Complex sentence: He also emphasized the need to integrate the ideas of Darwinian evolution into palaeoanthropology, which had not always been the case in much earlier research into human origins that had often relied on non-Darwinian models of evolution.
Split into simpler sentences: He also emphasized the need to integrate the ideas of Darwinian evolution into palaeoanthropology. Much earlier research into human origins often relied on non-Darwinian models of evolution.