Just jumping in with an interesting piece of correspondence from a paleontologist:
"The important part about chimps that nobody has yet noted is the
evolutionary relationship between humans and chimps. Accepting all
the caveats that humans do not come directly from chimps and all that
jazz, humans have undergone paedomorphosis compared to chimps.
Paedomorphosis means that we come to full maturity in all ways while
not completing all of the steps of development that a chimp would go
through. For instance, if you were to take a picture of a young
child's face and "map" points on a grid (nose, mouth, chin, etc.) you
would find that those points match up very well with where the same
points would match on a baby chimp.
Now, if you look at how these points change with time you would notice
that they both go through similar changes, except for the human
changes stop much earlier. Chimp faces would continue to develop past
that point. The reason that adult faces look different than
children's faces is that adults look more apelike. You can check this
using a thin-plate spline for analysis, just type it into google.
Another consequence of this is muscle development. You never really
complete the muscle development that would happen later in life for a
chimp as your body stops short of it. You simply don't have the
tissue there to do it and the muscle tissue isn't nearly as dense and
efficient. An untrained chimpanzee can not move and easily pull over
300 lbs along the ground with one arm. Any human would have to train
for months or years to accomplish the same thing, and even then you
would see much larger amounts of muscle tissue (bulging biceps and the
like) for the chimp none of that is needed. Consequently, full grown
chimps can easily overpower a man without really even trying that
hard, and can often do it by accident.
All of that physical development that the chimp gains humans bypass in
order to keep the brain growing it's thought. This possible explains
why even though you finish growing at around 18-20 your brain
continues to develop until 25 and your thought process continues to
change up until that point. There is some debate over whether brain
development happens faster in women than men, but I digress.
The short of it: full grown humans are the equivalent of juvenile
chimps. Plan your monkey boxing demonstrations accordingly."
This came from the National Review website, of all places, and is a very interesting read. For those of you who are pressed for time, here's the gist: Chimpanzees, for all their similarities to humans, are quite different developmentally. They continue to develop well past the point where a human is considered "fully mature." Their muscles are denser and more efficient than fully matured human muscles. Even if a human can outlift a monkey, the use of those muscles in combative situations can only be trained into a human, while a chimp *naturally* knows how to fight - viciously, efficiently, and in some significant fraction of fights, successfully.
All human martial arts training flies in the face of thousands of years of self-domestication. We have no natural weapons (claws, fangs, talons, horns, etc.), and all human disciplines dedicated to creating "fighting machines" assume that other humans are the enemy. Strictly speaking, it's like breeding a toy poodle to fight other toy poodles. You wouldn't bet on the toy poodle if the opponent was a pitbull, would you?
Also, what has intellgence to do with a fight for survival? Looking for an escape route, possibly. I doubt that many humans have the sheer cold-bloodedness required to be a tactical computer when a pissed-off chimp is trying to eat your face. Perhaps you could look around for a weapon while the chimp uses the ones he was born with to maul you. Intelligence is great for keeping you out of a fight with a wild animal - if you have the misfortune to get into one despite that, intelligence isn't going to do much unless you're very lucky.
I'm sure there are people who can outdo chimpanzees in feats of pure strength. The bodybuilder here who mentioned previously that he could deadlift 650 pounds, for example. But between a man who can lift 650 pounds with some (much? I wouldn't know) exertion and a chimp who can pull 300 pounds along the ground with only his arm, I'd rather be thrown in a cage with the man.
As for the assistance a knife might provide, I won't say anything. I don't know how tough a chimp's skin is, or anything else about a chimp's anatomy. Certainly they might be vulnerable to slashes or stabs in a certain region, but if I had the wherewithal to find out a chimps sensitive areas I'd rather use my resources to find out the chimpanzee gesture for absolute submission and learn how to do that. I'd rather lose my pride than my balls to a chimp.
(Sorry for the long post. But I love off-beat topics like this one - It's about chimp fighting, for heaven's sake!)