Common European traits like pale skin evolved relatively recently in central and southern Europe.
Researchers had long assumed that skin lightened as humans migrated from Africa and the Middle East into Europe around 40,000 years ago.
Experts had speculated that shorter day lengths and a sun lower in the sky favoured lighter skin, which more easily synthesised vitamin D.
But a groundbreaking 2015 analysis of the genomes of 83 prehistoric Europeans showed that populations in Europe about 8,000 years ago were still mixed and diverse.
Traits commonly associated with modern Europeans, such as tallness, the ability to digest milk, and lighter skin tone, only became ubiquitous in Europe relatively recently.
Experts found that about 8,500 years ago, early hunter-gatherers in central and southern Europe, including Spain, Luxembourg, and Hungary, had darker skin.
They lacked versions of two genes, called SLC24A5 and SLC45A2. These genes were responsible for ‘depigmentation’, and hence pale skin, in Europeans today.
In the far north of Europe, where low light levels favoured pale skin, the team found hunter-gatherers had a lighter complexion.
Two light-skin gene variants, SLC24A5 and SLC45A2, were found in seven people from the 7700-year-old Motala archaeological site in southern Sweden.
A third gene found in the group, HERC2/OCA2, has been linked to blue eyes and may also contribute to blonde hair and light skin.
The research shows that, contrary to previous theories, Europe was still a diverse continent up to at least 8,000 years ago, showing that pale skin developed in central and southern Europe much later than first thought.