Misc: "The Voyage of The Beagle" told of which scientist's discoveries?

Questions

humans are the only primates that do not have ---------- in the palms of their hands?

if you go blind in one eye you only lose about one ---------- of your vision, but all your sense of depth?

if you have a tapeworm in your stomach, it will come up while you're asleep to lick the ---------- off your lips?

if you lock you ---------- while standing long enough, you will pass out?

if you suffer from---------- , you have three nipples?