I've always wondered what life was like before history. What it must've been like for our ancestors, the hunter-gatherers: the Cro-Magnons, Neanderthals, Denisovans, and the countless others for whom we have no names. What we have left are fossils (bone, teeth, and tools), burial sites (jewelry, adornments, and clothing), trash pits (with the remains of animals and enemies), and speculation. Lots, and lots of speculation. The best known examples of our common thread with ancient humanity from this time period are paintings on cave walls, deer antlers turned to flutes, and a kind of compassion demonstrated by strong evidence of prolonged care for the dying and a seemingly deliberate arrangement of the dead. A certain notion of the future that goes beyond earthly planning, beyond the next few days, the next few seasons, years, and generations. A notion of the future that goes so far ahead it wraps back around.
The Neanderthals co-existed with the direct ancestors of modern humans for tens of thousands of years. Many scientists have come up with different theories of what first encounters must have been like (the Neanderthals ranged over a vast portion of Europe and Western Asia, so there must have been numerous first encounters) and why these people one day vanished off the face of the earth. Jared Diamond, for example, the author of Guns, Germs, and Steel, suggests violent conflict and displacement. The same thing that happened in history when the Europeans first landed in America. A technological divide so vast, one culture could not help but completely dominate the other. It sounds like a sad fate for a people where much evidence suggests an intelligence on par with modern humans, a cranial capacity on average exceeding our own, the possession of a gene closely linked with advanced language skills, and a culture that valued the injured and held a capacity for a concept of the afterlife.
Others suggest climate change. Still others a volcanic eruption. None of these theories are mutually exclusive. They could have all worked in tandem, contributing collectively to the sealed fate of an ancient race of human beings. But an alternate explanation has come up in recent years, thanks to more advanced techniques in DNA analysis. That is, one of interbreeding. About 1-4% of modern European and Asian genes are believed to be inherited from the contributions of the Neanderthals. These genes are only present in Africans when present in both Europeans and Asians, but not the other way around, suggesting that these traits were brought into the gene pool after migration from Africa.
Paleontologist Björn Kurtén wrote a fictional account of a possible scenario playing out involving interbreeding. He called it Dance of the Tiger. In his short novel, he imagines a world where the Neanderthals are enamored when encountering Cro-Magnons. Their height, softer facial features, darker skin, ability to make speech with fluency and ease. All these things came together and captivated the hearts of Neanderthals. Whenever they could, they would interbreed. The only problem was, and this is supported by the same DNA analysis mentioned earlier, that when a Neanderthal woman had a child with a Cro-Magnon man, their child would be infertile. Much like when a horse mates with a donkey to produce a mule. However, when a Cro-Magnon woman had a child with a Neanderthal man, this was not necessarily the case. But DNA evidence suggests that in order to account for a 1-4% contribution to the overall gene pool, this only happened about once in every 30 years.
In other words, according to this theory, an entire race of humans died off because they loved other humans who did not love them back.