Over time, it is the size of the skull particulary that of the jaw bones, that can help determine the evolutionary relationship of two hominid species. It was believed that the jaws of hominids change as time passes by because the size of the brains changes too.
A family of orientation refers to the family into which a person is born. A family of procreation describes one that is formed through marriage. These distinctions have cultural significance related to issues of lineage.
