Thursday, September 15, 2011

What you might have wrong about evolution

In my previous blog I mentioned that evolution is misunderstood by most people – even those who do believe in it.  There is an excellent FAQ on this topic at Berkeley, but I’ll take a moment and try to clarify some things. Most of this is well agreed; some is my current opinion within an existing controversy.  I hope it is interesting to a casual reader.
First, the main reason most Americans don't believe in evolution has nothing to do with reasoning; evolution just comes up against preexisting beliefs, depending on their culture, and probably from childhood.  To the argument that complex life could not have "just occurred" without a conscious designer, I must simply wonder how would that designer (who would be much more complex than his creations) have come into being.  Wouldn't that be less likely still?  And to the argument that gaps in scientific record discredit evolution, yes there are gaps in our knowledge.  Of course.  The gaps just get smaller. 

Natural selection prefers survivors, who pass on their traits to offspring. Thomas Malthus wrote about 1800 that population naturally grows exponentially while food supplies increase much more slowly, and so there is a lot of premature dying that happens.  Malthus had a big influence on Darwin, and on Wallace, it turns out.  Creatures which don't perish often survive for a practical reason, which is often inherited, and so that trait becomes more common. That much is now common knowledge. 

But, there are the misconceptions too, like thinking evolution always drives toward complexity.  Bacteria have evolved by going in the opposite direction; they have stripped down rather than tooled up.  They adapt to single specific niche rather than become adaptable to various environments.   Although we are doing well now, in the long run the bacteria will probably out survive us.

Then there's the idea that what evolves is always better, that evolution is a drive toward perfection.  A lot of things evolution comes up with are not optimal, because they must always result from cumulative changes.  Sometimes traits are lost due to disuse and random deterioration (we've nearly lost our sense of smell, for example).  Some traits are poorly done to begin with.  Our eyes are poorly designed, for example -- we have a blind spot which other animals don't have.  And some were once useful, and now work against us.  We crave sugar, salt, and fat because they were so hard to find that we didn't need a good regulator.  Now we have an overcharged appetite and we're surrounded by sugar, fat, and salt.  We overeat these things simply because we still want to, and now we can.
There's a simplistic model in which genes are little switches for discrete things, like height or alcoholism.  Some do work this way, but not many.  We do have just 25,000 genes or so, but they work in combination.  And they interact with the environment.  Many genes influence a single trait, and each gene influences many traits.  Imagine an immense Rube Goldberg  machine; that's more or less how it works.

A very common misunderstanding is that evolution works at the level of the species -- that animals do what is best for the group.  Not so.  An individual who "cheats" the group for his/her own selfish benefit will likely out survived the others, and to the extent that genes contributed to the cheating behavior those genes will be passed on.  What is more controversial is whether or not the organism is the unit of selection.  I'll use an example: a fierce lion or a camouflaged moth out compete other less aggressive or more obvious peers.  The lions get tougher and moths get darker.  It seems as simple as that, but I think Richard Dawkins (in The Selfish Gene) probably has it right:  The competition actually takes place at the level of the gene, the code which simply makes proteins which eventually have an outward effect (sharper claw, darker wing).  In this way of thinking the organism is just the result of a group of genes working together; the individual parts -- the genes -- are being naturally selected.  

The book I mentioned and Dawkins' subsequent Extended Phenotype  explain this in detail.  Others writers, like Stephen J. Gould, say it happens at the organism or at the group level.  I'll explain by example why I have thing Gould is wrong.   Human males may produce 350 million sperm a day while females incubate one fertilized egg for a long long time. So if one male can impregnate thousands of women, wouldn't the group do better if there were 95 women for every man?  Any population with a gender ratio like that would grow a lot faster and out compete other groups.  But gender ratios in almost all animal species are about 50-50.  This is because within a female-heavy population any male would successfully spread his genes widely.  So a mutation which produced a Y chromosome would end up being copied many times. Although this is by mutation and not design, I like the way Dawkins puts it: They cheat.  
Maybe because of this selfishness aspect, there is a common misperception that evolution lends itself to amoral behavior.  Doesn't evolution suggest we shouldn't care about others?  No, it doesn't.  Just as there was an advantage for cells teaming up into multicelluar organisms, people do better for themselves by joining groups.  Working well with others -- and hence, caring about them -- is naturally selected. 

Dawkins wrote something else in The Selfish Gene which has really resonated with me.  Natural selection comes into play when three things are in place: 1. something replicates (copies itself), 2. it sometimes makes mistakes or changes when doing so and 3. it matters in the real world.  Genes do this, with DNA replicating, sometimes mutating, and causing “phonenotypes” such as blue eyes, sharp claws, opposable thumbs, and so on. 
When sophisticated brains are around, information meets these criteria too.  If I think up a good idea and tell you, you may find it interesting enough to tell others.  Someone along the line will change or improve the idea and some of these changes will make the idea more likely to be shared, and some less so.  The idea, in other words evolves.  

A joke spreads, sometimes getting funnier by embellishment or adaptation, but sometimes it's told poorly and falls flat.  Humor has its component parts -- I've read that jokes often involve something tragic, separated by time or distance.  Some use words with two meanings where one interpretation is the opposite of the other.   Dawkins suggested calling these idea-particles "memes," a sort of counterpart to genes  If a meme is something like a gene, then a group of memes may make something like an organism.  It could be a political system, the scientific method, a concept of fairness, an ideology, a religion, a culture.  Take the scientific method -- at its core you'll find evidence-based reasoning, conjecture, hypothesis, statistical testing, random samples, theory building, accumulation of knowledge, peer review, etc.  These ideas have worked very well together.  Ever since language has allowed us to share thoughts, the thoughts in essence, have moved among us, not unlike viruses; they are not living in themselves, but come "alive" in our minds.  You could say they use us.  Just like genes do.
Some people, like Stephen J. Gould, consider science and religion to be in "non-overlapping magisterial,"  completely compatible with one another -- even complementary. I think that's wrong, unless we're talking about a religion with a completely non-interventionist deity.  An intervening God introduces the supernatural, which is simply not allowed in science.  Moreover, evolution has quite a lot to say about consciousness, perception, morality, free will, spirit, human behavior, and the origin of life.  It's not just that science does well without religion.  Science and supernaturalism contradict one another.   It's a matter, I believe, of choosing to believe something because you choose to, or because it is probably true.  

Evolution is a theory, but being a theory does not in itself cast any doubt upon itself; it simply means that the idea is held to a high standard -- it is subjected to evidence-based testing.  Religions are not theories in this way; they are assertions, although some assertions can be -- and I would suggest should be -- tested anyway.  The power of prayer, for example, telepathy, divine predictions.  Anyone who supports the rigorous testing of religious claims has elevated their religion from an assertion to a theory, and that is commendable.  And for theories, to survive, they must be supported by evidence.  When there is vast evidence (as for evolution or for gravity), the theory becomes -- though never immutable truth -- highly, highly, reliable.   

Yet I do believe there is some faith in the scientific method: faith in reason.  Before they have any evidence to support the idea, scientists must have faith in evidence-based reasoning itself -- that is, they must have faith that one can learn by careful observation.  In comparison to religious faith, though, as Dan Dennett has pointed out, this is puddle jumping.  It's not like walking on water.
So far I've been referring to the natural sciences but when it comes to evolution there is quite a lot of disagreement among social scientists - whether or not evolution affects the way we think and act (via our neurology of course).  Some people disparage evolutionary psychology as a collection of "just so" stories.  I don't think it's wise to dismiss it out of hand. 

Why do we fall in love?  Robert Wright, in his excellent book The Moral Animal puts it this way, and I'll risk oversimplifying it. In terms of finding mates (and in human interaction generally) we have developed excellent bullshit detectors, because being tricked is often costly or dangerous.  This is why it's difficult to conceal a lie.  A woman, for example, may be woo'd by a male who pretends to be more devoted than he actually is. She may pay for her mistake with a pregnancy and single motherhood.   His genes are passed on -- an evolutionary win!

When a woman is impregnated and then abandoned is usually not a good thing for the child's survival, so by now her B.S. detectors are so keen that she is unlikely to fall for a faker.  In order to convince her that he is devoted, it is quite useful if he actually feels it, first.  So he falls in deeply in love, it's an infatuation that at the time feels boundless, which is a self-deception of course but it allows him to honestly look deeply into her eyes and tell her with all his heart, in a thousand ways, that she is perfect, perfect, perfect.  She will see that he does really feel that way and perhaps she may be convinced, and a child may be born and if it is, the child will likely have the innate inclination, when it reaches a certain age, to fall in love too.  Just so.

The lesson here is simply that our genes may incline toward behaviors that help our genes, and that emotions can be an effective way to do this.  In other situations they may give us the confidence to face down an intimidating opponent.  They may cause flight at the right moment, empathy, and so on.  The whole range of emotions may exist to push us this way and that.

This is evolutionary psychology, and at its root I think you will find the biggest question of all: do we have free will?  If we are programmed by genes, if we are vessels for memes, and if we are manipulated and deceived by our emotions, what is left of self-determination?  Sam Harris has the best answer I've seen.  Maybe nothing.  It's possiblel that we only think we have free will because we can rarely predict what we're going to decide next.
So to summarize, common misperceptions about evolution include the simple ones based on an aversion to contradictory life perspectives.  Evolution is not a drive toward complexity or toward perfection.  It doesn't happen to groups and probably not even to organisms -- it's simply genes and traits at play.  Evolution is just a theory -- which makes it much better than an assertion but more reliable too.  It does not naturally lead to immorality.  It probably applies to ideas and behaviors just as it does to genes and physical characteristics.  And -- I think --- it is sufficient to explain life as we know it.  Not only is no supernatural intervention necessary, unfortunately, it's not allowed.

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