Theoretical substantiation of the handicap principle

[Spathi]

TL;DR Summary

A handicap is a harmful thing, like a peacock's tail, that attracts females precisely because it is harmful. Dawkins uses the following analogy: if two men are running a marathon, one of them has a bag on his shoulders, and they arrive at the same time, then the woman can choose the man with the bag, because her instincts know that he is strong (since he ran fast despite the bag).

https://en.wikipedia.org/wiki/Handicap_principleThe handicap principle is a controversial hypothesis, possible confirmed by Alan Grafen. I would like to understand his reasoning.

A handicap is a harmful thing, like a peacock's tail, that attracts females precisely because it is harmful. Dawkins uses the following analogy: if two men are running a marathon, one of them has a bag on his shoulders, and they arrive at the same time, then the woman can choose the man with the bag, because her instincts know that he is strong (since he ran fast despite the bag). But this is probably not a correct analogy, because in wildlife such a bag is worn all his life, and is not removed after the demonstration.

I will use a simple model. All men are divided into strong and weak, and into drinkers and non-drinkers (four combinations in total). The weak men drink a lot and this makes it very difficult for them to survive. The strong men drink moderately, this also hinders them, but not much. Women don't know if a man is strong or weak, but they know whether he drinks and that he survived. Therefore, if a woman sees a drinking man, she knows that he is more likely to be strong than a non-drinking man.

Here is the weakest point - where did this correlation come from, that the weak drink much, and the strong drink a little?

You can also suggest that a man stops drinking after the wedding, but somehow it turns out to be strained.

 

[jim mcnamara]

It is not accepted widely:

The handicap principle was proposed in 1975 by Israeli biologist Amotz Zahavi. The generality of the phenomenon is the matter of some debate and disagreement, and Zahavi's views on the scope and importance of handicaps in biology have not been accepted by the mainstream.

---
https://en.wikipedia.org/wiki/Handicap_principle

You are on your own in terms of figuring this one out.

Here is an in depth discussion of why it has problems and how research stands today (Grafen models refuted)

"The Handicap Principle: how an erroneous hypothesis became a scientific principle"
https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12563

Bottom line - hypothesis testing has failed.

 

[berkeman]

TL;DR Summary: A handicap is a harmful thing, like a peacock's tail, that attracts females precisely because it is harmful. Dawkins uses the following analogy: if two men are running a marathon, one of them has a bag on his shoulders, and they arrive at the same time, then the woman can choose the man with the bag, because her instincts know that he is strong (since he ran fast despite the bag).

https://en.wikipedia.org/wiki/Handicap_principle

The Biology/Medical forum is a technical forum at PF. You are required to post links to peer-reviewed journal articles to start discussions like this. Can you please do that? Thanks.

 

[berkeman]

No response from the OP, so this thread is closed for now...

 

[berkeman]

The Biology/Medical forum is a technical forum at PF. You are required to post links to peer-reviewed journal articles to start discussions like this. Can you please do that? Thanks.

I received a response via PM, so the thread is re-opened for now:

Please unlock the thread. Here is the article of Grafen:

1. Grafen, A. (1990). "Biological signals as handicaps". Journal of Theoretical Biology. 144 (4): 517–546. doi:10.1016/S0022-5193(05)80088-8. PMID 2402153.

 

[Spathi]

I hope other members will be interested in this topic, and if this discussion continues, I will read and cite the article of Grafen too.

 

[Godot_]

It would be helpful to have something published in an open-access journal...

Assuming that the handicap principle model is still in use (and the Grafen paper being cited 1750 times, one should presume so...) there should be some other publication available, or maybe a paper or three where the model gets refined, modified,...

JTheorBiol isn't really your standard university library fare, and, more importantly, not all forum people live near a university. Also, cnrses on Elsevier's greed department...

 

[jack action]

Here is the weakest point - where did this correlation come from, that the weak drink much, and the strong drink a little?

I'm not sure where you took the example, but I think the amount of alcohol consumed is irrelevant (we assume they all drink the same amount). The model assumes 3 groups of men:

Weak men that drink -> they have trouble facing life, so obviously weak men
Strong men that drink -> they can still go about their life, thus obviously strong men. They may or may not face harder times while still drinking, but can definitively face harder times if they stop drinking.
Men that don't drink -> they can all go about their life, but we cannot distinguish the strong from the weak, i.e. who could survive given a harder life. Furthermore, a strong man not fully exploiting his strength regularly might not be able to use it when needed.

 

[Spathi]

Perhaps, in order to understand (or refute) the handicap principle, it is useful to understand the concept of Fischer's runaway (I guess it is not denied by anyone now).

https://en.wikipedia.org/wiki/Fisherian_runaway

I've read this article, as well as Dawkins’s explaining of the concept, but still don't get the gist of it. Male peacocks have extremely large tails and females have a love to large tails. When a male with a long tail leaves offspring, those offspring inherit both the long tail genes and the “female love to big tails genes”. It is not clear why this should produce a positive feedback? Or so: why the natural selection does not support females who prefer short tails? If a male with a relatively short tail and a female with a preference for short tails appeared in a population of peacocks, wouldn't they leave relatively viable offspring?

 

[jack action]

why the natural selection does not support females who prefer short tails?

Reading that question really leads me to the only answer I can think of:

​

 

[Spathi]

Reading that question really leads me to the only answer I can think of:

I don't understand your reply, suppose this is a kind of trolling. However my question is simple. Suppose there are 100 males and 100 females in a population of peacocks. 80 males have long tails, 20 males have short ones; 80 females prefer long tails, 20 females prefer short. As a result, offspring are born by them, 80% with long tails and 20% with short ones. And because short tails are beneficial, those 20% eventually replace the other 80%. What should be added to this model in order to understand the concept of fisherian runaway?

 

[jack action]

Let me ask my why question:

• Why would a female prefer a short tail?

Birds like these have a great advantage for survival when they can hide in their environment. The drawback is that you are also hidden from your possible mate.

One solution is to have one of the mates be overly exposed such that it can be found by the other sex. That sex will necessarily have a lower survival rate because it will be hunted more easily. That sex cannot be the female as it is the sex that will carry - and take care of - the offspring. The male has a much lower role in reproduction and is therefore more expendable.

So, why would a female prefer a long tail? They probably don't. They just are easier to find for them compare to males with short tails.

The corollary is that females will never prefer a male with a short tail as they will never meet.

 

[BillTre]

These displays have been hypothesized to have some of these possible benefits:

• Colorful displays can be indicative of healthiness and having good nutrition. Indicates good genes for general health.
• Colorful displays may indicate the male is able to survive in its environment despite this "handicap" in its survival efforts.

However, some of the garish displays can be hidden from view when not needed (like a peacock's tail).

These mate choices are not something the animal sits there and thinks about, they are instinctive behaviors that have been selected for over many generations and built into their nervous systems.
If there is a predominance of females in a population selecting flashier tails (or whatever), then longer tails will predominate and less flashy tailed males will have a harder time finding mates and successfully leaving offspring.

Edited to add an important "not" that was left out.

 

[Spathi]

If there is a predominance of females in a population selecting flashier tails (or whatever), then longer tails will predominate and less flashy tailed males will have a harder time finding mates and successfully leaving offspring.

This concept explains the Matthew effect, but not the irrational love of females to very long tails. If only this factor was present, in a population of peacocks with average tails both long tails and short tails trends would be resisted by the sexual selection. But we see that in this situation the tails continue to become longer and longer, until the utilitarian natural selection blocks this trend.

 

[BillTre]

This concept explains the Matthew effect, but not the irrational love of females to very long tails. If only this factor was present, in a population of peacocks with average tails both long tails and short tails trends would be resisted by the sexual selection. But we see that in this situation the tails continue to become longer and longer, until the utilitarian natural selection blocks this trend.

My interpretation of what you said:

the irrational love of females to very long tails

as being a strong desire by the females for males with "very long" tails.
Sounds like a behavior that is "hardwired" in the the adult female nervous system. This would have been selected for due to its success in reproducing (due to successful meet ups with the females). If this over time, becomes deeply integrated into more widespread controls, it will become more difficult to just remove. Evolving a specific inhibitor might be a solution.

The production of the very large tails can be come costly in resources and in being more easily seen by a predator would be expected to be selected against. However, a hardwired tendancy for the females to choose particular males could drive selection in the other direction. There are a bunch of different selective forces being balanced here to affect the outcome.

 

[Rive]

Just a

...irrational love of females to very long tails.

Just a random idea, but feels related