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Zachriel



Posts: 2596
Joined: Sep. 2006

(Permalink) Posted: April 07 2007,16:51   

jerry    
Quote
When objects (in this case biological organisms) are organized because of some type of similarity it is likely that there will be various forms of hierarchies used. If it assumed that the descent of the hierarchies on the paper used to show these hierarchies represents a time order then that can be checked against independent information.

When people classify objects, they often use a categorical scheme. The key aspect of biological organization is that classification by the vast majority of traits yields a unique nested hierarchy. For instance, we can categorize organisms that have vertebrate, and those that don't. We can then categorize those that have mammary glands, and those that don't. But we immediate note that those with mammary glands are always vertebrates.

So, we continue with our classification. One nested set looks like this: eukaryotes, vertebrates, fish, tetrapods, reptiles, mammals, primates, etc. Eventually, we can reliably predict the existence of mammary glands just by looking at a single tooth, or the structure of a heart from a feather. This is called correlation, and it is strongly predictive.

The nested hierarchy is exactly the pattern we would expect from common descent. If we look at fossils, we can see the evolutionary succession. When we look at embryos, we have the same nested hierarchy, including vestigial structures. And when we examine genomes, we find the strongest possible confirmation of common descent.

jerry    
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It could very well be common descent but common descent says nothing about the mechanism that produced the new organisms.

That's correct. Common Descent does not directly address the mechanism of evolution. But let's be clear on this point. Life has evolved and diversified from common ancestors.

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