More and more, biologists are discovering that organisms thought to be different species are, in fact, but one. A recent example is that the formerly accepted two species of giant North American mammoths (the Columbian mammoth and the woolly mammoth) were genetically the same but the two had phenotypes determined by environment.
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In genetics, genes are disrupted by mutations and permanently changed. Epigenetic effects take place when single genes along a long strand of DNA become “polluted” with very small molecules, which each attach to only a single small site along the long DNA molecule. This can cause a gene that was actively in use—such as one dictating the production of a specific protein—to become blocked from its normal activity. That protein is no longer made.
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In this way, epigenetic change can radically and quickly transform the anatomy of an organism—for better or worse.
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This is a stark change from the theory of evolution through natural selection. Heritable epigenetics is not a slow, thousand-year process. These changes can happen in minutes. A random hit to the head by an enraged lover. A sick, sexually abusive parent. Breathing in toxic fumes. Coming to God in religious ecstasy. All can change us, and possibly change our children as a consequence.
Read full, original post: Why the Earth Has Fewer Species Than We Think