"Because Africa is n't one big homogeneous ecosystem . There are jungles , plains , deserts , swamps . Himps living in the jungle were n't in competition with himps that started migrating out onto the plains . Their food sources are different , their territories are different . The more suited to plains-dwelling we became , the less attractive a prospect it was to return to the jungle . Pretty straightforward , really ."
"But himps living in the jungle were in competition with other himps which did n't migrate to the plains . And pressures from predators , climate and changes in the ecosystem should have continued to force the need or desire to control their environment as our line of himp grew to do . My point is that with all of the same basic tools to start out with such as fingers , opposable thumbs and walking upright , there is no reason why only our line evolved to the level that human beings have attained with the same hundreds of millions of years , and the same pressures pushing us all forward , or towards extinction ."
"The more suited to plains-dwelling we became , the less attractive a prospect"
"there is no reason why only our line evolved to the level that human beings"