Wednesday, December 21, 2011

it's lonely out there – the evolutionary explanation for the fermi paradox

Baen | What kick-started intelligence in humans? Given that our powerful brains have so many disadvantages and not much payback in terms of survival, at least in the early stages before technology, why was increasing brain power been selected for, generation by generation, until the evolution of the human mind?

The primary selection pressure is survival but the second is reproductive success: Darwin pointed this out in the Origin of Species. Complex animals reproduce sexually so success involves mating. Vertebrates have complex signalling systems and behavior to persuade another individual to choose them as a suitable partner. This can result in the evolution of anatomical features that are neutral or even disadvantageous to survival. For example, the growth of antlers in deer have a high metabolic cost, offer little survival advantage, but are essential for a male deer to intimidate competitors to win the hooves of fair deer maidens.

The more complicated an organism's reproductive system the more likely the sexes of a species are to have different reproductive strategies, and the mammalian system is very complicated. The best explanation of human intelligence is that it is the result of sexual selection by women. Men tend to be attracted to women who are fit, healthy, young and not yet pregnant (slim waist).

These characteristics are not unimportant to women (well, except the last) but women get stuck with the baby so, given that people are social animals, women are attracted to high status men who will be able to provide support for them and their children. In a social animal, high status revolves around sophisticated interaction, for which intelligence is an advantage because of the need to manipulate, and enjoy good relations with, other members of society.

Even our verbal facility is probably the result of female sexual selection. In British English, boys attempt to "chat up" girls at parties. If women kept selecting for intelligence in men then this would overcome any counter-survival effect of "wasting" resources on high energy brains.

But note that the exact choice of a sexual selection feature is a haphazard process. Women might have selected on developing an oversized red nose, the ability to hop around in a circle with effortless grace, or antlers. Female birds often select on feather coloration patterns and there is evidence that therapod dinosaurs had similar behavior. Bipedal therapods were mostly predators, like wolves or tigers, whereas we are social omnivores and that is probably the key difference.

The take home message is that intelligence is a rather unlikely end result that depends on a conjunction of haphazard ecological and evolutionary features.

Maybe an intelligent species of social therapod dinosaur might still have evolved if the Cretaceous Great extinction had not happened — but major catastrophes from local events up to mass extinctions are a regular feature of life on Earth.

Species survival over time, particularly for a large organism, is to a large extent a matter of sheer luck. We almost didn't make it. About seventy-five-thousand years ago there was a catastrophe, the Toba super-volcanic eruption. The Toba Event seems to have taken human beings to the very brink of extinction. Genetic evidence suggests that we were reduced to between one and ten thousand breeding pairs. All modern humans are genetically closely related, which is why inbreeding is so very dangerous for us.

Toba was a volcanic pinprick compared to the Deccan Traps associated with the Cretaceous great extinction, or the Siberian Traps with the larger Permian extinctions, but it was enough to nearly do for a large animal geographically restricted to Africa. Toba may even have given the kick needed to evolve the human mind and civilization, but our survival was touch and go.

And here, I think, is the explanation for the Fermi Paradox. There does not need to be anything special about Earth or H. sapiens. Applying the Principle of Mediocrity, the universe probably teems with life, quite complex life. But intelligent life is simply unlikely because the evolutionary dice are rigged against it. It is very unlikely that a large complex animal, with the right sexual selection system, will survive long enough for circumstances to kick start the path to a technological civilization.

You don't need a special, unique planet to evolve an intelligent organism. You just need a lot of life on a lot of planets and one or two will win the lottery no matter how unlikely the probability. It's just a matter of random luck. There is nothing special about someone who wins the national lottery.

I suspect it is the "probability of evolving intelligent life" that is the key variable that governs the Drake Equation: the probability must be close to zero. Should we survive long enough to break free of our solar system cradle, the last variable, I suspect we will find life in abundance but will probably never ever meet intellectual peers.

It's going to be lonely out there.

7 comments:

nanakwame said...

No human life on those two similar "Earth" planets we have just found? Then we are going to take it there?  What is life again? 

John Kurman said...

Actually, the genetic evidence points to several bottlenecks, not just Toba. And not just in our genes, but in the genes of our parasites. Pubic lice, for example, are very recent (long after we lost most of our body hair) who's closest living relative infests gorillas. What our recent ancestors were doing with gorillas I canna say. But chances are, not only is intelligence not selected for, but it is self-limiting. My guess is the Great Filter is still in our future, and it will be strictly out of left field (i.e. not due to the usual suspects such as revocation of geological consent, nuclear holocaust, designer diseases, comet strike, ecological collapse, etc., and we will all say "Wow. Didn't see that coming!" thus proving intelligence ain't all whut it cracked up to be).

CNu said...

and so the quest for artificial language/mind is brought into clearest relief as the only means by which the hazards of biology (inclusive of disgusting pubic hitchhikers) may be overcome and our quest to repair the face of God achieved http://subrealism.blogspot.com/2010/05/farmers-in-fields-of-stars.html everything else is merely conversation...,

nanakwame said...

I tend to agree with that observation, why I say there must be a split coming which is the heart of the Mayan prediction imho, as we build intelligent "branes" or Augmented IT - what some called mindfulness created by human evolution. It may be persons of weaker muscles but their sanguineness will be sharper than ever in history. Or is that Syfy?

John Kurman said...

Maybe. Could be. Could be. Maybe. Then again, there's no reason to think silicon-or-other-media-based intelligence will be any longer lasting than protoplasm. Protoplasm has at least a billion year warranty. Got any chips that last that long? Spooky-action memory diamond? Black hole event horizon? Have you noticed how our storage media have become more and more ephemeral?  There's a left field thing to work on.

CNu said...

lol, time to introduce you to eshel ben jacob http://star.tau.ac.il/~eshel/ Blessed is he who will take his place in the beginning; he will know the end...,

nanakwame said...

Gems among the junk -one of my favorite epigram - nice

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