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May 15, 2005
Observed speciation?
Creationists are fond of arguing that we've never observed speciation and that this casts doubt on evolution. For instance:Darwinism's claim that new species arose from very gradual changes from older species is not observable either because the process is so slow that no one can live long enough to see it happen or because we have yet to fully understand the biochemistry which actually is the source of change. Accordingly, both theories rely upon indirect evidence.
Actually, there's a simple example of a single mutation which simultaneously renders the new organism unable to interbreed with the wild type (a common definition of species) and confers enormous reproductive advantage: navel oranges. Navel oranges are generally seedless and so can't easily breed with ordinary oranges. Navel orange trees are propagated by grafting (actually, most oranges are propagated by grafting, though in principle non-seedless oranges can be bred).
There's a natural tendency to argue that this doesn't really count because it's not natural. But there are lots of species which can't reproduce without the help of other species, either voluntarily (plant pollination by insects) or involuntarily (malaria). This is just a case where the organism has convinced humans rather than some other animal to assist in its reproductive strategy.
Posted by ekr at May 15, 2005 2:37 PM | Filed under:
Comments
What about corn? It can't reproduce without human intervention.
Bananas seem like they live in the same category as navel oranges, too: seeds only very, very rarely show up in modern bananas.
Over in the Animal Kingdom, you might think about silkworms.
I bet that an "intelligent design" arguer would only claim that all of these examples show you that speciation requires the presence of a designer.
I don't know what a hardcore creationist would say. Probably that "microevolution, sure, it exists, but you didn't change 'kind' in those speciation event." Getting to a definition of "kind" seems impossible, however.
Posted by: Bruce Ediger at May 17, 2005 12:26 PM
If I agree that the navel orange is a new species (and I don't). Then I would observe that you have found evolution being directed by an Inteligent Design.
Posted by: Nathan Zook at May 23, 2005 10:57 AM