Can reconnection of continents be sufficient reason for the evolution of sapience?

Question

So, the process that began the evolution of sapience in humans was ultimately triggered by a changing climate forcing chimpanzees into a drastically new habitat; I am trying to write about a race of sapient arboreal aliens who are adapted for forest dwelling much better than humans are physically anatomically adapted for plains-dwelling.

It occurs to me that, for this to work, they will have to evolve sapience without their basic habitat changing, so I came up with this explanation: Their presapient ancestors lived on one of two continents that had been separated for tens of millions of years, and eventually these two continents remerged with one another; As a result of this, there was essentially two species for every ecological niche on the same landmass, which caused a drastic increase in interspecies competition; Sapience then evolved as a result of needing to rapidly develop a drastic advantage in order to avoid being outcompeted by a species brilliantly adapted to the exact same ecological niche.

My question, then, is this: Is this actually enough evolutionary pressure to cause sapience? Is the need to outcompete a equally (if not more so) well adapted rival enough justification for sapience, or does the scenario I've worked out not work in reality? If not, how else can sapience emerge without a change to basic habitiat?

Answer 1

When for a reason or another two or more species compete in the same niche, what usually happens is that one of them becomes extinct, or is pushed into refuges or subniches where the other is not competitive. See the effects of the Great American Interchange, for example.

The problem with sudden interspecific competition is that it is sudden and very often takes the form of a short sharp shock, leaving but little time for adaptation. Natural selection is powerful but slow.

But you need not worry. What the interchange can do is alter the conditions in some other subtler ways than direct interspecific competition. For example, a traditional source of food may become rare, because it is outcompeted by a newly arrived species; or a new, more dangerous, predator may arrive on the scene; or the forest itself can change, with new kinds of trees and lianas; or the climate may change subtly, with more pronounced seasons requiring better preparation for the drier or colder or wetter or whatever season.

The point being that it is change which begets change. Something must change, so that the species will evolve. The change must be strong enough to drive evolution, but not so strong as to drive the species to extinction.

Now, you will ask, what is a strong enough change, but not overpoweringly strong? The answer is that there is no universal answer. When we recount the evolutionary history of a species we reason a posteriori, from the known effects to the likely causes. Nobody has yet devised a method to predict what will happen to a species in changed conditions. Overall, all evolutionary history is a just-so story. We know what happened, and we can make reasonable guesses about why it happened; but we are rarely able to tell in advance what will happen when something changes.

In conclusion, if you want to species to evolve strong problem-solving, tool-making and communication skills in response to the appearance of a competing species, that perfectly fine: it is unlikely to happen, but it is not impossible to happen. In the end, all evolutionary changes are unlikely; most species which have ever lived are extinct. What we see around us are the species which were lucky to adapt, or to find that they were preadapted to the new conditions and the required ecological fitting was within their pre-existing variability.