Physical Anthropology
Physical Anthropology examines human biological evolution, primate anatomy and behavior, osteology, genetics, and adaptation. On the DSST General Anthropology exam, this domain rewards the ability to read skeletal traits as evidence and to separate evolutionary patterns from popular misconceptions.
Core concepts
- Evolution is a change in allele frequencies across generations. Natural selection, mutation, gene flow, and genetic drift are mechanisms; natural selection is not the same as progress.
- Hominins are the lineage including humans and their extinct bipedal relatives after the split from the chimpanzee lineage. Bipedalism is the earliest defining trend, not big brains or tool use.
- Skeletal indicators of habitual bipedalism include an anteriorly placed foramen magnum, a short and broad pelvis, laterally flared iliac blades, a valgus knee, and a non-opposable big toe.
- Encephalization and culture are later trends. Tool use, fire, and symbolic behavior are not unique to Homo sapiens, though their forms differ.
- Genetics: humans share most DNA with chimpanzees; mitochondrial DNA and Y-chromosome markers trace maternal and paternal lineages. Human variation is clinal and largely within-population.
- Primatology tests models of early hominin behavior, but living primates are not direct ancestors.
Worked example
A fossil has a short, broad pelvis, a foramen magnum centered under the skull, and femora that angle inward at the knee. The best inference is habitual bipedalism. The foramen magnum position places the head over the spine; the valgus knee brings the feet under the center of gravity; the broad pelvis stabilizes trunk muscles. This combination does not prove the fossil is Homo sapiens, nor does it establish brain size or tool use. Australopithecus afarensis shows these traits and is not a modern human.
Traps that cost marks
- Treating evolution as a ladder to humans. It is branching, with side branches such as Paranthropus.
- Equating bipedalism with Homo or with large brains.
- Assuming cranial capacity alone identifies a species.
- Using race as a set of discrete biological packages. Clines and within-group variation matter.
- Confusing Lamarckian inheritance of acquired traits with Darwinian natural selection.
- Claiming a fossil is a 'missing link'; transitional features are expected, not a single chain.