Thursday, December 17, 2009

Taking a break from politics

...or trying to. Seriously.

Maybe palaeoanthropology isn't strictly apolitical, but it sure is fascinating. For example: consider the shellfish. More and more, studies of ancient human settlement patterns are focusing on the early coastal enclaves, and the evidence that early exploitation of protein and Omega-3-rich shellfish provided both a rich food source, and specifically a real jolt to our developing brains in the Middle Stone Age.

Curtis Marean's lecture, if you can spare the 60 minutes or so to watch it, is very interesting. Basically, he may have located -- with impressive precision -- the geographical location where our ancestors come from.

About 170,000 years ago, the Earth was going through a dramatic cooling phase, and Africa's climate got drier very quickly. This meant that hominid populations died out all over, and we know from genetic evidence that the human population shrank dramatically, to a number of breeding individuals certainly less than 1000, and probably around 600-700.

The small band that survived the cataclysm seems to have endured because of their love of shellfish. Basically, their coastal enclaves provided them with highly predictable, energy-rich sustenance while also being located close to diverse plant life that the humans had easy access to. More interestingly, in order to harvest shellfish efficiently, you need a relatively impressive brain and the ability to explain unconnected events in the world around you -- such as the phases of the moon and the tides.

So we have deserts expanding, food resources disappearing, and human populations dropping. If it hadn't been for a larger-than-normal brain, capable of figuring out how to capture, cook, and eat shellfish, you and I literally might not be here today. At the southernmost tip of Africa, driven to near-extinction, a small band of humans held on for just a little longer, and when the glaciers started to recede on the other side of the Earth, this bunch of bipedal, tool-using, and most importantly symbolically-communicating hunter-gatherers would eventually thrive and spread across the globe.

Bill Bryson starts his phenomenal Short History of Nearly Everything by saying, "Congratulations!" By definition, if you're alive today, you are extraordinarily lucky -- every single one of your ancestors for more than 3 billion years survived long enough to reproduce. The odds are not in your favour, and yet here you are. It's kind of silly, but a humbling point nonetheless.

Some nights, I wonder about the ones who never made it. About the African hominids that died in the great cooling that pushed our species to a thin beachhead at the bottom of the world. [1] I'd say they were experiencing the apocalypse, except that they might not have invented religion yet. One thing we can say for them, unlike our modern day Rapture fetishists, is that their world really was ending, and if they weren't being judged they sure as hell were being tested.

There's a sense in which all that was necessary for us to be here today -- that cooling would open up new opportunities for the survivors, who would go on to be fruitful and multiply. Those people were our great-times-10^?-grandparents, and we're fortunate they made it. But, well, tell that to the dead, right?

Of course, I can't resist a little politics, so it's worth pointing out that people who think the human past is a reason to not worry about climate change in the future don't know what they're talking about. The reasoning that "hey, we survived enormous climate change in our distant past, so climate change in the future won't be too bad" ignores a number of complexities, but most importantly ignores the whole "species driven nearly to extinction, with only fortune itself between us and oblivion" thing.

[1] Suck it, Australia.


Zack said...

What does it say that I actually finished reading an article starting with this slightly-less-than-exhilarating sentence:
"For example: consider the shellfish."


Declan said...

Interesting post. I don't have much to add other than, since we're sort of on the topic, I'm always surprised how little importance anthropologists seem to attach to the aquatic adaptations of the human species vs. the other primates.

john said...

Zack: yes, it's a bad opener. But a pretty decent close in the footnote, no?

Marta said...

I'm going to write a book about the importance of shellfish in human evolution:

"The Shellfish Gene"

Zack said...

Indeed. "Suck it, Australia" is right up my intellectual alley!

perhaps fittingly, I lol'd @ "shellfish gene"

adam said...

The madness of Adam and Eve was an interesting read which posited that the essential change in the early hominid brains that lead to the creativity and rapid cultural change of Homo Sapiens was linked to the origin of Schizophrenia and related disorders.

Part of his argument is that many such disorders were much less debilitating in earlier times, because a diet rich in the fatty acids present in seafood helps brain function. The saturated fats in modern Western diets are structurally similar enough to occupy the same spots in the brain, but don't provide the same function. So someone who's completely debilitated in our society may have been merely 'odd' (i.e. shamans and similar) in a pre-agricultural society.

Interesting book. Highly speculative, as is the case with evolutionary development stuff, but pretty well argued.