A
Aloysium
Guest
This has to do with Mendelian genetics. The workings of the genome are still being studied and what we have are a variety of genes, some dominant and some recessive. The expression of genes is complicated with variable expression seen in the phenotype determined by different areas in the DNA, extranuclear factors and influences from the environment including maternal hormones.My point with dogs and different races is how small genetic changes can impact a species over time. A poodle and a great Dane for example are different from wolves. Not mention Chihuahuas.
And with humans, we all share common ancestors, yet those physical differences became manifested over time, which is a way of demonstrating some of evolution’s principles in regards to change over time.
Those differences in chromosomes between members of the same species are attributed to different influences. Neo-Darwinism calls it random and creationists call it God; both are of-the-gaps explanations. We don’t really know. I can speculate as to the direct influence of God, because I know God to exist. I also am acutely aware that matter left to its essential properties will decompose the structure established by an external ordering agent on the atoms of which it is formed. The belief that mold, insects and vermin are spontaneously created from dirt is wrong, not only in the short term but also when it involves billions of years.
I recall a family friend’s dalmatian had pups from some stray mongrel. When they were distributed, we got one that looked like the mom, but with spots at least four times the size. Some were black and a cousin got the one with a feral pattern - black and dark brown stripes on a brown background. What we see are variations in the expression of different genes that go into the shapes and colours seen on animal hides.
As to human beings, skin and hair colour is determined in about 98% of the population by the amount of melanin produced. Red hair is associated with recessive allele on a chromosome that includes the information required to produce the melanocyte-stimulating hormone receptor protein on specialized cells called melanocytes. Stimulation of the receptor causes a cascade of chemical reactions resulting in the production of eumelanin. They thereby control the type of melanin being produced, which by default would be phaeomelanin (yellow or red) and brown or black, when activated. The altered nonfunctional version of the receptor protein, probably caused by a random mutation at some point in the history of mankind, results in a lack of eumelanin and therefore lighter skin and red hair. Here’s a situation where evolutionary theory describes the defects that occur in species. Other examples of this sort of process include Sickle Cell Anemia and Thalassemia, where a genetic disorder has a serendipitous benefit, in these cases protection against malaria.
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