Document Detail


Causes of early human population growth.
MedLine Citation:
PMID:  8967327     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The archaeological record indicates large increases in human population coincident with the emergence of food production about 10,000 years ago. The cause of the growth is unclear. Extreme views attribute the change to increases in the birth rate or to decreases in the death rate. Many argue that sedentism led to improved ovarian function and higher fertility through higher caloric intakes or reduced activity levels. Similarly, shortened lactation periods may have reduced birth spacing and increased fertility. Others attribute the rise in population to decreases in mortality, arguing that the evidence from skeletal populations indicates improvements in health and the expectation of life at birth, though others use the same evidence to argue that mortality increased. An analysis presented here draws on findings that indicate substantial increases in the survival of young children as populations switch from nomadic to sedentary lives. Projections indicate that this improvement in child survival is so critical that it may be followed by substantially larger decreases in survival at later ages, yet result in higher population growth rates and reduced expectation of life at birth. Increases in the birth rate are not necessary for population growth, even when overall mortality increases. Large increases in overall mortality can be associated with large increases in population. Because positive population growth can occur while the expectation of life at birth declines, this analysis shows that this summary statistic is not an appropriate indicator of population fitness.
The archaeological record indicates large increases in human population coincident with the emergence of food production about 10,000 years ago. However, the cause of this growth is unclear. Some attribute the change to increase in the birth rate or to decreases in the death rate, while others argue that sedentism led to improved ovarian function and higher fertility through higher caloric intakes or reduced activity levels. Shortened lactation periods may have reduced birth spacing and increased fertility. Still, others attribute the rise in population to decreases in mortality, arguing that the evidence from skeletal populations indicates improvements in health and the expectation of life at birth. The author uses a 1975 model developed by Brass and modified by Ewbank et al. in 1983 to describe changes in mortality patterns which mimic the proposed improvements in child survival following the transition to agriculture. The goal is to make sense of seemingly paradoxical population statistics while showing that they are consistent with interpretations of the archaeological record. Available data indicate that there were substantial increases in the survival of young children as populations switched from nomadic to sedentary lives. Projections indicate that such improvement in child survival was so important that it may have been followed by substantially larger decreases in survival at later ages, yet resulted in higher population growth rates and reduced expectation of life at birth. Increases in the birth rate are not necessary for population growth, even when overall mortality increases.
Authors:
R L Pennington
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Publication Detail:
Type:  Historical Article; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  American journal of physical anthropology     Volume:  99     ISSN:  0002-9483     ISO Abbreviation:  Am. J. Phys. Anthropol.     Publication Date:  1996 Feb 
Date Detail:
Created Date:  1996-12-04     Completed Date:  1996-12-04     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0400654     Medline TA:  Am J Phys Anthropol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  259-74     Citation Subset:  IM; J; Q    
Affiliation:
Department of Anthropology, University of Alabama, Tuscaloosa 35487-0210, USA.
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MeSH Terms
Descriptor/Qualifier:
Archaeology
Birth Weight
Child
Female
Fertility
History, Ancient
Humans
Infant Mortality
Infant, Newborn
Life Expectancy
Life Tables
Male
Models, Biological*
Mortality
Population Growth*

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


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