Sensory bias

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The "Sensory bias" theory (Engl. Sensory preference ) founded the female preference for certain male characteristics in mate choice in the attraction conspicuous characteristic attributes (color, size, beeps, etc.) that can be better perceived by the female sensory system. Since z. B. long, brightly shining plumage are more noticeable, these are more likely to be perceived by female birds and therefore preferred. This reduces the female investment costs when looking for a partner, which leads to the fact that the reproductive success increases.

Basic theory

Charles Darwin explains in his theory of sexual selection that in the course of evolution, due to the choice of females, above-average male characteristics have developed. It gives no indication as to why males usually court females and choose females from among the males recruiting. It is assumed that the reproductive effort between the sexes is asymmetrical and that the behavior can be traced back to this: Female conspecifics mainly invest in parental care, i.e. H. in the search for the one, right partner, males especially in (advantageous) courtship signals .

Classic models

On the basis of these considerations, various hypotheses were drawn up on the development of preferences in the choice of female partners . These include, for example, the classic ideas derived from sexual selection such as Fischer's theory of the Runaway Selection (1930) or the Good Genes hypothesis according to Zahavi (1975).

The "Runaway Selection" states that females prefer certain male characteristics when choosing a partner, which leads to a positive feedback, so that on the one hand the development of the preferred characteristics is favored in the males and on the other hand the associated female preference (for these characteristics ) is also successfully passed on from generation to generation.
The second theoretical model states that the presence of a certain trait (e.g. bright colors or long tails in birds) promises genetic advantages; H. that the male has good genes. This means that these advantages can be passed on to the next generation.

In both concepts - which are not mutually exclusive - it is predicted that the preferences of female partner choice correlate with the presence of male characteristics.

Modern concepts

Newer theories, the so-called receiver bias models , have existed since the 1980s . You observe male characteristics and female preferences in the context of communication theory. There are several similar models such as B. "Sensory Exploitation", "Sensory Trap" and "Sensory Bias" or "Sensory Drive". These concepts are primarily about the design or structure of the male signals that are used for advertising.

Sensory Bias or Sensory Drive (Endler 1992)

The “ sensory bias” model postulates that the preferences of female partner choice are by-products of natural selection by the sensory system . This concept is used to explain two phenomena: first, that the design of male signals evolved to stimulate the sensory system of females, and second, why females have specific preferences. Of particular importance is the interpretation of the quantitative development of female preferences in partner choice, i.e. why some male characteristics have developed into sexual signals through the behavior of the females and others not. The effectiveness of some signals depends on the type and structure of the signal and which one the recipient - i.e. the female - perceives better. Specific environmental conditions influence the evolutionary direction of behavior, which has an effect both on the time and place of the signal effect and on the preferences of the individual living space. It is therefore a co-evolution between the biophysical environmental conditions, neurobiology and genetic predispositions.

Endler & Basolo assume that there are five different types of inclination:

  1. Tendencies that result from properties that once had a function but have lost it
  2. Tendencies that arise by chance, although they have no influence or function on the organism
  3. Tendencies that are important outside of sexual communication
  4. Tendencies that are important for sexual communication but are so fundamental to the sensory system that they influence all further development
  5. Tendencies that were initially not important, but have nonetheless established themselves in the course of evolution due to mutations

Sensory Exploitation (Ryan 1990; Basolo 1990)

The model assumes that the development of sexually selected characteristics is influenced by pre-existing preferences. With this assumption, a prognosis can be generated about the historical structure of the evolution of trait preferences that developed before the sexually promising traits. This approach is completely different from the models of the “good genes” and “runaway” hypotheses, in which preferences and traits evolve in mutual agreement.

Sensory Trap (West-Eberhard 1979)

In this model, the author assumes that the design of male signals is based on the existing preferences of the females. In addition, the hypothesis emphasizes that these sensory preferences of the females for certain signals arose in a (non-sexual) context subject to natural selection, e.g. B. to find food. Males imitate these signals in order to trigger beneficial reactions from the females and thus increase their reproductive success.

The Mating Mind

Geoffrey Miller offers a popular scientific view of the topic of sexual selection in his book "The Mating Mind - How Sexual Choice Shaped the Evolution of Nature" (2001, German "The sexual evolution. Partner choice and the emergence of the mind.") It is about the following Ask:

  1. How did the human brain develop into such a complex organ in evolution?
  2. Is it possible that the human brain has grown so rapidly because of natural selection, even though the selection apparently only led to the development of tools long after the "modern" brain size had been reached?
  3. How can specifically human characteristics such as B. Humor and creativity or our consciousness provide a survival advantage?

Geoffrey Miller offers sexual selection as a decisive factor in his approach. The author tries to illustrate with a comparison that the targeted female preference for male individuals with greater intellectual capacity can explain the rapid brain development: A large brain - similar to the magnificent tail of a peacock - is first of all a handicap for its owner: it is much harder to survive with. However, since the owners survive, their genetic fitness must be excellent. Humans exist today because they have had an uninterrupted series of successful sexual relationships, each generation. A hominid female who wants to obtain good genes for her own offspring should therefore prefer a carrier with a large brain - evidence that suggests this quality could be creativity, humor or imagination, for example. On the basis of this basic idea, Miller looks at a number of human behaviors and speculates about the evolutionary origins of language, altruistic behavior or the possession of jeeps.

Footnotes

  1. ↑ Endler 1992; Endler & Basolo 1998

See also

literature

Popular science

  • The Mating Mind - How Sexual Choice Shaped the Evolution of Human Nature, New York 2000, ISBN 0-385-49516-1 (German: Die sexual Evolution. Partnerwahl und die Geistung des Geistes, Heidelberg 2001, ISBN 3-8274-1097- 5 )

Specialist literature

  • Dawkins MS and Guilford T. (1996). Sensory bias and the adaptiveness of female choice. American Naturalist, 148 , 937-942.
  • Endler, JA (1992). Signals, signal conditions, and the direction of evolution. American Naturalist 139 (Supplement), 125-153.
  • Endler, JA, and Basolo, AL (1998). Sensory ecology, receiver biases and sexual selection. Trends in Ecology and Evolution 13, 415-420. Retrieved April 27, 2007, website: http://cas.bellarmine.edu/tietjen/Ecology/sensory_ecology.htm
  • Johnstone RA (1995). Sexual selection, honest advertisement and the handicap principle: reviewing the evidence. Biol. Rev., 70 , 1-65.
  • Ryan MJ and Keddy-Hector A. (1992). Directional patterns of female mate choice and the role of sensory biases. American Naturalist, 139 (Supplement), 4-35.
  • Ryan MJ (1990). Sexual selection, sensory systems and sensory exploitation. Oxford Surveys in Evolutionary Biology, 7 , 157-195.
  • Shaw K. (1995). Phylogenetic tests of the sensory exploitation model of sexual selection. Trends in Ecology & Evolution, 10 , 117-120.
  • Sherman PW and Wolfenbarger LL (1995). Genetic correlations as tests for sensory exploitation. Trends in Ecology & Evolution, 10 , 246-247.
  • West-Eberhard, MJ (1979). Sexual selection, social competition and evolution. Proceedings of the American Philosophical Society, 123 , 222-234.

Web links

http://www.panevolution.com/sozialeevolution/sexselektion2.html - Fischer's runaway selection