The situation might not have been pretty, but Neanderthals and Homo sapiens were both living in Europe at the same time for around 5,400 years, according to a new study that has many other implications.
For starters, it's now possible that Neanderthals and our species mated and otherwise interacted for some 20,000 years.
PHOTOS: Are You Related to Neanderthals?
"Significant interbreeding between Neanderthals and early modern humans had probably already occurred in Asia more than 50,000 years ago, so the dating evidence now indicates that the two populations could have been in some kind of contact with each other for up to 20,000 years, first in Asia then later in Europe," Chris Stringer, research leader in Human Origins at the Natural History Museum in London, explained.
"This may support the idea that some of the changes in Neanderthal and early modern human technology after 60,000 years ago can be attributed to a process of acculturation between these two human groups," Stringer said.
For the study, published in the latest issue of the journal Nature, project leader Thomas Higham of the University of Oxford and his colleagues obtained new radiocarbon dates for around 200 samples of bone, charcoal and shell from 40 key European archaeological sites ranging from Russia in the east to Spain in the west.
The sites were either previously linked to the Neanderthal tool-making industry, known as Mousterian, or were so-called "transitional" sites containing stone tools associated with either our species or Neanderthals.
VIDEO: How Old Is the Human Race?
The results showed that both human groups overlapped for a significant period, giving what Higham and his team say was "ample time" for interaction and interbreeding.
We already know the latter happened.
Stringer said, "Neanderthals are our closest-known relatives, and research has recently shown that nearly all humans alive today have a small percentage of Neanderthal DNA in their genomes. This interbreeding probably occurred soon after small groups of early modern humans began to leave their African homeland about 60,000 years ago."
The "small percentage" isn't necessarily because so few interbred. Also, other studies have concluded that one-fifth (and possibly more) of the Neanderthal genome survives in modern humans and influences skin color, hair color and texture, and other traits.
As for what happened to the Neanderthals afterward, researchers still aren't entirely sure. The new chronology established by the paper suggests that Neanderthals may have survived in dwindling populations in pockets of Europe before they became extinct.
NEWS: First Love Child of Human, Neanderthal Found
"Extinct" is also somewhat of a loaded term, because Neanderthals and their culture were absorbed into the modern human population. Their distinctiveness as a separate species, however, bit the evolutionary dust. As Stringer said, "Neanderthals had largely, and perhaps entirely, vanished from their known range by 39,000 years ago."
He mentioned that this point in time intriguingly coincides with a long spell of miserable weather - cold and dry conditions - throughout much of Europe. The climactic event, he said, might have "delivered the coup de grâce to a Neanderthal population that was already low in numbers and genetic diversity, and trying to cope with economic competition from incoming groups of Homo sapiens."
Photo: A recreation of a Neanderthal family. Credit: JPL/NASA