It's dim up north

Jul 27, 2011
Skulls from the 1800s used in the study.

The farther that human populations live from the equator, the bigger their brains, according to a new study by Oxford University. But it turns out that this is not because they are smarter, but because they need bigger vision areas in the brain to cope with the low light levels experienced at high latitudes.

Scientists have found that people living in countries with dull, grey, cloudy skies and long winters have evolved bigger eyes and brains so they can visually process what they see, reports the journal Biology Letters.

The researchers measured the eye socket and volumes of 55 , dating from the 1800s, from museum collections. The skulls represented 12 different populations from across the globe. The volume of the eye sockets and brain were then plotted against the latitude of the central point of each individual’s country of origin. The researchers found that the size of both the brain and the eyes could be directly linked to the latitude of the country from which the individual came.

Lead author Eiluned Pearce, from the Institute of Cognitive and Evolutionary Anthropology in the School of Anthropology, said: "As you move away from the , there's less and less light available, so humans have had to evolve bigger and bigger eyes. Their brains also need to be bigger to deal with the extra visual input.  Having bigger brains doesn't mean that higher latitude humans are smarter, it just means they need bigger brains to be able to see well where they live."

Co-author Professor Robin Dunbar, Director of the Institute of Cognitive and Evolutionary, said: ‘Humans have only lived at high latitudes in Europe and Asia for a few tens of thousands of years, yet they seem to have adapted their visual systems surprisingly rapidly to the cloudy skies, dull weather and long winters we experience at these latitudes.’

That the explanation is the need to compensate for low light levels at is indicated by the fact that actual visual sharpness measured under natural daylight conditions is constant across latitudes, suggesting that the visual processing system has adapted to ambient light conditions as have moved across the globe.

The study takes into account a number of potentially confounding effects, including the effect of phylogeny (the evolutionary links between different lineages of modern humans), the fact that humans living in the higher latitudes are physically bigger overall, and the possibility that eye socket volume was linked to cold weather (and the need to have more fat around the eyeball by way of insulation).

The skulls used in the study were from the indigenous populations of England, Australia, Canary Islands, China, France, India, Kenya, Micronesia, Scandinavia, Somalia, Uganda and the United States. From measuring the brain cavity, the research suggests that the biggest brains belonged to populations who lived in Scandinavia with the smallest being Micronesians.

This study adds weight to other research that has looked at the links between eye size and light levels. Other studies have already shown that birds with relatively bigger eyes are the first to sing at dawn in low light. The eyeball size across all primates has been found to be associated with when they choose to eat and forage – with species with the largest eyes being those that are active at night.

Explore further: A clear, molecular view of how human color vision evolved

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DavidMcC
5 / 5 (3) Jul 27, 2011
There's more information about the results here:
http://www.guardi...s-brains
A 20% eye diameter difference between the north pole and the equator. That's quite a lot for only 10,000 years!:
"Dunbar said the increase in brain volume must have evolved relatively recently in human history. "It's only within the last 10,000 years or so that modern humans have occupied all latitudes right up to the Arctic circle. This is, I guess, an adaptation that's happened within the last 10,000 years."
LKD
5 / 5 (3) Jul 27, 2011
That would beg the question of what changes are apparent between sea level and high altitude evolution.
that_guy
3 / 5 (4) Jul 27, 2011
I'd like to point out that another study found that countries with the smallest manhood also had the highest per capita gdp. Now if you combine those things, you get the highest per capita wealth, and best managed countries. These are all nordic countries like Denmark, norway, sweden...and they all have the biggest brains and smallest manhoods...They have little or no national debt, high quality of life, and high citizen satisfaction - right wing terrorist not withstanding.

I am being a bit tongue in cheek, so don't take me too seriously.
jamesrm
5 / 5 (1) Jul 27, 2011
"That would beg the question of what changes are apparent between sea level and high altitude evolution"

Altitude and its effects on selected risk factors of coronary heart disease
http://www.med.ui...dex.html

Might also be of interest

When Inuits are exposed to cold, the blood flow to their hands and feet rapidly increases.

Aborigines of Australia usually respond physiologically to the cold in a different way. Thick fat insulation develops around the vital organs of the chest and abdomen. In addition, their skin cools due to vasoconstriction at night. As a result, heat loss is reduced and the core body temperature remains at normal levels. However, the skin feels very cold.

rgds
James

Where are all the inellegent design... eh individuals?
Djincss
1 / 5 (1) Jul 27, 2011
First why didnt they measured the eyes instead of the orbits of the skulls?
After they saw this correlation they should have checked this(measuring the eyes actually) before to release the news.
after that they should check the actual size of the brain responsible for processing info from the eyes, maybe also to check the size of the retina, and the size of the optic nerve(its diameter ).
As the article itself says maybe it is just the more fat around the eyes that can explain this.
And the bigger brain is due to the bigger head and the bigger and more stocky body, which you need if you live so north.
jmcanoy1860
1 / 5 (2) Jul 27, 2011
I'd like to point out the Inuit, their Soviet counterparts, and the Mongolians. Correlation with eye size has been falsified.
Shelgeyr
not rated yet Jul 27, 2011
I'm having trouble with the idea that light level was the primary factor involved. Leaving race/ethnicity entirely out of it for a moment, isn't it the general consensus that "easy" environments produced people who were not as "survivally gifted" as those from harsher environments? Let me stress that this is not a "white" thing... Whether equatorial desert or arctic tundra, challenging environments select for intelligence. And I don't think it is just a "climate thing" either.

The most dangerous things to humans are other humans, so if you're a people living fat and easy, you're probably not going to be that sharp, but if you're constantly beset by war then you get good at it or you get yourself perished.

I'd like to see a study like this based on "historically adverse conditions" rather than latitude. I'm betting "Conquerors" and "historically oppressed but not eradicated minorities both show high intelligence.
Gpnum
not rated yet Jul 27, 2011
I wonder how exactly they took into account the size difference between those population.
Scandinavian are typically taller than micronesian, and brain size is linked to body size.
brianweymes
not rated yet Jul 27, 2011
Interesting study. Could do a lot to explain the differences in skull or brain size between different populations and in a way not thought about before. I suppose the Inuit didn't have the biggest eyes to brains because they haven't been living and evolving there for quite as long as the Scandinavians.
Djincss
5 / 5 (1) Jul 28, 2011
Inuits both have lived longer and are better adapted to cold than scandinavians.
LKD
not rated yet Jul 28, 2011
Altitude and its effects on selected risk factors of coronary heart disease


I was thinking along the lines of physical differences in lung capacity and size in comparison. Would there also be a size difference in the entire cardiovascular system?
DavidMcC
not rated yet Jul 28, 2011
First why didnt they measured the eyes instead of the orbits of the skulls?

Because the eyes themselves don't fossilise?
DavidMcC
5 / 5 (1) Jul 28, 2011
The original paper in "Biology Letters" makes it clear that it is orbit and VISUAL CORTEX size that are correlated with latitude, NOT overall brain size:
http://rsbl.royal...570.full
Also, the study was limited to skulls in museums, and was not large enough to even attempt to study subtle differences between groups at similar lattitudes.

Visual acuity was confirmed to be independent of latitude, using living subjects.
that_guy
5 / 5 (1) Jul 28, 2011
Altitude and its effects on selected risk factors of coronary heart disease


I was thinking along the lines of physical differences in lung capacity and size in comparison. Would there also be a size difference in the entire cardiovascular system?


There is a well known and studied population in the Andes Mountains that has significant variation in their cardiovascular system that allows them to tolerate high altitudes much better than the average population.
brianweymes
not rated yet Jul 28, 2011
The Inuits are descendants of the Thule Culture that spread across Alaska to Canada circa 1000 AD. Scandinavian populations in contrast lived there starting from at least 9500-7000 BC.
Djincss
not rated yet Jul 28, 2011
So inuits arrived to the north only 1000 years ago and before that they were living in the tropic right?
these people have evolved for living in the north first in Asia maybe for more than 30 000 years, you will see they have the best adaptation to cold weather, actually the population of the most north parts of scandinavia is mixed with such people, just because they are better adapted for cold.

We talk here about who have lived more long in cold areas, no who have arrived somewhere at some point.
Djincss
not rated yet Jul 28, 2011
First why didnt they measured the eyes instead of the orbits of the skulls?

Because the eyes themselves don't fossilise?


Yes I didnt knew that, thanks for the information, maybe I was thinking that in the 21st century we have the incredible technology to measure people's eyes without to stick them out with a spoon, but maybe we will live long enough to witness the development of this technology by NASA.
Or maybe there is some unwritten rule that only fossils should be used , and I just didnt knew that.
DavidMcC
not rated yet Jul 29, 2011
Strictly speaking, I should have said that eyes rot too quickly rather than "don't fossilise", because the measured bones were just that - bones, not fossils per se.
sherriffwoody
1.5 / 5 (2) Jul 29, 2011
So if i move closer to the poles i'll be smarter, have better vision, have a bigger rooster and be richer with less debt?? Is that right?? LOL
DavidMcC
5 / 5 (1) Jul 29, 2011
So if i move closer to the poles i'll be smarter, have better vision, have a bigger rooster and be richer with less debt?? Is that right?? LOL

No!
If your ancestors had moved north many generations ago, your eyes would probably be bigger and more ensitive to light. That's all. The bigger cranium has to do mainly with thermoregulation (see ref. 37 in the RSP paper).
DavidMcC
5 / 5 (3) Jul 29, 2011
Neanderthals are known to have had bigger crania/brains than modern humans', and are also known to have been better cold-adapted than us. This may well be the same effect.
cyberCMDR
5 / 5 (1) Jul 29, 2011
Our current generation of politicians could certainly use more vision and bigger brains.
that_guy
1 / 5 (1) Jul 29, 2011
So if i move closer to the poles i'll be smarter, have better vision, have a bigger rooster and be richer with less debt?? Is that right?? LOL

No, you would have a smaller rooster. Countries that have higher GDP tend to have citizens with SMALLER manhoods. It's as if they are compensating for something.
Husky
not rated yet Jul 31, 2011
possibly this could shed some "light" on the possible crossbreeding of modern man with neanderthal, some neanderthal skulls have huge eye sockets, So it could have evolved long before and aquired by crossbreeding
Caliban
not rated yet Jul 31, 2011
Our current generation of politicians could certainly use more vision and bigger brains.


Would that be to better see where to insert their tiny manhoods?

I don't think that lack of brains or visual acuity has very much at all to do with the failure of the political class to serve the public interest.

In fact, I would argue quite the opposite.

No disrespect intended, cyberCMDR.

Caliban
5 / 5 (1) Jul 31, 2011
possibly this could shed some "light" on the possible crossbreeding of modern man with neanderthal, some neanderthal skulls have huge eye sockets, So it could have evolved long before and aquired by crossbreeding


@Husky,

Now that you mention it...there always has been something creepy about those hairy-assed Neanderthals. Could it be that they were NOCTURNAL hunters? Possibly even VAMPYRES?

Could this be the reason for their sudden eradication from the face of Old Europe and Asia? Were they a plague that H S Sapiens had to eliminate in order to survive and prosper?

Of course, along the way, some of our ancestors were bound -it being human nature, afterall- to have put their manhoods into some of the ophthomegalic Neanderthalensis females.

Perhaps this accounts for the numerous crypto-vampires(currently resident in such places as the the Hamptons, Manhattan, Luxembourg, the Alps, the Cayman Islands, etc.) that have survived to continue to plague us to this very day

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