We who live in the industrial and technological twenty-first century and who are aware of the perpetually-increasing human influence on the earth think of prehistoric man as benign, and having had a relatively slight impact on the environment. However, this may be only a myth. Studies of game consumption by ancient hunter-gatherers in western Asia indicate that humans, although highly-dispersed and at low densities, placed significant hunting and collecting pressures on local prey populations, as indicated by shifts in the proportions of different species consumed over time. When more easily available species such as shellfish and tortoises became rare (as indicated by decreasing size of prey captured as time went on), man either migrated elsewhere or consumed species more difficult to catch, such as birds and hares. As the human population grew during the Middle and Late Paleolithic periods, shortages of the more desirable (i.e., slower-moving) edible species became chronic.
The time of human arrival often corresponds to extinctions, particularly of large animals, such as the moa of New Zealand, the flightless geese of Hawaii, and giant lemurs of Madagascar. A population of approximately 160,000 moas was hunted to extinction within a few decades by Maoris settling in New Zealand (Holdaway and Jacomb, 2000; Diamond, 2000). In Australia, 28 genera and 55 species of vertebrates disappeared after human arrival on the continent. Some of these animals were gigantic – a 200-pound kangaroo and the largest known bird, Genyornis, weighing 60 pounds (Dayton, 2001). In the western hemisphere, too, most large animals, including the fabled sabre-tooth tiger and the woolly mammoth, became extinct at about the time that humans arrived on these continents. Whether these extinctions were due to human activity or to climatic change is still being debated. However, recent computer modeling suggests that the destruction of large fauna was an almost inevitable consequence of human consumption pressures, not just because of direct hunting pressures, but because of the changes in ecosystems due to removal of certain species, particularly large herbivores (Alroy, 2001).