According to my brief internet searches, Homo erectus
was begotten by Homo habilis
around 1.8 million years ago, began in Africa
, spread into Asia
, and merges into Homo sapiens
(us) about 400 000 years ago.
Homo erectus were very successful in developing cultural technologies that allowed them to adapt to new environmental opportunities. They were true pioneers in developing human culture and in moving out of Africa to populate tropical and subtropical environmental zones elsewhere in the Old World, possibly as early as 1.8 million years ago. Surprisingly, however, they remained largely unchanged anatomically until about 600,000 years ago. After that time, there were progressive evolutionary developments in features of the head that were characteristic of modern humans. By about half a million years ago, Homo erectus evidently was able to move into the cooler temperate environmental zones of Asia and the fringes of Europe for the first time. This migration was made possible by greater intelligence and new cultural technologies.
Below the neck, the Homo erectus were anatomically like modern humans.
Tutorial on Human evolution, Dennis O'Neil, http://daphne.palomar.edu/homo/homo_2%20.htm
"new cultural technologies" may refer to the domestication of fire, which is thought to have taken place around half a million years ago. Given the homo symbolicus argument that our tools shape us, perhaps the new technologies were the spur for the "progressive evolutionary developments" that brought us about.