Like it says in the title: what animal eye would be the best for replacing a human one in a Xenotransplant…assuming, of course, that you’d solved the tissue rejection and optic-nerve connection problems solved? (I know, I know, that’s a big ol’ “assuming,” there.)
I’d think that the three main concerns would be eyeball size (closest to the recipient’s eye size would be best); visual range (something closer to the average human would be best—though tricky, most animals are some form of colorblind); and availability of donor organs/animals (pigs would be easier to procure than endangered gorillas, for example).
I imagine appearance and aesthetics would come in a very distant fourth.
So rather than sneaking into the zoo at night with an awl and a set of calipers, I thought I’d ask here (better knowledge base, and less mess.) What animal eye would be the best practical replacement for a human eye?
Purely from the point of size, the dolphin has a similar sized eye according to this chart. Not sure how well that would work assuming a dolphin’s eye is adapted for seeing underwater. Bear is the next size smaller. Cougar the next size larger. Pig is not listed.
Bonobo chimpanzees are our closest living relative so I would go with those. The basic problem is availability. They are vastly fewer in numbers compared to people so there is no reason to pursue that line of research. It would be much more effective to focus on human-to-human eye transplants using donors that come from people in brain-dead comas or very recently deceased accident victims. Pigs make relatively (still not very) good donors for some organs but I don’t think they would be very suitable to emulate a human eye even if you could overcome all the other obstacles like rejection and optic nerve connections.
Basically only great apes and old world monkeys have three colored vision. With new world monkeys the situation is more complicated, but some percentage (I think 2/3) of the females and none of the males do. The reason is complicated and interesting. A somewhat overly technical explanation is: Evolution of color vision in primates - Wikipedia
Apes are nearly extinct, but there are some largish monkeys, baboons come to mind. But they would look odd since the “whites” are actually brown. Still that would be my choice.
I think the ability to make sense of small detailed objects in relation to one another would be the big difficulty, and that human eyes are very unusually good at this in the animal kingdom. I kind of have the idea from reading several different things that other animal’s eyes would not be able to interpret a knot, or learn to read, or follow runs on a circuit board, or associate an entry in a table with the proper column and row headings. This isn’t just a brain function, but rather part of how the retina encodes information. Eyes aren’t cameras - they participate in analysis.
I’ve had a couple of retina reattachment surgeries. During a follow up appointment I asked the surgeon what he practiced on for the various procedures he performed. He said rabbit eyes. I assume there must be structure similarities with a human eye.
The split between bonobos and the other chimps is more recent than the split of that line from the one that produced humans, so we’re equally closely related to either of them.