Back in the early ’00s, he and his team had identified a particular piece of DNA in the human X chromosome that seemed out of place with everything else, and they wondered whether it might have originated from a non-human source.
That answer came with the first sequencing of the Neanderthal genome last year. Dr. Labuda compared 6,000 chromosomes from all over the world to the corresponding part of the Neanderthal sequence. With the exception of people from sub-Saharan Africa – whose ancestors would have been unlikely to come into contact with Neanderthals, since their territories didn’t overlap – every chromosome featured evidence of the Neanderthal sequence.
That even includes particularly far-flung groups of humans like native Australians, who are thought to have reached the island continent by as far back as 40,000 years ago. For that sequence to show up even in such geographically isolated groups, it suggests that there was a lot of interbreeding between the two hominid species, and that pretty much all ancient humans that left Africa passed through Neanderthal territory and had close interaction (read: a ton of sex) with their evolutionary cousins.
* for those who don’t know, this is the comedy catchphrase of UK light entertainment veteran Bruce Forsyth, who so far as I know is no more and no less Neanderthal than the rest of us non-subSaharans.