It seems odd to think that man has evolved from water-dwellers with fins and scales, but the evolutionary leap seems less preposterous when you examine the structural and DNA evidence that proves how much our bodies owe to prehistoric fish. With vivid CG animations, the three-part series “Your Inner Fish” brings the intriguing story to life.

“The road maps to our bodies are seen in other creatures,” says host Neil Shubin, the paleobiologist whose 2008 bestseller of the same name inspired the series. “There’s something incredibly profound in the idea that inside every organ, cell and gene of our body lie deep connections to the rest of life on our planet.”

Shubin, a professor and an associate dean at the University of Chicago, began thinking about a TV version during his author tour for the book, but it was a meeting with the documentary and science education arm of the Howard Hughes Medical Institute “that set the fire in me,” he says.

The series offers an accessible, fun perspective on evolution and the human body to relate it to the viewers, executive producer Michael Rosenfeld adds. 

“It draws on all sorts of scientific disciplines, putting those pieces together to tell a new story.  We don't think about the way our bodies connect us to this history that goes back hundreds of millions of years," Rosenfeld says. "And that's something we really worked hard on capturing, both connecting our bodies to these sort of ancient characters from the past, and also by seeing how things that are within our body also connect us to that history, such as the way we hear."

Shubin and fish skeletonIllustrating his points with fossil discoveries and anatomical structure dissections, Shubin demonstrates the similarities between human anatomy and fish gills. "We see that transformation, the lines of evidence that merge to this profound comparison,” he says.

Advances in gene mapping make this work possible. "We can look at fossils, and with developmental biology, we look at how organs form over time," Shubin says. "All of them come together to show this deep connection."

Shubin retraces his most significant archaeological discoveries, including the product of six years of expeditions to the Arctic where he and colleagues found a missing link, a fossil of a fish that filled in a piece of the evolutionary chain. In addition to scales and webbed fins, the fish had a neck, an arm and even a wrist.

"We tell the story of that fish, but then we also tell how we interpret it," Shubin says. "I can tell you with great certainty that the wrist I can bend and the head I can shake all derived from fish living 375 million years ago."

Shubin also explains the evolution of the male sex organs, and the reason males are susceptible to hernias (again, blame your inner fish) — and in the second and third installments, which focus on “Your Inner Reptile” and “Your Inner Monkey,” he examines the correlations between us and creatures a bit further down the evolutionary chain, and how all species are still evolving.

“We live in a continual evolutionary arms race with the microbes that are inside us and outside us," he says. "Our systems are continually adapting, and that kind of evolution can actually be measured."

But where will evolution take us in the future, given the enormous external environmental, technological and cultural forces at play?

“I tend to think that we’ve reached a point where these forces of change may be swapping out the three and a half billion-year change that we have within us,” Shubin says, offering our diet as an example. “Our physiology was geared for particular kinds of environments. They weren’t geared for trans fats. We do have this disconnect between what we eat and the chemicals that were part of our history.”

Nevertheless, in many aspects our inner fish still rules, “affecting our lives day to day, our survival, and how we adapt to threats like microbes,” he points out.

Shubin presents these concepts in personal, engaging manner. “We wanted to step back and make it appealing because, to some extent, we live in a society where many people are intimidated or antagonistic to science,” he says. “We definitely kept it light. This is very hard science, and we never lost the seriousness of the story we’re telling, but we do it with a light touch.”

"Your Inner Fish" premieres on April 9 on PBS.

Related on MNN:

'Your Inner Fish' traces human evolution back to our earliest ancestors
A new, engaging PBS series explores our evolutionary past, starting with prehistoric fish.