Scrutinizing our primate history is a key tenet of biological anthropology. Primatologists focus on nonhuman primates and share their findings, which help us to learn more about ourselves as a species. Paleoanthropologists pore over the fossils of our ancient human ancestors to give us a better understanding of how we evolved.
The main issue in primatology today is conservation of primates in the wild. However, even studies with that goal in mind can help us to understand more about humans. For example, observing how baboons interact with their environments, how chimpanzees commit infanticide (the killing of the very young by an adult) or how gibbons form monogamous relationships helps us to unearth patterns of social interactions. Can those patterns be directly projected onto primates of the human persuasion? Not necessarily, but they do give us clues about how we derived from primate biology, and how we diverged from it.
Biological anthropologists don't just research our living nonhuman primate relatives. They also dig deep into studying our nonliving primate ancestors. Literally, they dig – fossils, that is. By reconstructing fossil remains of past humans and human ancestors like Homo erectus, anthropologists are able to propose possible lines of descent, arriving at the modern-day human. Paleoanthropologists analyze and interpret fossils to learn things about the environment at different times in history and even propose genealogical relationships among ancient species.
Proper classification of hominid fossil records is hard. Even our best guesses of which fossils belong to which species are just that – guesses. We can never get proof of the way things were back then (until, of course, we invent a time machine). Anthropologists have estimated anywhere from three to nearly 20 prehuman species [source: Marks]. Despite this uncertainty in species identification, scientists still have learned a lot about how and when these different species adapted and evolved. For example, they've learned about the emergence of walking, chewing and thinking, all notable adaptations in human evolution.