This summer the Scientific American magazine published a special edition on human evolution that gave prominence to the notion of a cultural “Big Bang”. An article by Ian Tattersall of the American Museum of Natural History argued that the use of symbols was an invention, the fruit of some insight, that led to an eruption of cultural behavior — the production of rock art, creation of decorative beads, etc. Although it would be a long time before speech would become written language, language is assumed to have been born when symbols were invented.
A variant on this idea was developed several years ago in a book by Richard G. Klein, The Dawn of Human Culture. Klein argued that less than 75,000 years ago something happened (“a fortuitous mutation that promoted the fully modern brain” is how Klein puts it on page 270). The chief evidence for the Big Bang is the sudden discontinuity in the archaeological record. Although it is not as revolutionary as proposed in Richard Klein’s book, there seems no doubt that 40,000 years ago there was an increase in discoverable arts. Rock drawings, decorative carvings, and beadwork start turning up with a new regularity. It would be pleasing to know why.
This blog holds a very skeptical attitude toward the notion of a revolution that produced speech, culture, and symbolic thinking in a sudden blow. Yes, the sudden rise of cultural artifacts is intriguing, but, human history is full of discontinuities and revolutions, yet we do not usually attribute them to sudden changes in the nature of being human. The rise of agriculture produced a similar break; the rise of written languages another; the prophecies of Mohammed still another; the burst of science a few centuries back still another. In all of these cases we are confident that the people who lived before the break would have managed well if, in other circumstances, they had been born after the break. The Big Bang theory seems to put a line across the calendar and say that people born after X time spoke; those before X did not. Wow.
The cultural Big Bang proposes a revolution in the most basic elements of human nature long after the genetically modern human had evolved. By 75,000 years ago Homo sapiens was scattered. The last common ancestor of all today’s humans probably lived 125 to 200 thousand years ago, well before the Big Bang. Newborns today start using words before their first birthday and are inventing very complicated strings of words long before they turn three. If they are deaf and cannot hear the words spoken around them, they will invent a sign language. It is difficult to combine this apparent biologically innate urge to use symbols with the Big Bang.
The usual explanation offered, and the one favored by Tattersall in his article, is that all these biological traits evolved for other purposes and were co-opted into supporting speech. Thus, our vocal tract, our big brain, our ability to expel a long blast of air while speaking without getting giddy, our manipulation of our tongue — these and many other traits evolved for non-linguistic reasons. We don’t know what those reasons were.
Then there are all those pockets of isolation, most notably Australia. It was settled long ago by the fully human version of H. sapiens and not resettled until late in the modern Age of Discovery. How could such isolated people have participated in a revolution taking place on the far side of the globe? (For the abstract of an article saying they could not have done so, click here.)
This blog (thank heavens) is not alone is considering the cultural Big Bang a dubious idea in which archaeological evidence is allowed to trump too much biology. One of the leader scholars in arguing that the revolution never happened is Sally McBreaty, an anthropologist at the University of Connecticut and lead author of “The Revolution that Wasn’t” in the Journal of Human Evolution (Nov., 2000) (click here for the abstract). She has turned up red ochre that was quarried at least 285,000 years ago and grindstones for working it, suggesting that a substance (rusted iron ore) was being used well before the rise of H. sapiens. McBreaty proposes it was used as a paint to decorate bodies, as it is still done today. However, proposing and proving are two different things.
When there is a dispute about how to understand the evidence, the wisest course seems to be to embrace the ambiguity and look for more evidence that can decide the matter one way or another. The list below itemizes issues this blog will track as it keeps an eye out for information that might push the argument in one way or another.
- Neanderthals split from our line about 200,000 years before H. sapiens came along. Evidence of speech, culture, or symbolic thought works against the cultural Big Bang. (See yesterday’s post for remarks on this issue.)
- One of the biggest weaknesses of the Big Bang theory is that H. sapiens was already scattered across the whole of Africa, Asia, Australia and much of Europe when the revolution was supposed to have occurred. Proponents need some very powerful mechanism for diffusion. A related feat that we know about was the invention of writing. It spread quickly but not universally. If proponents could solve this diffusion problem, the Big Bang would seem less miraculous.
- A non-linguistic explanation for the vocal tract is also needed. This anatomical change has a multi-million year history. We need to understand what it was about if it wasn’t to promote speech.