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Reply to Levinton

Published online by Cambridge University Press:  08 February 2016

G. Philip Rightmire*
Affiliation:
Department of Anthropology, State University of New York, Binghamton, New York 13901

Extract

Levinton notes that the number of individuals available to my study of patterns in the evolution of Homo erectus is low, especially when cranial base breadth is considered. If measurements of biauricular breadth are related to stratigraphic age of the fossils using linear regression, the slope obtained is small (−1.52). The confidence interval includes zero, and there is no evidence that a real trend is present. At the same time, the .95 interval is large (±26.81), so slopes differing by even a substantial margin cannot be distinguished. Levinton suggests that this negates a claim for stasis, and I agree that there are grounds for doubt. But by his reasoning, a case for stasis can never be established. While it is true that the occurrence of (very small) trends can never be denied, even if an analysis of many fossils shows a zero slope bracketed by narrow confidence limits, surely these “trends” must be dismissed as insignificant. Given such an outcome, a conclusion of no (directional) change would be quite justified.

Type
Evolutionary Stasis in Homo Erectus?
Copyright
Copyright © The Paleontological Society 

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References

Literature Cited

Cronin, J. E., Boaz, N. T., Stringer, C. B., and Rak, Y. 1981. Tempo and mode in hominid evolution. Nature. 292:113122.CrossRefGoogle ScholarPubMed
Rightmire, G. P. 1981. Patterns in the evolution of Homo erectus. Paleobiology. 7:241246.CrossRefGoogle Scholar