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How Humans Shape Evolution, and Why It Matters

People have some wide-ranging effects on other species—and, ultimately, on ourselves.

By Nathan Collins


Altering the course of evolution, one catch at a time. (Photo: Christopher Irwin/Flickr)

It’s clear humans have a major effect on our environment. Maybe the best-known is anthropogenic climate change, but we’re having a major effect on the evolution of all manner of plants and animals. Now, a review of the evidence looks at the broad ways in which we’ve shaped biological evolution worldwide—and how that’s already coming back to haunt us.

“Humans have dramatic, diverse and far-reaching influences on the evolution of other organisms,” Andrew P. Hendry, Kiyoko M. Gotanda, and Erik I. Svensson write in the introduction to a special issue of Philosophical Transactions of the Royal Society B on humanity’s awesome evolutionary power. “[T]he time has come to consider them together and thereby seek important similarities and differences.”

To get a sense for how humans might shape evolution—and how that evolution, in turn, affects us—consider fishing. Typically, anglers and commercial fisheries prefer to catch only the largest fish, and they’re often required to release any fish they catch under a legal minimum size. That gives smaller fish an evolutionary advantage since they’re less likely to be caught and subsequently eaten, meaning average fish size is likely to decline over time. That could have ecological consequences, and it could mean that fish populations are less robust and less sustainable. If nothing else, it means fewer and smaller fish for us to eat.

In contrast, climate change might have less direct, and also somewhat less predictable, consequences at the ecosystem level. As the planet warms, some species will benefit and some will not—that is, some species’ numbers will grow, while others’ numbers will shrink. Those relative population shifts have the potential to radically alter the structure of an entire ecosystem. For instance, climate change may aid invasive grasses in the western United States’ forests, with potentially devastating consequences for native trees. That spells trouble for those who rely on forests for their livelihood, and for species that call those forests home.

Those are just two examples of the ways in which humans have influenced evolution and, in turn, gotten ourselves into some trouble, and there’s still a lot to learn, Hendry, Gotanda, and Svensson write.

Yet there are also opportunities, the authors argue. For instance, awareness of drug-resistant germs has led to the development of new techniques to prevent or slow resistance in HIV, bacterial infections, and even some cancers. Similarly, evolutionary thinking has led researchers to rethink fisheries management policies to put less emphasis on size limits and the like.

“In short, evolutionary thinking is already having practical applications in biodiversity, human health, agriculture and natural resource management The future affords even greater opportunities to influence evolution in informed, effective, restrained and safe directions,” the team writes.