There’s an interesting cover article in Scientific American this month. A researcher has found a potential human ancestor in South Africa called Australopithecus sediba. This is surprising because it seemed until now that the Australopithecus to Homo transition happened in East Africa, not South Africa. It’s always the case that researchers argue for their own find to be the keystone species in some great transition, and the argument reminds me of nothing so much as the 2000 presidential election in which supporters of Gore knew that Gore got the most votes, while supporters of Bush were just as convinced that their man had the numbers. How did either side know?
But that’s not the interesting part. The most interesting statement came early in the article by Kate Wong. Here it is:
“Conventional wisdom holds that the broad, flat pelvis of australopithecines evolved into the bowl-shaped pelvis seen in the bigger-brained Homo to allow delivery of babies with larger heads. Yet, A. sediba has a Homo-like pelvis with a broad birth canal in conjunction with a teeny brain – just 420 cubic centimeters, a third the size of our own brain. This combination shows brain expansion was not driving the metamorphosis of the pelvis in A. sediba‘s lineage.” (Sci. Am, April 2012, p. 34)
Caveats are in order. No one yet knows if A. sediba is really a human ancestor. No one knows if these early findings will hold out over time. No one knows lots of things that could make this argument moot. However . . . if this holds up, it is incredibly interesting.
As Wong says, the conventional story is that our ever-expanding brains forced an anatomical change in human females, altering the pelvis in such a way to let the big-brained babies out into the world. But what if that’s not true? What if our brains could only grow as they did if our mothers were pre-adapted, purely by accident, to allow larger-brained babies to be born?
Perhaps some other pressure – a different way of walking, a different way of fighting off a predator, even sexual selection – drove our ancestors toward a new pelvis shape. Perhaps that new shape, purely by accident, allowed for larger brains. And only later did other pressures cause the brain to evolve into its larger size.
So what? So this. Maybe (just maybe) this is another example of just how tenuous is our existence. Maybe, just maybe, this is another case that shows that there is nothing inevitable about our intelligence and our consciousness. Perhaps if our ancestors hadn’t ended up, quite by accident, with large enough hips to later on let big-brained babies out, then our brains might have remained small – or, unable to respond to the pressures for larger brains, we might have become extinct.
People are often disappointed when they find that I am not of the opinion that intelligent life is common in the universe. I just think there are too many ways to survive without human-level intelligence, and (as maybe this example shows), too many unlikely accidents that led to us. Consider that life went along quite nicely for nearly four billion years without a whiff of us. Even the Earth itself spent most of its history without human-like consciousness (or, if you prefer, human-level technology). I think it quite possible that we are, in fact, alone.
Don’t get me wrong. I’d love for ETI to exist, and I’d thrill at the discovery of a technological civilization in the stars. But the universe is not obligated to please me. We get what we get, and we make the best of it. If we are alone, that tells us something about just how precious we are. As Carl Sagan said, “If a human disagrees with you, let him live. In a hundred billion galaxies, you will not find another.”