Human Family Tree

Herb Huston wrote:

   There's a minority view that holds that the division of pongids
   and hominids is unjustifiable based on findings in molecular
   biology.  These folks would group chimps, bonobos, and us
   (and possibly gorillas) together leaving the orang as odd ape
   out.

   It is (IMHO) ridiculous to put humans in a separate family when
   we are more genetically similar to chimps than many sister
   species are to each other. Pongids are (in the current
   classification) a paraphyletic clade; e.g. species derived
   from others within the clade are excluded.

orangutan     gorilla         chimp   human
 |              |               |       |
   \                \               \   /
       \               \              |
           \              \         /
               \             \  /
                  \           |
                      \    /
                         |

Chris Colby wrote:

   To me it doesn't make sense to have a group consisting of
   gorillas and chimps, but not humans. (The same could be
   said for reptiles and fish, incidentally -- these groups
   are also paraphyletic.)

Brett J. Vickers wrote:

"The traditional phylogenetic reconstruction looks like this:

orangutan     human           chimp   gorilla
 |              |               |       |
   \                \               \   /
       \               \              |
           \              \         /
               \             \  /
                  \           |
                      \    /
                         |

but (as you prove) there is a dispute as to which phylogeny is more
accurate.  Some studies and data suggest that your phylogeny
is the best, but others suggest the traditional one.
BJV>
      "Some tentative chromosomal data have suggested that
       humans and chimps share a more recent ancestry after
       separating from gorillas (Yunis and Prakash, 1982).
       A more controlled study, however, with consideration
       of within-species variation of karyotype (Stanyon and
       Chiarelli, 1982), has supported the more traditional
       branching order, where humans and both African apes
       diverge first -- followed later by a separation of
       chimps and gorillas." [1]

The following amino acid, antigenic and DNA distances are reported
here just because I find them interesting:

                              Amino Acid      Antigenic       DNA
                              Distance        Distance        Distance
                              ------------    ------------    -----------
Human--chimp                  0.27            1.0             1.8
Human--gorilla                        0.65            0.8             2.3
Human--orang                  2.78            2.0             4.9
Human--gibbon                 2.38            2.6             4.9
Human--macaque                        3.89            3.6             --
Human--spider monkey          8.69            7.6             --
Human--tarsier                        --              8.8             --
Human--loris                  11.36           11.2            42.0
Human--tree shrew             --              12.6            --
Primates--other placentals    --              12.11-14.91     --
Placentals--marsupials                --              15.83           --

The numbers listed above are unitless.  The scales are relative.

If you buy the hotly contested molecular clock theory that
antigenic distance determines phylogenetic branching dates, then
you can pick the branching dates out of the data above.  I have
to admit I'm a little partial toward the theory because one of
my anthropology professors had Vincent Sarich as his advisor.

Some people believe chimps and humans should belong to the same
genus. That way we'd have Homo sapiens and Homo troglodytes
[1].  I think the only reason that we don't is because humans
like to think they're special.

[1] H. Nelson, R. Jurmain, _Introduction to Physical
Anthropology_, 4th edition, West Publishing Co., St. Paul, 1988.


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