It's long been known that Neanderthals and early Cro-Magnon man coexisted early on, but it has never been established how or why Neanderthals went extinct well before the advent of civilization. Some theories include inter-species warfare, or even inter-breeding that eventually "bred out" the Neanderthal line. In fact, author Jean Auel and others have made a career of postulating what the relationship between early humans and Neanderthals may have looked like. Michael Crichton's novel Eaters of the Dead even reimagined the story of Beowulf as fighting not dragons or monsters, but a race of mountain-dwelling Neanderthals that cannibalized the local human population. According to recent findings by the University of Montreal Pediatrics, as reported on Wired Science, there is strong evidence of what that relationship may have actually looked like, and it seems Neanderthals and early humans were close...very close.
The findings, published in Molecular Biology and Evolution, the research team analyzed 6,092 x-chromosomes from individuals of "all inhabited continents" to look for genetic markers, or segments of x-chromosomes common along genetic lines. They found that a significant population, nine percent of those contemporary individuals analyzed, contained a Neanderthal-derived segment of the x-chromosome. The official report explains, "this confirms earlier hypotheses that early moderm man and Neanderthals mixed and mated."
Neanderthals and modern man both originally evolved on the African continent, eventually migrating outside of the continent to eventually populate much of the world. However, Neanderthals left the African continent 200,000 to 400,000 years ago and had disappeared from the face of the Earth by around 30,000 BC. Early modern man migrated 80,000 BC to 50,000 BC, which leaves a significant amount of time in which early humans and Neanderthals were contemporaries and populations certainly maintained some form of contact with one another.
Furthermore, an earlier study explains how the team was able to identify the particular segment of the x-chromosome, called a haplotype, as being derived from Neanderthals. The Neanderthal genome was sequenced in 2010 and was quickly compared to the human genome, of which 6,000 genes were held in common. Of those types was a particular haplotype from the x-chromosome that was identical. This particular sequence was found in men of all inhabited continents with the exception of sub-Saharan Africa. They were also to pinpoint the highest frequency of inter-special mating. According to Discovery News, “The team believes most, if not all, of the interbreeding took place in the Middle East, while modern humans were migrating out of Africa and spreading to other regions.”
Though evolution remains a controversial topic yet among small segments of the population, these more recent findings have powerful implications for the interconnectedness of human populations. Derogatory remarks such as one is a "caveman" or a "neanderthal", the stuff of popular Geicko commercial campaigns, have less punch when it's revealed that every population maintains some connection to our predecessors. Races, ethnicity's, and populations all over the world seem to share the same genetic markers. Ultimately, even those populations that may have intermixed with an aberrant branch of the human lineage, have spread throughout the world and evolved into societies as culturally different, but genetically similar, as any other.