Human evolution: Bigger eyes and brains in northern arctic populations?

[Halfcentaur]

http://www.bbc.co.uk/news/science-environment-14279729

The claim is the increased brain size was only in accommodation for the increased visual processing. While still early in this discovery, it's another interesting way to see human's evolving for cold climates.

I'd be interested in identifying living humans with these features and seeing just what's going on with some visual testing, night vision, etc.

[engagechad]

It makes sense I guess, if there were enough time of course a population could be selected based on ability to identify food/predators against a visually harsh backdrop (snow..?).

It would also be nice to find an opposite situation and study those affects as well.. arctic population vs. tropical and look at the selective pressures

[FattyCatty]

According to Reuters (http://www.reuters.com/article/2011/07/27/us-brains-north-idUSTRE76Q1HD20110727?feedType=RSS&feedName=scienceNews&rpc=76),
People from northern parts of the world have evolved bigger brains and larger eyes to help them to cope with long, dark winters and dim skies, scientists said on Wednesday.My first thought on reading this was, "Aha, an explanation for why the Norwegians were able to react more reasonably to terrorism than Americans were." Alas, the article goes on to say:
It's not because they are smarter, however, but because they need bigger vision areas in the brain to cope with the low light levels at high latitudes, the scientists said in a report of their findings in the journal Biology Letters.


The article by Eiluned Pearce and Robin Dunbar is found in Biology Letters (http://rsbl.royalsocietypublishing.org/content/early/2011/07/12/rsbl.2011.0570.full.pdf+html):
Abstract:

Ambient light levels influence visual system size in birds and primates. Here, we argue that the same is true for humans. Light levels, in terms of both the amount of light hitting the Earth’s surface and day length, decrease with increasing latitude. We demonstrate a significant positive relationship between absolute latitude and human orbital volume, an index of eyeball size. Owing to tight scaling between visual system components, this will translate into enlarged visual cortices at higher latitudes. We also show that visual acuity measured under full-daylight conditions is constant across latitudes, indicating that selection for larger visual systems has mitigated the effect of reduced ambient light levels. This provides, to our knowledge, the first support that light levels drive intraspecific variation in visual system size in the human population.

[Halfcentaur]

It's because of those pretty northern lights,... generations of wide eyed tourists get trapped and spawn there,... The Japanese do so by choice.

[DC]

i see Creationist storming in saying how it's adaptation and not evolution :D

[casebro]

i see Creationist storming in saying how it's adaptation and not evolution :D

I suspect that your larger visual center in your brain helped you to see that. Just as mine helped e to see that you saw it... See? Or is your visual cortex too small? :)

[Captain Obvious]

So how come the eskimos are so squinty-eyed?

[DC]

So how come the eskimos are so squinty-eyed?

becaue they are looking angry, because some people keep calling them eskimos instead of Inuit? :D

[casebro]

So how come the eskimos are so squinty-eyed?

Eskimos have only been there about 10,000 years. Europeans have been there for 40,000-200,000. Just a couple more generations involved.

[Halfcentaur]

So how come the eskimos are so squinty-eyed?

And it's their eye sockets that are bigger, not their eyelids. It could possibly be for insulation, more fat around the eye. Asian eyelids seem to possibly be a cold weather development as well to aid against snow blindness.