Bears are the classic symbol of the act of hibernating to save energy during the winter. However, wild rats, squirrels and bats, as well as many other animals also do it. And as a new study suggests, the first humans hibernated. The researchers published the study in the French journal Anthropology .

In most of Brazil, we don't suffer much from winter. However, in mountainous regions and latitudes with temperate or polar climates, winters harshen life - both plant and animal - causing a shortage of food. Therefore, the best way to survive is to save energy and keep your body working only for essential functions. That's wherehibernation enters - through it, the animal dramatically reduces its metabolism.

First, however, I must remember that this is still a hypothesis. "Extraordinary claims require extraordinary evidence," as Carl Sagan once said. So, for now we cannot say with certainty that early humans hibernated

Evidence?

Researchers found evidence at archaeological sites. The bones suggest the behavior for Neanderthals and other human species predecessors to sapiens. The last human species to inhabit the planet were Neanderthals; the two species co-habited the planet for tens of thousands of years.

They were based on bones found at an excavation in the Sima de los Huesos cave in Atapuerca, in northern Spain. The remains of these primordial humans date back more than 400,000 years - even before the homos sapiens arise.

The Spanish archaeological site was already of great importance previously, as it was one of the key points for the understanding of human evolution and behavior throughout Europe. There, researchers found fossilized human remains from a great period of time in a 15-meter deep pit.

The excavation site. (César Manso / AFP).

They argue that a pattern of lesions on the bones are the main evidence supporting the claim. The lesions would indicate some seasonal variations in bone characteristics, that is, temporal variations. According to the authors, bone growth stopped at various times, at intervals of a few months.

"Both animal hibernation and human renal osteodystrophy are characterized by high levels of parathyroid hormone in serum. To test the hibernation hypothesis in an extinct human species, we examined the collection of hominid skeletons from Sima de los Huesos, Cave Mayor, Atapuerca, Spain, for evidence of hyperparathyroidism after a thorough review of the literature."report the researchers in the study.

These injuries even caused bone diseases in individuals.

What if the first humans didn't hibernate?

One of the foundations of science lies in questioning, so the researchers decided to test some questions themselves. To this day, many people live in primitive ways in extremely cold places, such as the Inuit and Sámi. But why, then, don't they hibernate?

According to the research duo, the Inuit and Sámi people get the energy and food they need for the winter from the fatty fish they catch, so there is no need to hibernate to conserve body reserves.

But for the region where the Sima de los Huesos cave is located there was no such immediate availability of food in the surroundings. The cave is located at a considerable distance from the coast for the constant obtaining of fish and seafood without adequate logistics, for example.

Northern bat hibernating (Magne Flåten / Wikimedia Commons).

"The aridification of the Iberian Peninsula could not provide enough fat-rich food for the Sima people during the harsh winter - causing them to resort to hibernating in caves," the researchers write.

In addition, they cite other mammals and primates with hibernation behaviors. According to the scientists, this could maintain the genetic and physiological basis for hibernation in humans.

What do other scientists think?

"It's a very interesting argument and will certainly stimulate debate," anthropologist Patrick Randolph-Quinney told the The Guardian However, there are other explanations for the variations seen in the bones found at Sima and we must address these fully before reaching any realistic conclusions. This has not yet been done, I believe.

Scientists who did not participate in the study are said to be fascinated by the possible idea that early humans hibernated, though extremely cautious.

The study was published in the journal L'Anthropologie, with information from The Guardian and Independent.