Cerebral rubicon

A "cerebral rubicon" in paleontology is the minimum cranial capacity required for a specimen to be classified as a certain paleospecies or genus. The term is mostly used in reference to human evolution.

The Scottish anthropologist Sir Arthur Keith set the limit at 750 cc for the genus Homo. The minimum cranial capacity for the species Homo sapiens is generally set at 900cc. ^[1]

One of the reasons for the proposal to exclude Homo habilis from the genus Homo, and renaming it as "Australopithecus habilis" is the small capacity of their cranium (363cc -600 cc).

Origin

The term is most-likely a reference to the Rubicon river, which in the time of the Roman Empire marked the boarded between Cisapline Gaul and Italy proper. Crossing the river with an army, as Julius Caesar did in 49 B.C., was illegal by Roman law and is commonly seen as the "point-of-no-return" for Caesar's revolution. As such, a "rubicon" can be used idiomatically as any strict dividing line or point-of-no-return.

See also

• Microcephaly

Notes

1. ^ The Origin of Races

References

• The Human Brain: Its Size and Its Complexity
• Ashley Montagu (April 1961). "The "Cerebral Rubicon": Brain Size and the Achievement of Hominid Status". American Anthropologist 63 (2): 377–378. doi:10.1525/aa.1961.63.2.02a00100. JSTOR 667535.