A move from rainforest to savannah and woodland led first to bipedalism (walking on two feet). Later, hunting and social needs led to larger brains and the making and use of tools. These differences between human beings and the other great apes are certainly important. However, a genetically based taxonomic classification shows the genetic differences are not enough to divide us into separate families. Genetics, rather than morphology, is generally more widely accepted as the critical standard. However, many scientists, including anthropologists, use the term "hominid" to mean humans and their direct and near-direct ancestors.