--- In
cybalist@yahoogroups.com, Piotr Gasiorowski <gpiotr@...> wrote:
> Perhaps a biological analogy will help: "warm-blooded animals" is a
> polyphyletic grouping that includes mammals (Mammalia) and birds
(Aves).
> Both of the latter seem to be well-defined natural taxa (clades), which
> means, among other things, that each grouping has developed from a
> single ancestral species, and that each contains all the descendants of
> such a common ancestor. But there was no "proto-warm-blooded animal"
> since the most recent common ancestor of Mammalia and Aves was also
> ancestral to many other groups (e.g. crocodylians, pterosaurs, lizards,
> snakes -- in fact, all known amniotes with the possible exception of
> turtles, according to some phylogenetic analyses). And the common
> ancestor wasn't even warm-blooded itself: endothermy developed
> independently in two different lineages of its descendants.
>
> Piotr
http://en.wikipedia.org/wiki/Polyphyletic
"Scientific classification aims to group species together such that
every group is descended from a single common ancestor, and the
elimination of groups that are found to be polyphyletic is therefore a
common goal, and is often the stimulus for major revisions of the
classification schemes. A polyphyletic group can be "fixed" either by
excluding clades or by adding the common ancestor."
Are the Indo-European linguists making any efforts to "fix" their
trees? For example following studies suggest that one could obtain
much cleaner trees by eliminating Germanic and moving around the
position of Albanian.
Fig 4:
http://www.stat.berkeley.edu/users/evans/659.pdf
pages 31-34
"The most we can say is that Albanian cannot occupy a position higher
in the tree than in Fig 8..(p. 37)
http://www.cs.rice.edu/~nakhleh/CPHL/RWT02.pdf
Fig 5, Fig 10
http://www.cs.rice.edu/~nakhleh/Papers/81.2nakhleh.pdf
Notably, IIr and Anatolian branch do not have any contact edges but
serveral European branches do.
M. Kelkar