CALGARY, Alberta— A nearly 2-million-year-old Australopithecus sediba skeleton from South Africa belonged to a boy who was just 7.5 years old when he plunged to his death in an underground cave, Harvard University’s Adeline Le Cabec reported on April 11 at the American Association of Physical Anthropologists annual meeting. Researchers previously assumed that the boy was no younger than 9 years old, based on the extent of his tooth eruption and bone development.
Le Cabec’s team used an imaging method called X-ray synchrotron microtomography to peer through the boy’s skull and tooth enamel. The technique enabled the researchers to measure microscopic enamel layers and to calculate the rate at which different teeth formed. The ancient boy’s teeth developed considerably faster than those of modern humans, Le Cabec’s team found, and a bit faster than those of related hominids, such as Australopithecus africanus. Examination of distinctive enamel layers inside molar teeth — some layers had formed daily, others had materialized every nine days — enabled the researchers to conclude that the A. sediba child was 7.5 years old.
