Handicap Theory and Defense Reactions

Discussion of everything related to the Theory of Evolution.

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Handicap Theory and Defense Reactions

Post by IPO » Wed Feb 10, 2010 4:31 pm

First off, allow me to apologize for my lack of knowledge of evolutionary biology. I went to school for environmental science/management and possess an at best cursory knowledge of genetic and evolutionary science.

I recently read an article about handicap theory and understand that it refers to signals for defense or reproductive viability wherein individuals produce signals (at a personal cost) that display their superior quality. The idea being that if they have the energy to spare on the signal then they aren't worth the chase or they are the most suitable mate. Some of the examples given include peacock tails (displaying that survival despite such increased potential predatory risk must indicate superior suitability), and gazelles stotting to warn potential prey that they are too fit to be caught so a chase would be a waste of energy (at least that is one theory of why stotting occurs).

My question is whether other biological means of defense could be considered as supportive of handicap theory. Specifically, I'm curious about blood-injury phobia in humans (theories state that the sudden drop in blood pressure--which leads to fainting--due to the sight of blood and injuries is due to an evolved trait for defense against predators or enemies). Other examples I was thinking about are those goats that pass out when startled or rabbits that hold perfectly still when startled before running away.

Would these forms of reactionary defense be considered aspects of handicap theory? Or does it focus specifically on unnecessary energy expenditure to display superiority?


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Post by Darby » Thu Feb 11, 2010 9:36 pm

They might handicap the individuals, but that's not what the theory is about. There, your looking for "bonus" features that confer no survival advantage and are in fact handicaps. The owners are advertising that even with such features holding them back, they have flourished and are ready for business. A male peacock with a huge symmetrical tail will only pass the tail to male offspring, but the features that kept him from being caught and eaten, even with that tail weighing him down, will go to all his offspring.

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