Lr. Godfrey et Mr. Sutherland, WHATS GROWTH GOT TO DO WITH IT - PROCESS AND PRODUCT IN THE EVOLUTIONOF ONTOGENY, Journal of Human Evolution, 29(5), 1995, pp. 405-431
Growth allometries are regularly used to diagnose evolutionary perturb
ations in the rate and timing of development, and to study their effec
ts on morphological change. Metric variables are measured for ancestor
and descendant, plotted on logarithmic scales, and the two estimated
linear relationships are compared. The relationship between these two
lines has been a tool of choice for inferring heterochronic history, p
articularly when age data are not available. Size, plotted on the absc
issa, is often used as a proxy for age; the variable plotted along the
ordinate typically measures some aspect of ontogenetic change. Under
the rubric of ''allometric heterochrony'', changes in the slopes and i
ntercepts of ancestral and descendant growth allometries are taken to
reveal heterochronic processes (changes in the rates of growth, offset
timing, and onset timing of shape relative to size) and their two pro
ducts-paedomorphosis (the retention in mature descendants of ancestral
juvenile characteristics) and peramorphosis (the acquisition in matur
e descendants of features that transcend ancestral adult characteristi
cs). This framework is said to be grounded in the pioneering work of G
ould (1977) and Alberch et al. (1979). In this paper, we examine the m
eanings of ''shape'' in heterochronic analysis. We argue that the curr
ent diagnostic toolkit departs significantly from those constructed by
Gould (1977) and Alberch et al. (1979), and bears little relevance to
the problems they addressed. We show why growth allometries (as typic
ally read) do not capture evolutionary relationships between growth (G
ould's ''size'') and development (Gould's ''shape''). (C) 1995 Academi
c Press Limited