A female gorilla at the Berlin Zoo, believed to be the oldest gorilla in the world, will celebrate her 67th birthday on Saturday. Fatou, who was born in the wild and has lived at the Berlin Zoo since 1959, was given a special early birthday treat of twigs, lettuce, grapes, bananas and some melon in a basket by zookeepers on Friday. According to the zoo, however, there was no room for too much fruit since zookeepers are carefully watching her diet. At her advanced age, Fatou needs very soft food that she can chew well even without teeth. Gorillas typically live up to 35 years in the wild and no…