Final answer:
Hominin skeletons exhibit traits that include small jaws and teeth, bipedal locomotion, humanlike feet, and a skull with a sagittal keel. Homo naledi is an example of a species with a mix of primitive and modern traits.
Step-by-step explanation:
The study of hominin skeletons reveals a combination of both primitive and modern traits that offer insights into human evolution. These traits include:
- Small jaws and teeth, with a third molar larger than the other molars, a characteristic found in australopithecines and some early Homo species.
- A skull shape resembling H. erectus or H. habilis, often with a sagittal keel, a small raised ridge on top of the skull.
- Bipedal locomotion with a human gait and humanlike feet featuring arches and ankles.
- Skull exhibits prognathism, suggesting a protruding face, with a primitive shoulder position for climbing.
- Curved fingers implying an adaptation for clinging or climbing.
- Homo naledi is known for a mix of old and modern traits, with feet indistinguishable from modern humans.
- Homo habilis showcases a brain size over 600 cc, reduced prognathism, and tool use.
- Homo antecessor exhibits traits such as an occipital bun for skull weight balance and facial depression above the canine tooth called the canine fossa.
- Neanderthals possess an occipital bun, large brow ridges, a large nasal cavity, and a robust build.
Aside from bipedalism, criteria for classifying a species under the genus Homo may include brain size, skull shape, tool use, and specialized anatomical features for particular movement and behavior.