There is a great deal of misunderstanding of the basic tenets of the Theory of Evolution. The main source of confusion stems from those who deliberately twist the principles to advance their own agenda.
Philosopher/economist Herbert Spencer once tried piggy-backing onto the excitement generated from Charles Darwin’s publication of “On the Origin of Species by Means of Natural Selection.” Spencer drew parallels between his ideas on laissez-faire economics and Darwin’s natural selection. In doing so, he coined the phrase “survival of the fittest.”
Unfortunately, Darwin eventually adopted this phrase as a metaphor for natural selection. However, it became emblematic of social movements of which, I’m sure, he would have disapproved. Known collectively as social Darwinism, most distorted his basic principles to justify things like eugenics, racism, Nazism and imperialism.
Today, the principle source of disinformation comes from “think-tanks” such as the Discovery Institute. They are typically funded by deep-pocketed “philanthropists.” Most zero in on Darwin, and some, in desperation, have come to disparage the very foundations of all science.
Darwin, as a natural philosopher, set the stage upon which modern biology developed. His disciplined work drew upon several areas of knowledge, integrating them into a coherent explanation of the diversity of life.
Being at the forefront always means uncertainties abound. Darwin’s genius lies with his having connected many dots on what was, in many instances, sparse data.
He was honest in his expressions of uncertainties and his hope for more data. But, to have achieved what he did and have it withstand a century-and-a-half of scrutiny essentially intact is remarkable. It justifies his confidence, as is the case with any groundbreaker, that future investigations will resolve lingering issues.
Darwin’s basic tenets are rather simple. First, all life is related through common descent. Second, the diversity of life on the planet, especially the adaptation of organisms to their environment, is attributable to a process he called natural selection.
Common descent, as he and many others thought, was demonstrated by comparative anatomy. Not just comparisons between living animals and plants, but between living and extinct organisms whose fossils were being dug up on every continent.
He was a student of geology. Though the fossil record available to him was sparse, he saw obvious relationships between the living and the dead. Patterns existed between what was found on separate but adjacent land masses such as South America and Africa. These testified to an ancient Earth and processes playing out over long periods of time.
Studies of embryos showed commonalities in the early development of different animals. These parallels were strongest among animals that were more similar as mature adults. Gross anatomy and embryonic development suggested familial relationships.
With the advent of molecular biology and genetics these relationships became undeniable. As we decode the genome of ever more animals and plants, just as Darwin thought, the paths of their lineages trace back unequivocally to earlier lineages.
The paleontological record is now very robust and grows daily. Though, as one might expect, fewer fossils exist from the time before organisms developed hard tissue, the aggregate collection of fossils in museums around the world abounds with transitional fossils.
Some 99 percent of all the organisms that ever existed are extinct. So, being able to compare skeletal structure from ancient times with those of animals alive today is important. Though debate is often vigorous between experts as to the precise branching in some parts of the tree of life, no one seriously doubts its overall structure or its implications.
Critics often assert there are no transitional fossils demonstrating common lineage between certain specimens. They’re undeterred when such fossils are found. No matter how robust the data, their mantra is the same, “Now you have two gaps, one on each side of the new fossil.”
Darwin’s second tenet asserts the diversity of life is attributable to adaptation of organisms to different environments. This he called natural selection. It should be clear he is talking about populations of organisms, not individuals.
He noted cattlemen and pet breeders had demonstrated great skill in enhancing certain traits by selective breeding of their stocks. Cows yielding more milk, steers with beefier muscle structure, and bird dogs, vermin seeking dogs, and poufy lap dogs could be bred from more general populations by selectively breeding those individuals tending toward desired traits.
Each generation’s offspring was isolated from the general population in order to maintain the new line. Darwin observed that something similar happened in natural settings. If one segment of a population was isolated from the rest, certain physical traits tended to become enhance while others diminished.
This was especially so where the environments of two populations differed. Perhaps populations became isolated by volcanic eruptions, or uplifts of new mountain ranges, or separation of land masses by wide expanses of ocean such as South America and Africa.
A given population could end up in a wetter or dryer climate, lower or higher elevation, or dependent on different food sources. Those members of the population with favorable traits for the local environment thrive, leaving more of their offspring. This is not unlike what breeders do when selecting for certain traits.
For birds, certain beak structures are better for gathering seeds. For wading birds in swamps, longer legs, necks and beaks are advantageous. In colder climates thicker fur is an advantage as is digging burrows and hibernating.
If adaptations don’t occur quickly enough in the face of change, the population is at risk of extinction. But, for those producing fertile offspring, eventually, a new lineage emerges. This and husbandry differ only insofar as the natural environment selects rather than a breeder.
Just as the simplistic descriptor “survival of the fittest” gave rise to abuses, extreme and simplistic characterizations of the basic tenets of evolution continue to be used to mislead the public. It would behoove us to harken back to the more nuanced concept of natural selection.
Steve Luckstead is a medical physicist living in Walla Walla. He can be reached at firstname.lastname@example.org.