We Are All Fish

Anti-evolutionists have at least one thing in common with climate-change deniers and anti-vaccine nuts: they keep repeating nonsense long after it’s been debunked, and if you debunk it one more time, they pretend they can’t hear you and just keep going. Lather, rinse, repeat—it just never ends.

One of the evolution-haters’ favorites, for example, is this: if evolution really happened, with one species giving rise to another, why aren’t there any transitional fossils? Put that in your pipe and smoke it, Professor Darwin.

It would be a devastating critique if true, but it’s hogwash. Our relatively recent ancestor Lucy had both apelike and human characteristics, and paleontologists have found many more examples going back hundreds of millions of years. One of the most dramatic was announced in 2006: an ancient fishlike creature dubbed Tiktaalik. Dating back some 375 million years, it had gills, scales and a mostly fishy body. But its fins concealed bones and joints of a type never before seen in a fish, which let it crawl around on land. It was either our great-great-great (repeat many times) grandfish. Or at least, it was related.

Neil Shubin, the University of Chicago scientist who led the team that dug up Tiktaalik, went on to write a best-selling book about it, titled Your Inner Fish. That led to a three-part PBS series, and now that series is available on DVD. It’s well worth watching.

Part of the reason Your Inner Fish deserves your now fully human attention is that Shubin is such an engaging guide to what could otherwise be a dry and dusty topic, but which, thanks to his genial enthusiasm and clarity, is anything but. The search for Tiktaalik was a scientific detective story, and that’s just how he lays it out. Fish, he reminds us, were the first animals with backbones, skulls and overall bony skeletons. They swam the world’s oceans 400 million years ago—and then, 40 million years later, the first amphibians were up on land.

Something must have happened in that 40-million year gap to make the transition to land possible, and armed with the knowledge of the timeframe and the places in the world where sedimentary rock of the right age was accessible, Shubin and his team ended up on Ellesmere Island, in spectacularly remote and austere landscape not far from the northern tip of Greenland. It took years of painstaking searching, requiring return visits during the brief Arctic summer year after year for a full decade until, in the second week of July, 2004, they found what they were looking for.

“I worked that site for ten years,” Shubin told TIME, “so making the documentary was like a homecoming. Being there again, telling the story to a fresh audience right at that wonderful, magical place was just wonderful.” Equally wonderful is the bombproof logic of what they found and what it meant. Darwin said such a creature must exist; previously known fossils dictated when it must have lived; and sure enough, there it was. That’s about as solid a demonstration of the scientific method in action as you could imagine.

The series is about more than just the search for Tiktaalik: parts 2 and 3 are titled Your Inner Reptile and Your Inner Monkey. Just as part 1 illustrates the legacy we still carry from our fishlike ancestors, the second and third installments reveal what we inherited from reptiles (our skin, teeth and ears in particular) and what we got from ancestral primates (hands, vision, brains, along with some less desirable traits such as weak backs and a poor sense of smell).

It’s a fascinating journey, and Shubin introduces us along the way to some of the giants in modern paleontology—his counterparts in the search for crucial transitional creatures, and his own scientific heroes. “To stand at the Lucy site with Don Johanson and to be out in the field with Tim White,” he says, “was a real privilege.”

At no point in the series does Shubin get preachy about why you really, really ought to accept evolution. It’s enough for him to demonstrate, in a captivating and powerful way, and for the millionth time, that evolution is the only conceivable explanation for the spectacular variety of species on Earth—or that, as Darwin put it, “….from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” It’s not the only explanation, of course.

It’s possible that God created the world 6,000 years ago and buried vast number of fossils that simply seem to be millions of years old, with a progression of forms that seem to prove Darwin’s theory over and over and over again. Seems like an awful waste of time, though.