Mike,
What would INDUCE adaptations? I thought mutations were random!?! Surely you COULD have open-territory traits that come to pass while living in trees - and those traits are culled as they are useless in trees. - I thought that would be a better explanation - ho hum.
Most primates can exist on the ground to a greater or lesser degree. Why come down from the trees at all? F O O D. Pure & simple. The moment you start making use of a previously untapped food supply on the ground you introduce new selective pressures. It doesn't mean you have to give up your arboreal existance, it just means you are better served by being a generalist (in this case). Of course, you will find yourself with what's known as an "exaptation" (aka preadaption) if deforestation starts. The selective pressures for terrestrialism vs. arborealism will swing strongly in favour of terrestrialism when forest becomes more like savannah, assuming you are at least partially a ground dweller.
Mark
[This message has been edited by mark24, 04-29-2004]
"Physical Reality of Matchette’s EVOLUTIONARY zero-atom-unit in a transcendental c/e illusion" - Brad McFall