Like bears. The claim is based on excavations at the “Pit of Bones” in Spain:
Evidence from bones found at one of the world’s most important fossil sites suggests that our hominid predecessors may have dealt with extreme cold hundreds of thousands of years ago by sleeping through the winter.
The scientists argue that lesions and other signs of damage in fossilised bones of early humans are the same as those left in the bones of other animals that hibernate. These suggest that our predecessors coped with the ferocious winters at that time by slowing down their metabolisms and sleeping for months.Robin McKie, “Early humans may have survived the harsh winters by hibernating” at The Guardian Paper. (paywall)
Others seem just as certain that they didn’t hibernate:
Humans don’t hibernate for two reasons. Firstly, our evolutionary ancestors were tropical animals with no history of hibernating: humans have only migrated into temperate and sub-arctic latitudes in the last hundred thousand years or so. That’s not quite long enough to evolve all the metabolic adaptations we would need to be able to hibernate.Natalie Harrison, “Why don’t humans hibernate?” at BBC Science Focus
As Harrison points out, humans also discovered fire and clothes in the meantime.
One might add, storytelling around the fire.
Of course, there is a serious question whether humans even can hibernate. Here’s an argument that it’s possible:
Anyway, we don’t. Maybe our ancestors didn’t either and the “signs of damage in fossilised bones” are due to other causes. Interesting idea though.