Cranial capacity

Cranial capacity is a measure of the volume of the interior of the cranium (also called the braincase or brainpan) of those vertebrates who have both a cranium and a brain. The most commonly used unit of measure is the cubic centimetre or cc. The volume of the cranium is used as a rough indicator of the size of the brain, and this in turn is used as a rough indicator of the potential intelligence of the organism. However, larger cranial capacity is not always indicative of a more intelligent organism, since larger capacities are required for controlling a larger body, or in some cases are an adaptive feature for life in a colder environment.

Examples of cranial capacity:

• Orangutans: 275–500 cc
• Chimpanzees: 275–500 cc
• Gorillas: 340–752 cc
• Humans: 1100–1700 cc
• Neanderthals: 1200–1700 cc

Examples of early hominids:

Taxon	Size (cc)	Number of specimens	Age (megannum)
Australopithecus afarensis	438	4	3.6–2.9
Australopithecus africanus	452	7	3.0–2.4
Australopithecus boisei	521	1	2.3–1.4
Australopithecus robustus	530	1	1.9–1.4
Homo habilis	612	6	1.9–1.6
Homo rudolfensis	752	1	2.4–1.6
Homo ergaster	871	3	1.9–1.7

See also

• Brain to body mass ratio
• Craniometry
• Human evolution
• Neuroscience and intelligence