A reappraisal of progress in evolution

Abstract

AbstractPhysics has its universal law of regress, the perpetual increase of disorder formalized by entropy, but biology lacks a generally accepted principle of progress even though it is obvious that life’s organizational complexity has progressed. The concept of evolutionary progress has been debated from before Darwin’s days, misused for political purposes, and remained controversial. As many have noted, lineages do not necessarily gain organizational complexity over time, but Ronald Fisher’s fundamental theorem established that progress should be real, albeit always relative, when we only consider adaptive evolutionary change shaped by natural selection. Progress is easier to grasp when focusing on the major transitions in evolution (MTEs), the unique “ratchet clicks” towards higher organizational complexity. The MTE concept is generally assumed to have arisen in the last decade of the 20th century, but goes back to William Morton Wheeler and, particularly, Julian Huxley in the first years of that century. I review these neglected insights to show that they were correctly and transparently argued, that they remained appreciated in their original form until the 1960s, and that they were, and remain, fully compatible with the neo-Darwinian perspective. In comparison, modern discussions of evolutionary progress and actual research on the MTEs have not been very productive. I follow Huxley and Bonner in considering the four canonical levels of nonhuman hierarchical organization and show how they define life’s domains of social evolution and the clicks of the MTE ratchet clicks between them. I then conjecture how these MTE origins can be explained by a single set of genetic information conditions, a basis from which I will develop the contours of a kin selection theory of organismality in the next two chapters.