Document Detail


Ontogenetic adaptation to bipedalism: age changes in femoral to humeral length and strength proportions in humans, with a comparison to baboons.
MedLine Citation:
PMID:  14585245     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The increase in lower/upper limb bone length and strength proportions in adult humans compared to most other anthropoid primates is commonly viewed as an adaptation to bipedalism. The ontogenetic development of femoral to humeral proportions is examined here using a longitudinal sample of 20 individuals measured radiographically at semiannual or annual intervals from 6 months of age to late adolescence (a subset of the Denver Growth Study sample). Anthropometric data (body weights, muscle breadths) were also available at each examination age. Results show that while femoral/humeral length proportions close to those of adults are already present in human infants, characteristically human femoral/humeral diaphyseal strength proportions only develop after the adoption of bipedalism at about 1 year of age. A rapid increase in femoral/humeral strength occurs between 1 and 3 years, followed by a slow increase until mid-late adolescence, when adult proportions are reached. When age changes in material properties are factored in, femoral strength shows an almost constant relationship to body size (body mass.bone length) after 5 years of age, while humeral strength shows a progressive decline relative to body size. Femoral/humeral length proportions increase slightly throughout growth, with no apparent change in growth trajectory at the initiation of walking, and with a small decline in late adolescence due to later growth in length of the humerus. A sex difference in femoral/humeral strength proportions (females greater) but not length proportions, develops early in childhood. Thus, growth trajectories in length and strength proportions are largely independent, with strength proportions more responsive to actual changes in mechanical loading. A cross-sectional ontogenetic sample of baboons (n=30) illustrates contrasting patterns of growth, with much smaller age changes in proportions, particularly strength proportions, although there is some indication of an adaptation to altered limb loadings early in baboon development.
Authors:
Christopher Ruff
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of human evolution     Volume:  45     ISSN:  0047-2484     ISO Abbreviation:  J. Hum. Evol.     Publication Date:  2003 Oct 
Date Detail:
Created Date:  2003-10-30     Completed Date:  2004-03-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0337330     Medline TA:  J Hum Evol     Country:  England    
Other Details:
Languages:  eng     Pagination:  317-49     Citation Subset:  IM    
Affiliation:
Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, 1830 E Monument St, 3rd Floor, Baltimore, MD 21205, USA. cbruff@jhmi.edu
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological*
Adolescent
Adult
Aging / physiology*
Analysis of Variance
Animals
Biomechanics
Body Constitution*
Child
Child, Preschool
Diaphyses / growth & development,  physiology
Female
Femur / growth & development,  physiology*
Follow-Up Studies
Humans
Humerus / growth & development,  physiology*
Infant
Longitudinal Studies
Male
Muscle, Skeletal / growth & development,  physiology
Papio / growth & development,  physiology*
Regression Analysis
Sex Characteristics

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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