According to a new study, early humans may have hibernated through the winters but it would have caused some serious side effects.
Experts came to this hypothesis based on data collected from an extinct human species who lived hundreds of thousands of years ago that was unearthed in a deep shaft of the Sima de los Huesos cave which is located at the UNESCO heritage site of Atapuerca in Spain. Antonis Bartsiokas and Juan-Luis Arsuaga, who are authors of the study, analyzed the human remains by using CT scans, microscopes, and close-up photography.
Based on their analysis, they discovered that the remains had vitamin D deficiency and the growth spurts in adolescents were relevant to certain seasons which suggested that the ancient humans may have hibernated in a dark location throughout the winter months. Bartsiokas and Arsuaga wrote in part, “The hypothesis of hibernation is consistent with the genetic evidence and the fact that the Sima de los Huesos hominins lived during a glacial period.”
But while they slept the winter away, their bodies suffered major side effects. For example, when bears hibernate, they build up a reserve of fat that gets them through the winter. The early humans, however, more than likely didn’t have that. Hibernating for so long could have caused bone and kidney disease in the humans.
While it’s still unclear as to which human species the experts analyzed, some of the remains have been confirmed as belonging to Homo heidelbergensis who lived during the Middle Pleistocene period, sometime between 770,000 years and 126,000 years ago. (A picture of the early human skull can be seen here.)
Homo heidelbergensis was the first early human species to live in colder climates and frequently hunt larger animals (wild deer, elephants, hippos, horses, and rhinos). They were also the first species to built shelters by using wood and rocks. As for what they looked like, they had a large brow ridge with a bigger braincase and a flatter face than other early humans. Males grew to an average of 5 feet 9 inches tall, while females had an average height of 5 feet 2 inches. Males weighed an average of 136 pounds (62 kilograms) and females weighed about 112 pounds on average (51 kilograms).
The researchers did note that their work is only in its preliminary stages but what they found so far is incredibly interesting. “While many questions about their life histories and metabolism are still open, there is no doubt as to the immense consequences that hibernation has for hominin/human physiology and life history,” they wrote. Their study was published in L’Anthropologie where it can be read in full.