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Evolution doesn't work on species level, but on individual level. There's still an in-species competition. Probability of gene A to fixate is roughly equal to

Evolution doesn't work on species level, but on individual level. There's still an in-species competition. Probability of gene A to fixate is roughly equal to 2s, where s is increased relative fitness. (e.g. 10% for gene that gives 5% increase). Such genes will spread even if species as a whole has a niche to populate. I would recommend reading [1] - a series of essays on evolution and math behind it. [1] https://wiki.lesswrong.com/wiki/Evolution#Blog_posts_.28sequence.29 https://wiki.lesswrong.com/wiki/Evolution#Blog_posts_.28sequ...

dwaltrip 9y ago
What about group selection & kin selection? (Not sure if those are the correct terms) Isn't that a huge reason for the existence of pro-social behavior?
jmull 9y ago
I get that there's in-species competition, and that the successful competitors will come to dominate, perhaps completely. But what I'm thinking is that when a species is established in a niche, the direction of that competition is arbitrary rather than being limited to competing for resources. Once the level of resources needed to procreate are generally available, the individuals can compete over anything at hand. As you say, "fitness" is a key concept, but fitness for what? If you don't need more resources, then on what basis are you competing to be more fit? If you happen to be a social tool using species, then it could be based on those things: more complex and subtle social structures (and the language to support that), more complex and subtle tool use (and the abstract thinking to support that).
CuriouslyC 9y ago
That's not entirely true. Evolution acts at the level of populations as well as individuals. A trait that neutral or even slightly negative for the individual having it but highly positive for the population will tend to increase because the population as a whole will select for its continued existence, since populations having it will out-compete other populations without it.

dwaltrip 9y ago

What about group selection & kin selection? (Not sure if those are the correct terms) Isn't that a huge reason for the existence of pro-social behavior?

jmull 9y ago

I get that there's in-species competition, and that the successful competitors will come to dominate, perhaps completely. But what I'm thinking is that when a species is established in a niche, the direction of that competition is arbitrary rather than being limited to competing for resources. Once the level of resources needed to procreate are generally available, the individuals can compete over anything at hand. As you say, "fitness" is a key concept, but fitness for what? If you don't need more resources, then on what basis are you competing to be more fit? If you happen to be a social tool using species, then it could be based on those things: more complex and subtle social structures (and the language to support that), more complex and subtle tool use (and the abstract thinking to support that).

CuriouslyC 9y ago

That's not entirely true. Evolution acts at the level of populations as well as individuals. A trait that neutral or even slightly negative for the individual having it but highly positive for the population will tend to increase because the population as a whole will select for its continued existence, since populations having it will out-compete other populations without it.