A "cerebral rubicon" in paleontology is the minimum
cranial capacity
The size of the brain is a frequent topic of study within the fields of anatomy, biological anthropology, animal science and evolution. Brain size is sometimes measured by weight and sometimes by volume (via MRI scans or by skull volume). Neu ...
required for a specimen to be classified as a certain
paleospecies
A chronospecies is a species derived from a sequential development pattern that involves continual and uniform changes from an extinct ancestral form on an evolutionary scale. The sequence of alterations eventually produces a population that is ...
or genus. The term is mostly used in reference to human evolution.
The Scottish anthropologist Sir
Arthur Keith
Sir Arthur Keith FRS FRAI (5 February 1866 – 7 January 1955) was a British anatomist and anthropologist, and a proponent of scientific racism. He was a fellow and later the Hunterian Professor and conservator of the Hunterian Museum of the ...
set the limit at 750 cc for the genus ''Homo''.
[ The minimum cranial capacity for the species ]Homo sapiens
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
is generally set at 900cc.[
One of the reasons for the proposal to exclude '']Homo habilis
''Homo habilis'' ("handy man") is an extinct species of archaic human from the Early Pleistocene of East and South Africa about 2.31 million years ago to 1.65 million years ago (mya). Upon species description in 1964, ''H. habilis'' was highly ...
'' 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
The Rubicon ( la, Rubico; it, Rubicone ; rgn, Rubicôn ) is a shallow river in northeastern Italy, just north of Rimini.
It was known as Fiumicino until 1933, when it was identified with the ancient river Rubicon, famously crossed by Julius C ...
river, which in the time of the Roman Empire
The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post- Republican period of ancient Rome. As a polity, it included large territorial holdings around the Medite ...
marked the border 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 idiom
An idiom is a phrase or expression that typically presents a figurative, non-literal meaning attached to the phrase; but some phrases become figurative idioms while retaining the literal meaning of the phrase. Categorized as formulaic language, ...
atically as any strict dividing line or point-of-no-return.
See also
*Microcephaly
Microcephaly (from New Latin ''microcephalia'', from Ancient Greek μικρός ''mikrós'' "small" and κεφαλή ''kephalé'' "head") is a medical condition involving a smaller-than-normal head. Microcephaly may be present at birth or it ...
References
External links
The Human Brain: Its Size and Its Complexity
*{{cite journal , author=Ashley Montagu, title=The "Cerebral Rubicon": Brain Size and the Achievement of Hominid Status , journal=American Anthropologist, date=April 1961, volume=63, issue=2, pages=377–378, doi=10.1525/aa.1961.63.2.02a00100 , jstor=667535
Anthropology