, Volume 48, Issue 6, pp 551–557

The matches, achieved by natural selection, between biological capacities and their natural loads

  • J. Diamond
  • K. Hammond
Multi-author Review Ecological Implications of Metabolic Biochemistry

DOI: 10.1007/BF01920238

Cite this article as:
Diamond, J. & Hammond, K. Experientia (1992) 48: 551. doi:10.1007/BF01920238


Natural selection tends to eliminate unutilized capacities because of their costs. Hence we ask how large are the reserve capacities by which biological capacities exceed natural loads, and how closely are related biological capacities matched to each other. Measured capacities (Vmax values) of small intestinal brush-border nutrient transporters are typically around twice their natural loads (dietary intakes of their substrates); the ratio is higher for a transporter of a hyperessential nutrient. Preliminary evidence suggests matching of capacities between different steps in carbohydrate metabolism, and between the intestine, liver, kidneys, and spleen. Symmorphosis — the postulated matching of capacities to each other and to loads — is a testable hypothesis of economic design, useful in detecting and explaining cases of apparently uneconomic design.

Key words

Small intestine brush border nutrient absorption sugar absorption lactation cold exposure symmorphosis safety margin reserve capacity 

Copyright information

© Birkhäuser Verlag 1992

Authors and Affiliations

  • J. Diamond
    • 1
  • K. Hammond
    • 1
  1. 1.Department of PhysiologyUniversity of California Medical SchoolLos AngelesUSA

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