[ExI] Armchair Evolutionary Psychology: Larks vs Night Owls

[Emlyn]

> > Lee wrote:
> Suppose that in a given tribe there really are genetic differences between
> the early risers and late risers. (I don't know if this is the case---I didn't
> follow all the URLs, and no one here so far has given me a Y or a N.)

Y

The original URLs I posted were about the genetic differences (a gene
called Per3 seems to regulate early/late rising).

> Then the population biologist has to ask, "How can that be? Why didn't
> whichever one that had even the slightest selective advantage come to
> predominate?  Why, for example, didn't the early risers take charge
> and create the best opportunities for themselves and leave less for the
> late ones?"

That's really hard to answer. The best stab at it that I could see was
the "sneaky fuckers" explanation (kudos Damien for nomenclature) -
that staying up late gets you more access to sex and so increases your
fitness, but I'll add to this that this strategy probably works best
in a mostly early riser environment.

Presumably there's an upper bound. The model might be something like
the tit-for-tat vs pure defectors equilibrium. I'd posit the early
risers as the norm, and the late risers as the "defectors". So, I'd
also posit that the late risers are relatively few compared to early
risers, and are taking advantage of an environment which is mostly
early risers.

> But we (I take it) seem to have an equilibrium: that is, there may be
> about the same number of each.

Equilibrium isn't 50/50, it's wherever the ratio is stable. I haven't
read any information on the actual ratio (although my guess is it's
mostly early risers, few late risers, pure guess). The original study
I posted actually selected for extremes of both types, and thus the
ratios in the experiment probably can't tell us anything about the
general ratio.

-- 
Emlyn

http://emlynoregan.com