Organismal form exhibits a highly complex geometry such that any sufficient quantification requires a large series of measurements. These many variables induce a high-dimensional shape or form space in which each measured specimen can be construed as one point. From the distribution of forms in this space, another geometry emerges, which is the target of all further statistical analysis and graphical data representation. Most concepts in evolutionary and developmental biology are qualitative at their roots, but they are often assessed statistically from stochastic biological data. The ‘translations’ from biological thought into quantitative reasoning, and vice versa, are not necessarily unique; they are in fact often highly contentious, such as for heterochrony, the quantification of which has been debated sine the first approach of S.J. Gould in the 1970s. Any translation from a formal statistical language to a qualitative biological concept must focus on the two geometries – the three-dimensional geometry of organismal form and the geometry of the population distribution in form space. However, empirical assessment and conceptual analysis are often complicated by the high-dimensional nature of form space. After a brief overview of the history and contemporary state of morphometrics, I will discuss the biological relevance of heterochrony and modularity, two central concepts in EvoDevo. I will demonstrate some of their statistical and geometrical ‘translations’ and present empirical examples from the evolution and the development of the human cranium.
Philipp Mitteröcker is currently a fellow at the KLI. He graduated in Biological Anthropology from the University of Vienna in 2001. He is about to defend his PhD Thesis on "Evolutionary and Developmental Morphometrics of the Hominoid Cranium" in the Department of Anthropology at the University of Vienna, where Professors Fred Bookstein, Gerhard Weber, and Horst Seidler are his advisers. His scientific interests are in human evolution and development, human behavioral biology, morphometrics, computational biology, theoretical biology, medical image analysis, and the philosophy of science.