Modern Human beings evolved in Africa from a variety of hominid species over a few million years. The first humans to leave the African continent were Homo erectus (upright man), who migrated northeast about 2 million years ago when present day deserts were grassland. These early hunters are thought at first to have been driven by changes in climate to follow migrating animal herds. Over time, they colonized the Middle East, southern Russia, India, the Far East and Southeast Asia. Homo erectus fossils have been dated in Georgia to 1.8 million years ago and in Java to 1.6 million years ago. Human fossil evidence from sites such as Atapuerca in Spain suggests that they were a form of Homo erectus (sometimes called Homo ergaster). Initial colonization was limited to the Mediterranean, but was probably not continuous with humans retreating to warmer environments during the colder phases of climate. There is slight evidence of humans in northern Europe from perhaps 700,000 years ago, but there seems to have been a major expansion over most areas from 500,000 years ago. These humans have been called Homo heidelbergensis after the site of Mauer near Heidelberg in Germany.
