Tuesday, January 06, 2009

Your Inner Fish by Neil Shubin

"We understand that we are simply a mosaic of bits and pieces found in virtually everything else on the planet" - Shubin (from the book being reviewed, duh ;)

An entertaining and informative paleontological tour through the developmental history of your body. Shubin was part of the team that discovered fossilized remains of an intermediate stage in the evolutionary history of fish and mammals (later named Tectolic) and Your Inner Fish examines this finding as it relates to the fossils and bones of our anatomy and our evolutionary common ancestors. The book is broken down into various sections, so I'll share a few comments for nearly each section and then some concluding thoughts.

Teeth - It was interesting that so much can be learned just from the mechanisms of chewing and the degree of alignment in teeth. Also, that I was presented with a specific factor in the various arms races that occurred (teeth are good for eating, but bones make it harder, so stronger/sharper teeth...etc).

Head - A useful review of the cranial nerves and skull bones as well as embryonic development.

Body - How the basic layout (symmetry, limbs) is used for identification. Yes, your anus is at the back and that is a good thing. More detail about the development of an embryo (i.e., the pervasive three germ layers that lead to future body parts - endoderm, ectoderm, mesoderm). -imagine a house making itself with just the information in its bricks. Shubin describes the fascinating event of cellular coordination, whereby a series of innate tendencies and molecular signals and switches cause cellular organization. "Imagine a house making itself with just the information in its bricks."
Further, that genes that lead to certain structures can be spliced into other organisms and then that structure develops appropriate to that organism (and beyond) is not new information, but amazing.
Additionally, I found how bones attached and interacts with cartilage interesting. More incredible though was when he talked about bodies making tracks in the land for the first time. Of course this had to happen, but to think of some organism a few millimetres in size making a path in earth and then having that preserved... wow. (Not to say the fossil trace is of the first time, but as a matter of logic there was a first time).

Scent - The book discusses the genetic expression for detecting smells as well as how dolphins morphed a nasal passage into blowhole over time. There was an informative presentation of how the removal ("knocking out") of certain genes can result in less scent detection. Further, if this path of certain genes which were used for smell are then representation differently, in a way, we traded smell for sight.

Ear - Along with numerous others, apparently the middle bone of our ear is 'from' a fish as well. Why are you actually tipsy when tipsy? Alcohol diffuses into the gel in the tubes in the inner ear, and this chemical change creates a different series of signals, thus a feeling of disequilibrium. This also works in conjunction with your eyes which automatically stay on an object even as you move your head around (and this feature is inhibited if intoxicated). Finally, once the alcohol is out of your body, the inner ear system now has to change back, so there will be another (perhaps seemingly continuous) feeling of disequilibrium. The body is truly amazing.

The Meaning of it All - Shubin explains the nature of descent with modification by discussing the comparisons to be made with other organisms and observe a list of commonalities. The further back one goes in time (organisms appearing in time), the fewer commonalities there are.
I liked his brief classifying breakdown of organisms (with us in mind): (1) Multicellularity; (2) Body plan with a front and back and top and bottom and left right symmetry; (3) Skulls and backbones makes it a vertebrate; (4) Hands and feet make it a Tetrapod; (5) A three bone middle ear makes it a mammal (as well as other features) and (6) A bipedal gait and large brains makes it us. All of this is reflected in the fossil record.
Your Inner Fish also briefly discusses how we have problems due to our parts and how we evolved. Our body was 'built' for an active lifestyle and is it hard to resist the pull of sweets and fats. Similar reasons are given for hemorrhoids, sleep apnea and hiccups. This last of which is thought to be highly related to gill breathing in tadpoles in terms of anatomy.

My final thoughts
We are stuff, a staggering complicated combination of amazingly diverse, physical, stuff. Isn't it incredible?! It boggles the mind (and the book led me to appreciate my skeleton :)

[I'm also pondering the viability an analogy I came up while finishing the book: Using the observation of societal happenings and processes (traffic, construction, business operations, activities in malls) as an indication of what is happening inside me in a space smaller than the period at the end of this sentence.]


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