Darwin and Adaptive variation
Darwin started from the observation that animals regularly produce far more offspring than the food supply can support, and plants produce many more than enough seeds to maintain the plant population. This puts every species in competition with others for survival. Only the survivors grow to maturity and reproduce themselves.
Almost always a species reproduces according to its own kind. Darwin proposed that the characteristics of a species vary slowly over many generations when exceptional offspring propagate new capabilities.
From time to time a random mutation produces an individual with some characteristic unusual for its species. A mutant dog may have only three legs, for example. Mutations are changes in the genetic structure that affect the development of the embryo. Usually such changes are fatal. Only a few mutant embryos develop to maturity. Even then, most mutations are disadvantageous. A three-legged dog cannot pursue prey as rapidly as a normal dog. Such a dog is unlikely to survive unless someone keeps it as a pet and feeds it.
Very infrequently a mutation changes a characteristic in a way that is advantageous for the individual’s survival. A beneficial mutation may provide better camouflage or stronger armor or faster escape from predators. The rare, favorably mutant individual is more likely than normal individuals to survive to maturity.
If the mutation is heritable the mutant will pass on its advantage to its offspring. In theory, these offspring in turn produce more and more favored mutants. The mutants compete for survival with dwindling numbers of normal individuals. After many generations, most of the individuals in the population have the mutation. In this way the mutants become the normal members of the species. Then a new cycle of improvement can begin.
The greatest survival potential thus selects naturally certain random changes in form or characteristics. This is what Darwin meant by the phrase “survival of the fittest.” Darwin said that biology goes through a natural process of evolution. (Evolution means development, but biologists reserve the word “development” for the growth of an individual organism from embryonic to adult form.) He published his speculations in The Origin of Species in 1859. Darwin pointed out that every species needs its food, and many species are the food of other species. Predators evolve at the same time as their prey. Every time a species evolves a variation that favors its survival, it disfavors some other species, and that species has to evolve, too, or decline in numbers. Darwin proposed that such cycles of improvement repeat themselves endlessly.
Today’s Darwinists say that the dominant variation of the species is the one that is “naturally designed” for survival. This, they say, is why some species are so well adapted that they appear to be creatively designed. They say that there is no designer apart from nature, but the struggle for survival constitutes a natural, “automatic” design mechanism.
Any design mechanism must make identifiable changes in the form or morphology of organisms for survival advantage, changes that clearly adapt the species to the environment. Statements like “the fit are more likely to survive” are vacuous if the only way we know an organism is fit is that it survives.
Almost always a species reproduces according to its own kind. Darwin proposed that the characteristics of a species vary slowly over many generations when exceptional offspring propagate new capabilities.
From time to time a random mutation produces an individual with some characteristic unusual for its species. A mutant dog may have only three legs, for example. Mutations are changes in the genetic structure that affect the development of the embryo. Usually such changes are fatal. Only a few mutant embryos develop to maturity. Even then, most mutations are disadvantageous. A three-legged dog cannot pursue prey as rapidly as a normal dog. Such a dog is unlikely to survive unless someone keeps it as a pet and feeds it.
Very infrequently a mutation changes a characteristic in a way that is advantageous for the individual’s survival. A beneficial mutation may provide better camouflage or stronger armor or faster escape from predators. The rare, favorably mutant individual is more likely than normal individuals to survive to maturity.
If the mutation is heritable the mutant will pass on its advantage to its offspring. In theory, these offspring in turn produce more and more favored mutants. The mutants compete for survival with dwindling numbers of normal individuals. After many generations, most of the individuals in the population have the mutation. In this way the mutants become the normal members of the species. Then a new cycle of improvement can begin.
The greatest survival potential thus selects naturally certain random changes in form or characteristics. This is what Darwin meant by the phrase “survival of the fittest.” Darwin said that biology goes through a natural process of evolution. (Evolution means development, but biologists reserve the word “development” for the growth of an individual organism from embryonic to adult form.) He published his speculations in The Origin of Species in 1859. Darwin pointed out that every species needs its food, and many species are the food of other species. Predators evolve at the same time as their prey. Every time a species evolves a variation that favors its survival, it disfavors some other species, and that species has to evolve, too, or decline in numbers. Darwin proposed that such cycles of improvement repeat themselves endlessly.
Today’s Darwinists say that the dominant variation of the species is the one that is “naturally designed” for survival. This, they say, is why some species are so well adapted that they appear to be creatively designed. They say that there is no designer apart from nature, but the struggle for survival constitutes a natural, “automatic” design mechanism.
Any design mechanism must make identifiable changes in the form or morphology of organisms for survival advantage, changes that clearly adapt the species to the environment. Statements like “the fit are more likely to survive” are vacuous if the only way we know an organism is fit is that it survives.
