Skulls of early humans carry telltale signs of inbreeding, study suggests
Buried for 100,000 years at Xujiayao in the Nihewan Basin of northern China, the recovered skull pieces of an early human exhibit a now-rare congenital deformation that indicates inbreeding might well have been common among our ancestors, new research from the Chinese Academy of Sciences and Washington University in St. Louis suggests. The skull, known as Xujiayao 11, has an unusual perforation through the top of the brain case -- an enlarged parietal foramen (EPF) or "hole in the skull" -- that is consistent with modern humans diagnosed with a rare genetic mutation in the homeobox genes ALX4 on chromosome 11 and MSX2 on chromosome 5.
These specific genetic mutations interfere with bone formation and prevent the closure of small holes in the back of the prenatal braincase, a process that is normally completed within the first five months of fetal development. It occurs in about one out of every 25,000 modern human births.
Although this genetic abnormality is sometimes associated with cognitive deficits, the older adult age of Xujiayao 11 suggests that any such deficits in this individual were minor.
Traces of genetic abnormalities, such as EPF, are seen unusually often in the skulls of Pleistocene humans, from early Homo erectus to the end of the Paleolithic.
"The probability of finding one of these abnormalities in the small available sample of human fossils is very low, and the cumulative probability of finding so many is exceedingly small," suggests study co-author Erik Trinkaus, the Mary Tileston Hemenway Professor of Anthropology in Arts & Sciences at Washington University in St. Louis.
"The presence of the Xujiayao and other Pleistocene human abnormalities therefore suggests unusual population dynamics, most likely from high levels of inbreeding and local population instability." It therefore provides a background for understanding populational and cultural dynamics through much of human evolution.
- Skulls of early humans carry telltale signs of inbreedingfrom Science DailyMon, 18 Mar 2013, 18:30:26 EDT
- Inbreeding Common in Early Humans, Deformed Skull Suggestsfrom Live ScienceMon, 18 Mar 2013, 17:30:39 EDT
- Skulls of early humans carry telltale signs of inbreeding, study saysfrom PhysorgMon, 18 Mar 2013, 17:00:53 EDT
Latest Science NewsletterGet the latest and most popular science news articles of the week in your Inbox! It's free!
Check out our next project, Biology.Net
From other science news sites
Popular science news articles
- Scientists identify possible key in virus, cancer research
- Caltech chemists solve major piece of cellular mystery
- Future climate models greatly affected by fungi and bacteria
- Moffitt makes important steps toward developing a blood test to catch pancreatic cancer early
- Researchers use DNA 'clews' to shuttle CRISPR-Cas9 gene-editing tool into cells
- Gravitational constant appears universally constant, pulsar study suggests
- California 'rain debt' equal to average full year of precipitation
- Robotic insect mimics Nature's extreme moves
- Special issue: Philae results shed light on the nature of comets
- Researchers find that Earth's magnetic shield is much older than previously thought