Debate continues over whether Homo erectus is a human ancestor. If Homo erectus and Homo ergaster are identified as separate species, Homo erectus would be a sibling rather than a true ancestor. Homo erectus was a successful, long-lived species that migrated out of Africa. Possibly the first humans to live in hunter-gather societies, they also used rafts to travel the oceans. One of the first specimens identified as Homo erectus was the Java Man fossil discovered in 1891. Orginally named Pithecanthropus erectus, it was not recognised as a close human relative at first, as old theories held that our ancestors would have had human brains and ape-like bodies, rather than the converse.