The Logic of Evolution

[gusl]

(this should go on My Notebooks eventually)

Why do kin help each other?

The answer is: evolutionary selection pressure towards kin-helping behaviour.
Individuals who accidentally developed genes that promote kin-helping behaviours caused their genes to spread more than individuals who didn't have such genes. So more babies with kin-helping genes were born than babies without kin-helping genes (because the kin helped were more likely to have the same kin-helping genes).


But why would I have a strong preference to helping my brother, when all humans have 99.9% of their DNA in common with me? (Why should I have a strong prefererence to helping my fellow humans when monkeys already have 98% in common with me?)

Humans used to compete among each other for limited resources (is this correct?), so helping everyone equally would not have made any appreciable difference to humanity, whereas helping your kin would have promoted your family's genes, at the expense of other genes in the pool.
(Are such behaviors different in populations where help is not reproductively zero-sum population-wide, by virtue of their environment?)

Also, it's not clear which genes are selfish, and whether some are more selfish than others. The kin-helping gene only promoted itself, so in that sense it's selfish.


I'm not comfortable with these answers. I'm ok with my assumptions, but I'm not comfortable with the fallibility of my own reasoning here, and the "selfish gene" metaphor isn't that clear me.

Comments

[jbouwens.livejournal.com]

> Why do kin help each other?

Your answer simply describes the mechanism, not the underlying reason WHY kin-helping is a trait that helps survival.

> But why would I have a strong preference to helping my brother

I believe humans share 99.9% of their DNA _structure_, not the actual "values" of these genes (But I may be mistaken here).

Also, much like the infamous butterfly that can cause a hurricane, a 0.1% difference in genotype may result in a radically different phenotype. It's the differences in phenotype that matters, not how similar or different our DNA is.

[gustavolacerda.livejournal.com]

Your answer simply describes the mechanism, not the underlying reason WHY kin-helping is a trait that helps survival.

*being*helped* helps survival and reproduction. Kin-helping is caused a selfish gene: it only helps humans' survival to the extent that this is linked to the gene's success.


(But I may be mistaken here).
I think you are. I don't know what you mean by "structure", but I suspect the accepted view is that all humans share 100% of it.


a 0.1% difference in genotype may result in a radically different phenotype
There is no a priori reason why you should help people with the same phenotype as you.
The selfish gene phenomenon is merely a selection effect: the genes we see are selfish merely because they are the ones that survived and multiplied.

[jbouwens.livejournal.com]

> *being*helped* helps survival and reproduction.

Right, that makes sense.


> There is no a priori reason why you should help people with the same
> phenotype as you.

Lacking a natural DNA sequencer, the only mechanism we have to establish kinship is examining phenotype.

[gustavolacerda.livejournal.com]

Lacking a natural DNA sequencer, the only mechanism we have to establish kinship is examining phenotype.

Okay, now you're making an interesting point. If the kin-helping mechanism uses human intelligence, then we need a way of recognizing our kin.
I think in practice, you recognize your kin simply because you grow up around them. Physical phenotype isn't a very reliable way of identifying people genetically similar to you, but again, that's not the point: we have no drive to help people who are genetically similar to us for its own sake (this seems like the fallacy where "selfish gene" is interpreted as "selfish people"). What we do have is simply caused by the selection effect.

This stuff is awfully confusing, don't you think? I'm getting all caught up with sense and reference, and probably contradicting myself in some places.

[jbouwens.livejournal.com]

If the kin-helping mechanism uses human intelligence, then we need a way of recognizing our kin.

Is kin-helping something uniquely human then? I think non-human species also employ kin-helping, and they don't have the mental capability to establish kinship rationally. They probably don't even make the link that sex causes offspring.


I think in practice, you recognize your kin simply because you grow up around them.

If that is true, then the only reason why kin-helping works is because the people you grow up with are more likely to be related to you genetically.

So there's not really a "kin-helping" gene, but rather a "help-the-people-you-know" gene.

I think "selfish gene" is a misnomer, as it implies (however subtly) some sort of intent on the part of the genes. What you say is correct: there is no "selfish gene", it's all a side-effect of the selection mechanism.

Think of chemical elements. You could say that when the universe started, stable elements had a higher chance of survival than unstable elements. Therefore, stable elements are now more abundant in the universe. Does this mean quarks or other sub-atomic particles are "selfish"?


This stuff is awfully confusing, don't you think?

It can be confusing because cause and effect are not always clear.

[gustavolacerda.livejournal.com]

Is kin-helping something uniquely human then?

No. But it is almost certainly true that kin-helping in humans takes advantage of human intelligence. (e.g. we may have a cultural duty to help them, or cooperate with them more than with non-kin)


So there's not really a "kin-helping" gene, but rather a "help-the-people-you-know" gene

Maybe. But I would say "people you grew up with" instead of "people you know". There's evidence that people don't feel sexually attracted to people they spent their early years with (even if they are not related). We believe this is a mechanism of preventing inbreeding.


It can be confusing because cause and effect are not always clear.

That would be no problem. The confusion for me comes from:
* the temptation of attributing intentions to inanimate things
* the fact that things can work on several levels at the same time
* all the self-referential processes (e.g. selfish genes)
* complexity: the multiplicity of possible mechanisms, and possible interactions between them

[jbouwens.livejournal.com]

But I would say "people you grew up with" instead of "people you know".

That's more precise, yes. Although in the past, the people you grow up with are also the people you end up breeding with. When humans were living in tight groups of 100-200 individuals, everybody was related to a certain degree.