Intermediate 
DNA taken from the wisdom tooth of a European hunter-gatherer has given scientists a glimpse of modern humans before the rise of farming. The Mesolithic man, who lived in Spain around 7,000 years ago, had an unusual mix of blue eyes, black or brown hair and dark skin, according to analyses of his genetic make-up.
He was probably lactose intolerant and had more difficulty digesting starchy foods than the farmers whose diets and lifestyles changed in the first agricultural revolution.
The invention of farming brought humans and animals into much closer contact and humans probably evolved stronger immune systems to fight infections from the animals. But scientists may have overestimated the impact farming had on the human immune system, because tests on the hunter-gatherers DNA found that he already carried genes that boost the immune system. Some of these gene mutations still exist in modern Europeans today.
Before we started this work, I had some ideas of what we were going to find, said Carles Lalueza-Fox, who led the study at the Institute of Evolutionary Biology in Barcelona. Most of those ideas turned out to be completely wrong.
The Spanish team started their work after a group of cave explorers found two skeletons in a deep and complex cave system high up in the Cantabrian Mountains of northwest Spain in 2006. The human remains, which belonged to two men in their early 30s, had been extremely well preserved by the cool environment of the cave.
Carbon dating put the remains at around 7,000 years old, before farming arrived in Europe from the Middle East. Other things were found at the site, including reindeer teeth that were strung and hung from the peoples clothing.
The scientists managed to put together one mans entire genome from DNA found in the root of a third molar. It is the first time researchers have got the complete genome of a modern European who lived before the Neolithic revolution.
The DNA brought some surprises. When Lalueza-Fox looked at the genome, he found that the man had gene variants that produce dark skin. This guy had to be darker than any modern European, but we dont know how dark, the scientist said.
Another surprise was that the man had blue eyes. The results suggest that blue eye colour came first in Europe and that the change to lighter skin happened throughout Mesolithic times.
On top of the scientific impact, artists might have to rethink their drawings of the people. You see a lot of reconstructions of these people hunting and gathering and they look like modern Europeans with light skin. You never see a reconstruction of a Mesolithic hunter-gatherer with dark skin and blue eyes, Lalueza-Fox said.
The Spanish team compared the genome of the hunter-gatherer to those of modern Europeans from different regions to see how they might be related. They found that the ancient DNA most closely matched the genetic make-up of people living in northern Europe, in particular Sweden and Finland.
Martin Jones, professor of archaeological science at Cambridge University, said the immunity genes were the most interesting result. There has been the idea that the move from a hunter-gatherer lifestyle to farming was bad for our health. There were a number of reasons for that, particularly living closely together with other humans and animals, which meant they competed for the same water supplies, he said.