JDG wrote: > > (...) That is, no one has ever actually observed the creation of a > new species over successive generations. > BS.
New species are created _every day_, even among human beings. Take, for example, the natural ocurrence of translocation [one chromossome "glues" to another chromossome, usually deleting parts that don't serve anything, as far as we know]. These people look like any normal human being, but, depending on which genes are involved, they have low fertility [*], unless they find someone with exactly the same translocation so that they can have viable offspring [and not offspring with too much or too few genes]. It's only the probability of finding a suitable partner that inhibits the appearance of these new species. Alberto Monteiro [*] technical details: a common form of translocation happens when when the the 21st chromossome glues to the 14th; these people are called [IIRC] 45 XX -21 -14 +14t21 [for females] or 45 XX -21 -14 +14t21 [for males]. [ok, for now on I will ignore the gender, and make everything X] Their eggs divide in either ... (22 X -21 or 23 X -14 +14t21) or ... (23 X or 22 X -21 -14 +14t21), because the 14th chromossome is much bigger than the 21st, so it must be separated. If they mate with an euploid partner, the chances are: 25% of a 45 XX -21 : not viable and aborts spontaneously 25% of a 46 XX : normal 25% of a 45 XX -21 -14 +14t21 : like the parent 25% of a 46 XX -14 +14t21 : with an extra 21 in each cell -> Down Syndrome However, if two such individuals mate with each other, there's a possibility that their offpring will come from _both_ the 22 X -21 -14 +14t21 eggs, so that their kid would be 44 XX -21 -21 -14 -14 +14t21 +14t21. This individual would be again indistinguishible from any other human being, and I leave as an exercise the "proof" that this is at the door of a new species. AM
