Not sure why this is lower than 50%. If we ever uplift any species, I would expect it to almost certainly be another primate. Uplifting a non-primate species means trying to give human-level intelligence to something that's totally different from humans. You wouldn't be able to just give them a brain structured like a human's and expect it to work.
@JosephNoonan I think it makes more sense to give human-level intelligence to something that's not a primate, because we already have humans. Also, there are lots of non-primate mammals available.
@MartinRandall I don't really get the first sentence, unless what you meant to say was "not similar to humans". I agree that that would make the most sense as an eventual goal, but I don't think we would jump from being unable to uplift anything at all to uplifting something that's very different from a human. Primates seem like the obvious first step.