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Chris Colby Herb Huston Brett J. Vickers HH> There's a minority view that holds that the division of pongids HH> and hominids is unjustifiable based on findings in molecular HH> biology. These folks would group chimps, bonobos, and us HH> (and possibly gorillas) together leaving the orang as odd ape HH> out. CC> "It is (IMHO) ridiculous to put humans in a separate family when CC> we are more genetically similar to chimps than many sister CC> species are to each other. Pongids are (in the current CC> classification) a paraphyletic clade; e.g. species derived CC> from others within the clade are excluded. CC> orangutan gorilla chimp human CC> | | | | CC> \ \ \ / CC> \ \ | CC> \ \ / CC> \ \ / CC> \ | CC> \ / CC> | CC> CC> To me it doesn't make sense to have a group consisting of CC> gorillas and chimps, but not humans. (The same could be CC> said for reptiles and fish, incidentally -- these groups CC> are also paraphyletic.) BJV> "The traditional phylogenetic reconstruction looks like this: BJV> orangutan human chimp gorilla BJV> | | | | BJV> \ \ \ / BJV> \ \ | BJV> \ \ / BJV> \ \ / BJV> \ | BJV> \ / BJV> | BJV> BJV> but (as you prove) there is a dispute as to which phylogeny is more BJV> accurate. Some studies and data suggest that your phylogeny BJV> is the best, but others suggest the traditional one. BJV> BJV> "Some tentative chromosomal data have suggested that BJV> humans and chimps share a more recent ancestry after BJV> separating from gorillas (Yunis and Prakash, 1982). BJV> A more controlled study, however, with consideration BJV> of within-species variation of karyotype (Stanyon and BJV> Chiarelli, 1982), has supported the more traditional BJV> branching order, where humans and both African apes BJV> diverge first -- followed later by a separation of BJV> chimps and gorillas." [1] BJV> BJV> The following amino acid, antigenic and DNA distances are reported BJV> here just because I find them interesting: BJV> BJV> Amino Acid Antigenic DNA BJV> Distance Distance Distance BJV> ------------ ------------ ----------- BJV> Human--chimp 0.27 1.0 1.8 BJV> Human--gorilla 0.65 0.8 2.3 BJV> Human--orang 2.78 2.0 4.9 BJV> Human--gibbon 2.38 2.6 4.9 BJV> Human--macaque 3.89 3.6 -- BJV> Human--spider monkey 8.69 7.6 -- BJV> Human--tarsier -- 8.8 -- BJV> Human--loris 11.36 11.2 42.0 BJV> Human--tree shrew -- 12.6 -- BJV> Primates--other placentals -- 12.11-14.91 -- BJV> Placentals--marsupials -- 15.83 -- BJV> BJV> The numbers listed above are unitless. The scales are relative. BJV> BJV> If you buy the hotly contested molecular clock theory that antigenic BJV> distance determines phylogenetic branching dates, then you can pick the BJV> branching dates out of the data above. I have to admit I'm a little BJV> partial toward the theory because one of my anthropology professors had BJV> Vincent Sarich as his advisor. BJV> Some people believe chimps and humans should belong to the same genus. BJV> That way we'd have Homo sapiens and Homo troglodytes [1]. I think the BJV> only reason that we don't is because humans like to think they're special. BJV> BJV> [1] H. Nelson, R. Jurmain, _Introduction to Physical Anthropology_, BJV> 4th edition, West Publishing Co., St. Paul, 1988.

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