What capabilities helped Homo erectus survive?
Homo erectus' ability to make complex tools was possible because of the strength and dexterity in its hands, which it owes to a certain hand-bone projection called a "styloid process" that was previously thought to only exist in Neanderthals and modern humans, according to a 2013 PNAS study.
How did Homo erectus change?
Homo erectus was the first known human species to evolve modern body proportions—including shorter arms and longer legs that indicate an upright walking lifestyle that permanently traded the trees for the ground.