"There is a grandeur in this view of life, with its several powers, having been originally breathed by the creator into a few forms or into one; and that whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning, endless forms most beautiful and most wonderful have been, and are being evolved." (Charles Darwin, 1859, On the Origin of Species)
In his final words on the final page of his book, “On the Origin of Species”, Charles R. Darwin gives credit to “the creator” for the origin of life and the subsequent evolution of all of life’s species. Thus, all debates about whether or not Darwin had disclaimed a creator or espoused atheism are entirely moot; for here on the last page of his book, Darwin himself clearly credits “the creator” for the origination and perpetuation of life… whether WE believe it or not. Further, Darwin thereby infers that his observations on Perpetual Change, Individual Variation, Natural Selection, and Species Evolution are all merely the means by which The Creator did it.
Species and the characteristic traits of individuals within a species are neither static nor stationary. They dynamically EVOLVE over time through the various processes of Perpetual Change. Darwin was not the first person to make this most astute observation. Farmers have known and proven these things since the dawn of agriculture. However, Darwin was among the first to study systematically the phenomenon of organic evolution and to publish his observations and findings in the modern age.
Darwin’s observations on Perpetual Change, in terms of what farmers and agriculturists have learned and known since time immemorial, are the subject of the first chapter of his book “On the Origin of Species”. What Darwin and many millennia of farmers and breeders did not know was the precise mechanism of Perpetual Change at a subcellular biochemical level as we now do.
Countless generations of farmers and Darwin did know, however, that mixtures of parental traits appear in the offspring. They used this knowledge to selectively breed livestock over the millennia to create offspring with the traits they wanted their livestock to have such as more docile cattle that produce more milk. Darwin himself selectively bred pigeons and based his theories on his own experimental observations as well as on what he observed during his world travels on the HMS Beagle.
Darwin and the millennia of farmers who preceded him did not know about the “Crossing Over” of parts of chromosomes during the process of meiosis – gamete formation to produce sperm cells and egg cells. The Crossing Over of genes during meiosis is a very important contributor to Individual Variation and to Perpetual Change. Analogous to “shuffling the deck” of genetic cards, Crossing Over ensures that although we are similar, we are also quite different from our immediate brothers and sisters.
Neither the farmers of history and prehistory nor Darwin had any concept at all of genes, chromosomes, and the DNA, which comprises them. Yes, they knew of differences and conferred differences, but they knew them merely as traits; and they used these traits to breed plants and animals to their own selective specifications. Nature, on the other hand, does this selecting according to the Laws of Survival of the Fittest and of Natural Selection.
Further, without knowledge of genes, chromosomes, or DNA, Darwin and our agricultural ancestors had no knowledge of Mutations – another major source of Variation and Perpetual Change via spontaneous alterations in the genetic code.
Mutations may or may not enhance an individual’s chances for survival or a greater survival rate of its progeny in the next generation. The selective processes nature and farmers choose which mutations survive via Natural Selection in nature or via Agricultural Selection on farms since in either case, only the naturally fittest individuals and groups, or those most-wanted by the farmer, survive to breed and reproduce.
Since mutations appear to occur throughout time at a constant rate, scientists use that knowledge to determine how long ago certain traits arose as well as when individuals with common traits split away from each other or from respectively lower branches on the evolutionary tree of life.
Variation is the driving force of evolution. Variation provides the raw materials upon which Natural Selection then acts. Variation leads to multiple sources of potential fitness, which improves the odds of survival. Nature then selects those individuals and groups best suited to survive in their respective environments.
Inbreeding and incest are generally taboo or at least “frowned upon” both by nature and by human societies because inbreeding reduces or opposes healthy variation and thereby potentially concentrates any negative genetic traits in the offspring. Healthy ancestry gives rise to healthy progeny.
Sexual reproduction, crossing over, mutations, mass extinctions, migrations, emigrations, and catastrophes of many kinds have all served as sources of variation in the genes of living things and have consequently affected the survival or ultimate extinction of every species on Earth.
Mapping the human genome has been so successful that both genealogists and geneticists use DNA and its known mutation rate in the new science of Genetic Genealogy. Genetic Genealogy traces our Family Tree and its several branches back to the most primordial members of our human ancestry. Further, the mapping of our human genome has demonstrated unequivocally the extent of our relationship to the other primates as well as to other taxonomic groupings whose genomes we have elucidated so far.
Perpetual Change seems to occur at a constant rate; and this is much to be expected since mutations occur at a constant rate and the genetic card shuffling during crossing-over in meiosis produces a large random assortment of possible genetic combinations. This constant gradual rate of change is known as Phyletic Gradualism and is one of the dominating forces in the overall evolution of species.
Periodically throughout the history of our planet, great catastrophic events as well as many minor ones have affected Perpetual Change by giving it a periodic shakeup. The asteroid that wiped out the dinosaurs quickly removed many genes from the biosphere and left great empty ecological niches to be filled in by newly evolving forms. The Great Permian Extinction event just before the age of dinosaurs left the door open for their rapid evolutionary expansion.
This occasional shakeup of the status quo is known as Punctuated Equilibrium as originally proposed by scientists Niles Eldredge and Stephen Jay Gould as it “shakes up” the equilibrium of Phyletic Gradualism and it appears to have done so periodically and frequently throughout the history of the Earth.
Both of these processes working together – Phyletic Gradualism and Punctuated Equilibrium – have lead to and constitute the Perpetual Changes proposed by Charles Darwin and that have occurred during the fascinating history of our planet and the evolution of life on Earth.