We are, of course, members of the animal kingdom, but also of an entire Linnaean taxonomy that places humans in relation to other creatures. There is as yet no complete agreement on human taxonomy.
Earthworms are kin to lobsters and flatworms are cousins of roundworms. These kinds of relationships have been drawn over the years by zoologists who painstakingly constructed evolutionary trees using animal morphology, or comparisons of form and structure. Morphology was, until recently, the best information available for such classifications. But new molecular evidencegleaned directly from DNA, the master blueprint of lifeis pruning the old evolutionary tree.
"Basically, we're redrawing the tree," says Jennifer Grenier, a Howard Hughes Medical Institute (HHMI) associate at the University of Wisconsin-Madison.
Grenier and HHMI investigator Sean Carroll, also at Wisconsin, were part of an international research team that performed the latest tree trimming. Their work substantiates earlier genetic investigations suggesting that the vast majority of animals, from oysters to humans, belong to one of three primary evolutionary lines, rather than the multiple branches suggested by morphological studies. The researchers reported their findings in the June 24, 1999, issue of the journal Nature .
