# Mathematical Digest

### Short Summaries of Articles about Mathematics

in the Popular Press

"Placentals' Family Tree Drawn and Quartered," by Elizabeth Pennisi.*Science,* 14 December 2001,pp. 2266-2268.

There isn't much math in this article, but it does offer an interestingapplication of Bayesian statistics. In this case, the application is aneffort to determine the evolutionary history of placentals-mammals that givebirth to live, fully developed young. The conclusion of the analysissummarized in this article is that placental mammals fall into four groups.Other researchers aren't so sure.

*--- Mike Breen *