People who go to bed early and wake up early have their ancient ancestors to thank for this habit, or at least the Neanderthals, scientists say.

The classic Neanderthal lived over a wide area from the Near East and Asia, where it existed 135,000 years ago, to Western Europe 70,000-30,000 years ago. So, the Neanderthal lived very close to us and then disappeared.

And the Neanderthal may not have contributed to our evolution, but the advances he made in behavior, thought, and culture are remarkable. Which suggests that in his gene pool related to our own the “expression” of increasingly advanced human traits perfected in our species had begun.

DNA inherited from our “cousins” may contribute to some people’s tendency to be morning types, researchers have found, making them more comfortable getting up and going to bed earlier than others.

While most genes acquired by modern humans through ancient interbreeding have been eliminated by evolution, a small sample remains, likely because they helped early modern humans adapt to the new environment when they left Africa for Eurasia.

“By analyzing the bits of Neanderthal DNA that remain in the genomes of modern humans, we discovered a striking trend“, said John Capra, an epidemiologist at the University of California, San Francisco. Many of these affected genes that regulate “body clocks” in modern humans, he said, in most cases “increasing the tendency to be a morning person.”

Waves of Homo sapiens migrated from Africa to Eurasia about 70,000 years ago. Upon their arrival they encountered the Neanderthals, who had already adapted to a colder climate, having occupied the area hundreds of thousands of years earlier. Thanks to interbreeding between the groups, humans living today carry up to 4% of Neanderthal DNA, including genes linked to skin color, hair, fat and immunity.

Capra and his colleagues analyzed DNA from modern humans and Neanderthals and found that different genetic variants were involved in the two groups’ “body clocks,” or circadian rhythms.

Since the ancestors of modern humans mated with Neanderthals, it was possible that some people living today carried the Neanderthal variants, they reasoned.

To check this, the researchers turned to the UK Biobank, which contains the genetic, health and lifestyle information of half a million people. Not only did many people carry the variants, but the genes were consistently linked to waking up in the morning, the scientists write in Genome Biology and Evolution.

Professor Mark Maslinof University College London, who was not involved in the study, said: “We now have genetic evidence that some of us really are morning people.”