Neanderthals and humans replacing one another, more than once

The discovery of tiny, fine points that had to be arrowheads in Grotte Mandrin, an inland rock shelter in southern France, was published this week in Science Advances by Laure Metz of Aix-Marseille University and Jason Lewis of Stony Brook University, led by Ludovic Slimak of CNRS. The arrowheads were found in alongside modern human teeth, which was reported by the same team and additional colleagues two weeks earlier.

The teeth and arrowheads were found in a sediment layer dating to between 56,800 and 51,700 years ago. This means that modern humans reached western Europe way before the roughly 45,000 years ago that had been believed until now.

These startling finds do not change the paradigm of when modern humans swept over Eurasia and persisted there, prevailing over rival human species once and for all, but they do make the picture of modern human-Neanderthal interface more complex.

For one thing, we learn of early “attempts” to spread to Europe. Archaeological analysis of the shelter detected no less than four alternating stages of replacement. (All the figures have a margin of error of a couple of thousand years either way.)

First, Neanderthals lived there until about 54,000 years ago, when modern humans equipped with bows and arrows arrived from the Levant (according to Slimak, in a paper in process). They didn’t stay long. Then Neanderthals regained the spot. Finally, modern humans came back around 44,000 years ago which is not long before the Neanderthals in Europe died out.

In fact, Slimak believes the peopling of Europe occurred in several waves, in which modern humans trekked from the Levant between 55,000 to 42,000 years ago. But now let us return to the rock shelter of Grotte Mandrin, where some of those people wound up.

One generation

This sequence of Neanderthal/sapiens switching is the first discovery of its kind in Europe, but it seems the humans and Neanderthals didn’t cohabit or influence one another, based on analysis of the stone tools. “Local Neanderthals and the incoming first modern humans of Europe show very distinct traditions,” Slimak explains.

Does that mean they didn’t meet? “It is very likely that these two populations developed some kind of interactions, and that these early Homo sapiens may have acquired some very specific knowledge from the local Neanderthals,” he says.

For instance, these modern humans could have learned from the Neanderthals about the territory's resources, particularly where to find the specific kind of flints these groups would want for their tools and weapons, he suggests. But there is no sign of technological influence per se.

Also, the first round of modern humans in the shelter, replacing the original Neanderthal inhabitants, seem to have come and gone quite quickly. They only seem to have stayed for about 40 years, Slimak says.

That is a highly intriguing duration, in his opinion. “If the humans who arrived in that territory [were aged] between, let’s say, 20 and 40 when they arrived, we then can state that they stayed in that territory until they were 60 to 80 years old. Meaning that they stayed all their lives, but had no descendants who stayed after their death.”

The upshot inference is a scenario of rapid replacement processes at this site, the archaeologists sum up. It also shows that the supplanting of the Neanderthals in Europe was a convoluted process, with populations going back and forth and replacing each other; in this shelter southern France, that occurred not once, but twice.

This cave is hardly unique. Last year, “environmental DNA” analysis of the soil in Denisova Cave found evidence of three human variants over a quarter-million years: first Denisovans, then Neanderthals, then the two species came and went and also interbred, and were supplanted by later versions of both species; and eventually Homo sapiens arrived and moved in about 45,000 years ago. In Israel’s Negev Desert, Neanderthals and modern humans were coexisting – if not necessarily cohabiting – 50,000 years ago.

Bone of contention

The last common ancestor of sapiens and Neanderthals is thought to have lived in Africa 700,000 or 600,000 years ago. Our line would emerge in Africa, and theirs in Eurasia.

In Africa, Homo sapiens arose and developed the anatomically modern form by perhaps 175,000 years ago (some say our brain hasn’t appreciably changed since that time). The paradigm has been that modern humans only exited Africa and conquered the rest of the world about 50,000 years ago, and that seems to be true – but it may not have been for want of trying.

Recent research has shown that during the early phase of sapiens evolution, we exited Africa time and again – we just didn’t survive the experience. No trace of those early exiters has been detected in latter-day humans (according to genetic analyses). But we tried. Fossils believed to be of Homo sapiens from about 200,000 years ago have been found in Israel and Greece; some may have reached India 120,000 years ago, and others got to eastern Asia 80,000 years ago (but not all agree on the identification).

Why did earlier sapiens excursions beyond Africa “fail?” Did these groups die out, like in Mandrin? We don’t know; perhaps the groups were very small and larger migrations were stymied by geographical constraints or Neanderthal resistance – maybe until we showed up 56,800 to 51,700 years ago with our flashy new technology, bows and arrows.

Stick it

The crudest tools produced by the hominin line go back over 3 million years and were basically big rocks used as hammers. Capuchin monkeys happily use rocks as hammers too, but the hominin tools showed signs of deliberate knapping – shaping the stones. Capuchins don’t knap.

Neanderthals had spears. They could glue stone tips onto wooden shafts, and they also had sophisticated knapping technologies, especially towards the end. Sapiens and Neanderthal technology cannot always be distinguished in the archaeological record.

Over the eons, Neanderthal technology improved, but sapiens may have been unique in discovering the innovation of propelling their points – not just stabbing a deer or neighbor, but throwing spears from a safe distance, and later, developing the bow and arrow.

The jury is still out as to whether Neanderthals also threw their spears. Once their spears had been thought too heavy to be properly projected, but a theoretical study in 2019 using robust javelin throwers, rather than weedy students, debunked the thought that they couldn’t.

Even if Neanderthals could throw their spears, arrows are another kettle of fossil fish. Nary a shred of evidence has been found that Neanderthals had bows and arrows, which can be thought of as mechanically accelerated weaponry. But modern humans did, possibly as much as 70,000 years ago in southern Africa. Separate work identified arrows in Sri Lanka that may be as old as 48,000 years.

In European contexts, bow-and-arrow technology appears with evidence of modern humans, but the finds are not categorical. Use-wear analysis indicates that some of the artifacts dating to 45,000 to 40,000 years ago found in the Grotta del Cavallo, Italy were arrowheads.

Now the nanopoints identified in Mandrin kick back the technology’s introduction to Europe by at least 10,000 years. The archaeologists even speculate that their users may have been poisoning the tips.

One immediately suspects the modern humans with fancy technology of shooting the Neanderthals from a safe distance. But, in their paper, the archaeologists merely suggest that the bows and arrows and other propelled projectiles gave their owners a competitive advantage in hunting the local herbivores: horses, ibexes, bison and deer.

Asked if they don’t think the competition might have had non-gastronomic aspects, Slimak answers that there is evidence that the humans hunted (and ate) the animals, but there is no evidence of war.

“However, among almost all traditional populations, the hunter is also the warrior, and martial activities are almost universally widespread among human populations,” he adds.

One can reach their own suppositions about what the humans did with their accelerated pointy projectiles, and exactly what the competitive advantage was.

Not that it worked, in the sense that the modern humans who lived in Mandrin intermittently with Neanderthals did not leave descendants in today’s world. After about 40 years, as said, they were gone, and replaced by Neanderthals, who were then replaced by another wave of modern humans – who also apparently went extinct.

Ruth Schuster