Figure 1 shows an attempt I made in 1979 to correlate some 

 features in hominid evolution with low-temperature episodes. The 

 hominid phylogenetic tree, as visualized then, was very simple in 

 comparison with any present day representation accommodating the 

 numerous new hominid taxa described during the last 20 years. As 

 Ian Tattersall (2000) has commented, our present situation of being 

 the only living hominid on earth is an unusual one; at any time 

 during the last few million years, several hominid taxa are likely to 

 have shared their habitats. The speciation that we observe in hom- 

 inid and other vertebrate lineages during the Plio-pleistocene in Af- 

 rica has almost certainly resulted from habitat fragmentation and the 

 isolation of small population groups. That open country was becom- 

 ing an important issue in this regard is clearly indicated by Elisabeth 

 Vrba's work (1995) on the first documented appearance of 37 new 

 antelope species, many of them open country grazers, between 2.7 

 and 2.5 million years, at a time when the robust australopithecine 

 lineage split from that leading to Homo. 



Some of the Dangers Inherent in More Open African Habitats and 

 the Need for Safe Sleeping Sites 



My emphasis here will be on predators known to have existed in 

 southern African savannah and grassland environments during the 

 last two million years, particularly those that would have posed a 

 threat to the security of hominids. Most of these animals are also 

 known to have existed further north in the continent, so they would 

 have interacted with the hominids whose fossil bones have been 

 found at the East African sites. In comparison to evergreen forests, 

 savannah environments certainly harbour a far wider range of car- 

 nivore species dangerous to hominids; but this is not to say that the 

 traditional forest habitats were without their hazards. Leopards, for 

 instance, have an extraordinarily wide habitat tolerance — from open 

 desert environments to tropical forests — and would certainly have 

 preyed on hominids before they left the forests. Other significant 

 predators would have been among the forest eagles, such as today's 

 Crowned Eagle, Stephanoaetus coronatus, although we do not have 

 information on its fossil history. It has been suggested (Berger and 



10 



