Evolution.
The theory of evolution actually predates Charles Darwin.
It was a theory that naturalists had been exploring during most of the late 1700s and early 1800s. With the exploration of the globe and the cataloguing of the animals from different continents, a body of evidence was growing that many animals occurred on many continents in slightly different forms.
As an example, just look at the "Great Cat" family with lions, leopards and cheetahs in Africa, tigers in Asia, panthers in South America, and mountain lions, bobcats and lynx in North America.
They are all obviously related, but distinctly different animals.
They had obviously evolved from a common ancestor. Evolution tells us that there must be a connection, but the early scientists didn't understand how that connection could be made.
It was Charles Darwin who is associated with the theory of evolution because he gave evolution a mechanism - a method of working. His ideas about "natural selection" and "survival of the fittest" framed much of the discussion about evolution after the mid-1800s. And his ideas have probably been abused more than any other scientific theory.
"Survival of the fittest" is an unfortunate phrase.
The connotation it invokes is survival of Charles Atlas rather than the 98 pound wimp on the beach. For many people, survival of the fittest implies that Arnold Schwarzenegger or Sylvester Stallone will be better off than the common man or an Albert Einstein.
After all, they are the fittest, aren't they? Physically, maybe, but they are certainly not the fittest if the selection criteria is intelligence. Personally, if intelligence is involved, I would prefer to have Albert on my side!
But the phrase "survival of the fittest" has been used to justify Social Darwinism on the basis that the rich and powerful are somehow more fit for survival. They must have a superior bloodline or lineage if they are rich.
It has been used to justify business dealings and the stock market. After all, strong companies will win out. Such rubbish is, unfortunately, all too common.
"Survival of the fittest" is really about "survival of the best adapted."
The organism that is best adapted to all aspects of its environment is the one that is most likely to produce offspring.
This includes all aspects of its environment - both the living world and other creatures along with environmental conditions such as climate and geography.
Being well adapted to survive in the rain is not a survival advantage in the middle of a desert. Being superbly adapted for the forest is not a survival advantage for the open plains.
It is this adaptation to a particular environment that also tends to keep species localized.
That is, if an organism is well adapted for survival under a certain set of conditions that tends to mean that animals will thrive in that environment. Its population will grow and it will come to occupy that environmental niche.
Why move if there is no need or no advantage?
Maybe more to the point, as the surroundings change or if the species moves, the chance of survival can be greatly diminished.
This is where natural selection fits into the picture.
Any characteristic - from hair and eye colour to the size of one's heart - is subject to variations within a population.
Some organisms will have larger hearts, some smaller; some will have blue eyes and some will have brown.
The distribution of characteristics or traits describes a bell curve.
The average is the most likely, but all sorts of extremes are possible.
Consider, for example, height in humans. It ranges from the very small to the very tall and everywhere in between. The modern average Canadian male is five-foot-nine and female is five-feet-four inches on average.
These numbers are taller than an average Gambian but shorter than an average German.
This variation in height is a trait upon which natural selection can work.
Some variations allow for adaptation to other environments or, more importantly, changes in the environment.
Maybe not complete adaptation but a measure of greater survival ability under adverse conditions.
Maybe being taller provides access to better food or being shorter ensures that someone can hide more effectively from a predator.
In any case, the environment provides a "selection pressure" that tends to make one member of a species more likely to survive than another.
That pressure is a natural part of the environment and drives the changes in species over the course of time.
It provides the impetus to be better adapted or to be "more fit."
Of course, the processes involved are not instantaneous.
They take many, many generations to improve a species. But in the end, that is what life is all about - the next generation.
And survival of the species.
