So, did Neanderthals interbreed with humans?

I’ve mentioned from time to time that Neanderthals interbred with humans. The evidence shows that we have upwards of 4% of their DNA, depending on where our relatively recent ancestors lived. That is, people of European and Asian descent have a far higher chance of sharing DNA with our Neanderthals cousins than someone more recently from Africa. This is good evidence that we were not entirely separate species, but rather close branches on the evolutionary tree. However, new evidence suggests that our cousins weren’t at the right place at the right time for this to all make sense:

Previous dating of bone fossils found at Neanderthal sites in the region put the youngest at about 35,000 years.

But researchers from Australia and Europe re-examined the bones using an improved method to filter out contamination and concluded that the remains are about 50,000 years old.

If true, the study, casts doubt on the idea that modern humans and Neanderthals co-existed — and possibly even interbred — for millennia, because humans aren’t believed to have settled in the region until 42,000 years ago.

As always, absence of evidence is not necessarily evidence of absence. It’s still quite possible that Neanderthals hung around for another one or two thousand decades. Alternatively, humans may have arrived on the scene earlier than once thought. The problem is that we don’t have the fossil record to back any of that up.

The way I think the way this alters our view is not that it shows that Neanderthals and humans didn’t interbreed. Obviously for the above given reasons, that isn’t tenable. Instead, I think we have to revise a whole host of specifics; this is a quantitative problem, not a qualitative one.

How should we treat cloned Neanderthals?

Harvard geneticist George Church was recently interviewed by a German magazine where he said that we need to start talking about the ethical and other implications of cloning a Neanderthal. He said that, whereas the technological possibility is foreseeable in the relatively near future, we need to start the conversation today. Unfortunately, English-based media sensationalized his comments and falsely claimed that he was looking for a surrogate mother:

Harvard geneticist George M. Church was quoted in the Daily Mail as looking for an “adventurous woman” to serve as a surrogate for a “cloned cave baby.” The shocking headline spread quickly across the media with no small amount of help from major news aggregators like the Drudge Report…

“I’m certainly not advocating it,” Church told the Herald. “I’m saying, if it is technically possible someday, we need to start talking about it today.”…

Church added that he wasn’t even involved in the particular aspects of the Human Genome Project focused on Neanderthals. Nonetheless, he hopes to use the mistake made by the media for the greater good. “I want to use it as an educational moment to talk about journalism and technology,” he said.

To compound the mistake made by the media, people like Arthur Caplan, writing for CNN, continues to spread falsehoods even after the correction has been made:

Despite a lot of frenzied attention to the intentionally provocative suggestion by a renowned Harvard scientist that new genetic technology makes it possible to splice together a complete set of Neanderthal genes, find an adventurous surrogate mother and use cloning to gin up a Neanderthal baby — it ain’t gonna happen anytime soon.

My beef is with the baseless accusation that Church was being intentionally provocative. Here is what he actually said:

SPIEGEL: Mr. Church, you predict that it will soon be possible to clone Neanderthals. What do you mean by “soon”? Will you witness the birth of a Neanderthal baby in your lifetime?…

SPIEGEL: Would cloning a Neanderthal be a desirable thing to do?

Church: Well, that’s another thing. I tend to decide on what is desirable based on societal consensus. My role is to determine what’s technologically feasible. All I can do is reduce the risk and increase the benefits.

In other words, the magazine asked him all these things. He gave pretty uncontroversial answers, even choosing to take a rather neutral stance when asked if we should clone a Neanderthal. I think the evidence is clear that not only was Church not being intentionally provocative, he was actually attempting to give benign answers.

At any rate, this all does raise the interesting question of how we would treat Neanderthals if we did clone them. Would we give them the same rights and protections? Would we develop a new application for the old scourge of apartheid? I’m not sure the answers to these questions, but I do have some input on how we should go about considering them.

Humans are awfully fond of talking about our special status in the animal kingdom. Indeed, many of us refuse to even consider ourselves animals, disregarding the affront to biology such a stance is. Of course, we have some good reasons for separating ourselves, at least in the context of morality and ethics. Though such practices, common across many taxa, are little more than game theory working itself out amongst genes and individuals, humans take it to another level. So while, for example, our ape cousins will show rudimentary understandings of right and wrong, we have far more complex rules for our society, rules that we can reason out and justify by way of our higher level of intelligence. We are different and that’s important.

How different, though, are Neanderthals? We know a fair amount about them, but they haven’t been around for 20 or 30 thousand years. No one has interacted with them, so a cloned baby would be an experiment in every sense of its life. So how different would it be? Would we have criteria established that said, ‘If the Neanderthal is different in these certain ways, it will not enjoy the same rights afforded everyone else under our laws’? I don’t know, but the concern is an interesting one because it raises the issue of why we think we’re so special.

Evolution is a continuous process. We are descended from species which were not human, but at no point did one species give birth to a brand new one. Every mother gives birth to offspring that are categorized in the same way she is. However, when enough time has passed, we’re given the luxury of defining different groups as species within this or that Genus under one or another Family. But look over the tape of evolution and everything eventually converges and lines blur. Just think about human evolutionary history: Back things up 100,000 years and we’re largely the same. How about 150,000? 300,000? 1,000,000? At some arbitrary point we pick, we’re going to start defining significant differences, but if we continually shrink the window of time, the differences start to disappear. (This is all a huge problem, in my view, for the Catholic or other theistic evolutionist who believes only humans have souls.) So from 500,000 years ago to 100,000 years ago, there will be notable change, but that change will be smaller between 400,000 and 200,000 years ago. And the differences become less when we look at our history from 300,000 to 200,000. Keep going and we may be talking about how different our ancestors from 272,000 years ago were from our ancestors living 271,000 years ago. Forget that our investigations into the history of life can’t get that specific. What’s important is that we have to realize there is no line in the sand that says “Species A ends there and Species B begins here”.

So if we do decide that Neanderthals are less deserving of the rights given to humans, we have to admit that humans, at some point in our lineage, were also not deserving. That is, our intelligence and consciousness become more and more comparable to our cousin apes (and now extinct man-like cousins) as we go back in time; we eventually arrive to a point where we would not give our ancestors the same rights that we enjoy. That means we are not inherently special, and I think that’s a major blow to a lot of our assumptions. The supposedly humble Neanderthal shines light on our human arrogance.

Humans may have left Africa sooner than once thought

I said my views on evolution are always evolving. This is a good example of that.

Modern humans may have left Africa thousands of years earlier than previously thought, turning right and heading across the Red Sea into Arabia rather than following the Nile to a northern exit, an international team of researchers says.

Stone tools discovered in the United Arab Emirates indicate the presence of modern humans between 100,000 and 125,000 years ago, the researchers report in Friday’s edition of the journal Science.

While science has generally accepted an African origin for humans, anthropologists have long sought to understand the route taken as these populations spread into Asia, the Far East and Europe. Previously, most evidence has suggested humans spread along the Nile River valley and into the Middle East about 60,000 years ago.

“There are not many exits from Africa. You can either exit” through Sinai north of the Red Sea or across the straits at the south end of the Red Sea, explained Hans-Peter Uerpmann of the Center for Scientific Archaeology of Eberhard-Karls University in Tuebingen, Germany.

“Our findings open a second way which, in my opinion, is more plausible for a massive movement than the northern route,” he said in a telephone briefing.

These findings are always interesting, but it takes so much evidence to come to any sort of conclusion that the theories put forth are always so tentative. We can say humans probably left Africa earlier than previously thought, but speculation on a new route is less solid.

One recent theory I recall hearing is that humans and Neanderthals once interbred. There is some evidence for it, and just last year some good DNA evidence was uncovered showing as much. In fact, I would go so far as to confidently proclaim that the evidence solidly shows humans interbred with Neanderthals very early in the human exit from Africa. Beyond that, I very much doubt there was interbreeding; the Neanderthals in all probability died out as a unique species, unable to breed with H. sapiens.

I mention this theory because the first thing that popped into my mind upon reading the first few paragraphs of the article was how long it would take until someone suggested Neanderthals may have been responsible for the toolmaking.

The techniques used to make the hand axes, scrapers and other tools found at Jebel Faya in Sharjah Emirate suggest they were produced by people coming from somewhere else, said Anthony E. Marks of Southern Methodist University in Dallas, adding that there are similar tools made about that time in East Africa.

“If these tools were not made by modern man, who might have made them?,” Marks asked. “Could Neanderthals have made them?”

Neanderthals were mainly in Europe and migrated into Russia but “there is no evidence for any Neanderthals south of that” zone at that time, he said. “To suggest one group of Neanderthals took a turn south and went several thousand kilometers … seems to me a very difficult explanation and one that doesn’t follow any reasonable logic.”

I have to agree with that assessment of the data. Humans moved towards Neanderthals, plausibly going through the areas of this recent discovery, not the other way around. Now that we have evidence left by our ancestors, this adds a new route humans took when leaving Africa. I find the scenario plausible, even likely. It still isn’t certain, but there is now some good evidence for it.