It has been established for quite some time that great apes have a theory of mind. They can relate to others, anticipate on their actions or perceived thoughts - like a chimpanzee pretending to be looking for a treat in a part of the enclosure where she knows the treat isn't in order to induce another chimp in error.
Pushed by curiosity and a fascination with our fellow primates, we, humans, have dedicated a lot of time and thought to compare ourselves to them. I recently stumbled upon a serious (yet funny for us in 2012) article in 1902 in Pearsons' Magazine, which dealt with the similarities of human babies compared to primate babies. The goal was to explain the theory of evolution and the author (Sydney Savory Buckman - geologist and palaeontologist 1860-1929) was trying to prove that humans did descend from an extinct monkey-like ancestor. He was careful to emphasize: "A man cannot be descended from his cousins who are living, but he is descended from his ancestors who are dead. And the now living monkeys stand to man as cousins, or collaterals, but in no wise as ancestors." He went on to outline what he considered proofs. I cannot help but quote some of these here: "A character in which a baby so much resembles a monkey is its face. Aristotle noticed that all babies were snub-nosed, which is correct. And this snub-nose, which is about as broad as it is long, and has the end cut off obliquely, showing two wide nostrils which seem to open almost straight into the head, is a character which goes back to quite a low form of monkey." I must admit I would never have thought of this! Here is another quote: "The baby has the power to move its toes independently - that wriggling of the toes so often commented upon by mothers. This form of movement is a heritage from those ancestors who, like modern monkeys, would have used the fingers of their hind feet as we do the fingers of our hands." He then explained the strength babies exhibit when sustaining their bodies with their arms as a remnant of the time our ancestors were tree dwelling, that babies like to sleep on their bellies much like quadrumani, all of this illustrated with pictures of monkeys and babies in similar poses.
Today researchers continue to study primates and compare them to humans - much like in the following videos which I found quite interesting.
Chimpanzee vs. Human Child Learning
Amazing Apes: Self-awareness
Experiments with altruism in children and chimps
ABC news, chimps vs. humans
Chimpanzee culture and learning
Hope you enjoyed these. Please let me know!