Review

Rating: 9

I discovered this book through a couple of the science blogs I read, as a follow up to news about the discovery of Tiktaalik, the first discovered quadruped fish (pictured on cover).

Neil Shubin, the author, was the lead scientist on the expedition far up north in the Arctic Circle where it was discovered.

This book is more than just a chronicle of his journey, or of the methodical process he and his colleagues use when determining where in the world to dig; This is, as the subtitle suggests, “a journey into the 3.5 billion year history of the human body,” exploring the minute details of our own bodies and comparing those oft-bizarre facets with our evolutionary predecessors.

It’s simultaneously informing and wondrous – when Shubin explains the development of the nerve pathways and bone structures in the head and neck, things, such as a shared tube among eating and breathing, start to make sense. When he shows other organisms that do not share those same inherited traits, but have developed other adaptations for their own environments INSTEAD, it’s even more amazing.

Weighing in at 11 chapters, spanning a mere 210 pages in the paperback edition (if you include the afterword), it’s certainly no substitute for in-depth courses in embryology, evolutionary biology, or cell biology — but for the science-friendly layperson, it’s a fantastic introduction to the material. What it lacks in depth it makes up for in comprehensibility.

Chapters 2 through 10 each focus on a specific aspect of our physiology, and explain the biological history found by comparing fossilized bones (many of them from aquatic organisms) and other organisms that would be distant cousins, genetically. They are:

• Getting a Grip (the evolution of hands, via fossil records)
• Handy Genes (the genetic component to the development of hands)
• Teeth Everywhere (the emergency of hard, hydroxyapatite-based surfaces, such as teeth, scales, and bones)
• Getting Ahead (the emergence of necks and independently moving heads)
• The Best-Laid (Body) Plans (a survey of Embryology and a crash course in Hox genes)
• Adventures in Bodybuilding (more of it)
• Making Scents (the development of our olfactory system)
• Vision (self-explanatory)
• Ears (ditto)

The embryology topics were probably the most intense, but arguably the most interesting, simply because the material is not covered in this kind of detail outside of upper level college courses.

Studying the development of the embryo from blastocyst to fetus shows commonalities among many different organisms, particularly the Pharyngeal stage.

The graphic to the right, a public domain lithograph from Gray’s Anatomy, illustrates this particular stage.

The Mandibular, Hyoid, and Third arches can be tracked in development and observed to slowly become the jaws, ears, and larynx, respectively.

But what’s more amazing than that is those same arches become homologous structures in nearly every other complex organism (fish, birds, reptiles, mammals, etc.) alive today!

Similar comparisons can be made with the cranial / facial nerves, plotting a human face, for example, against a shark’s head. At purely superficial appearance, it would appear we have nothing in common with sharks (aside from two eyes, a nasal passage, and a mouth with teeth in it….), yet these sorts of in-depth comparisons yield stunning dualities.

“The Best Laid Body Plans” compares a human spinal cord with the thorax of a fruit fly (Drosophila). Since insects are not even Chordates, and thus lack a spine, it would seem we have even less in common with them than with sharks. But a close look at the Hox genetic sequences in both humans and fruit flies again shows direct correlation between the procession of genetic material and how it maps directly to the procession of both our vertebrae as well as the segments of the fruit fly’s thorax.

The illustrations and photographs in Your Inner Fish are perhaps the penultimate asset of the text, second only to Shubin’s relatively accessible prose. (Basic college-level biology is more than adequate) The graphics and photographs use shaded areas to show the bones / genes that are homologous across multiple inter-related organisms. They really help to quickly visualize the topics at hand.

Definitely a terrific book for anyone that enjoys either biology and/or learning how things work on the inside (in this case: us).

As a side note: Anyone who may be on the fence about the Evolution issue (because let’s be honest, the nay-sayers do a substantial job of inventing controversy) should read “Your Inner Fish”, as well as “Why Evolution is True” by Jerry Coyne, and “Survival of the Sickest” by Sharon Moalem (and, if you can stomach it, “The Greatest Show on Earth” by Richard Dawkins — he is a terrific science communicator, but some people get tripped up on his whole atheism thing).