About 2 million years ago. the first members of a new species, Homo erectus, appear, and their oldest remains so far have been found at the sites of Drimolen in South Africa and Garba in Ethiopia. Both sites were found at an altitude above 1600 m. At the Garba site, the oldest, even more sophisticated, stone tool of the Acheulean period was found. Sites at higher altitudes, as well as the fact that members of this species were the first to spread from Africa to Eurasia, speak of complex cognitive abilities and successful survival in areas with new biomes, i.e. other plant and animal species and food sources. More complex cognitive abilities also result from the increase in brain volume that is present at the beginning of this species, and the trend of increasing brain volume continues further within this species.