早期人类可能存在近亲繁殖现象
- 24小时月刊
- 2024-11-30
- 16
Buried for 100,000 years at Xujiayao in the Nihewan Basin of northern China, the recovered
skull
1 pieces of an early human exhibit a now-rare
congenital(先天的)
deformation
2 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(穿孔) through the top of the brain case -- an enlarged
parietal(头顶骨) foramen (EPF) or "hole in the skull" -- that is consistent with modern humans diagnosed with a rare
genetic
3
mutation
4 in the homeobox
genes
5 ALX4 on
chromosome
6 11 and MSX2 on chromosome 5., ,These specific genetic mutations
interfere
7 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
8
deficits
9, the older adult age of Xujiayao 11 suggests that any such deficits in this individual were
minor
10., ,Traces of genetic abnormalities, such as EPF, are seen unusually often in the
skulls
11 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
12 probability of finding so many is exceedingly small," suggests study co-author Erik Trinkaus, the Mary Tileston Hemenway Professor of
Anthropology
13 in Arts & Sciences at Washington University in St. Louis., ,"The presence of the Xujiayao and other Pleistocene human abnormalities therefore suggests unusual population
dynamics
14, 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.
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