Did an ice age boost human brain size?

[SkinnyDevil]

Figured some of y'all would dig this:

http://www.newscientist.com/article/mg20327194.000-did-an-ice-age-boost-human-brain-size.html

[Josh]

Hmm...it's counter intuitive to me. I seem to think quicker in the heat, and when very cold my brain kind of shuts down. I don't live near the equator though to be fair.

[RawZi]

    I did feel like tropical heat where I used to live was baking my brain.  I guess it did a good job, as I can't decide whether it's true that the ice age made our brains larger.  Intuitively I would say yes, as if I ever get a headache, if it goes away for part of the day..that's at night when the weather happens to be cooler.  Head, brain, whatever..I'm still not sure.  With warm weather we need less shelter and less food.  It's why I had changed location to the tropics.  We do have to think more when it's cold.

[Raw Kyle]

Didn't read the article yet but would like to add that I heard a story on NPR about a study that showed that on average nations with lower average temperatures have higher GDP's. Also within the same nation the domestic product is higher in the winter in the poor countries but not the rich ones, and the proposed explanation was climate control in the rich countries.

Another point here was years ago I had a conversation with a college friend about a book her read that showed that industrialization could not have happened in Africa or other equatorial, warm places because building a blast furnace for working metal would have made no sense. They would have passed out from the heat of primitive blast furnaces.

I think it works out though, because in a warmer climate there is more food and you don't have to work as much, and in a colder climate you need to secure shelter, food and warmth and could use more brain power.

[TylerDurden]

This is most interesting. I seem to recall that the Arctic-living Inuit have the largest skull-size of all groups(not necessarily an ultimate method for determining intelligence but a good rule of thumb).

[JaredBond]

I think it did, for some of the reasons discussed here.  Colder climates do seem to require more brain power to survive in, especially for unadapted creatures like us.  However, I don't think that the actual heat coming from our heat has anything to do with it.  Homo sapiens were obviously capable of thriving in warm climates, and I mean before air conditioning.

Also not mentioned is that colder climates might have pushed for more fatty animals (to retain heat)- fat being the densest source of calories for energy hungry large brains.  Also I believe that agriculture could have been practiced by humans, or even various hominids, in between ice ages.  It stands to reason that they could fall into the same carbohydrate trap that we have, which may have resulted in less than optimal nutrition, and were only forced to return to exclusively animal foods when the climate changed and they could no longer grow plants in sufficient amounts.

[TylerDurden]

Not sure whether this is relevant, but I seem to recall that most conquering tribes/peoples have nearly always come from the North and invaded eventually southwards. Examples include the Mughals invading India, vikings invading the rest of Europe, Spaniards invading south/central america, Mongols and manchus invading China etc. That may just have to do with greater resources being present in warmer climes(eg:- Persia, which in mediaeval times, was a sort of breadbasket of orange groves etc. etc.)

[SkinnyDevil]

Jared Diamond addresses the climate issue in "Guns, Germs, and Steel".

[PaleoPhil]

Not sure whether this is relevant, but I seem to recall that most conquering tribes/peoples have nearly always come from the North and invaded eventually southwards. Examples include the Mughals invading India, vikings invading the rest of Europe, Spaniards invading south/central america, Mongols and manchus invading China etc. That may just have to do with greater resources being present in warmer climes(eg:- Persia, which in mediaeval times, was a sort of breadbasket of orange groves etc. etc.)

There is some of the reverse too--most notably Rome invading north under Julius (seeking mainly gold to pay off huge government debts and boost a sagging economy--sound familiar?) and massacring millions of Celto-Germanic peoples in one of the greatest mass slaughters in human history. The northward invaders tended to be middle-latitude expanding empires rather than southern-latitude. The southern latitudes are also cold, but the land masses are much smaller and narrower than Eurasia, which Jared Diamond also discussed.

[TylerDurden]

There is some of the reverse too--most notably Rome invading north under Julius (seeking mainly gold to pay off huge government debts and boost a sagging economy--sound familiar?) and massacring millions of Celto-Germanic peoples in one of the greatest mass slaughters in human history. The northward invaders tended to be middle-latitude expanding empires rather than southern-latitude. The southern latitudes are also cold, but the land masses are much smaller and narrower than Eurasia, which Jared Diamond also discussed.

Well, to be fair, most of the Roman expansion occurred southwards(for example, North Africa was considered far more crucial to Roman interests as it was the main breadbasket that fed Rome).

[PaleoPhil]

Well, to be fair, most of the Roman expansion occurred southwards(for example, North Africa was considered far more crucial to Roman interests as it was the main breadbasket that fed Rome).

Sure, they expanded southwards also, and I think that the general tendency of southward invasion does hold--just thought I'd add that there are some important exceptions to the general rule. There are others too, such as a biggie that I momentarily forgot--the Arab Islamic empire that invaded north into Europe as well as West into northern Africa on multiple occasions.

One of the differences is, invasions that originate in "barbaric" areas, such as the "Viking" invasions of central and southern Europe from the north, tend to sack and pillage the centers of agrarian or mineral wealth or treasuries of gold, jewels and metalwork, and then return north to their homelands shortly thereafter or after holding them for relatively brief periods with loose administration, or controlling only certain prime trading cities (such as Kiev and Dublin by the Vikings) whereas the invasions that emanate out of the agrarian centers (Rome, the Egyptian Nile, the Tigris-Euphrates, the Chinese river deltas, etc.) tend to involve longer term conquests with more intensive administration and centralization of authority.

In both cases of southward and northward invasion, the plentiful resources of the river delta areas that you mentioned do play a key part. The barbarians invaded south to get the food and agrarian-created wealth and the empires invaded north and east-west by using the food and wealth they accumulated to hire standing armies.

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On second thought, from my memory of history, the most common invasion direction was probably from east to west, rather than north to south, as one "barbarian" tribe after another left or was pushed out of Asia and Eastern Europe, often following herds of cattle and/or game, and invaded or aggressively migrated to Central and Western Europe (Celts, Scythians, Goths, Tatars, Huns, Mongols, etc.), but on the north-south axis I do think that southward invasion was more frequent, though less long-lasting and having less long-term impact on societies than northward-and-westward conquests (for example, Celto-Germanic nations like France, Spain and the British Isles now speak Romanized languages rather than vice-versa).

[SuperInfinity]

Hmm...it's counter intuitive to me. I seem to think quicker in the heat, and when very cold my brain kind of shuts down. I don't live near the equator though to be fair.

Could human brains be like computer processors, with heat dissipation having been a problem until the ice age?

Actually brain metabolism is more efficient when in the cold.... it cools down and doesn't need the same amount of fuel. That's another theory as to why people in higher climates have a bigger brain... because it uses about the same energy in the cool climate even though it's bigger, so it can be bigger. If it cools down, this could mean that it's going at a SLOWER rate. So the warmer it is the higher the brain metabolism. I SERIOUSLY considered wearing a hat for a while... but it's hard to imagine the idea really being of practical use.

[PaleoPhil]

If invaders have the biggest brains, wouldn't that suggest that the biggest, most effective invaders of all time--the Mongols--have the biggest brains?

For what it's worth, counter evidence has also been raised against claims of correlations between geographic latitude and brain size:

Hominins are a single lineage: brain and body size variability does not reflect postulated taxonomic diversity of hominins
linkinghub.elsevier.com/retrieve/pii/S0018442X04000137

I'm not particularly interested in correlations between brain size and latitude or climate or warlikeness, anyway, as much of this stuff seems beside the point to me. I'm more interested in optimizing my health and that of friends and relatives and coming up with ways that humanity might gradually and voluntarily move the planet back toward a healthier WOE. Focusing on alleged differences in brain sizes of people at different latitudes doesn't seem to help much in this regard. The effects of diet on the intelligence and general health of all humans seems more relevant.