A look at two-million-year old early homonin ear bones from South Africa revealed some interesting qualities that have researchers from Binghamton University and Texas A&M saying ear bones could be a vital clue in our evolutionary history.
"The discovery is important for two reasons," Darryl de Ruiter, a professor in the Department of Anthropology at Texas A&M, said.
"First, ear ossicles are fully formed and adult-sized at birth, and they do not undergo any type of anatomical change in an individual lifetime. Thus, they are a very close representation of genetic expression. Second, these bones show that their hearing ability was different from that of humans - not necessarily better or worse, but certainly different.
Ossicles are the smallest bones in the human body, composed of the malleus, incus, and stapes, and are extremely rare for scientists to come across in fossils. Analysis of one complete set from a Paranthropus robustus and an incomplete ossicle set from an Australopithecus africanu shows a mixture of human and ape-like features, leading the team to state that ear structures could also help shed light on key evolutionary links.
"Bipedalism (walking on two feet) and a reduction in the size of the canine teeth have long been held to be 'hallmarks of humanity' since they seem to be present in the earliest human fossils recovered to date," de Ruiter said. Our study suggests that the list may need to be updated to include changes in the malleus as well."
The team hopes to continue its study with high-resolution 3-D virtual reconstructions in order to more conclusively establish the importance of ossicles in human evolution.
You can read the full published study in the Proceedings of the National Academy of Sciences of the United States of America.