Rationality Reading Group: Part L: The Simple Math of Evolution

by Gram_Stone3 min read21st Oct 20154 comments

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This is part of a semi-monthly reading group on Eliezer Yudkowsky's ebook, Rationality: From AI to Zombies. For more information about the group, see the announcement post.


Welcome to the Rationality reading group. This fortnight we discuss Minds: An Introduction (pp. 539-545), Interlude: The Power of Intelligence (pp. 547-550), and Part L: The Simple Math of Evolution (pp. 553-613). This post summarizes each article of the sequence, linking to the original LessWrong post where available.

Minds: An Introduction

Interlude: The Power of Intelligence

L. The Simple Math of Evolution

131. An Alien God - Evolution is awesomely powerful, unbelievably stupid, incredibly slow, monomaniacally singleminded, irrevocably splintered in focus, blindly shortsighted, and itself a completely accidental process. If evolution were a god, it would not be Jehovah, but H. P. Lovecraft's Azathoth, the blind idiot god burbling chaotically at the center of everything.

132. The Wonder of Evolution - The wonder of the first replicator was not how amazingly well it replicated, but that a first replicator could arise, at all, by pure accident, in the primordial seas of Earth. That first replicator would undoubtedly be devoured in an instant by a sophisticated modern bacterium. Likewise, the wonder of evolution itself is not how well it works, but that a brainless, accidentally occurring optimization process can work at all. If you praise evolution for being such a wonderfully intelligent Creator, you're entirely missing the wonderful thing about it.

133. Evolutions Are Stupid (But Work Anyway) - Modern evolutionary theory gives us a definite picture of evolution's capabilities. If you praise evolution one millimeter higher than this, you are not scoring points against creationists, you are just being factually inaccurate. In particular we can calculate the probability and time for advantageous genes to rise to fixation. For example, a mutation conferring a 3% advantage would have only a 6% probability of surviving, and if it did so, would take 875 generations to rise to fixation in a population of 500,000 (on average).

134. No Evolutions for Corporations or Nanodevices - Price's Equation describes quantitatively how the change in a average trait, in each generation, is equal to the covariance between that trait and fitness. Such covariance requires substantial variation in traits, substantial variation in fitness, and substantial correlation between the two - and then, to get large cumulative selection pressures, the correlation must have persisted over many generations with high-fidelity inheritance, continuing sources of new variation, and frequent birth of a significant fraction of the population. People think of "evolution" as something that automatically gets invoked where "reproduction" exists, but these other conditions may not be fulfilled - which is why corporations haven't evolved, and nanodevices probably won't.

135. Evolving to Extinction - It is a common misconception that evolution works for the good of a species, but actually evolution only cares about the inclusive fitness of genes relative to each other, and so it is quite possible for a species to evolve to extinction.

136. The Tragedy of Group Selectionism - Describes a key case where some pre-1960s evolutionary biologists went wrong by anthropomorphizing evolution - in particular, Wynne-Edwards, Allee, and Brereton among others believed that predators would voluntarily restrain their breeding to avoid overpopulating their habitat. Since evolution does not usually do this sort of thing, their rationale was group selection - populations that did this would survive better. But group selection is extremely difficult to make work mathematically, and an experiment under sufficiently extreme conditions to permit group selection, had rather different results.

137. Fake Optimization Criteria - Why study evolution? For one thing - it lets us see an alien optimization process up close - lets us see the real consequence of optimizing strictly for an alien optimization criterion like inclusive genetic fitness. Humans, who try to persuade other humans to do things their way, think that this policy criterion ought to require predators to restrain their breeding to live in harmony with prey; the true result is something that humans find less aesthetic.

138. Adaptation-Executors, Not Fitness-Maximizers - A central principle of evolutionary biology in general, and evolutionary psychology in particular. If we regarded human taste buds as trying to maximize fitness, we might expect that, say, humans fed a diet too high in calories and too low in micronutrients, would begin to find lettuce delicious, and cheeseburgers distasteful. But it is better to regard taste buds as an executing adaptation - they are adapted to an ancestral environment in which calories, not micronutrients, were the limiting factor.

139. Evolutionary Psychology - The human brain, and every ability for thought and emotion in it, are all adaptations selected for by evolution. Humans have the ability to feel angry for the same reason that birds have wings: ancient humans and birds with those adaptations had more kids. But, it is easy to forget that there is a distinction between the reason humans have the ability to feel anger, and the reason why a particular person was angry at a particular thing. Human brains are adaptation executors, not fitness maximizers.

140. An Especially Elegant Evolutionary Psychology Experiment - An experiment comparing expected parental grief at the death of a child at different ages, to the reproductive success rate of children at that age in a hunter gatherer tribe.

141. Superstimuli and the Collapse of Western Civilization - At least 3 people have died by playing online games non-stop. How is it that a game is so enticing that after 57 straight hours playing, a person would rather spend the next hour playing the game over sleeping or eating? A candy bar is a superstimulus, it corresponds overwhelmingly well to the EEA healthy food characteristics of sugar and fat. If people enjoy these things, the market will respond to provide as much of it as possible, even if other considerations make it undesirable.

142. Thou Art Godshatter - Describes the evolutionary psychology behind the complexity of human values - how they got to be complex, and why, given that origin, there is no reason in hindsight to expect them to be simple. We certainly are not built to maximize genetic fitness.

 


This has been a collection of notes on the assigned sequence for this fortnight. The most important part of the reading group though is discussion, which is in the comments section. Please remember that this group contains a variety of levels of expertise: if a line of discussion seems too basic or too incomprehensible, look around for one that suits you better!

The next reading will cover Part M: Fragile Purposes (pp. 617-674). The discussion will go live on Wednesday, 4 November 2015, right here on the discussion forum of LessWrong.

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