These early hominids experienced the interpreted environmental changes. These changes, however, probably had little negative affect on this hominid. In fact, the adaptations that permitted Homo erectus to leave Africa were most likely well suited to the open woodland environments subsequently encountered. These adaptations include larger body size compared to earlier hominids, bipedality, linear body proportions, and a more sophisticated tool kit (Spencer, 1997).
Specifically, bipedality would have permitted foraging in open environments (Rodman and McHenry, 1980), whereas large body size would have been useful for surviving interactions with large predators also found in these habitats (Walker, 1993). Others (Anton et al., 2002) have suggested that the maintenance of this large body size, as well as increased brain size, may have resulted from greater nutritional dependence on animal fat and protein. This may have necessitated the increase in tool sophistication for acquiring this additional component of the diet. Finally, the long, linear body proportions found in Homo erectus might have been an advantage for heat dissipation in tropical, open grasslands, like those found in Java during this time (Ruff, 1994).
Anton et al. (2002) have proposed a model for the initial hominid dispersal from Africa. They suggest that ecological change provided an increase in niches within grassland and wooded grassland environments for terrestrial herbivores. Hominids of relatively larger brain and body size, in turn, took advantage of these animal resources and ultimately increased their own reproductive success (Leonard and Robertson, 1997; Anton et al., 2002). As foraging strategy and the ecosystem structure changed, the home range of these hominids increased leading to greater dispersal capability. Additionally, the dispersing herbivores not only provided a subsistence resource but may have also served as an impetus for hominid dispersal (Anton et al., 2002).
It has been shown that the Middle Pleistocene faunas of Java are closely related to the faunas of India and Burma (de Vos, 1995). Thus, based on the model of Anton et al. (2002), it can be inferred that as these species migrated southward, they began to occupy the open grasslands, densely vegetated river valleys, and upland forests of Java during the Early to Middle Pleistocene. As the hominids followed the migrating herbivores, they too would have taken advantage of the resources afforded by the landscape at this time. The Sunda Shelf then became exposed approximately 800,000 years ago, grasslands expanded, and more species began to enter Java. This increased resource base may have lead to increased reproductive success of Homo erectus.
3 The Asian Homo erectus
The relationship of Asian Homo erectus to Asian Homo sapiens has long been a source of discussion. In the simplest terms this problem takes the form of whether or not modern and recent Asian populations show morphological affinities to earlier populations attributed to Homo erectus. Again the currently unresolved question of the genetic