Many animals hibernate (冬眠) for the winter. They stock up on food and hide away in a hole or cave to try (escape) the snow and cold. Scientists now believe early human beings may have hibernated too. The scientists, who are experts in studying fossils (化石) and ancient bones, looked (careful) at the fossils of bones from our early ancestors that lived around 430,000 years ago. They say that the cuts and other signs of damage on the bones (examine) by them are similar to those on bones of hibernating animals, like bears. They also say that early humans may have hibernated so they could escape the extreme cold. Winters were much (cold) hundreds of thousands of years ago than today.
The scientists say is evidence that early humans slowed down their metabolism (新陈代谢) so they could survive longer in winter without food. However, humans could not slow their metabolism like a bear. Bears can wake up after (month) of hibernation and their body will be the same as when they went into hibernation. The bones of the early humans showed people suffered health problems because hibernation. At that time, many of the problems (cause) by a lack of vitamin D, humans get from sunlight. This can make their bones weaker. The scientists say, "In the end, we have to say that hibernating is not always (health)."
