The first whole human genome from the bones of a southern European who lived before farming shows he was blue eyed, dark skinned, lactose intolerant and well equipped to fight diseases.
The discoveries about the 7,000-year-old Mesolithic ancestral European suggest the young man represents a transition that was still underway to create the lighter-skinned, milk-drinking people of more recent millenniums.
The genome of what's called the La Braña individual appears to have already acquired immunities to diseases that were thought to have been introduced to humans later, at the time when Europeans domesticated animals, which are thought to have transmitted the diseases to humans. The results were a surprise to the researchers who fully expected the man would have lighter skin and a more ancient set of immunity alleles, or groups of genes.
"What we found was just the reverse," said Carles Lalueza-Fox, one of 24 authors on a Jan. 26 paper reporting the discovery in the journal Nature. "So we're not sure what that means."
Other researchers agree that the precocious immunity of the La Braña individual is especially intriguing.
"The most surprising and interesting part is that the authors detected derived alleles in pathogen resistance genes," commented Albert Zink, director of the Institute for Mummies and the Iceman in Bolzano, Italy. "This can shed new light on the evolution and interaction of diseases in human populations. This is of particular interest as we know from other studies that some infectious diseases, such as tuberculosis, most probably have been present long before the Neolithic and doesn't necessarily have a (animal) origin."
The blue eye color was just as unexpected, but less problematic, said Carles Lalueza-Fox.
"We tend to think both things (skin and eye color) are related, but they are different genes," Carles Lalueza-Fox explained.
It's also not clear if there's any evolutionary advantage to blue eyes. It could just be from random genetic drift and not have any purpose. Skin color, on the other hand, is thought to be an adaptation to different amounts and intensity of sunlight.
Just how dark the La Braña man was is impossible to say, Lalueza-Fox told Discovery News, but it's clear he was much darker than modern Spaniards and that his genome is quite unlike that of the modern population level Spanish genome.
The man's lactose intolerance is the one thing that was not surprising, since a hunter-gatherer would not drink milk beyond infancy -- just like other mammals and all modern humans with the exception of those who come from milk-drinking cultures, Carles Lalueza-Fox explained.
The bones for the study came from a skeleton found in a cold cave at 5,000 feet (1,500 meters) elevation in the mountains of northern Spain. The cold was key to keeping the DNA intact for so long, said Lalueza-Fox. It's also the reason why there are so few ancient humans remains with such complete genomes available in the generally warmer climate of Southern Europe, he said.