Neanderthals living in Europe were fair skinned, freckled and had ginger hair, a study has revealed.
The gene known as MC1R suggests the Neanderthals had fair skin and even freckles like redheads.
In a major breakthrough, Spanish scientists have discovered the blood group and two other genes of the early humans who lived 43,000 ago.
After analysing the fossil bones found in a cave in north-west Spain, the experts concluded they had human blood group "O" and were genetically more likely to be fair skinned, perhaps even with freckles, have red or ginger hair and could talk.
The investigating team from Spain's government scientific institute, CSIC, used the very latest forensic techniques to remove the bones for analysis to prevent them getting contaminated with modern DNA.
Carles Lalueza, an evolutionary biologist with the investigation, said: "What we were trying to do was to create the most realistic image of the Neanderthals with details that are not visible in the fossils, but which form part of their identity."
The report, published in BMC Evolutionary Biology, concludes that: "These results suggest the genetic change responsible for the O blood group in humans predates the human and Neanderthal divergence" but came "after humans separated from their common ancestor ... chimpanzees."
The Spanish scientists also describe how they also discovered two other genes.
One gene known as MC1R suggests the Neanderthals had fair skin and even freckles like redheads.
Another, a variety of FOXP2, is related to speaking and the capacity to create a language and therefore suggests they could communicate orally.
Neanderthals are believed to have numbered about 15,000 and lived in Europe and Asia for about 200,000 years until they became extinct about 30,000 years ago.
Since 2000, archeo-paleontologists, wearing special sealed white suits, masks and helmets have been painstakingly sifting through 1,500 bone fragments found in the "Tunnel of Bones" in the Sidrón cave complex in Borines, Asturias, north-west Spain.
Unnatural striations in the bones suggest that the Neanderthals practised cannibalism and broke the bones to pick out succulent bone marrow.
But why this group died, without wild animals discovering and contaminating their remains, or why indeed the Neanderthals in general became extinct, still remains a mystery.
"Really we can't establish a direct relation with why the Neanderthals disappeared," says Antonio Rosas.