Evolutionary development of a chick

Evolutionary development of a chick

Biological systems engage in evolutionary (variational and selective) process, and they also develop (have heredity, reproduction, a predetermined, predictable and convergent series of hierarchical emergences within a life cycle). In living organisms, these two processes comprise the general model of “evolution”. Yet evolutionary and developmental processes are actually quite different, even antagonistic in their roles in living systems. Evolutionary process is fundamentally creative and contingent, while developmental process is fundamentally conservative and convergent with respect to the generation and handling of biological information. Both processes are fundamentally necessary to the self-organizing phenomenon we call life, and they may also be fundamental to all complex replicating systems in the universe.  

We propose therefore that the phrase “evolutionary development,” or “evo devo,” is a more useful description of organic change than the term “evolution,” which has historically ignored or minimized the role of developmental process (organismic development, group development, environmental development) in guiding and constraining long-range evolutionary processes at all scales. The new generation of “evo-devo” (hyphenated) biologists (Carroll 2006; Kirshner and Gerhart 2006; Callebaut and Rasskin-Gutman 2009; Laublichler and Maienschein 2009; Pigliucci and Muller 2010; Jablonka and Lamb 2014) understand this, as they stress the long-range effects of organismic and environmental developmental constraint on evolutionary process across all of the thirty orders of magnitude of scale inhabited by biological life, from the smallest cells to the planet as a system.

DevelopmentalBiologyGilbert10th

Gilbert 2013

Developmental constraint is obvious in developmental genetics, including homeobox genes, body plans, and various developmental path dependencies that emerge from those genes. But we also find it in our emerging understanding of convergent evolution (McGhee 2011), in models of multi-level selection (Pigliucci and Muller 2010), and in our ecology, which experiences predictable life cycle effects, like ecological succession, developmental ascendancy (Coffman 2006), and panarchy (Gunderson and Holling 2001). Astrobiology (Lunine 2004) also seeks to differentiate between statistically constrained processes in biological emergence, and those likely to be contingent and unpredictably different on all life-supporting planets.

We can also identify many developmental processes in ecology-culture interactions, including the emergence of cooperativity, self-domestication and niche construction. All intelligent species on Earth inevitably develop culture. Their emerging society permanently alters and constrains their evolutionary selection dynamics. We explore that topic, evo devo sociology, as the third theme of the EDU blog and community.

Selected References