If building muscles requires a high protein diet, then how are gorillas so muscular with a diet of bannanas?

One of the common misconceptions is that gorillas are completely vegetarian, all the apes do eat animal protein when they eat insects, insect eggs and the larvae that nest on the plants and fruits they eat. If your thinking of humans then yes protein is important to build muscle but eating 100% protein wont make you big & strong you need to have a high calorie diet and do lots of weight bearing exerise. Male gorillas are huge but this is probably more to do with genetics and testosterone than working out.

Dan -- there are two ways to answer your question. First, plants are full of protein too - maybe not as much as a fillet steak, but plenty for an animal interested in pumping iron. After all, a large proportion of humans are either vegetarian for religious reasons or because meat is scarce. Second, as regards gorillas in particular, my friends at Bristol Zoo, where there are some western lowland gorillas, tell me that about 67% of their diet is fruit, 17% is leaves, seeds and stems and 3% is termites and caterpillars. Certainly vegetation isn't as protein-rich as meat, so you have to eat much more of it to get the same nutritional value, and that's why gorillas and other plant-eaters spend so much time... well, eating. Maybe the termites and caterpillars give them a special protein fix too? Although we in the west don't go in for eating insects much, they are protein-packed too and, I am sure, delicious. But don't try eating them without advice from an expert (or gorilla), as some are poisonous!