Researchers link human skull size and climate
Hot head v cool head v Mr Potato Head
Humans grew bigger brains as the climate they lived in got cooler, according to researchers at the University at Albany, New York.
The researchers concluded that humans got brainier because they had to adapt to a more challenging environment. They base this assertion on a plot of cranial capacity of 109 fossilised human skulls against the corresponding paleontological record of two million years of changing climate.
As well as a relationship between a cooling earth and growing skulls, the researchers report that where the skulls were found matters, too, because the further you get from the Equator, the more varied the weather becomes.
Gordon G Gallup Jr, a professor of evolutionary psychology at the university, and co-author of the work along with graduate student Jessica Ash, commented: "It became clear that seasonal variation in climate may also have been an important selective force behind the evolution of human cranial capacity. Specifically, we found that as the distance from the Equator increased, north or south, so did brain size."
Lower temperatures and seasonal variations threw up new challenges for the early human, such as fluctuations in the availability of food and the need for fire and clothes to keep warm, the researchers argue. More co-operation would have been needed to find, preserve, and store food; and the people would have needed more complex tools. Along with that, more intricate social structures would have evolved, which in turn would have required more grey matter.
The researchers suggest that having to adapt to the impact of lower temperatures could account for as much as 50 per cent of the increase in the size of our skulls.
The researchers don't mention whether or not the extra small human skull found on the island of Flores was included in the sample. ®
Helps to explain the South (US)
What is head size for?
AFAIK, there is no proof that "intelligence" varies with distance from the equator. Equally, there is no evidence that "intelligence" varies with brain size (for "normal" brains). If there were, I'm sure we'd have heard about it by now :-)
Rather than assuming that distance from the equator allowed brains to grow to a more "productive" size, we should consider what other eveloutionary benefits might arise from moving to a cooler climate. I can think of one straight off: plumbing.
The brain is a very energy-intensive and blood-intensive organ. A larger head in a hot climate will presumably absorb more heat, which is inefficient for the body as a whole and the brain in particular (cheetahs can only run at top speed for a few seconds because their brains can overheat and they can pass out). By adapting the brain's plumbing to a cooler climate, evolution is making sure that growing a head is as simple as necessary (why waste effort - and risk failures - by fitting the plumbing into as small a space as possible?) and giving the body - and the brain in particular - another way to cool down.
Just because mankind's "intelligence" has allowed it to survive and thrive, we assume that it is more important than any other bodily function; nature doesn't care and is far smarter than us!
I'm not a biologist, BTW - please feel free to point out any errors in my assumptions :-)
Speaking of Self-Appointed...
"Either you want to improve the world or you want to play passive aggressive, games- judgemental and superior posturing to impress the ladies with your clarity and restraint, but it strikes women, more and more, as simply patheic posturing and parroting as compensation for not having any conviction in your self generated observations..."
Speaking of tiresome isn't this rant just a bit 1980's feminist. Letting a discussion devolve into personally-driven gender issues and screed doesn't speak well of your ability to make a cogent point. I did appreciate, however, the subtle irony of your lapse into precisely those behaviours against which you rail - judgmentalism, posturing, parroting, self-generated observations. Nice touch.