Neanderthals... In Northeast Georgia?

Discover isn't a political magazine and doesn't get into the politics of the science stories it publishes. Something tells me, though, that lunatic fringe science-deniers on the House Science Committee, like Paul Broun (R-Pit of Hell), Mike McCaul (R-TX), Cynthia Lummis (R-WY), Steve Stockman (R-OK City Federal Building), Steven Palazzo (R-MS), Mo Brooks (R-AL), Tom Massie (R-KY), Kevin Cramer (R-ND), Jim Bridenstine (R-OK), Randy Weber (R-TX) and Chris Stewart (R-Utah), don't subscribe. They should-- if, for no other reason-- to get a better understanding of the people who vote for them. At least in this fascinating new article by distinguished science author Carl Zimmer on Interbreeding with Neanderthals.

Did you watch the Paul Broun video at the "Pit of Hell" link above? If you agree with him that the earth was created 9,000 years ago in six 24 hour days, you might as well stop reading right now, since the premises in Zimmer's essay include something about humans and Neanderthals going their separate ways about 700,000 years ago. The essay is about how the branches kept linking up again all over the world-- humans and Neanderthals interbreeding. Harvard Medical School geneticist David Reich is who's been doing the work and examining the DNA, that Rep. Broun, a John Birch Society freak running for the open Georgia Senate seat (and not especially as a joke candidate), would term "lies from the pit of hell."

Some 200,000 years ago, our ancestors evolved in East Africa. They spread throughout the rest of the continent and then moved out into Asia and Europe. As they journeyed along coastlines and over mountains, they encountered Neanderthals and other human relatives. And at least once in a while, they had sex.

We don’t know the prurient details of those encounters, although it is possible that someday Reich and other scientists will be able to fill in a few of them. But the work Reich has done already leaves no doubt that interbreeding was a major feature of human evolution. Billions of people carry sizable chunks of DNA from Neanderthals and other archaic human relatives. Some of those genes may play important roles in our health today.

And politics. It certainly goes a long way to explaining why the South is still the South so long after we whooped them in the mid-1860s. White supremacists like Broun would not be happy with conclusions scientists are drawing like "today’s Europeans are not latter-day Neanderthals but African immigrants." Thems fightin' words in the backward part of northeast Georgia that elects Broun to Congress, one of America's most racist and bigoted areas.

Reich was curious about what happened when these groups came into contact with each other. Even though they would probably remain mostly separate, some individuals might interbreed. Reich wondered if he could look at the genomes of living humans and find evidence of those ancient liaisons.

Detecting these signs is not easy. Imagine that two people from very distant parts of the world—a woman from Spain, say, and a man from Polynesia-- get married and have a girl. She is born with 23 pairs of chromosomes: one set from her mother and one from her father. Her mother’s chromosomes are loaded with genetic markers that pinpoint her Spanish heritage. Likewise, her father’s DNA is unmistakably Polynesian. But as the girl’s own eggs develop, her DNA gets mixed up.

In the cells that give rise to an egg, a Spanish chromosome will pair up with its Polynesian counterpart. Segments of the chromosomes switch places. Each egg ends up with a new, hybrid chromosome. Now imagine that the girl grows up and marries a Spanish man. The DNA of her children will be only one quarter Polynesian, and the Polynesian DNA will be chopped up into even smaller segments. As the generations pass, the signs of interbreeding get even fainter.

Despite the challenge, Reich thought that detecting interbreeding could be important. It could expose some of humanity’s hidden history, or even shed light on why people are susceptible to certain diseases. When Reich arrived at Harvard Medical School, he began a study on prostate cancer that proved the value of this type of analysis by revealing the genes that make certain men more likely to develop such cancers. “Prostate cancer occurs 1.5 to 2 times more often in African American men than in European men,” Reich says. “We were able to find the reason why.”

To do so, Reich had to reconstruct the genetic history of African Americans, who came to the United States as slaves beginning in the 17th century. White owners sometimes had sex with their slaves and fathered children, thereby introducing European genes into the African American population. Freed slaves also had children with Native Americans and Latinos. As a result, African Americans today may have up to 80 percent European DNA.

...Finally, Reich and his colleagues had no choice but to conclude that Neanderthals had mated with humans. They estimated that the DNA of living Asians and Europeans was (on average) 2.5 percent Neanderthal. They had to reject a pure version of the out-of-Africa model. Instead, their model was closer to out-of-Africa-and-get-to-know-some-Neanderthals-very-well.

The patterns Reich and his colleagues identified can help narrow down when and where the interbreeding took place. Since Africans do not carry Neanderthal DNA, it would appear Neanderthals bred only with the ancestors of Europeans and Asians. One possibility is that when humans emerged out of Africa some 50,000 or more years ago, they encountered Neanderthals in the Near East.

Once humans and Neanderthals mated, the humans continued to expand into Europe and Asia, taking Neanderthal genes with them. Another possibility is that the interbreeding came later. Neanderthals lived across a vast range, from Spain to Russia. As humans came into contact with Neanderthals, they might have mated in several places... Clearly the hybrid children from these interbreedings had to have been accepted into human cultures. But we can’t say whether these couplings happened as rapes during violent battles between humans and Neanderthals or when individual Neanderthals were welcomed into human society. 

Max Blumenthal concluded his epic book, Republican Gomorrah-- Inside The Movement That Shattered The Party with an epilogue, an anecdote about Broun from 2009 called "The Anointing." By any definition, Broun is a Bronze Age throwback, a time which came considerably after we thought Neanderthals had gone extinct. He may well be the living proof that they're still alive and well. Blumenthal caught up with Broun and a couple of his crackpot friends trying to anoint a door that Obama would pass through with crosses painted in oil (or lard).

Although he was only a backbencher, Broun presented himself as the future of the House Republicans. Joining other right-wing members, he opposed the emergency financial bailout, attacked any efforts at immigration reform, and sponsored a bill to protect soldiers from images of unclad women. "Our troops should not see their honor sullied so that the moguls behind magazines like Playboy and Penthouse can profit," Broun proclaimed. His spokesman testified to his expertise as an "addictionologist" who is "familiar with the negative consequences associated with long-term exposure to pornography."

On cave walls?