At the beginning of the twentieth century Haeckel’s biogenetic law was widely questioned. On the one hand, there were those who wanted to dismiss it altogether: ontogeny and phylogeny did not have any systematic or interesting relation. On the other hand, there were those who sought to revise it. They argued that while Haeckel’s recapitulationism might have been erroneous, this should not deter the research over the relation between evolution and development. The British embryologist Walter Garstang was one of the (...) main figures on the “revisionists” side. In this paper, I first situate Garstang’s contribution to embryology and evolution within the extraordinarily creative period of the first three decades of the twentieth century. Then, I review some of Garstang’s specific ideas in detail, especially his most well-known 1922 paper “The Theory of Recapitulation.” Finally, I look at how the demise of the biogenetic law in light of Garstang’s views—as well as from the perspective of contemporary developmental evolution—should be understood. My main concern is not about the dismissal of Haeckel’s law or the sidelining of embryology in the twentieth-century evolutionary biology. I am rather interested in exploring why Garstang’s revised version of biogenetic law—which was entirely consistent with the neo-Darwinian perspective underpinning the Modern synthesis—did not spur a major new agenda in evolutionary biology after the 1930s. (shrink)

The roles played by physics in the study of the life sciences have taken many forms over the past 100 years. Here we analyze how physics can be brought to bear on the contemporary study of morphogenesis, where new tissue-scale forms arise out of simpler, more homogenous, initial structures. We characterize how morphogenesis has been studied through reductionist approaches and discuss their limitations. We suggest that an alternative way of approaching morphogenesis that begins with a consideration of the whole may (...) also serve as a fruitful mode of scientific inquiry. Through historical analysis of concepts relevant for contemporary systems biology, we illustrate how physical thinking oriented toward the biological whole (“holistic biophysical thinking”) was exemplified in the biological theories presented earlier by D’Arcy Thompson (1860–1948) and Pere Alberch (1954–1998). We contrast the use of physics to develop the conceptual foundations of holistically oriented systems biology with the more prevalent contemporary use of physics that focuses on technological development and quantification, embedded within reductionist strategies. As an in-depth contemporary case study, we describe how in our research we have used holistic biophysical thinking to develop biological theories of vertebrate morphogenesis that account for and extend beyond genetic, molecular, and cellular processes. We propose a theory of skin development where _both_ molecular _and_ morphological patterns are orchestrated by emergent physical processes at the supracellular scale. We further posit that holistic biophysical thinking at the supracellular scale may advance theories of diseases such as cancer. (shrink)