2013 Fiscal Year Final Research Report
New approach to the origin of human secondary altriciality
| Project/Area Number |
24657173
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical anthropology
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| Research Institution | National Museum of Nature and Science, Tokyo |
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Principal Investigator |
KAIFU Yousuke 独立行政法人国立科学博物館, 人類研究部, 研究主幹 (20280521)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMIZU Daisuke 京都大学, 理学系研究科, 研究員 (60432332)
NISHIMURA Takeshi 京都大学, 霊長類研究所, 准教授 (80452308)
YANO Wataru 朝日大学, 歯学部, 助教 (80600113)
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| Project Period (FY) |
2012-04-01 – 2014-03-31
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| Keywords | 進化 / ライフヒストリー |
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| Research Abstract |
Unlike other primates, Homo sapiens deliver helpless newborns about 10 months earlier than expected from its adult brain size. This unique aspect of human life history, called secondary altriciality, is generally thought as a consequence of the human-specific conflict between the large brain and the small birth canal associated with bipedalism. When hominins developed this radical compromise, which implies considerable selection forces for a larger brain, is an important but difficult question. As a new, potentially effective approach to this question, we hypothesized that "deformational plagiocephaly" (DP9 is a directly observable skeletal marker of secondary altriciality, DP is an asymmetrical cranium caused by repeated pressure to the same area of the head during the infancy, and is ubiquitous in modern humans. Our metric comparisons indicate that great apes (Pan, Gorilla, and Pongo) suffer from much less frequently and far lighter degree of cranial deformations.
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