Geology shapes human evolution

The Earth is, to put it lightly, a pretty important factor in humanity’s origin, for a start we live here. But the extent to which features of the planet like rivers, rock type and plate boundaries have shaped our evolution and human history, runs very deeply. It affects everything from our development of intelligence, right up to who you might vote for at the next election. Don't believe us, well Lewis Dartnell from the University of Westminster, has just written a book on the topic, it's called Origins: how the earth made us, and Georgia caught up with him to find out why we’ve been so shaped by our own planet…

Lewis - Humans are an animal species just like any other organism. We have been adapting to our environment, we've been influenced by our ecosystem, by an environment we've been growing up in. So in some sense it's not surprising that as a species we've been crafted by our natural world. And the reason that we evolve such high intelligence in East Africa is because the environment was exceedingly unstable and very quickly fluctuating, because of a combination between the plate tectonics and that interacting with climate cycles to do with Earth's wobbling orbit. So it was our environment that created us to be very intelligent.

Georgia - Why would a changing climate help us become super smart?

Lewis - Because if you have a relatively static environment, so say its environment that's always pretty dry, an animal can evolve a very good survival strategy to that like a camel, and it would store a lot of water in its body and recycle all of that water and have kind of humps to minimise its body fat. But if you've got an environment that is always changing, fluctuating back and forth, there's no no one body solution to that. And the best solution that evolution can come up with in that case is a behavioural solution, it makes complex adaptable behavior, it gave us intelligence.

Georgia - Right. So if we'd had it good and easy and everything stayed the same would have become simple camel type.

Lewis - We probably wouldn't be having a conversation on the technology, in fact we wouldn't have language or tool use had it not been for this wildly fluctuating environment in East Africa. 

Georgia - How about more recently, I say recently, like when humans started to start making civilisations.

Lewis - So we look at the first civilisation and I'm sure everyone is familiar with Mesopotamia. There's a very fertile region between the rivers Tigris and Euphrates and that's where the first large cities popped up. That's where the very beginnings of civilisation began. And again there's something really quirky about the plate tectonics in that region where humanity first built civilisations. And what's happening is the Arabian Peninsula is swinging away from Africa like this great big barn door of continental drift and it slammed into the southern margin of Eurasia, of the other continental plate, and crumpled up a range of mountains called the Zagros mountains. And when you've got a great big heavy mountain range it pushes down the crust, the earth's crust alongside it, and you get what's known as a foreland basin. And we often find rivers like the Tigris and Euphrates flowing through that foreland basin and they fill up with a very fine, very fertile river deposited soil. And so in a sense humans settled and built their first civilisations in the place was easiest to get settled with agriculture and build these big populations and these first cities. And it was plate tectonics again that created that environment for us to settle into.

Georgia - And what about us today just like day to day lives. Is there anything that we've been influenced by that we might not know?

Lewis - Another great example that really jumped out to me when I was writing Origins, was it's not just ancient history. We still bear this deep imprint of the earth and the kind of geology underlying our feet in something as current and free flowing as politics, and there's a couple of examples in Origins. There is a very very clear correlation between Labour-voting constituencies and rocks dating back to the carboniferous era. So looking as far back in Earth's history as 300 million years now, and again that deep link is actually profound it jumps out at you when you just look at the two maps that I put into Origins. And the explanation is is actually quite simple because carboniferous age rocks are where the coal deposits are, and coal is what powered us through the industrial evolution in Britain and it's been, and it still is, an incredibly important energy source in the modern world. And the reason that the Labour constituents map over where the coal deposits is that the Labour political party rose out of trade unions, so that the link there is relatively simple. But I still think is absolutely profound when you think about it that something like the political map of where people just happen to vote for different political parties correlates so strongly with the age of geological rocks that happen to lie beneath your feet.