posted on Nov, 17 2007 @ 06:47 AM
12. Nobody has ever seen a new species evolve.
Speciation is probably fairly rare and in many cases might take centuries. Furthermore, recognizing a new species during a formative stage can be
difficult, because biologists sometimes disagree about how best to define a species. The most widely used definition, Mayr's Biological Species
Concept, recognizes a species as a distinct community of reproductively isolated populations--sets of organisms that normally do not or cannot breed
outside their community. In practice, this standard can be difficult to apply to organisms isolated by distance or terrain or to plants (and, of
course, fossils do not breed). Biologists therefore usually use organisms' physical and behavioral traits as clues to their species membership.
Nevertheless, the scientific literature does contain reports of apparent speciation events in plants, insects and worms. In most of these experiments,
researchers subjected organisms to various types of selection--for anatomical differences, mating behaviors, habitat preferences and other traits--and
found that they had created populations of organisms that did not breed with outsiders. For example, William R. Rice of the University of New Mexico
and George W. Salt of the University of California at Davis demonstrated that if they sorted a group of fruit flies by their preference for certain
environments and bred those flies separately over 35 generations, the resulting flies would refuse to breed with those from a very different
13. Evolutionists cannot point to any transitional fossils--creatures that are half reptile and half bird, for instance.
Actually, paleontologists know of many detailed examples of fossils intermediate in form between various taxonomic groups. One of the most famous
fossils of all time is Archaeopteryx, which combines feathers and skeletal structures peculiar to birds with features of dinosaurs. A flock's worth
of other feathered fossil species, some more avian and some less, has also been found. A sequence of fossils spans the evolution of modern horses from
the tiny Eohippus. Whales had four-legged ancestors that walked on land, and creatures known as Ambulocetus and Rodhocetus helped to make that
transition [see "The Mammals That Conquered the Seas, " by Kate Wong; Scientific American, May]. Fossil seashells trace the evolution of various
mollusks through millions of years. Perhaps 20 or more hominids (not all of them our ancestors) fill the gap between Lucy the australopithecine and
Creationists, though, dismiss these fossil studies. They argue that Archaeopteryx is not a missing link between reptiles and birds--it is just an
extinct bird with reptilian features. They want evolutionists to produce a weird, chimeric monster that cannot be classified as belonging to any known
group. Even if a creationist does accept a fossil as transitional between two species, he or she may then insist on seeing other fossils intermediate
between it and the first two. These frustrating requests can proceed ad infinitum and place an unreasonable burden on the always incomplete fossil
Nevertheless, evolutionists can cite further supportive evidence from molecular biology. All organisms share most of the same genes, but as evolution
predicts, the structures of these genes and their products diverge among species, in keeping with their evolutionary relationships. Geneticists speak
of the "molecular clock" that records the passage of time. These molecular data also show how various organisms are transitional within evolution.