Cat intelligence
The brain of the domesticated cat is about long, and weighs . If a typical cat is taken to be long with a weight of , then the brain would be at 0.91% of its total body mass, compared to 2.33% of total body mass in the average human. Within the encephalization quotient proposed by Jerison in 1973, values above 1 are classified big brained, while values lower than 1 are small brained. The domestic cat is attributed a value of between 1–1.71 relative to human value that is 7.44–7.8. The largest brains in the Felidae family are those of the tigers in Java and Bali, of which the largest relative brain size within the "panthera" is the "tigris". It is debated whether there exists a causal relationship between brain size and intelligence in vertebrates. Correlations have been shown between these factors in a number of experiments. However, correlation does not imply causation. Most experiments involving the relevance of brain size to intelligence hinge on the assumption that complex behavior requires a complex (and therefore intelligent) brain; however, this connection has not been consistently demonstrated.
History of anthropometry
Several studies have demonstrated correlations between race and brain size, with varying results. In some studies, Caucasians were reported to have larger brains than other racial groups, whereas in recent studies and reanalysis of previous studies, East Asians were reported as having larger brains and skulls. More common among the studies was the report that Africans had smaller skulls than either Caucasians or East Asians. Criticisms have been raised against a number of these studies regarding questionable methods.
In "Crania Americana" Morton claimed that Caucasians had the biggest brains, averaging 87 cubic inches, Indians were in the middle with an average of 82 cubic inches and Negroes had the smallest brains with an average of 78 cubic inches. In 1873 Paul Broca (1824–1880) found the same pattern described by Samuel Morton's "Crania Americana" by weighing brains at autopsy. Other historical studies alleging a Black-White difference in brain size include Bean (1906), Mall, (1909), Pearl, (1934) and Vint (1934). But in Germany Rudolf Virchow's study led him to denounce "Nordic mysticism" in the 1885 Anthropology Congress in Karlsruhe. Josef Kollmann, a collaborator of Virchow, stated in the same congress that the people of Europe, be them German, Italian, English or French, belonged to a "mixture of various races," furthermore declaring that the "results of craniology" led to "struggle against any theory concerning the superiority of this or that European race". Virchow later rejected measure of skulls as legitimate means of taxonomy. Paul Kretschmer quoted an 1892 discussion with him concerning these criticisms, also citing Aurel von Törok's 1895 work, who basically proclaimed the failure of craniometry.