path at the back of his house named the "Sandwalk", corresponding with intellectuals around the world and constantly interrupting his research with salutary visits to spas and resorts for "natural" treatments that were sometimes of dubious value.

But peaceful as his life was, psychologically Charles Darwin was fomenting a maelstrom of revolution that was to have earth-shaking implications. Another fact that is frequently emphasized is his hesitation to not publish his ideas for another twenty five years in the form of the famous "The Origin of Species". Darwin was planning to write it for a while, but was finally jolted into writing it when he received a letter from an obscure young naturalist named Alfred Russell Wallace who was living a hard life of science and natural history exploration in Indonesia. Wallace had read some of Mr. Darwin's papers and manuscripts and had been struck by the similarity of his ideas to his own. Would Mr. Darwin comment on them? Darwin finally realized that he had to act to prevent getting scooped but characteristically credited Wallace in his published work.

In my mind however, Darwin's procrastination and its story sounds much simpler than the mystique and psychological speculation that sometimes envelop it. As we noted earlier, Darwin was a highly trained biologist and scientist of the first caliber. He knew that he would have to exhaustively document and classify the windfall of creatures, plant and rock specimens that he had collected on his voyage. Apart from thinking and writing about his Beagle collections, Darwin also maintained an astonishingly comprehensive and detailed research program on marine invertebrates and barnacles. More tellingly, he did experiments to find out if seeds are viable even when dispersed over long distances over salt-water. He visited gardens and zoos, and quizzed pigeon breeders about their profession. Much of this was in preparation for the grand act that was to follow. In case of the barnacles and marine creatures, Darwin's research was second to none. He published several extremely detailed books on the minutiae of these organisms; some of these had titles which would have put anyone to sleep.

And yet the level of detail in them reflects the extraordinary patience, power of observation and meticulous hard work that characterized the man, characteristics crucial for developing the theory of natural selection. Darwin was also very fortunate to have had several friends and colleagues who were experts in areas that he was not, who helped him classify and name all the material. Foremost among his correspondents were Charles Lyell and Joseph Hooker to whom he confided not just his scientific questions but also his emerging convictions about the interconnections and implications that were emerging from his research and writing. Also as noted above, John Gould accomplished the crucial task of reminding Darwin that his Galapagos birds were finches. With help from these collaborators and his own studies and thoughts on his observations, thoughts that filled literally dozens of rough drafts, scribblings and private diaries, Darwin finally began to glimpse the formation of a revolutionary chain of thought in his mind.

But Darwin did not rush forth to announce his ideas to the world, again for reasons that are obvious; Victorian England was a hotbed of controversy between science and religion, with many distinguished and famous scientists there and in other countries not just fervently believing in God, but writing elegant tomes that sought a supernatural explanation for the astounding diversity of life around us. Cambridge was filled with intellectuals who sought a rational framework for God's intervention. Darwin would have been quite aware of these controversies. Even though Darwin's grandfather (a more pugnacious character) himself had once propounded an evolutionary view, Darwin was finely attuned to the sensitive religious and social debate around him. Not only did he not want to upset this delicate intellectual and spiritual balance and get labeled as a crackpot, but he himself had not started his voyage as a complete non-believer. 

One can imagine the torment that he must have faced in those early days, when the evidence pointed to facts that flew in the face of deeply-held or familiar religious beliefs. One of the factors that dispossessed Darwin of his religious beliefs was the stark contradiction between the observation of a cruel and ruthless race for survival that he had often witnessed first hand, and the image of an all-knowing and benign God who kindly reigned over his creations. As the evidence grew to suggest a relationships between species and their evolution by the forces of natural selection that preserved beneficial characteristics, Darwin could no longer sustain two diametrically opposite viewpoints in his mind.

Opponents of evolution who want to battle the paradigm not from a scientific viewpoint (because they can't) but from a political one frequently raise a smokescreen and proclaim that evolution itself is too complex to be understood. The tricksters who propagate intelligent design further attest to the biochemical complexity of life and then simply give up and say that only an omniscient God (admittedly more complex than the systems whose complexity they are questioning) could have created such intricate beauty. The concept of a struggle for survival has also been hijacked by these armies of God who proclaim that it is this philosophy that would make evolution responsible for genocide, fascism and the worst excesses of humanity.

This is a deeply hurtful insult to natural selection and evolution as only the most dogmatic believers can deliver. One thing that constantly amazes you about evolution is its sheer simplicity. Stripped down to its essentials, the "theory" of evolution can be understood by any school child.

1. Organisms and species are ruthlessly engaged in a constant struggle for survival in which they compete for finite resources in a changing     environment.
2. In this struggle, those individuals who are more adapted to the environment, no matter how slightly, win over other less adapted individuals and produce more offspring.
3. Since the slight adaptations are passed down to the offspring, the offspring are guaranteed to preserve these features and therefore are in a position to survive and multiply more fruitfully.
4. Such constant advantageous adaptive changes gradually build up and, aided by geological and geographical factors, lead to the emergence of new species.

It's almost like a simple three-step recipe that when followed keeps on churning out culinary wonders of staggering complexity and elegance. In my mind the beauty of evolution and natural selection is two-fold; firstly, as Darwin emphasized, the slightest adaptation leads to a reproductive advantage. Such slight adaptations are often subtle and therefore sometimes can sow confusion regarding their existence; notice the debate between driver and passenger mutations in fields ranging from evolutionary biology to oncology.

But the confusion should be ameliorated by the second even more striking fact; that once a slight adaptation exists, it is guaranteed to be passed on to the offspring. As Gregor Mendel hammered the mechanism for natural selection in place a few years after Darwin with his discovery of genetic inheritance, it became clear that not every one of the offspring may acquire the adaptation. The exact pattern may be complex. But even if some of the offspring acquire it, the adaptation is then guaranteed to confer reproductive fitness and will be passed on. This fact should demolish a belief that even serious students of evolution, and certainly laymen, have in the beginning; that there is something very uncertain about evolution, that it depends too much on "chance".

The key to circumventing these misgivings is to realize the above fact, that while adaptations (later attributed to mutations) may arise by chance, once they arise, their proliferation into future generations is virtually certain. Natural selection will ensure it. That in my mind is perhaps Darwin's greatest achievement; he finally found a mechanism for evolution that guarantees its existence and progress. As for the struggle for survival, it certainly does not mean that it results in non-cooperation and purging of other individuals. As examples in the living world now document more than convincingly, the best reproductive fitness can indeed come about through altruistic leanings and cooperative behavior.

Every one of these factors and facts was detailed and explained by Darwin in "The Origin of Species", one of the very few original works of science which remain accessible to the layman and which contained truths that have not needed to be modified in their basic essence even after a hundred and fifty years. It was readable even when I picked it up as a callow young college student. No one who approaches it with an open mind can fail to be taken with its simplicity, elegance and beauty. One of the most extraordinary things about Darwin and something that continues to stupefy is how right the man was even when he lacked almost all the modern tools that have since reinforced basic evolutionary ideas. As one of Darwin's intellectual descendants, the biologist E O Wilson says, it is frustrating for a modern biologist to discover an evolutionary idea through his work, and then go back a hundred and fifty years and discover that the great man had hinted at it in his book.

And yet as Darwin himself would have acknowledged, there is much in the book that needed to be modified, there was much that he could not explain. Darwin had no inkling of genes and molecular biology, nor could he come up with a convincing mechanism that explained the sheer age of the earth required for evolutionary processes to work their charm (the mechanism was found later with the discovery of radioactivity). The exact mechanism of passing on adapted characteristics was unknown. Major fossils of primates and humanoid ancestors had yet to be discovered. Quite importantly, random genetic drift which is completely different from natural selection was later discovered as another process operating in evolution. The development of viral and bacterial resistance in causing diseases like AIDS finally brought evolution to the discomfort of the masses. It was only through the work of several evolutionary biologists and geneticists that Darwin finally became seamlessly integrated with the understanding of life in the middle twentieth century. Genomics has now proven beyond a shade of doubt that we truly are one with the biosphere. But in the absence of all these developments, it is perhaps even more remarkable how many of Darwin's ideas still ring true.

There is another factor that shines through in "The Origin"; Darwin's remarkable modesty. One would have to search very hard in history to find a scientist who was both as great and as modest. Newton may yet be the greatest scientist in history, but he was nothing if not a petty, bitter and difficult man. Darwin in contrast was a symbol of kindly disposition. He doted on his children and told them stories. He loved and respected his wife even though their religious views gradually grew more distanced. His written correspondence with her was voluminous and fond. His correspondence with his collaborators, even those who disagreed, was cordial and decent. Never one for contentious public debates, he let his "bulldog" Thomas Henry Huxley fight his battles; one of them with Bishop Samuel Wilberforce ended in a famous showdown when the Bishop inquired whether it was through his father or mother that Huxley had descended from an ape, and Huxley countered that he would rather descend from an ape than from the Bishop. Darwin stayed away from these entertaining confrontations; as far as he was concerned, his magisterial work was done and he had no need for public glory. To the end of his life this kind and gentle man remained a wellspring of modest and unassuming wonder. His sympathetic, humane and sweet personality continues to delight, amaze and inspire reverence to this day.

In the later stages of his life Darwin became what he himself labeled as an agnostic but what we today would probably call an atheist. His research into the progression of life and the ruthless struggle that it engenders made it impossible for him to justify a belief in a paternal and loving deity. He was also disillusioned by popular conceptions of hell as a place where non-believers go; Darwin's father was a non-believer and yet a good doctor who treated and helped hundreds of human beings. Darwin simply could not accept that a man as kind as his father would go to hell simply for not believing in a version of morality, creation and life trotted out in a holy book. Probably the last straw that convinced Darwin of the absurdity of blind faith was the untimely death of his young daughter Annie who was his favorite among all the children. According to some accounts, after this happened, Darwin stopped even his cursory Sunday trips to church and was satisfied to take a walk around it while not at all minding his wife and children's desire to worship inside.

The second fact is also in tune with Darwin's kind disposition; he admittedly had no problem reconciling the personal beliefs of other people with his conviction about their falsity. Darwin's tolerance of people's personal faith and his unwillingness to let his own work interfere in his personal life and friendships is instructive; to the end he supported his local parish and was close friends with a cleric, the Reverend John Innes. Darwin's example should keep reminding us that it is actually possible to sustain close human bonds while having radically different beliefs, even when one of these is distinctly true while the other one is fantasy. Nurturing these close bonds with radical scientific ideas that would change the world for ever, Charles Darwin died on April 19, 1882, a content and intellectually satisfied man.

To follow, nourish and sustain his legacy is our responsibility. In the end, evolution and Darwin are not only about scientific discovery and practical tools arising from them, but about a quest to understand who we are. Religions try to do this too, but they seem to satisfied with explanations for which there is no palpable evidence and which seem to be often contradictory and divisive. It is far better to imbibe ourselves with explanations that come from ceaseless exploration and constant struggle; the very means that constitute these explorations are then much more alluring and quietly fulfilling than any number of divergent fantasies that can only promise false comfort. And these means promise us a far more humbling and yet grand picture of our place in this world.

Especially in today's age when the forces of unreason still threaten to undermine the importance of the beautiful simplicity in the fabric of life that Darwin and his descendants have unearthed, we owe it to Charles Darwin to continue to be amazed at the delightful wonder of the cosmos and life. We owe it to the countless shapes and forms of life around us with whom we form a profoundly deep and unspoken connection. And we owe it to each other and our children and grandchildren to keep rationality, constructive skepticism, freedom and questioning alive.

LITERATURE ON DARWIN:

I don't often write about Darwin and evolution here for a simple reason; there is literally an army of truly excellent authors and bloggers who pen eloquent thoughts about these subjects and the amount of stuff published about him will fill up entire rooms. You could probably put together a thousand-page encyclopedia simply listing works on Darwin. His original work as stated above is still very readable. Every aspect of his life and work - the scientific, the psychological, the social, the political and the personal - has been exhaustively analyzed. I have certainly not sampled more than a fraction of this wealth of knowledge, but based on my interest in Darwin and selected readings, I can recommend the following.

For what it's worth, if you want to have the best overview of Darwin's life after he came home from his voyage on the Beagle, I think nothing beats the elegance of language and wit of David Quammen's "The Reluctant Mr. Darwin". Quammen has exhaustively researched Darwin's post-Beagle life and work, and no one I have come across tells the story with such articulate enthusiasm, fondness and attention to detail in a modest sized book.

Janet Browne's magisterial biography of Darwin is definitely worth a look if you want to get all the details of his life. Browne pays more attention to the man than the science, but her work is considered the authoritative work, and there are nuggets of eloquence in it.

As a student in high school I was inspired by Alan Moorehead's "The Voyage of the Beagle" noted above which combines an account of Darwin's life and voyage with beautiful and full page illustrations.

Getting to evolution now, there's an even bigger plethora of writings. Several books have captured my attention in the last many years. I don't need to extol the great value of any (and indeed, all) of Richard Dawkins' books. If you ask me which ones I like best, I would suggest "The Selfish Gene", "The Extended Phenotype", "Climbing Mount Improbable" and "The Blind Watchmaker".

For a journey into our ancestral history, Dawkins' strikingly illustrated "The Ancestor's Tale" is excellent. Speaking of ancestral history, Neil Shubin's "Our Inner Fish" charts a fascinating course that details how our body parts come from older body parts that were present in ancient organisms. So does his recent book "The Universe Within". Shubin provides scores of interesting tidbits; for instance he tells us how hernias are an evolutionary remnant. Another great general introduction to evolution is Carl Zimmer's "Evolution"; Zimmer has also recently written excellent books on bacteria and viruses in which evolution plays a central theme.

No biologist- not even Dawkins- has had the kind of enthralling command over the English language as Stephen Jay Gould. We lost a global treasure when Gould died at age sixty. His books are relatively difficult to read and for good reason. But with a little effort they provide the most sparkling synthesis of biology, history, culture and linguistic exposition that you can ever come across. And all of them are meticulously researched.

Out of all these I personally would recommend "Wonderful Life" and "The Mismeasure of Man", and if you want to challenge yourself with a really difficult unedited original manuscript written just before he died, "The Hedgehog, the Fox and The Magister's Pox". In general, pick up any Gould book and you would have access to an extraordinary writer and mind. His collections of essays - "Full House" and "Eight Little Piggies" for instance - are also outstanding. One has to guard against the frequent intrusion of Gould’s political ideology into his writings, but as a man who could turn a phrase he had few peers.

I don't want to really write about books which criticize creationism since I don't beat that horse much, but if you want to read one book about the controversy that rips apart intelligent design proponents' arguments, read Ken Miller's "Finding Darwin's God" which makes mincemeat out of the usual "arguments from complexity" trotted out by creationists which are actually "arguments from personal incredulity". He also has a book covering the Dover Trial. I have only browsed it but it seems to be equally good read. What makes Miller a tough target for creationists (and puzzling for evolutionists) is that he is a devout Christian.

This is an updated and revised version of a post originally written on Darwin's 200th birthday.