On 7/19/06, Guettarda guettarda@gmail.com wrote:
source that statement. It's very easy to find someone who has said that, but to source it to anyone in particular could be misleading because it implies that there is some special relationship between the idea and the source. If something is common knowledge it should only be sourced if the sourcing helps to establist the origin or development of the idea. Just sticking in a source at random can be misleading.
One solution is to source it to a very general reference work, such as Britannica, or even an introductory science textbook. You can also put "e.g." in the citation, to reinforce the idea that this is just one possible reference amongst many.
Overall, citing common sense is probably still beneficial as it doubles as "further reading" material for readers. If the reader is really interested in whether evolution is responsible for this diversity, why not give them a place to check that statement out? A low priority for us, but not harmful.
Steve