New research examines decoupling of novelty and innovation in evolutionary processes

A conceptual framework for examining the role of novelty and innovation in evolution--and their differences--is the subject of a comprehensive article in the journal Biological Reviews, published Aug. 31, 2020. 

Douglas H. Erwin, senior research biologist and curator of Paleozoic invertebrates at the Smithsonian's National Museum of Natural History in Washington, D.C., begins with an overview of current and past theoretical views of the subject, dating back to Charles Darwin.

In Erwin's view, evolutionary novelty precedes innovation. He has compared novelty to an invention with a patent, whereas innovation is like an economically significant invention. In biology an example of an innovation would be a change in the structure of ecological communities.

Erwin challenges the view that the primary driver of novelty and innovation is "ecological opportunity," and he presents a theoretical framework for distinguishing between novelty and innovation in evolution.

Current Science Daily asked Erwin to summarize the key points of his article.

"Novelty and innovation are distinct phenomena, both interesting, but not the same," he said. "Lags between novelty and innovation have been well-documented in the fossil record, necessitating the need to distinguish the two (which does not mean that lags will always occur, just that we must be aware of the possibility)."

There are many types of definitions of novelty, mostly differing in how they look at the number of taxa, their ecological or evolutionary impact, or how distinct the novel organisms are from the ancestor (radicality), he wrote. Erwin argues for definitions that address radicality, because the other definitions depend on how an innovation "plays out, or doesn't, that may have little to do with whether a novelty was, well, novel."

Why distinguish between novelty and innovation?

"Conflating novelty and innovation has led to all sorts of problems," Erwin said. "Many evolutionary biologists have followed Ernst Mayr, George Gaylord Simpson and others, and emphasized the importance of ecological opportunity, assuming that the 'right' sort of variation will arise.

"Developmental biologists have tended to do the opposite, focusing on the generation of novelty without worrying about how the novelties translate into ecological success. Distinguishing between them (following Joseph Schumpeter's work in the 1930s in economics) allows one to study how they interact. As is often the case in science, one must first pose the right questions." 

Asked what data led him to recognize that ecological opportunity could not be the primary driver of novelty and innovation, Erwin said: "A combination of data from the fossil record showing the frequency of macroevolutionary lags (the origin of clades with novelties before they become ecologically widespread, or taxonomically diverse) along with work over the past couple of decades in comparative studies of animal development demonstrating the significance of distinct novelties, such as the origin of distal enhancers (as mentioned in the paper), or particular methods of rewiring gene regulatory networks."

Erwin added, "Macroevolutionary lags are important because they show that clades with novel morphologies may originate and persist for millions of years in some case before they take off--sort of a long fuse."

Nitrogen fixation

Current Science Daily asked Erwin to discuss the example of nitrogen fixation in terms of his conceptual framework.

"I have long found nitrogen fixation fascinating," Erwin said. "It is so critical in delivery of an essential nutrient to many plants. One problem with the example is that it is still unclear whether the potential for nitrogen fixing nodules in plant roots arose once and was realized as a novelty multiple times in different clades (which I suspect is probably the case), or whether the novelty arose independently many different times." 

He added, "If the first is true, then it shows the importance of potentiating events (prior mutations in this case) in establishing the conditions under which a novelty can arise. Absent the potentiation the events generating the novelty either can't occur, or if they do, they won't generate the novelty." 

The future

How does Erwin think his new framework will help evolutionary biology in the coming years? 

"There has been considerable interest in the generation of novelty among developmental biologists, but that provides few insights into how, or whether, these novelties will succeed in an evolutionary sense." he said. "I hope this new framework will help evolutionary biologists develop a more nuanced understanding of novelty and innovation."

He added: "The book I am working on uses this framework to examine not just biological novelty/innovation but also culture and technology, posing the question of whether it is possible to develop a more general understanding of novelty and innovation across biological, cultural and technological domains."