I think maybe Spiratu’s point here was not that beavers build something, but that what they build affects the landscape, when the water pools up behind the dam. I can’t think of any other animals off the top of my head that “engineer” the landscape like that.
Actually, the animal that makes the largest change to the landscape is neither beaver nor man, but coral. The largest structure on earth built by any living thing is the Great Barrier Reef, off the east coast of Australia. (I may be overstating the case here. The sum total of all human structures probably has more weight and/or volume than the sum total of all coral structures.) Coral reefs are a major part of many islands, and definitely affect the environment.
The original post regarding beavers said “purposely” and I suppose you could argue that coral polyps don’t have enough brains to do anything purposely.
The sex thing I agree goes the other way. I doubt that any other animal besides humans are aware that sex = procreation. They do it because they get the urge and it feels good. I’m sure the reason that it feels good is that otherwise nothing would ever do it.
According to this web site
http://micro.magnet.fsu.edu/vitamins/pages/vitaminc/sample9.html
and many others, there are several primates (monkeys, apes, etc.) which don’t produce their own vitamin C. If your pet store carries monkey food, you’ll find that it is fortified with vitamin C.