ABSTRACT
Biologist Thomas Huxley called it “the question of questions”: the nature of the exact relationship between humans and their closest living relatives such as the chimpanzee and the gorilla-the question of human origins. Ever since his day, scientists have been locked in controversy as they trace the complex evolutionary history of humanity back to its very beginnings. At fi rst, they thought in terms of simple, ladder-like evolutionary schemes. These theories have now given way to highly tentative studies of early human evolution completed by reconstructing precise evolutionary relationships from fossil specimens, a process fraught with diffi culty when bone fragments are the raw materials. It is a matter of fi ne and careful judgment, the comparing of anatomical details, the weighing of different characteristics, and the assessment of chronology and stratigraphy. An extremely thin fossil record between 5 million and 1 million years ago (mya), representing fewer than 2,000 individuals, compounds the problem. Most of these are single teeth found in fossil-rich South African caves. Much rarer are skull fragments or jaws, the most valuable of all fossil fi nds. During this 4-million-year time period, our ancestors went through dramatic transformations, visible only through an incomplete paleontological lens. We know that many hominin forms fl ourished in tropical Africa during this period. Which of them, however, were direct human ancestors? We can achieve an understanding of human evolution only by getting to know as many species as we can, and this task has hardly begun. In this chapter, we examine some of the controversies that surround the biological and cultural evolution of humankind and describe what we know about the behavior and lifeways of our earliest ancestors.
