The work by Matthew Knope and research colleagues argues that animals have not only evolved increased resiliency to environmental change, but have also made the physical environment increasingly more stable.
A review article by University of Hawai‘i at Hilo evolutionary ecologist Matthew Knope, and a collaborative research team from several universities, was published June 12, 2020, at The Royal Society’s Interface Focus. The article, “The evolution of complex life and the stabilization of the Earth system,” is the product of an invited paper presented to The Royal Society, delivered by team member Jonathan Payne, chair of the Department of Geological Sciences at Stanford University, CA, on behalf of the group.
The work focuses on the evolution of complex life, and posits that animals have not only evolved increased resiliency to environmental change, but have also made the physical environment increasingly more stable, helping to explain the well-documented decrease in background extinction rates in the animal fossil record over the past 500 million years.
“Scientists have long been interested in better understanding the feedbacks between the living and non-living components of Earth across time,” says Knope. “Based on evidence from paleontology, geochemistry, and comparative physiology, we argue that the evolution of complex life, on the whole, has actually decreased volatility in the climate system, and increased the habitability of the planet for animals, including ourselves.”
The half-billion-year history of animal evolution is characterized by decreasing rates of background extinction. Earth’s increasing habitability for animals could result from several processes: (i) a decrease in the intensity of interactions among species that lead to extinctions; (ii) a decrease in the prevalence or intensity of geological triggers such as flood basalt eruptions and bolide impacts; (iii) a decrease in the sensitivity of animals to environmental disturbance; or (iv) an increase in the strength of stabilizing feedbacks within the climate system and biogeochemical cycles.
There is no evidence that the prevalence or intensity of interactions among species or geological extinction triggers have decreased over time. There is, however, evidence from palaeontology, geochemistry and comparative physiology that animals have become more resilient to an environmental change and that the evolution of complex life has, on the whole, strengthened stabilizing feedbacks in the climate system.
The differential success of certain phyla and classes appears to result, at least in part, from the anatomical solutions to the evolution of macroscopic size that were arrived at largely during Ediacaran and Cambrian time. Larger-bodied animals, enabled by increased anatomical complexity, were increasingly able to mix the marine sediment and water columns, thus promoting stability in biogeochemical cycles.
In addition, body plans that also facilitated ecological differentiation have tended to be associated with lower rates of extinction. In this sense, Cambrian solutions to Cambrian problems have had a lasting impact on the trajectory of complex life and, in turn, fundamental properties of the Earth system.
Knope’s research on evolution and extinction rates is making a big impact on the field. Notably, in 2016, was the publication of his collaborative work on the emerging biodiversity crisis in the world’s oceans in the journal Science. By comparing modern extinction risk data with information on ancient extinctions, Knope and his colleagues determined the potential for future human-driven mass extinction could rival the largest mass extinctions in the past, and that the current biodiversity crisis is unlike any the planet has ever experienced.
Recently, a collaborative study led by Knope and published Feb. 28, 2020, also in the journal Science, uncovers findings that challenge long-held assumptions in the field of evolution, positing that animal biodiversity in modern oceans is best explained by lower extinction rates in animal groups that are ecologically diverse, rather than by higher origination rates as previously predicted.