Sunday, September 20, 2009

Why are My Eyes on the Front of My Head?

One of the problems with understanding evolution, and genetics in general, is that it is offer explained in the language of teleology. This appears to be an unconscious habit, but it confuses the learner and does not reflect the current state of knowledge.

A few days ago I spoke about a man who talks nonsense about human evolution, and who should have known better, since he is a man formed in the sciences, not some cultural studies/lit crit type.

Máximo Sandín has clearly decided to join the ranks of unreason because he thinks it will help him defend his beliefs with regard to great apes and animal conservation in general. Perhaps he also wants to get back at the international academy for not recognising him as a genius. And, as I said in the original post, he's just not as bright as he thinks he is.

He has no excuse. Plenty of people do have an excuse, however, because of the habit of saying that Homo erectus had a pronounced zygomatic arc because it had to chew hard foods, that a thick skull is to protect from blows, that a rabbit has big ears so that it can hear predators and zebras developed stripes to confuse lions. None of this is true, because no organ or characteristic or phenotype has a purpose beyond the use that an animal puts it to. They arrive by chance, by recombination or mutation, and they can be passed on down the generations. If they offer a significant survival advantage it is possible that, over a very long period of time, those with the new characteristic will outnumber those without, because they use it to live longer and reproduce more.

These changes come about by chance. They were not planned, conceived, created in response to some purpose. These characteristics do not develop because they are needed, but because those who have them happened to survive, while the rest got eaten. A group of Miocene equids did not sit around a table and say, 'Hey, let's paint ourselves black and white. That'll get the lions going.' It just happened, and they find it useful.

I'm not saying anything new or revolutionary here, just pointing out one source of misunderstanding. After all, if there is a purpose, there must be someone or something that can both conceive the purpose and bring about the means of achieving it.


JonnyN said...

Huh, "if there is a purpose, there must be someone or something that can both conceive the purpose and bring about the means of achieving it".......

True, there is a valid distinction between "a rabbit has big ears so that it can hear predators" and "a rabbit has big ears because big ears help it to hear predators", but I don't think people confuse the second with the first too often do they? Maybe they do.... Who is usually seen as intending the change - God?

Vincent said...

According to Aristotle, there are four causes: material, formal, efficient and final. He says all other causes serve the final cause (telos).

Through science we have learned the efficient cause of the zebra stripes. It is natural selection. The final cause (purpose) is easy to see: camouflage.

Final cause is not a matter for science. Human beings using their common sense rather than specific training in how to see scientifically, see final causes. This too has an efficient cause (survival value).

If scientists maintain that nothing is outside their scope, that's their hubris. And they can't have it both ways. Since scientists are also human beings with common sense, they have to maintain boundaries, so as to think and speak scientifically within the discipline, and like the rest of us in normal life. Perhaps this is where Maximo Sandin has strayed?

CIngram said...

@JonnyN & Vincent

The distinction is between 'a rabbit has big ears because they help it hear predators' and 'rabbits can hear well because they have big ears.' It matters because it confuses people's attempts to understand the subject.

Most people don't distinguish between types of cause, and assume that a purpose presupposes a purposer. And our current knowledge of evolution suggests that one is not required to explain what we see.

Or perhaps there is a purposer, one who set in motion and guided the series of changes that let to, inter alia, the zebra's stripes.

Science has nothing much to say about God, because He cannot be reached by observation of the physical world. Which doesn't stop some of them trying- Richard Dawkins sounds not so much like an atheist as someone with a visceral hatred of God. Whereas Máximo Sandín probably does try to use poor science to support his moral beliefs about the natural world.

Vincent said...

Moment in Time

"What is Fate?" Nasrudin was asked by a Scholar.

"An endless succession of intertwined events, each influencing the other."

"That is hardly a satisfactory answer. I believe in cause and effect."

"Very well," said the Mulla, "look at that." He pointed to a procession passing in the street."

"That man is being taken to be hanged. Is that because someone gave him a silver piece and enabled him to buy the knife with which he committed the murder; or because someone saw him do it; or because nobody stopped him?"

(from a Sufi story, told by Idries Shah)

CIngram said...

There is still a chain of causes and efects, though not all of them may be readily predictable beforehand nor discernible a posteriori; and, although one may suggest many causes that conribute to the hanging, 'most people' would instinctively and strongly identify the primary cause as the will of the hanged man to commit the murder, rather any one of the other circumstances which, had they been different, might have resulted in his not killing his victim.