Friday, January 8, 2010

280. Babel 2

When I first heard about Cosmic Inflation it seemed ugly and I hated it. It seemed too cleverly contrived to make up for an embarrassing discrepancy that should either have been resolved more elegantly or else stopped the Big Bang theorists in their tracks completely, forcing them back to the drawing board at square one. Over time, however, as I’ve become more interested in evolution, I’ve come to appreciate Guth’s idea -- because, as most people tend to forget, the Big Bang is really as much about evolution as it is about physics and math. Now for most people evolution means smooth continuous development based on universal principles, and that’s the way it was understood for a great many years. Which is why the standard models were all based on some kind of universal impulse driving all living things to develop through “stages,” from simple to complex, from animal to human, from “primitive” to “advanced.” What was not so well understood, though clearly Darwin understood it, was the role of sheer randomness in evolution, the crucial importance of contingencies, totally unexpected events that can suddenly change the entire course of a species’ or a culture’s future. What now impresses me most about Guth’s theory is the fact that it introduces this same evolutionary principle into cosmology. Because the Universe evolved, and was not elegantly constructed by some intelligent designer laying down immutable laws, it too would have been, and still is, subject to contingency. Cosmic Inflation is a wonderful example of how a completely unpredictable event could change the course of history.

It’s important to understand the difference between explaining something on the basis of universal principles and contingencies. In the first case, we hypothesize some basic principle or law and then test to see if events have followed it. In the second case, we start with a situation that can’t be explained in terms of basic principles and ask ourselves what sort of event could have produced those conditions. In one case we look forward, in the other we extrapolate backward. The evolution of the Universe in the first few seconds after the Big Bang could be explained on the basis of the first method, but that only went so far. To explain the conditions that would have to exist after the first few seconds, it was necessary to introduce a contingent event (Inflation), based on extrapolating backward from current conditions to where the problem lay. In the second case, various details of the discrepancy serve as a valuable clue to the retrospective recreation of the contingent event. This is not to say that any old explanation that fits will be acceptable. Cosmic Inflation has been subject to all sorts of tests and has thus far passed with flying colors. But when it was proposed initially, it was mostly just an idea that happened to “work,” mainly because it explained so much that could not be explained any other way.

So what’s the point of all this? The point is that we are faced with a remarkably similar situation as we try to understand the early phases of the Out of Africa migration. As with the Big Bang, we can base the first few “seconds” on a smooth, continuous process, as the ancestral group makes its way from the Horn of Africa, across the Bab el Mendab, along the Arabian coast, to the coast of Iran, following the banks of the Indian Ocean across the Indus Delta, through southern Pakistan, Southern India, and beyond to Southeast Asia, what is now Indonesia and the Sahul. But we encounter a problem along the way. Because the picture we have drawn, so smooth and simple, is not compatible with the state of the human universe as it now exists. So what, you might say, many things have changed over tens of thousands of years. That’s true. And until we developed genomic methods that help us relate the lineages and cultures of peoples now living to the migrations of their ancestors, (analogous to the development of modern telescopes and spectroscopes), we could not have seen the problem. The difficulty goes way beyond the issues I’ve raised so far on this blog, because there are very fundamental questions that go the heart of who we are, and why we are the way we are, questions so obvious that hardly anyone bothers to pose them anymore.

Until population genetics began to revolutionize the way we think about “deep history,” it was generally assumed that the many differences we see among various human groups, both physical and cultural, can be traced to differences that go back to our earliest, pre-homo sapien ancestors. Thus, East Asians are different from Europeans because East Asians are descended from Homo Erectus hominids based for millions of years in Asia and Europeans are descended from Neanderthals based for a comparably long time in Europe. And we speak different languages because different language families developed in different parts of the world, African languages in Africa, European languages in Europe and Asian languages in Asia.

(to be continued . . . )

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