In short, Nicholas Nassim Taleb is a technoskeptic who believes that people often get into deep trouble with sophisticated models of complex phenomena, when those phenomena depend on very rare events that have very large effects. The point is that statistical models use information about the past to understand future events, but some events are too rare to have any prior information about, and so they are effectively unpredictable. When those rare events have outsize roles in future outcomes, using sophisticated models can have catastrophic consequences, as they did in the financial crisis of 2007-2008 that resulted in the Great Recession. Taleb has a lot of street cred precisely because he made an enormous amount of money banking on the eventual failure of sophisticated models on Wall Street that effectively predicted that sufficiently rare events never, ever happen.
When I read Taleb's essay, I naturally started thinking about evolution. It’s clear that black swan events occur over evolutionary time. For example, I wonder whether humans would have evolved in a counterfactual world where an asteroid didn’t cause a mass extinction wiping out the dinosaurs and most life at the end of the Cretaceous. Or human intelligence: did that evolve due to some freak accident of evolutionary history, or was there some time at which human intelligence would evolve deterministically?
My graduate adviser, Rich Lenski, has run a long-term evolution experiment with E. coli in order to study repeatability in evolutionary history. One of the big findings of his research program is that black swan events happen in laboratory evolution experiments. In one of the twelve replicate flasks (little evolutionary worlds) of the experiment, a new kind of E. coli evolved, one able to metabolize citrate in addition to glucose in aerobic conditions. That work, led by Zachary Blount, is well worth reading, both the original research papers (Blount 2008; Blount 2012) as well as popular coverage (by Carl Zimmer) and blog posts written by Rich and Zack (this one by Rich, this one by Zack). Zack carried out replay experiments in which he demonstrated that the probability for the ancestral REL606 strain used in the LTEE to evolve citrate usage was 1 in 10 trillion (!!). This rare evolutionary innovation is a paradigmatic black swan event, in which the carrying capacity of the bacterial ecosystem increased by roughly an order of magnitude.
It’s a bit like how the industrial revolution made vastly more energy available to humans, ushering in an unprecedented era of social and technological innovation. Similar innovations have occurred in the history of life with even further ranging consequences. A current hypothesis put forward by Nick Lane and Bill Martin (and argued eloquently in this recent book argues that an improbabably rare symbiosis between a bacterium and an archaeon that resulted in mitochondria-containing eukaryotes gave those early eukaryotes 1000 times more energy per gene compared to their prokaryotic ancestors. That advance in the availability of biological energy catalyzed the evolution of morphological complex organisms, including plants and animals. It’s an intriguing idea that hinges on a black swan event.