Human evolution
Main article: Human evolution A small African ape living around 6 Ma was the last animal whose descendants would include both modern humans and their closest relatives, the chimpanzees . Only two branches of its family tree have surviving descendants. Very soon after the split, for reasons that are still unclear, apes in one branch developed the ability to walkupright . Brain size increased rapidly, and by 2 Ma, the first animals classified in the genus Homo had appeared.Of course, the line between different species or even genera is somewhat arbitrary as organisms continuously change over generations. Around the same time, the other branch split into the ancestors of the common chimpanzee and the ancestors of the bonobo as evolution continued simultaneously in all life forms. T he ability to control fire probably began in Homo erectus (or Homo ergaster ), probably at least 790,000 ...