mortifiedpenguin said:
We humans are very persistent. A strait would not stop or even considerably slow down our expansion into South America.
I would tend to agree with that.
Where it gets interesting is, as DQ said, when you factor in a greater opportunity for sea travel among the native states. What kind of technological leaps could they have made if they had the impetus to develop sea-worthy vessels?
Then you have to take into account the differing migration patterns into SA caused by a strait - what kind of empires arise there? Are there still Chimu, Inca, Aymara, or similar states, or something completely different?
And again like DQ said, think about how New World colonization is going to proceed with such a nice convenient passage to the Pacific. It's quickly going to become one of (if not THE) most hotly-contested piece of real estate in the world. All European colonization drives will focus on that area, and only when some power finally has an unshakeable claim and control of it, will colonization expand north and south, although certainly there will probably be small 'starter' colonies in other locations in the Americas.