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TagArik Kershenbaum

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Crab close up, Cuba

If We Find Life on Exoplanets, Some of It Might Be “Crabs”

Over millions of years, many crustaceans gradually grew to look more and more like crabs, a process called convergent evolution

The earliest crablike creatures are thought to date from about 365 million years ago (the Late Devonian period). But the odd thing is that many creatures that did not start out looking like crabs have, over tens of millions of years, grown to look like them. A good many lobster-like decapods (= they have ten feet) began to look like crabs (carcinization). Possible causes include greater mobility (some crabs can climb trees), easier hiding in narrow spaces, and less temptation for predators (no juicy tail). Biologists call this process convergent evolution — life forms converge on the same solutions to their problems even if they are not closely related. So we might ask, if we find life on other planets,…

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alien

Zoologist: Law of Evolution Can Predict What Aliens Will Be Like

Arik Kershenbaum’s new book argues that convergent evolution on Earth helps us understand what to expect from extraterrestrial life

Cambridge zoologist Arik Kershenbaum, author of Zoologist’s Guide to the Galaxy (2021), thinks that convergent evolution here on Earth can offer us guides to what must happen on other planets that can support life. “Convergent evolution” means that radically different life forms arrive at the same solutions. He told science writer Dan Falk in an interview: Sometimes this “convergence” of traits is for something obviously useful, like wings. But sometimes convergence produces bizarrely similar creatures that share so many characteristics, it can be hard to believe they’re not closely related. The recently extinct thylacine [a large predatory marsupial native to Tasmania and mainland Australia], for example, could easily be mistaken for a peculiar breed of dog, but it’s much more…