Mil ojos, mil piernas:

A reader just asked me a question about why eye dominance exists.

A good question, and I have not found an explanation yet. But then, I only looked for five minutes, and thought about it for four.

One possible reason might be that it's really, really, really hard to get eyes to be the same strength, and so one will dominate no matter what (or that humans will come up with a sensitive enough test to tell the difference).

The real question is why would dominance evolve, and what advantage does it confer?

That led me to wonder (out of non-posting guilt) about the crab question again, and then on to a new quandary:

If dominance is a feature of bilateral creatures, does it exist in crabs? Do they have a dominant leg? Or legs? Is it by pairs? What about centipedes (one leg pair per segment), and millipedes (two leg pairs per segment)?

"Oh no! Another set of unanswered questions on the blog!"

While fretting about that, I completely forgot to add this link, which does away with the whole dominance and 3-D vision correlation. You can perceive a 3-D effect with only one eye in what Jim Gasperini did ages ago with two-image GIFs (although it does seem more real with two eyes open).