Science Seen Physicist and Time One author Colin Gillespie helps you understand your world.
What Do Neanderthals Say About Race?
Okay, this is not about Sochi. It’s about racial distinctions, and what physics can contribute to out understanding of them. ‘Race’ once referred to a group with a common line of descent. But over time it became less clear. Nineteenth-century racial distinctions were built on emerging sciences of linguistics and physical anthropology.
Many scientists were critical of the whole concept of race. But the tools available to them, such as craniometry (the study of skull shape―try googling Sherlock+Mortimer+skull, like many others Conan Doyle seems to have been serious about this!) left much to be desired. Then in the late 1890s the work of a German monk, Gregor Mendel, came to light. Working with generations of peas, he spawned a whole new field of science―genetics. And lots of pseudo-science. Even Mendel’s data were shown later to have been cooked up.
Genetics gave a whole new meaning―and seeming scientific substantiation―to race. The concept of race came to be based on heredity, in which supposed genetic commonalities and differences played key though ill-defined roles. By the end of the twentieth century it was a scientific mess.
Now physics rides to the rescue. Race studies recently got a whole new tool: DNA sequencing. And it is cheap. The cost to read the entire genetic code of one person dropped from $100,000,000 in 2001 to $1,000 in 2014. And we can read it from a single cell.
Enter from stage left, the Neanderthals. A ‘race’? Many anthropologists regard Homo neanderthalensis as a distinct species, though maybe they could have intermingled with Homo sapiens migrating out of Africa. The Neanderthals lived in Europe until they died out maybe 30,000 years ago. They left bones containing DNA. Their DNA is similar to ours. The difference is about one-tenth of the human-chimpanzee difference (which in turn is about 4%).
So what about that intermingling question? Our DNA says that they could and did. The genes of every Caucasian (and Asian and Australasian) individual include a few percent of Neanderthal DNA. But they don’t all have the same few percent. Thus, across DNA from many samples, one-fifth of the Neanderthal genome survives.
What about ‘races’ closer to our time? DNA sequencing reveals that the differences in genetic makeup between so-called ‘races’, such as Asian and Caucasian, are small compared with individual differences among Asians or among Caucasians. In other words, ‘race’ is a distinction that has no genetic difference.
There is a curious exception to this rule: Physics says those stay-at-home Africans missed out on the intermingling; they have no Neanderthal DNA.
Ed Yong, “Surprise! 20 Percent of Neanderthal Genome Lives On in Modern Humans, Scientists Find”, National Geographic, 29 January 2014; http://news.nationalgeographic.com/news/2014/01/140129-neanderthal-genes-genetics-migration-africa-eurasian-science/
Jennifer Viegas, “How Neanderthal DNA Changed Humans”, Discovery News, 29 January 2014; http://news.discovery.com/human/evolution/how-neanderthal-dna-changed-humans-140129.htm