Classical science is based on the belief that there exists a real external world whose properties are definite and independent of the observer who perceives them. According to classical science, certain objects exist and have physical properties–such as speed and mass–that have well-defined values. In this view, theories are attempts to describe those objects and their properties, and our measurements and perceptions correspond to them both. All other observers who look will measure the same properties, and the object will have the same properties whether anyone observes them or not. In philosophy, that belief is called realism.
An example of the scientific method offers a refutation of the irreducible complexity argument from creationism. That argument holds that a hormone and its receptor cannot have come about through evolution. Joseph Thorton, et. al, working at theUniversityofOregon, reconstructed an ancestral receptor and using the process of gene resurrection, worked backwards to infer what the gene was for in the ancestral receptor, a molecule that existed 450 million years ago. They found aldosterone and another hormone that both fit the ancestral receptor which was fully functionally employable as the “keyhole” for the second hormone. Aldosterone appeared by random mutation and co-opted the existing receptor. Scientists argue that bacterial flagellae and the lens of the eye could also have evolved by the same process of co-opting the pre-existing structure.
17. Sexual Selection and Evolution: Sexual selection theory, as part of evolution, allows for testable predictions. With the rarest of exceptions, if a species shows sexual dimorphism in which only one gender (almost always the male) shows brilliant plumage, dramatic antlers, imposing size, performs impressive mating rituals, makes more dramatic calls, or builds elaborate structures to lure the opposite sex (almost always the female) into acceptance of sexual advances, the more elaborate or ingenious sex will be in active competition with other members of the same sex. Species showing less sexual dimorphism, such as penguins and geese, show less such behavior and are more likely to be monogamous and to exhibit sexual fidelity.
There are exceptions to the finding that it is the male that is the most beautiful and alluring, and these exceptions further make the point indicated above. In sea horses, for example, it is the male that fertilizes and carries the brood of eggs in a specialized pouch—becomes pregnant—and has a longer gestation period than it takes the female to produce a new batch of eggs. Males, therefore, invest more in child bearing than females among sea horses. As would be predicted by evolutionary theory, the female is the more highly decorated with brighter colors and more ornamentation and competes for the favors of males. Phalaropes, shore birds that breed in North America and Europe, have a polyandrous mating system (one female and many males). Males are responsible for nest building, child care, and feeding of the young while the female moves around mating with other males. Again, the male’s investment in offspring far exceeds that of the female, and she must compete for the favors of other males. As predicted, in phalaropes, the females are by far the most brilliantly and beautifully colored.
This correlation of sexual dimorphism and competition is predictable and explainable only by the principles of evolution. Creationist explanations offer no rational alternative theory. The fundamental question is: why should there be a correlation between sexual dimorphism, with all its elaborate displays and ostentation, except to further the process of evolution by the enhancement of sexual reproduction of the fittest individuals and the strengthening of the species? The well-tested answer from evolution is that the less ornamental sex–usually the female–gains in two ways from having the privilege of choice. First, directly, the female gets to choose a fitter male to produce more and healthier offspring in a safer and more propitious environment guarded by the male during the period of child care. Second, indirectly, the female secures better genes for her offspring and therefore an advantage in the next generation.
Evolution Blogspot 6. Expanded Definitions, Part V
And both that
morning equally lay
In leaves no step
had trodden
black,
Oh, I kept the
First for another
day!
Yet knowing how
way leads to way,
I doubted if I
should ever come back.
–The Road Less Travel By–
-Robert Frost
The culmination of the many factors that result in evolution and the production of the great plentitude of species on Earth is the division of the descendants of a common ancestor into distinct and separate species. In the course of life of plants and animals there have been millions of different species that have evolved, and more than 90% of them have become extinct. Considering all domains of life, it is estimated that there are about 8.7 million species globally, of which about 2.2 million are marine creatures. Despite 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, evolutionary scholars suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description. These same experts calculate that between 0.01 and 0.1% of all species will become extinct each year. continued…