Encephalization quotient
The encephalization quotient ( EQ ) is a measure of the relative size of the brain based on a certain expected value. The actually measured brain weight is put in relation to the brain weight that would be expected for a certain species with a comparable body weight.
The EQ was introduced in 1973 by HJ Jerison in an attempt to quantify a relationship between brain weight and cognitive ability. For the EQ, the simple ratio of brain mass to body mass (as the relative brain weight) of the individuals of one species is determined and related to the results of the allometry of other species. The EQ can thus be used to compare different animal species, just as it can be used in anthropology to compare different human species with one another.
An EQ> 1 initially only shows that the brain is heavier than expected in comparison; this can be an indication of increased cognitive abilities. However, the EQ itself is only suitable to a very limited extent as a measure of cognitive abilities. On the one hand, it depends on the comparison group for which the expected brain mass is calculated; on the other hand, the structure and structure of the brain, which are of great importance for cognitive abilities, are not taken into account.
calculation
The EQ is calculated from the ratio
The underlying "expected brain mass" is an empirically determined quantity and is calculated from the average relative brain size (body mass-related brain mass) of the type of living being for which one would like to compare using EQ.
In general, in organisms of the same type, the brain mass increases with increasing body mass , but not in the same proportion as this, but less rapidly. The relationship between the dependence of the brain mass on the body mass (given in grams), which is typical for a certain vertebrate species, can often be approximated by a power function : where is the exponent (so-called negative allometry ).
If you want to compare the average mass ratio of brain to body (as the relative brain size of adult individuals) of one species with that of other species, you can, for example, determine and specify an averaged power function (as a regression line ) for the different values within a group of mammalian species , how much the value measured for a species deviates from the expected value formed in this way. As an indication of the quotient for the same body mass, this is an EQ.
Examples
Humans have a very high EQ compared to other animals. The EQ of warm-blooded animals is significantly higher than that of other animals.
| species | Encephalization quotient (EQ) |
|---|---|
| human | 7.4-7.8 |
| Bottlenose dolphin | 5.3 |
| chimpanzee | 2.2-2.5 |
| Rhesus monkey | 2.1 |
| whale | 1.8 |
| African elephant | 1.3 |
| dog | 1.2 |
| cat | 1 |
| horse | 0.9 |
| sheep | 0.8 |
| mouse | 0.5 |
| rat | 0.4 |
| Rabbits | 0.4 |
| EQ compared to the cat as the standard species: EQ (cat) = 1 | |
Individual evidence
- ^ Jerison, HJ: Evolution of the Brain and Intelligence . Academic Press, 1973, ISBN 0123852501 .
- ↑ a b Onur Güntürkün: When is a brain intelligent? . In: Spectrum of Science . November 2008. Retrieved February 12, 2011.
- ↑ Miriam Noel Haidle: Ene, mene, muh - and are you smart? On the development of human thinking ( Memento of the original from June 11, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 2.5 MB). Institute for Prehistory and Early History and Archeology, University of Tübingen.
- ^ Suzana Herculano-Houzel: The Human Brain in Numbers- A Linearly Scaled-Up Primate Brain . (pdf) In: Frontiers in Human Neuroscience . 2, 2009, pp. 1-11. doi : 10.3389 / neuro.09.031.2009 .
- ↑ Jim Moore: Allometry. Retrieved February 12, 2011 .
- ^ Björn Widmann: Neuroscience and School Pedagogy . GRIN Verlag, 2008, ISBN 9783638925907 , p. 11.
- ^ Gerhard Roth and Ursula Dicke: Evolution of the brain and Intelligence . In: TRENDS in Cognitive Sciences . 9, May 2005, p. 250. doi : 10.1016 / j.tics.2005.03.005 .
