Thursday, April 21, 2011
Your Inner Fish
I love evolution. The concept elegantly explains a wide range of old observations even as new discoveries keep turning up that confirm it.
Not surprisingly, I also love books that do a good job of explaining evolution.
One of the best that I've read in recent years is Your Inner Fish: A Journey into the 3-Billion-Year History of the Human Body by Neil Shubin. It's a work by a leading scientist that's both very informative and very entertaining.
Shubin was one of the discoverers of Tiktaalik, a now-extinct fish with elementary limbs, fingers, and lungs. Shubin describes how its fossilized remains were found exactly where they should be if the theory of evolution is true - in sedimentary rock approximately 375 million years old. It's quite the story - one that merits MUCH more attention than it's received - but is responsible for no more than half of the book's appeal.
The other half rests on Shubin's somewhat detailed examination of the human body in light of his expertise in the anatomy of other species and earlier life forms. That examination quite clearly reveals us humans to be Rube Goldberg-like devices that natural forces have assembled out of highly imperfect, pre-existing elements.
In other words, it's exactly the sort of book that the nose of every creationist ought to be rubbed in.
The specific pleasures of this book for those already blessed with a scientific mindset are too numerous to list. Among my personal favorites were these:
----- All animals with limbs (or even pseudo-limbs, such as those found in Tiktaalik) exhibit the same pattern of big bone-two bones-many blobs-fingers/toes. Both our arms and legs have this pattern, but so do the appendages of bats, birds, lizards, whales, and dinosaurs. Perfect design by a common divine creator clearly had nothing to do with it (though Shubin never feels the need to make this point explicit) - descent from a common ancestor did.
----- The mechanisms that bind our cells together can be found at work in sponges and other primitive creatures. About 100 years ago H.V.P. Wilson performed a fascinating experiment in which he ran a sponge through a sieve, then watched as the disconnected cells came back together to form a new sponge. The mechanisms responsible for that aren't under the direction of angels but are quite natural and continue to work within all of us (albeit in somewhat different ways).
----- Why did cells come together in the first place? Experiments by Martin Boraas and others seem to provide one possible answer. They took a single-cell alga and watched it for over a thousand generations. Then they exposed it to a single-cell predator. The alga responded by clumping together - first in groups of hundreds of cells, than in groups as small as 8 (apparently the optimal size to avoid being eaten). Once the predator was removed, the alga continued to reproduce and form communities of 8 cells. Under the pressure of environmental conditions, a single cell organism had turned into a multi-cellular one. Again, no angels required.
----- Detailed analysis of DNA in recent years has repeatedly confirmed and extended the theories of evolutionists. And - according to Shubin - it's surprisingly easy to extract DNA in your own kitchen! Just take once-living tissue from peas or chicken (or apparently almost anything else), add salt and water, mix it all up in a blender to break the tissue down, add some dish soap to break down cell membranes, add some meat tenderizer to break down proteins, then add rubbing alcohol. The alcohol will float on top and attract DNA to it. You'll find it towards the top in the form of goopy white balls. (Shubin doesn't say whether it's best served with white or red wine, however.)
In addition to those stories the book passes along many delicious factoids as Shubin discusses the many often surprising links between our bodies and those of other, older species.
Among my favorite:
----- Only mammals have pinnas (i.e., external ear flaps).
----- Humans have been losing their sense of smell while expanding their sense of sight for a long time. About 3% of the human genome is devoted to smell. Dolphins and whales can't smell at all. Lampreys and hagfish have only one nostril. Pigeons, ducks, geese, and turkey vultures have a much better sense of smell than robins, sparrows, and cardinals. The US perfume industry took in $25 billion in 2005.
----- Many mammals experience hiccups. If yours don't stop after the first 5-10 spasms, they'll probably persist for an average of 60. The longest bout recorded in a human being lasted almost 70 years (1922-1990). Why do we experience them at all? Apparently you can blame tadpoles. They use both lungs and gills to breathe and the transition from one to the other requires a form of hiccup to be successful.
There are a lot of other fascinating facts and stories packed into this book of just over 200 pages. If you read it for yourself (and I hope you do), please come back here and tell me what some of YOUR favorites might have been.
(And if it leaves you in the mood to learn even more about our many links with earlier creatures, be sure to check out Elaine Morgan's eye-opening The Scars of Evolution: What Our Bodies Tell Us About Human Origins.)
Posted by DJ at 2:04 PM