WASHINGTON — A new study is raising questions about when ancient human ancestors in Europe learned to control fire, one of the most important steps on the long path to civilization.

A review of archaeological sites across Europe shows habitual use of fire beginning about 400,000 years ago. That’s a lot more recent that most archaeologists thought, considering the fact that Neanderthals and modern humans lived in that cold climate long before that time.

Other researchers have argued that the use of fire to cook food could have occurred as much as a million years ago. That would have provided improved nutrition, allowing for bigger brains and the development of modern people.

The new research is in Tuesday’s edition of the Proceedings of the National Academy of Sciences.