Late last year, scientists unveiled the complete genome of a female Neanderthal whose 130,000-year-old toe bone had been found in a cave in Siberia. As it turned out, her sequence of some 3 billion DNA letters was not all that much different from mine or yours. The researchers identified only about 35,000 places in the genome where all modern humans differ from our ancient hominid cousins. And only 3,000 of those were changes that could impact how genes are turned on and off.

But if our DNA is so similar to Neanderthals’, why were they so…different? They were brawnier than our ancestors, with short but muscular limbs, and big noses and eyebrows. They didn’t carry certain genetic variants