Many animals hibernate the winter. They stock on food and hide away a hole or cave to escape the snow and cold. Scientists now believe early human beings may have hibernated too. The scientists looked the fossils of bones our early ancestors who lived around 430,000 years ago. The bones were found a site in the north of Spain. The scientists are experts in studying fossils and ancient bones. They say that the cuts and other signs damage the bones they examined are similar to those bones of animals who hibernate, like bears. They also say that early humans may have hibernated to escape the extreme cold. Winters were much colder hundreds of thousands years ago.
The scientists looked the bones of several dozen humans. Scientist Antonis Bartsiokas said there is evidence that early humans slowed down their metabolism so they could survive longer winter without food. However, humans could not slow their metabolism a bear. Bears can wake after months hibernation and their body will be the same as when they went hibernation. The bones the early humans showed people suffered health problems because hibernation. Many of the problems were caused a lack of vitamin D, which we get sunlight. This can make our bones weaker. The researchers said: "We have to emphasise that hibernations are not always healthy."