Thalamic inhibition in the evolution of human intelligence: Evolutionary pressure for cortical inhibition

Journal/Book: Mankind Quart. 1998; 38: 1133 13TH St NW, #C-2, Washington, DC 20005. Inst Study Man. 319-335.

Abstract: One characteristic of a civilized society is the ability and propensity of its members to refrain from acting in a way that disrupts the harmony of the group. While this is not intelligence as measured by IQ, it is a form of social intelligence that will aid those having it in their ability to propagate. This characteristic is not unique to human societies but rather is true of most social species. This report deals with one aspect of brain chemistry that may underlie this social intelligence, defined as the ability of a species to inhibit its thoughts as well as its behaviors. Selective pressure has unrelenting consequences on the mechanisms of brain function? and perhaps the first mechanism to be affected is the chemistry of the brain. Changes in brain chemistry and function can be explored by an investigation of species selected to represent the phylogenetic sequence leading to mankind. In an examination of nine species selected on this basis, we have found that one consequence of selective pressure is an increase in the potential for cortical inhibition. We suggest this may be a major component of the evolution of human intelligence.

Note: Article Glendenning KK, Florida State Univ, Program Neurosci, Tallahassee,FL 32306 USA

Keyword(s): intelligence; thalamus; inhibition; comparative psychology; evolution; mammals; receptor binding; GABA; muscimol binding; amniotic vertebrates; ACID DECARBOXYLASE IMMUNOREACTIVITY; CENTRAL NERVOUS-SYSTEM; RAT-BRAIN; GABA RECEPTOR; QUANTITATIVE AUTORADIOGRAPHY; MUSCIMOL BINDING; VERTEBRATE; NUCLEI; CAT

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