Four years ago, while digging in the Canadian Arctic, paleontologist Neil Shubin discovered the 375 million-year-old fossil of a fish that appeared to have both neck and hands. It was seemingly clear evidence of the transition from life in water to life on land. Scientists heralded the find as their best answer yet to the creationist argument that an absence of such “missing links” is evolutionary theory’s most obvious flaw.

But while world headlines marveled at the idea that our own hands were somehow descended from these fish fingers, Shubin began exploring the anatomical vestiges of our previous lives. If we evolved from fish, he reasoned, our body design should look more convoluted than rational. Over the next few years, he found ample evidence to support his claim: our veins meander inefficiently, our knees give out easily under the weight of bodies they were not designed to support and our brains are clumsy upgrades from earlier models. “Turning a fish into a human is like turning a Beetle into a hot rod,” Shubin says. “As a species, we are actually kind of jury-rigged.” In his new book, “Your Inner Fish,” Shubin explains how a range of medical conditions, from hiccups to heart disease, are the byproducts of our clunky evolution. “The extraordinary disconnect between our past and our human present means that our bodies fall apart in certain predictable ways,” he says. “Our circulatory systems are a good example. They were designed for activity, but we now have the lifestyles of spuds.”

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