Did an ice age boost human brain size?

2 minute read

What is going on? I mean, the heat this summer seems to have gotten to people’s heads. Except, it hasn’t been that hot. Heck, nothing could be hot enough for this:

Did an ice age boost human brain size?
About a decade ago, biologists David Schwartzman and George Middendorf of Howard University in Washington DC hypothesised that our modern brain could not have evolved until the Quaternary ice age started, about 2.5 million years ago.

And how did that work out for them? Well, we can do a quick Google Scholar check. Sure, it doesn’t have to be cited to be true. I don’t have anything against bioastronomy as a source for paleoanthropologists. Why should I? There are lots of smart bioastronomers. They’ve thought long and deeply about human brain evolution, I’m sure of it. Er…</b>

The two periods of pronounced Phanerozoic cooling, the PermoCarboniferous and late Cenozoic, corresponded to the emergence of mammal-like reptiles and hominids respectively, with a variety of explanations offered for the apparent link. The origin of highly encephalized whales, dolphins and porpoises occurred with the drop in ocean temperatures 25-30 mya.

Of course it would help if the paper were actually about the Pliocene/Pleistocene boundary, instead of the whole Phanerozoic!

Sweet mother of Madge. Thank goodness it can’t get any worse. Er…d’oh!

A new study by Schwartzman and Middendorf suggests that a small drop in global temperatures may have made a big difference. The pair used basic equations of heat loss to estimate how fast the small-brained Homo habilis would have been able to cool off. Assuming overheating limited the size of H. habilis's brain, they then calculated what drop in air temperature would have been needed for Homo erectus to be able to support its bigger brain (see diagram). They found that a drop in air temperature of just 1.5 C would have done the trick (Climatic Change, vol 95, p 439).

I think this paper may single-handedly destroy the credibility of Climatic Change. I mean, gee, it’s not like people today live with mean temperatures that differ by 1.5 degrees. Wow, those tropical brains must be </i> smokin’</i>.

Well, I guess there’s always a bright side:

Greenhouse brains
If global cooling allowed humans to evolve their big brains, will today's global warming take them away again? "I'd hate to think that a difference of 1.5 C might mean the end of humans because our brains cook," says George Middendorf of Howard University in Washington DC, "but I guess it's a scenario that might play out."

OH NOES! Me brain, she be sizzlin’ away like a hot ball o’ buttah. WHAAAAAAH! hot Hot HOT HOT!