by ChicknLittle » Wed 08 Feb 2006, 18:04:24
$this->bbcode_second_pass_quote('smallpoxgirl', ' ')I'd always heard that definition of species also, but I was reading recently that all of the major dog species are able to interbreed. Timbershepards are pretty well know (canis lupus + canis familiaris). There is also something called a Coydog (coyote + domestic dog.) I know Timbershepards are fertile and I think Coydogs are as well.
"Quietly, without fanfare in September 1993, wolves and dogs were recognized as the same species. Per the American Society of Mammalogists' Mammal Species of the World, adhering to the Code of the International Commission on Zoological Nomenclature." so they were combined to better fit the definition of species...
As in the flat earth/ round earth debate scientists are doing all the work and moving mountains while fundamentalists just sit back and claim to be unconvinced. Science has provided mendedlian genetics followed up by demonstration of the molecular basis (DNA) for combination and heritability of traits. Changes in genetic code (by error, translocation) and expression switches (supressor genes) have been demonstrated. The occurance of small changes is visable everywhere (in resistance developing in microbiology, in the spontaneous occurance of hemoglobinopathies and metabolic disorders). In short scientists have demonstrated, spelled out and (are) mapping the very genetic material that makes up human, and shown it to be unstable. They have also demonstrated the process by which random changes and variation in a population can change the average code carried in a population... that force or process driving genetic drift is survival advantage. The above make up the toolbox needed for microevolution. Evidence is everywhere, from weeds and bacteria developing resistance to toxins/antibiotics (the surviving organisms have a different genetic makeup than the preceeding population) to farming/horticulture, where people so inclined create animals/plants/flowers with new charachteristics over a period of a few years through selective breeding. The world is holding it's breath hoping that Avian Influenza code doesnt change to make it more infectious to humans... by change they mean EVOLUTION into a pathogen with new capability and new genetic material.
The step from microevolution to macro-evolution (new features and new species) is slower, especially in larger animals, because it requires the change of more than a few genes... But as the process has been going on over a timeframe in which contenents have drifted across the planet, mountains have formed and erroded, magnetic poles have shifted ect. huge genetic change would be expected with anything other than perfect genetic replication.
The planet's surface is filled with fossils showing evidence of this process. Through careful excavation the precursors of todays animals can be traced back down through the rock (backwards in time) from familiar to less familiar to strange common forms. Whales can be traced back to a precursor land animal. Birds can be traced back to a common feathered reptilian animal. The branches of ancestory suggested by the fossil record is confirmed in DNA, where increasing time since evolutionary divergance is reflected in increasing DNA disparity. (Tellingly, the difference between Human and Chimpanzee DNA base pairs is only about 2%). The drift of continents predicts isolation and separate development of unique populations on each continent and that is exactly what is seen (australia is an excellent example, with marsupials thriving in an area where ancesteral mammals did not take hold. (the fundamentalist/non evolutionary explaination for this unique concentration of marsupials could only be that Noah chose to drop marsupials off in australia, and other mammals off on other contenents).
Anyway, science has done plenty of work while fundamentalists continue to say the evidence is not enough. As before, the pope only recently admitted the earth orbited the sun (many years after we visited the moon)... So it will probably be a while until a similar statement is issued regarding evolution.