Several weeks ago I sent a sample of my spit off to a commercial lab for DNA analysis. I got some results back yesterday. Some of the medical stuff was a little scary. I won’t go into that.
What did interest me was a finding I wasn’t looking for.
I need to give you a little background first. Over the past couple of decades, scientists have figured out how to sequence the DNA of organisms from very small samples. Sometimes they can recover enough DNA to do their tricks from the unwashed glass you drank from last week or from the bones of a several-centuries dead king who turned up buried under a British parking lot.
(In case you haven’t heard about that, what has now been confirmed to be the remains of Richard III turned up under a car park. As you might gather from how they threw him out with yesterday’s eggshells and pizza crusts, he wasn’t a popular guy.
Geneticists have confirmed that the skeleton belonged to the Tricky Dick of the fifteenth century by comparing DNA extracted from the bones with the DNA of living people who have well-documented genealogies showing them to be the several-times-great-grand nieces and nephews of the king voted most likely to have the cook spit in his soup. Don’t remember Richard III? Now is the winter of our discontent? The little princes in the tower? The really cool Third Reich film version of the Shakespeare play from a few years back? No? Never mind.)
Think those were old bones under that Toyota? Ha!
DNA analysis can now be done with bones of people who have been dead not for a measly few hundred but for tens of thousands of years! Scientists have been able to pull usable DNA from the bones of our cousins the Neanderthals.
It turns out that they were kissing cousins.
The short version is that unless all your ancestors decided to hang out in Africa over the last 50,000 years or so, somebody in your family line probably got intimate with a Neanderthal. You know how it is: long Ice Age night, there won’t be anything on television for 35,000 years, and somebody just invented beer. . . .
Neanderthals and the branch of proto-humans who eventually evolved into modern humans in Africa had parted company several hundred thousand years earlier. By the time a few modern humans started trickling out of Africa about 50,000 years ago and having family reunions with their long-lost kin in Eurasia, the two groups had evolved into different species. Think tigers and lions. Definitely some noticeable differences, but still similar critters in many respects.
Sometimes closely related species can make whoopee and produce viable offspring. It tends to be more the exception than the rule—most of the time it doesn’t work—but it can happen.
By comparing the DNA of long-term African humans with the DNA of Neanderthals and the DNA of non-African modern humans, geneticists have been able to identify genes that came into our modern global gene pool from our Neanderthal cousins.
It looks as if the aforementioned whoopee produced viable offspring often enough that a little Neanderthal DNA made its way into the human gene pool. We even have what looks like the skeleton of a first-generation hybrid. The DNA of some living individuals is as much as 4% Neanderthal.
Having that much Neanderthal DNA is rare. The average for non-Africans is about 2.5%. According to my test results, 3.2% of my DNA is Neanderthal, which apparently means I have more Neanderthal DNA than 99% of modern humans.
By the way, there is evidence that Neanderthals used cosmetics, cared for their sick (Neanderthal skeletons exist showing healed fractures that would have at least temporarily kept the injured individuals from surviving without help) and 60,000 years ago were tenderly burying their dead in graves lined with flowers. All that suggests that they were hardly the hulking brutes of popular imagination.
So what happened to our cousins?
At this point, we don’t know. Were they unable to adapt to climactic changes? Did modern humans engage in the genocide of an alien species that was competing for the same ecological niche? (They looked quite different from homo sapiens, and we know for damn sure that “kindness” is not a word that comes to mind in describing how humans treat even members of their own species who seem at all odd.) Were they decimated by diseases introduced by modern humans the way that diseases like smallpox introduced by Europeans all but wiped out Native American populations? At this point, the explanation is up for grabs.
What is clear is that, whether or not we ever meet extraterrestrial aliens with whom we can make whoopee (take a look at Mr. Spock’s family tree), modern humans have already encountered another intelligent humanoid species. In the end, the planet wasn’t big enough for both of them. Stephen Hawking thinks it might be a bad idea to attract the attention of alien societies. Maybe he has a point.