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.
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).
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.