The point was that you don't need stereopsis to do that.
Basically, could you do it with one eye closed? Without stereopsis, tasks involving close-up things are harder, but farther away things are not.
Basically, could you do it with one eye closed? Without stereopsis, tasks involving close-up things are harder, but farther away things are not.
If I'm running through the woods, trying to escape from a bear, stereopsis is pretty useful, because dodging trees while at a dead run is life or death.
I don't do either of those, but some of my ancestors probably did. But I play sports. I may be able to catch a ball with one eye. Getting myself to where the ball is going? I couldn't do that as well with only one eye.
So: Do I need stereopsis? No. Did the human race? Yes, it was a competitive advantage to have.
I would love to see a sports game where one team can use both eyes, and the other team only has one eye uncovered. I imagine it'd be downright funny.