In what year was it shown that the higher primates (chimpanzee) eat meat (big animals, i.e. not just insects)?

Answer 1

The first description was indeed by Jane Goodall.

I think it would be 1960. The Jane Goodall Institute says that she first observed a chimp eating a bushpig 3 months into her research (which was commenced in the Summer of 1960 in Gombe National Park, Tanzania).

Answer 2

I'm fairly certain the was determined in the 1970s when primatology got into full swing. Since carniverous activity is unusual for chimpanzees, it makes sense that only scientists really dedicated to watching them would have seen it. In fact, check to see if Jane Goodall wrote anything on it. I know Frans de Waal did in Chimpanzee Politics, written in late 70s or early 80s.