marsupials vs. placentals

[Bill Adlam <wa105@mead.anglia.ac.uk>]

Chris Nedin remarked:

>Indeed, as I tell the students here, The only things proclaiming the
>inferiority of marsupial reproduction are a) placental and b) male.

Not so.  I remember a very good lecturer whose name I can't remember (I'll 
look it up if you wish).  She argued that the current successes of mammals 
are due mostly to the females.  Among other points, she said that placental 
females have just as much control over their litters as marsupials.  By 
controlling blood flow and hormones, and ultimately by selectively aborting 
greedier sons, placental females can control both the quantity and the 
quality of their offspring.

I might also point out that those who defend marsupials seem to have 
certain marsupial tendencies.  Compared to other apes, humans are born 
several months too early: in size and general development human neonates 
are on a par with ape foetuses.  Human babies are generally weaned later, 
although there is a lot of variation in age.  And among eutherians (but not 
among primates), most human mothers are unusual in carrying their young 
babies around with them.  

                                                                        Bill