[ExI] Armchair Evolutionary Psychology: Larks vs Night Owls

[Emlyn]

Hi all,

In a discussion I was having today, the topic of the evolutionary
basis of early rising vs late rising behaviour came up (you know, as
it does). There is evidence that tending toward early rising vs late
rising is strongly genetically determined [1] [2]. Also, it looks like
there might be personality differences between these early people and
late people [3].

One person put forward the theory that we might have evolved these
differences in the past so that there would always be someone awake in
a tribe. But that's got two problems; one, there still seems to be a
significant gap in the night (very few people are awake between 3 and
4), and two, it assumes group selection, which is pretty much always a
poor idea.

I tried to think of a good individual selection oriented explanation,
came up blank. If you have an imbalance between early people and late
people in a group, what is the individual selection pressure that
rectifies this, making it an ESS? Anyone got any ideas on this?

[1] http://news.bbc.co.uk/1/hi/health/2996364.stm
[2] http://www.ncbi.nlm.nih.gov/pubmed/12841365
[3] http://www.theatlantic.com/doc/200712/primarysources?wtID=33.3czt.11.3lcx
(scroll down for "How you sleep is who you are")

-- 
Emlyn

http://emlynoregan.com