Final answer:
The average cranial capacity of Homo sapiens is roughly 1,400 cc, while chimps average 350 cc, and gorillas have a cranial capacity similar to australopithecines at about 500 cc. Neanderthals had larger brains, but brain size alone does not equate to intelligence.
Step-by-step explanation:
The average cranial capacity of Homo sapiens is about 1,400 cubic centimeters (cc). The cranial capacity of chimps averages 350 cc, and the brain of gorillas averages 500 cc, which is within the australopithecine range. While Neanderthals had an average brain size of 1,520 cc, comparing brain size to intelligence is not straightforward. Factors such as different anatomical areas being emphasized and the reorganization of the brain play a role. For example, the Neanderthal brain had a less developed frontal region but a more developed back of the brain, which could be a survival adaptation for hunting in harsh conditions.