Sunday, September 23, 2018

Book Alert: The Origin of Species

I’m so honored by the number of people who read my last post and who reached out to comment on it. (First post to pass 500 hits!) I can’t imagine any of my currently planned posts will have as much interest- so today we’ll go a completely different direction and I’ll tell you all about the book I just finished reading: Charles Darwin’s “On the Origin of Species” originally published in 1859.

Overwhelmingly, whenever someone saw me reading it (since it took so long), they'd ask "Why would you do that?"  This book is not for the faint of heart and, sorry to whoever gets the royalties for purchases of it, I would not recommend you go out and pick up a copy.  I was out with two friends at a used book store in Edmonds, WA when I came across a reprint of the first edition which, for some reason, had to come home with me.  When you work in medicine, you study A LOT of science and Darwin's theories are at the core of so much of that learning, it seemed like fate.  I had to check it out, and while I'm glad I did, I think I could have better used my time reading an article or two on Wikipedia and then moving on.

I started reading it in January 2018 and was fascinated by many of the ideas and with the scientific approaches Darwin considered while writing it.  In my opinion, there were far too many pages on the structure of bee hives or on the hybrid forms of dogs or on the reproduction mechanisms of plants, but Darwin was trying to show numerous examples of the same concepts to prove his points and I came to respect his methods.  Other readers might be fascinated by these parts and less amused by the similarities between the animal and plant kingdoms that I was so enthralled by.  I stopped reading for a few months mid-way through to do some continuing education courses, picking it up again recently to finish it.  I'll spare you the time of reading it by providing you with this summary!  If you’re a true fan of science- feel free to check it out, but you've been warned.  It wasn't as bad as Moby Dick - which I tried to read for six months before finally giving up and watching the movie.  At least I learned things from this book...  I found some of it to be fascinating between segments of repetitive boredom.

First, a bit about the author.  The introduction of the book notes that Darwin was destined to be a physician, but that he couldn't stomach observing surgery, so he changed career paths and studied botany and geology. Plants and rocks are definitely less nauseating than incisions and innards. He spent five years (1831-1836) on The Beagle, a ship that traveled around the world with inland expeditions to collect his data.  He wrote a different book about his observations on the ship, called "The Voyage of the Beagle," after which he wrote many other publications on his research.  "On the Origin of Species." was published in 1859, 23 years after his voyage. At that time, religion overwhelmingly superseded science, so a book about evolution went against many societal beliefs and accepted thoughts.  This book was groundbreaking and Darwin is considered to be the Father of Evolution because of this work.   Fun fact: Charles Darwin shares the same birth date as Abraham Lincoln: February 12, 1809.

There are two overarching themes throughout "The Origin of Species" that are founding theories of evolution. These main themes are supported by additional observations that Darwin described in detail.  The first theme is natural selection - the concept that creatures evolve into more and more advantageous versions of themselves and will reproduce to pass on these more ideal traits.  This aligns with "survival of the fittest" in which the strongest beings survive and multiply while the weakest will not procreate and will ultimately become extinct.  The second concept is “common descent with branching evolution.”  This is the idea that all living creatures on Earth come from the same origin, and are genetically related. It is the basis of the belief that humans are closely related to apes.  Darwin never mentions the relationship between humans and primates, but it was nonetheless extrapolated from scientists who reviewed the book, and that is how it has remained understood to this day.

Darwin comes across as both humble- referring often to those whose work came before his- as well as open-minded.  He recognized that though he had scientific evidence supporting his theories, he could suggest ways that they could be disputed - and he sought evidence to disprove his own ideas.  He ultimately did not find contrary evidence to his proposed theories of evolution.  In fact- most of his ideas have remained undisputed. He even recognized that his suggestions were controversial and did not align with the beliefs of the church, but that they were backed by scientific data. While I’m sure this isn’t the oldest piece of evidence-based literature, by any means, it’s certainly the oldest research I think I’ve ever read.

Some of the concepts he described that support his overarching themes include variation between creatures, adaptations to stresses, instincts, heredity, extinction, geological time, and environmental influences on development.  He presents numerous ideas with all sorts of animal and plant examples to demonstrate his principles.  Here are some of the examples he presented that I found most interesting.  

On adaptations to stresses: 
A duck in the wild was compared to a duck in captivity.  The bone density of the wings and legs to compared to the bone density of the rest of the body differed.  The wild duck had larger wing bones whereas a captive duck had larger leg bones. This makes sense because the duck in the wild will fly to escape from predators more often than a duck in captivity which would have a greater tendency to walk, as it is protected.

But what would happen if you took one and put it into the other’s circumstances- would it ultimately adapt to the opposite presentation?  Over time, would it evolve back into the adaptations that were previously present?  The duck adapted in response to the stresses of its environment.  I liked this because it corresponds well to principles in physical therapy and body healing - such as adaptation to stresses in bone after a fracture or the response of muscle tissue to progressive loading.  

On interacting with the environment: 
Similar to the above example, wild dogs generally have their ears erect more than captive dogs, who would adapt more floppy ears - because they are not in danger and use those ear muscles less. 

On variation:
Darwin spends more than 80 pages in this edition discussing variation and how this contributes to natural selection and heredity. At length he compared pigeons of all different types ultimately concluding they must have come from a common ancestor. He describes differences in their characteristics with regard to color, size, and bone structure and discusses how different types of pigeons may not resemble one another very much, but through long periods of time with small changes, tracing steps backwards, they would likely have a common ancestor.

In consideration of my work as a physical therapist, I can appreciate that all my patients are human but that they don't have exactly the same anatomical features, and that they certainly look different from person to person. This is not a good example of variance, however.  More of a variance would be a child born with Down Syndrome, who has a genetic difference - Trisomy 21.  The likelihood of a person with Down Syndrome reproducing is decreased compared to the typical population. Darwin also goes into detail about ways that variation can influence fertility and how it fits into the "survival of the fittest" mentality with varieties that are most efficient becoming more and more prevalent.

On extinction:
The negative response to variation is when changes occur which do not optimize function for the species.  When a creature no longer exists on earth, it is extinct.  Based on Darwin's theories, people with Down Syndrome will not reproduce sufficiently to continue passing on the Trisomy 21 trait and ultimately (over a very, very long time) the whole group would be extinct.  But the mutation doesn't come entirely from heredity... the cause is unknown.  I wonder how Darwin would have dealt with some of the unique circumstances of 2018 if he was here to see the world today, and had access to the equipment now available.

I had previously never considered that this is the ultimate effect of natural selection, but it becomes apparent that if a species is repeatedly at a disadvantage, it should ultimately cease to exist. These changes take extremely long periods of time to occur, and as such, the descendants of an original species may have created other variations that persist- the long lost cousins may not even resemble one another and their ancestors being extinct are not likely to be identifiable.

There are many other ideas to consider throughout the Origin of Species, but overwhelmingly, a more thorough understanding of "The Survival of the Fittest" was what appealed to me most.  With an appreciation for the slight variations that occur within a species, it is easy to understand that any variation that occurs which is profitable will be passed through generations.  Darwin chose the name Natural Selection because the way nature selects differs from how humans select the characteristics of their animals when they breed them - but the purpose for doing so is ultimately the same: to make the best version of an animal or plant possible.

Ultimately, Darwin should get the credit for the science behind “is it true that if you don’t use it, you lose it?” Because yes! According to Darwin it is!!!  His presence on my bookshelf makes me seem a lot smarter... but now I'm ready to go do some light reading, like a Harry Potter book.

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