Friday, February 13, 2009

Evolution - I "The Problem Is.....?"

It’s the good old question, isn’t it? Evolution or Creation… In its January issue, the Scientific American published its own (200 page) take on the question. It’s evolution, SciAm concluded, in no uncertain and rather lengthy terms. Before embarking on an (endless) voyage into the actual topic, let me address another question that bothers me. Why is this debated at all?

If I were to pick a topical scientific theory to debunk, purely on the basis of its understandability, my choice would certainly not be evolution. Perhaps it would be quantum physics. Evolution would have to undergo plenty of evolution before it can even compare on the counter-intuitiveness scale to quantum physics. Or it might be cosmology. It’s one thing telling people that stars are born, belch fire for millions (or billions) of years and die, but quite another showing them the process in action. It’s highly unlikely that you, me or our great-great grandchildren will see anything different from the bright yellow star we see every day. Do the good intentioned scientific-theory-bashers stand up, raise their hands and say – ‘But I can’t see it happen! It can’t be true…’ No, there isn’t even a whimper. And like quantum physics and cosmology, evolution is strongly supported by empirical evidence. Why, then, is evolution scornfully rejected?

Despite my many protestations to the contrary, I already know the answer to that (rhetorical) question. Evolution concerns you, me, God and the human race. Science can chug away, filling in holes in our understanding of the universe. It’s a good deal; everyone gets TVs (and televangelists), refrigerators and Playstations. But when impudent little Science steps on the toes of religion (and anthropoid ego- see footnote), things change. Evolution reduces human beings from the Chosen ones to just another species. As if that wasn’t bad enough, Evolution proclaims that we are all descended from hairy, filthy apes. (Anyone smell racism here?) Evolution has the cheek to imply that the world may be millions of times older than what some religions claim. Evolution even suggests that the biological diversity around us may have arisen without a supernatural controlling power.

One of the most common arguments made against the validity of evolution concerns its ‘intuitiveness’. ‘Can you possibly imagine fish on land flopping their way to getting a pair of legs?’ they ask with tones of pure indignation. Human intuition is precisely that. It’s Human. It’s a mixture of knowledge about the environment shared by all humans and an individual’s personal experiences. It would be stupid to expect us to possess intuition that can grasp timescales of hundreds of millions of years when our life spans measure a measly hundred . Evolution is not all that counter intuitive when you look at it from the point of view of natural selection. A mutation that favours your chance of survival will have a greater probability of being selected. ‘Survival of the fittest’ (a phrase that has filtered down to colloquial usage) is often used to paraphrase the concept of natural selection.

Anthropoid Ego - my pet term for the notion of human supremacy; the tendency of human beings to think that they are the rightful inheritors of the planet. Anthropoid ego can be held accountable for a major part of the environmental degradation we see around us; it shows its hand in everything from global warming to animal extinctions.

Part two continues here, don't go anywhere!

Evolution - II "The Scientific Arguments"

Another argument raised against evolution concerns emergent complexity. ‘Is it conceivable that purely random changes lead to greater complexity all the time?’ One point to be noted here is that natural selection often reduces complexity; natural selection can eliminate a part for you if it doesn’t necessarily improve reproductive fitness. ‘Ha!’ Creationists exult, ‘Then a guiding hand that directs life towards complexity must exist!’

Actually, complex organisms are by no means the most numerous. Single celled organisms comprise ninety percent (or something like that) of the biosphere numerically. Insects are far more numerous than mammals, and so on. As organisms become more and more physically complex, their numbers seem to decrease. Perhaps, a conservation of the population-complexity product exists for all species (which still begs the question of how to quantify complexity).

Also, (unbeknownst to many people) natural selection is not the only causative agent driving evolution. There’s another phenomenon called genetic drift where purely random mutations accumulate in populations over time. Obviously if the populations under consideration are smaller, the effect of genetic drift is greater. In many cases genetic drift becomes just as important as natural selection in directing evolution. Other scientists have argued that complexity arises randomly when there is no selective pressure. A copying error may cause an organism to duplicate large parts of its genome, and natural selection might choose for new, beneficial functions to these genes. Also, despite their debatable meaningfulness, many complex evolution simulating algorithms have actually reported observations of increased complexity in the system.

‘Irreducible complexity’ is yet another concept propounded to debunk evolution. It’s a top down approach which starts off with a complex organism and proceeds to progressively chop off parts of the organism. The moment you obtain an organism that doesn’t ‘work’ anymore, you have reached irreducible complexity. Life around us, the argument goes, exhibits irreducible complexity; so evolution, which claims to build up a complex whole from simple constituents must be wrong. This argument is less inane than it sounds; it is, in fact, the core principle behind the theory called ‘Intelligent Design’. To counter this argument one has to see that DNA base pairs don’t always code something (the so called ‘junk DNA’); sometimes useless base pairs accumulate in a species, until through another mutation they join with existing genes to encode a new and complex feature of the organism. This combining of functions to produce a new one can happen with non-junk DNA as well; then the old genes are like scaffolding that is only retained till the construction is completed.

A fourth argument against evolution asks why we can still see apes around us, when we are supposed to have evolved from them. This question really doesn’t make sense to me. Evolution, by definition is a random process. It favours mutations that help an organism’s chance of survival. If some apes mutate slowly and produce a ‘stable’ species called human beings, then we merely have a new species. Evolution doesn’t go back and scrub off apes from the face of the planet simply because they are higher up in the evolutionary tree than homo sapiens. Had that been the case, we certainly wouldn’t have any bacteria around us.

Part three's here.

Evolution - III "The Not So Scientific Arguments"

However, people who try to debunk it aren’t evolution’s only opponents. A far more dangerous category of people don’t try to debunk evolution; instead they try to portray it as a theory under threat (I call them ‘doubt farmers’- they sow the seeds of doubt). They would have us believe that evolution is, in reality, one of many scientific theories that can explain the diversity of life, and that it does not represent the dominant view among biological scientists. ‘Evolution is only a theory, it’s not a fact’ they thunder.

Anyone who has done anything primary school science upwards can see through that claim. If you really want to split hairs, you’ll have to agree that nothing in science is a fact. More evidence supporting a theory will only increase its acceptability, but no amount of evidence is enough to truly make it a fact. On a more practical note, theories with far less supporting empirical evidence than evolution have been accepted as facts (anything in a primary school textbook would support that claim). The more articulate of these doubt farmers try to compress two centuries of research in evolution into an umbrella term called ‘Darwinism’. If they can portray ‘evolutionism’ as a cult, rather than a science, creationism can be presented as a valid alternative to it.

Scientists are guilty of this too, usually unintentionally. Darwin’s book on natural selection ‘On the Origin of Species’ is often recommended to readers, not because they want to spread Darwinism; but simply because the content is fleshed out in a non technical, intuitive way. Contrast this with something like Newton’s Principia, the pioneering work on mechanics. Why is it not recommended to physics students? The Principia is not only a highly arcane book, but it’s written in Latin.

Finally, when all else fails, anti-evolutionists turn to character assassination. ‘If you’d known Darwin, you would have despised him.’ I have no idea what Darwin the man was like, but several aspects of his personality have been documented, like his opposition to slavery and his insistence on acknowledging Alfred Wallace as the co-postulator of the theory of natural selection. Anyway, if people try to counter criticisms of Darwin’s character by showing counter-evidence of his good nature, they only risk playing into the hands of the creationists (SciAm is particularly guilty of this). The temptation to idealize Charles Darwin as an iconic scientist and an impeccable human being must be resisted. February 12, 2009 marked the bicentennial anniversary of Charles Darwin’s birth. It is a historic occasion, not to celebrate Charles Darwin the man, but to celebrate the remarkable theory that changed the face of biology.

The final section in my evolution discussion: part 4 is here.

Evolution - IV "What About Us?"

Many people who are otherwise comfortable with the theory of evolution balk at the thought of human descent from primates. It might seem na├»ve to assume that defining human characteristics like music, humour and culture have evolved in tandem with a rapidly growing brain. For me though, the intuitive ‘stretch’ needed to imagine this evolution wasn’t too much different from the sort that produced primates from bacteria. The point of contention for me, concerns abstract human perceptions like ethics and morality, which often vary across even small time periods. Are these ideas modified through some sort of cultural evolution? We can view the entire human race as one giant information processing machine, with ‘culture’ the data model in use at any instant in time. The theory of memes argues, in fact, that concepts of biological evolution can be extrapolated to a similar theory of cultural evolution. Or, on the other hand, are cultural concepts hard coded biologically? I came to the conclusion that cultural (and not biological) evolution is responsible for variations in cultural ideas. Immediately I came to another tangential conclusion that biological evolution of human beings had all but ceased. Our bodies (and brains) are, physically, no different than those of the Stone Age humans. Globalization was my favourite explanation for the end of human evolution; if the entire human race is always connected, how can some humans evolve away so much that they no longer retain reproductive compatibility with the rest of the human race? The human notion of the dignity of life seemed to me, to actively counteract evolution. Evolution selects against people with brain disorders; but human ethical tenets demand that we provide extra medical care to such people. I was surprised (and pleased) to find out that this idea was the dominant view among evolutionary biologists (including Stephen Jay Gould) until recently. However, recent studies on human skulls (by John Hawks and his team) show that human evolution rates have actually risen to up to a hundred times over the historical average. The reason for this is actually quite intuitive once you get past the mandatory mental gymnastics. Large populations favour quicker spread of evolutionary changes forced by natural selection, simply because larger populations can produce more offspring that inherit this evolutionary bias. Early human beings did not have the capacity to break down milk beyond a certain age, as the production of the enzyme lactase stopped during adolescence. However a mutation in the human genome switched off the gene that controlled lactase production, with the result that people with that mutation could drink milk throughout their lives. Today that mutation is no longer the anomaly but the standard. Accepting the fact that human evolution is alive and well brings up inevitable questions about the future of the human race. Will the future human world look like an X-men comic strip? I think that humans will evolve away from specialized physical machinery, rather than towards (so much for the X-men idea). It’s unlikely that human evolution will force us to grow a pair of wings; what is more likely is that our limbs will become vestigial, or completely disappear. The reasoning is obvious: a pair of wings do not improve our evolutionary fitness when we already have aeroplanes and helicopters. Similarly, hands and legs may be selected against if we build machines that perform the same function, better. On the other hand, if some catastrophic event happens to destroy a majority of the human race and break the world’s landmasses into separate islands, evolution will work differently. Maybe in that scenario, we might even evolve the long sought for pair of wings.