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To: FairWitness
Before we can understand the history of life, we need to find the order in which we are all cousins, the topology or branching order of the tree of life. This can be done without having to make any prior assumptions about cause and effect, or ancestry and descent. These branching diagrams, which look , misleadingly like genealogies, are proper scientific hypotheses that can be tested by examining the strength or liklihood of alternative orders of branching--different orders of cousinhood--in the light of the anatomy of the organisms in whose relationship we are interested. As long ago as 1950, a German entomologist called Willi Hennig used these simple principles as a basis for a new way of looking at the living world. Hennig sought to understand creatures in terms of how they shared features with one another, independently of time, rather than in terms of their history of ancestry and descent. Hennig called his philosophy 'phylogenetic systematics', but it came to be known as 'cladistics' and its practitioners, inevitably, as 'cladists'. The branching diagrams cladists drew up to represent orders of cousinhood between organisms--patterns of relationship--became known as 'cladograms'.

How exactly does this differ from what Linnaeus did two centuries earlier?

3 posted on 06/09/2003 9:57:17 AM PDT by inquest
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To: inquest
How exactly does this differ from what Linnaeus did two centuries earlier?

Linnaeus did not have a computer to sort through the myriad possibilities available for relationships?

7 posted on 06/09/2003 10:09:45 AM PDT by FairWitness
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To: inquest
How exactly does this differ from what Linnaeus did two centuries earlier?

Linnaeus lacked several hundred thousand fossils that have been dug up since his lifetime, genomes for determining closeness of relationship at the DNA level, and a century of genetic research that studies the rather remarkable structural changes that can result from single mutations. Among other things.

Like asking the difference between B.F. Goodrich dropping a bit of rubber on the stove and Michelin designing your next set of tires.

17 posted on 06/09/2003 11:09:56 AM PDT by js1138
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