Long before this cave painting was made, our ancestors met and interacted with multiple types of ancient human. (Credit: Jannarong/Shutterstock)

For the past ~40,000 years, Homo sapiens — modern humans — has been the only Homo species on Earth. But for most of our history, there were close evolutionary cousins of ours, human but not quite like us, coexisting and evolving at the same time in different regions.

Some of our now-extinct relatives, such as the Neanderthals, are well known. Oth