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Author Topic:   Cases Troublesome for Scientists
Taq
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Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 17 of 30 (551377)
03-22-2010 3:33 PM
Reply to: Message 9 by InGodITrust
03-21-2010 3:35 PM


My example of ornaments may have been a bad one. I wasn't sure how scientists saw it. But as a lay person, the explanations seem weak.
If you study bird behavior it is not weak at all. In many bird species sexual/courtship displays are extremely important in finding a mate. Some of the most extravagant can be seen in the birds of paradise. Color displays are used by hundreds of species to tell predators that they are poisonous. Some non-poisonous species even copy the color displays of poisonous species to reduce predation (e.g. coral snakes and king snakes).
Mr Jack, your reply, "some may quibble with the 'by natural selection' bit" tells me there are cases of evolution for which at least a percentage of scientists struggle to see how natural selection is responsible.
There are probably millions of such cases. That's why science is so much fun, there are millions of things to figure out. The important thing here is that the theory of evolution has been a very useful tool in figuring these things out. At the genetic level, the theory of evolution is an indispensible tool for finding genes that are under selection and might be responsible for specific characteristics. Scientists use the theory of evolution because it works. If some other theory is proposed and it works better then scientists will use that theory.

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 Message 9 by InGodITrust, posted 03-21-2010 3:35 PM InGodITrust has replied

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Taq
Member
Posts: 9973
Joined: 03-06-2009
Member Rating: 5.7


Message 22 of 30 (551607)
03-23-2010 10:46 AM
Reply to: Message 18 by InGodITrust
03-22-2010 5:21 PM


I still believe that it is accurate to say that Darwin did not come to the more general concept of natural selection by first contemplating sexual selection with ornaments.
Yes and no. One of the first things that piqued Darwin's curiosity was animal husbandry, and pigeon breeding specifically. He noticed that in just a few generations pigeon breeders could produce amazing variety through strict selection of mates. In fact, Darwin devoted an entire section of Chapter 1 in "Origin of Species" discussing pigeons in particular (entitled "On the Breeds of Domestic Pigeon). Darwin even raised pigeons himself:
quote:
Believing that it is always best to study some special group, I have, after deliberation, taken up domestic pigeons. I have kept every breed which I could purchase or obtain, and have been most kindly favoured with skins from several quarters of the world, more especially by the Hon. W. Elliot from India, and by the Hon. C. Murray from Persia. Many treatises in different languages have been published on pigeons, and some of them are very important, as being of considerably antiquity. I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs. The diversity of the breeds is something astonishing. . .
Great as the differences are between the breeds of pigeons, I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock-pigeon (Columba livia), including under this term several geographical races or sub-species, which differ from each other in the most trifling respects.--"Origin of Species", Chapter 1

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