He speculated that the rise of agriculture had led to human encroachment on wild forests, giving the chimp version of the bug, P. reichenowi, the chance to find a new host.

• 利文斯通推测，应该是在原始农业兴起、人类祖先慢慢侵入原始森林的时候，生长在黑猩猩身上的亚种疟原虫伺机寻得了新的宿主。