Originally Posted by orangewallflower
Here is a good PDF of a journal article which explains the science behind the Cambrian Explosion. It is short and readable. It is aimed at science teachers who need to deal with creationist arguments. It has some great questions for critical thinking at the end like why don't *any* of these species still exist if they were the product of intelligent design?http://www.springerlink.com/content/...g/fulltext.pdf
It is an interesting article. The thing is, I was not making creationist claims when I brought up the Cambrian Explosion. I was using it as an example of things which do not follow the usual outline of how organisms evolve. The article's main intent does not seem to be finding or expressing the truth about the Cambrian Explosion, but making sure creationist arguments are effectively discouraged.
|Every single case of this that I have tracked has been a hoax. Every single one.
There have been a number of "footprint" hoaxes perpetrated, so I had trouble tracking down the one I was referring to. I think it is now being described as the footprints of a small, three toed dinosaur rather than a hominid.
The fossilized, apparently human femur, though, was discovered by Richard Leakey's team, and I very much doubt Leakey would be involved in a hoax intended to cast doubt on evolution.
|How in the world does this contradict evolution? Yes, it may contradict something Darwin said because he knew nothing of genes and recessive/dominant traits, but I don't see how it contradicts the idea of natural selection at all. In fact it seems to me to affirm it. Which scientists' work was dismissed?
The example of blind cave animals does not actually contradict evolution; it does contradict some well established ideas about how evolution works, and how physical traits are passed on.
Animals find their way into a completely dark cave. Over many generations, they lose their eyesight and their pigmentation. Some even no longer have eyes. What we often hear is, they no longer had any need of eyes or skin colour in complete darkness, so those traits were lost.
Logically, this should not happen. Animals are not supposed to evolve away from a characteristic when it is not needed, only when it affects their survival or their ability to reproduce. It should certainly not disappear from their genetic code.
First, there was no real survival advantage in being blind or albino, even in a dark cave. The only attempt at explaining this oddity, that I know of, came from a scientist who suggested the animals who kept their eyes might be more likely to injure them by bumping into cave walls. There is certainly no reason cave animals would, as a group - fish, salamanders, crickets, etc. - all lose their colouring.
Second, these changes, including genetic changes passed along to the next generation, seem to have occurred in response to the animals' environment. In complete darkness, they developed a gene for blindness or eyelessness, and for lack of pigment. The conventional explanation is that changes in environment affect survival. This does not apply to cave animals, who would survive just as well in the dark if they had eyes and colouration. If environment actually affects the development of hereditary traits (apart from survival issues) that affects evolutionary theory at a basic level.
Paul Kammerer was a nineteenth century scientist who did some work in this area. He found he could cause amphibians to produce young with different colouration, within a few generations, according to the colour of the parent animal's environment. He is not considered a shining light of the scientific community, but it is interesting how furious he made scientists who followed standard evolutionary theory, and how anxious they were to shut him up.