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The scientists looked at the bones of
dozen humans. Scientist Antonis Bartsiokas said there is
that early humans slowed down their
so they could survive longer in
without food. However, humans could not slow their metabolism like a bear. Bears can wake up after
of hibernation and their body will be the same as when they went into
. The bones of the early humans showed people suffered health
because of hibernation. Many of the problems were caused by a
of vitamin D, which we get from sunlight. This can make our bones
. The researchers said: "We have to emphasise that hibernations are not always
."
