Final answer:
Common features of all hominins include bipedalism, similar foot structure to modern humans with arches and adapted ankles, increased cranial capacity with a trend towards larger brain sizes, changes in skull shape including a rounder skull and smaller jaws, and the use of tools indicative of advanced cognitive abilities.
Step-by-step explanation:
Hominins, a term referring to species more closely related to humans than to chimpanzees, share several common features. Firstly, all hominins are bipedal, which means they have the ability to walk on two feet. This is evidenced by skeletal adaptations such as a broader pelvis, longer legs, arched feet, and a humanlike gait. Early hominins like Homo erectus and Homo habilis show these traits to a degree nearly as efficient as modern humans.
Another defining feature is the structure of their feet, which in many hominins were virtually indistinguishable from modern human feet, with arches and adapted ankles. The cranial capacity also increased over time in hominin evolution. Starting with a brain size of over 600cc, as proposed by researchers such as Mary Leakey, Louis Leakey, and John Napier, significant cranial expansion is a trend across hominin species. Moreover, changes in skull shape, such as reduced prognathism, a round, globular skull, and smaller jaws and mandibles, are indicative of hominin evolution.
Tool use is another characteristic associated with hominins, signifying an advanced cognitive ability. The archaeological evidence reflects the sophistication of hominin species in their ability to create and utilize tools, which is linked with the emergence of language. It is important to note that while these features are common to all hominins, various species may display a mosaic of traits that reflect different stages in human evolution.