Tag Archives: evolution

On military bravery

All countries and armed groups emphasize the bravery of their soldiers for propaganda purposes. Such claims are made regardless of whether there is any actual valour. Going to a dangerous situation or even certain death is not necessarily courageous, in particular if there is no knowledge of the danger or no choice. Are sheep going into a slaughterhouse brave? They are calmly walking to certain death, after all. But usually this is not ascribed to courage, but to ignorance. Analogously, soldiers used in early tests of the physiological effects of radiation exposure who were marched through an area of a recent nuclear explosion are not considered brave. They did not know the cancer risk.

If there is no choice, which usually means there are only perilous choices, then putting oneself in danger is not usually accounted brave. Jumping out of a burning building offers a higher probability of survival, so people do it despite the substantial risk of falling to death. When a sufferer of a painful terminal disease chooses euthanasia, this early death is commonly not considered brave. Some cultures even believe suicide to be a sign of cowardice. If a military has a well organized system for catching deserters and administering the death penalty to them (and their family in some regimes), then a soldier charging enemy machineguns is merely maximizing his survival probability. The enemy might miss, the firing squad rarely does.

The greater the probability of victory for one’s own side, the less attractive desertion becomes, because being caught is more likely. This explains the propaganda emphasis on own victories and the punishment of “defeatist talk” in wartime. The greater the military advantage of a party in an armed conflict, the less bravery its soldiers need.

Genuine bravery exists, but it is rare. Evolution favours cowardly bullies who attack the weaker (prey) and run from the stronger (predators). People who face no compulsion to fight in a war and know the dangers, yet still join, are brave. Freedom fighters (insurgents from the other side’s viewpoint) against a dictator qualify. With the caveat that only joining the fight initially requires bravery – after that, losing would mean being tortured to death by the dictator, so continuing the war is the safer option. Similarly, volunteering for the military requires some bravery (the more the greater the likelihood of being sent into danger), but once military law applies, desertion is usually more dangerous than the duty.

Military courage is proved for those who start the war as a weaker side against a stronger, if a continuing peace is not a slow death. Peasant revolts were often driven by hunger, meaning the participants may have perceived the probability of death from starvation as higher than the probability of being killed by the aristocrats.

People who have never faced an informed choice between a safe and a dangerous option may be “latently brave”, in the sense that given such a choice, they may exhibit courage. They are not proved brave, however, until they have made the choice. There are likely to be some latently brave people in the world’s militaries and armed groups. Probably a greater percentage than among the general population.

There are some proven brave folks even in the militaries of powerful countries, but the proof requires knowingly choosing a dangerous option when there is no future punishment for cowardice. For example, when nobody would know of the choice.

A topical question is whether suicide terrorists and other fighting religious fanatics are brave. Their behaviour may be driven by the fear of punishment either in the afterlife or by their fellow fanatics. It may also be due to ignorance – believing in an afterlife is like believing that one cannot really die and thus the danger is not real. In both cases, no courage is required for choosing death.

The belief in the impossibility of dying may even be literal – W.E.B. Griffin had a story of a witch doctor convincing the fighters of his tribe that his magic had made them immune to bullets. Great was the fighters’ surprise later… Their charge with spears against guns was not due to bravery, however.

Probability of finding true love

The concept of true love has been invented by poets and other exaggerators. Evolutionarily, the optimal strategy is to settle with a good enough partner, not to seek the best in the world. But suppose for the sake of argument that a person A’s true love is another person B who exists somewhere in the world. What is the probability that A meets B?

There is no a priori reason why A and B have to be from the same country, have similar wealth or political views. Isn’t that what poets would have us believe – that love knows no boundaries, blossoms in unlikely places, etc?

Given the 7 billion people in the world, what fraction of them does a given person meet per lifetime? Depends on what is meant by “meets” – seeing each other from a distance, walking past each other on the street, looking at each other, talking casually. Let’s take literally the cliché “love at first sight” and assume that meeting means looking at each other. A person looks at a different number of people per day depending on whether they live in a city or in the countryside. There is also repetition, i.e. seeing the same person multiple times. A guess at an average number of new people a person looks at per day is 100. This times 365 times a 70-year lifespan is 2555000. Divide 7 billion by this and the odds of meeting one’s true love are thus about one in three thousand per lifetime.

Some questionable assumptions went into this conclusion, for example that the true love could be of any gender or age and that the meeting rate is 100 per day. Restricting the set candidates to a particular gender and age group proportionately lowers the number of candidates met and the total number of candidates, so leaves the conclusion unchanged.

Someone on the hunt for a partner may move to a big city, sign up for dating websites and thereby raise the meeting rate (raise number met while keeping total number constant), which would improve the odds. On the other hand, if recognizing one’s true love takes more than looking at them, e.g. a conversation, then the meeting rate could fall to less than one – how many new people per day do you have a conversation with?

Some people claim to have met their true love, at least in the hearing of their current partner. The fraction claiming this is larger than would be expected based on the calculations above. There may be cognitive dissonance at work (reinterpreting the facts so that one’s past decision looks correct). Or perhaps the perfect partner is with high probability from the same ethnic and socioeconomic background and the same high school class (this is called homophily in sociology). Then love blossoms in the most likely places.

Why messages of attraction are ambiguous

There are many behaviours by which one human shows being sexually attracted to another – staring at them, running fingers through one’s hair, standing close, smiling at them, etc. Most of these are ambiguous, meaning they can be explained away by nonsexual reasons. Staring may be due to being lost in thought and looking absently at a single point, which happens to contain a person. Adjusting the hair could happen because the hair feels messy. One could randomly stand close to someone, smile because one is happy for unrelated reasons and so on.
There are obvious benefits of clear messages – no wasted effort chasing someone not interested, no awkward situations, no false accusations that one’s partner was sending signals of interest to someone else. Why has evolution led to messages of attraction that create doubt in the observers?
If someone’s sexual advances are unsuccessful, this is interpreted as a negative signal about the rejected person and lowers their chances in the future. Rejection makes one wonder what the rejecter knew about their admirer that is unattractive. If a person has characteristics that makes others reject them, the offspring of that person are likely to inherit these and also be unsuccessful in mating. Unsuccessful offspring mean the fitness of the rejected person is low, justifying rejecting them. This evolutionary mechanism is called Fisherian sexual selection. Because of it, nobody wants to be seen to be rejected. One way to hide rejections is to hide the wooing and if rejected, pretend to be uninterested anyway (sour grapes).
Someone attempting to cheat on their partner obviously does not want others to see their advances on another person. People gossip, so hidden signals with plausible deniability are useful.
Some people take advantage of those attracted to them (the advantage may differ for men and women), so it is good to send messages of attraction only to those who are attracted in return. Someone who is interested pays more attention to a person, so is more likely to notice ambiguous messages from them. Wishful thinking makes an interested recipient interpret mixed messages favourably. Of course there is a positive probability of a mistake, but the difference between the probability of interested people versus unintended recipients noticing a signal is greater for ambiguous than clear messages. This is like encryption – there is a positive probability of friendlies having lost the encryption key, but the difference between the probability of friendlies versus hostiles understanding the message is greater for encrypted text.
Dating websites have probably figured this out, because they allow private messages. An additional improvement may be self-destructing messages that can only be viewed once. This makes it harder for the recipient of a message to prove someone’s interest to others and thus lower their admirer’s reputation after rejecting them. Randomly generating messages of attraction and sending them to people would give plausible deniability to those who are rejected. The benefit of deniability must be weighed against the loss to the recipients of false signals.

Raising grandchildren, not children

Currently in all species I know of, each generation raises its children, who in turn raise their children, etc. This can be described as an overlapping generations model where each generation lives 2 periods, receives resources from the old of the previous generation in its youth and transfers resources to the young of the next generation when old. There is another equilibrium: each generation raises its grandchildren, has its children raised by its parents, and the children in turn raise their grandchildren. Instead of transferring resources to the next generation and receiving them from the previous, transfer resources two generations forward and receive them from two generations back. There are an infinite number of such equilibria: for each n, transfer resources n generations forward and receive them from n generations back. There are of course practical problems with large n, because the organisms do not live long enough to meet their level-n offspring.

There are complaints in developed countries that childbirth is postponed in life to acquire education and start a career. A possible solution is transitioning to an equilibrium of taking care of grandchildren, together with having children at a young age so that the grandparents are still alive to see the teenage years of their grandchildren. However, the equilibrium transition from taking care of children to taking care of grandchildren means that one generation must raise both children and grandchildren. The equilibrium transition in the other direction is easy – one generation does not raise its children or grandchildren, because its children are raised by its parents and its grandchildren by its children. Any other equilibrium is less stable than the raising-children one, because it is difficult to transition to it and easy to transition away.

The equilibrium stability comparision is similar to the social security equilibria in overlapping generations. In one equilibrium, everyone saves for their own retirement and consumes their savings when old. In another, every generation when young pays the social security costs of the previous generation who is old at the same time. The transition from the saving equilibrium to the equilibrium of paying the previous generation is easy, because one generation gets its savings and the contribution from the young, while the young do not save and receive the contribution of the next generation. The reverse transition is difficult, because one generation does not get a contribution from the young in its old age, but has to finance the retirement of the previous generation when young.

Evolving adaptable adaptability

If the environment changes, then there is a fitness benefit to being an adaptable organism. On the other hand, adaptability is costly (bigger brain for adjusting behaviour, various backup systems in the body like the camel’s hump need to be carried around). So adaptability gives a net benefit if the environment changes sufficiently rapidly.
If periods of change alternate with periods of constant environment, then it would be useful to have the ability to switch adaptability off for a while. This is adaptable adaptability. The ability to switch adaptability off is in turn costly. It is useful to have if periods of environmental change alternate with periods of stability sufficiently rapidly. It would be good to have an ability to switch off the ability to switch adaptability off if changes and stability alternate with different frequency over time. Even more complex patterns may necessitate the ability to switch the ability to switch the ability to switch adaptability, etc. Hierarchies of abilities controlling abilities arise.
Perhaps after an infinite hierarchy, there is some meta-ability that can switch all lower order abilities. Self-awareness or something similar.

Sexual signals are similar to money

Ronald Fisher analyzed signalling in biology through traits that do not confer direct fitness advantage (higher survival or fecundity), but are desired by the opposite sex. This attraction is an equilibrium in a coordination game – if a potential mate has traits desired by the opposite sex, then the offspring with that mate are likely to have these traits as well and succeed in attracting the opposite sex. The traits confer a mating advantage, which is part of a fitness advantage, justifying the desirability of the traits.
It is a coordination game, because in a different equilibrium, traits without a direct fitness advantage are not desired. Then these traits do not give a mating advantage to the offspring and therefore do not have an indirect fitness advantage either. Then it is not fitness-enhancing to desire them. In summary, if a trait is expected to be desirable in the future, then it is desirable now, and if a trait is expected to be neutral or undesirable, then it is neutral or undesirable now.
Fiat money is inherently worthless, but in one equilibrium of the money game, has positive value in terms of other goods. If everyone expects that others will accept money in return for goods in the future, then it is useful to obtain money now. So everyone is happy to deliver goods in return for (a sufficient sum of) money now. The money game is a coordination game, because if everyone expects money not to be accepted in the future, then they do not give goods for money now. If money is expected to be worthless, then it is worthless, and if money is expected to be valuable, then it is valuable.
An overview of signalling in biology is at http://en.wikipedia.org/wiki/Signalling_theory and Fisher’s theory at http://en.wikipedia.org/wiki/Fisherian_runaway
The coordination game of money is studied by Kiyotaki and Wright (1989, 1993): http://www.jstor.org/stable/1832197 http://www.jstor.org/stable/2117496 and more simply explained in van der Lecq “Money, coordination and prices” https://books.google.com.au/books?id=r1r40SB0Wn8C&pg=PA29&lpg=PA29&dq=fiat+money+coordination&source=bl&ots=iI0M96m-qz&sig=lRHBAWIXYZs2V5S-iNFeH-2yar8&hl=et&sa=X&ei=d3lqVeneJ8TvmAX4vIGgDg&ved=0CEoQ6AEwBw#v=onepage&q=fiat%20money%20coordination&f=false

Of beauty

What is beauty in human beings? Poets have written a lot about it. I will take a different approach. Beauty is the traits that humans have evolved consider attractive. The characteristics of a good mate, in other words. A good mate is someone with whom one would expect to have numerous fit offspring. A healthy and fertile person. Beauty consists of the outward signs of health and fertility.
Health signals are similar for men and women – good posture, energetic movement, strength and speed, neither excessive fat nor skeletal thinness, smooth skin without patches of different colour, clear voice, bright eyes, no strange smells, thick lustrous hair etc. Posture, movement and strength signal that there is no internal disease that causes weakness or fatigue. Excessive fat or thinness suggest metabolic problems or malnutrition. Skin diseases manifest as roughness and redness. Clear voice signals absence of throat or lung diseases, bright eyes show no eye infection etc.
Fertility signals differ somewhat across genders. Youth and health are associated with fertility in both genders, but a masculine or feminine figure is a fertility signal only for the appropriate gender. Broad shoulders, big muscles, wide angular face and hairyness are all caused by high testosterone levels. These suggest a fertile male, but if observed in a female, are signs of some endocrine disease. Smooth curves, large breasts, narrow waist and wide hips are signs of high oestrogen levels and a fertile female. The narrow waist further suggests the woman is not pregnant already (pregnancy means current sex is unlikely to lead to offspring, which can be interpreted as temporary infertility as far as the current partner is concerned).

Recursive definition of fitness

Evolutionary theory predicts fitness maximization by organisms over a large enough number of generations. Fitness is described as the ability to survive and reproduce given the environment, but I have not seen a formal definition of fitness even in mathematical models of adaptation.

A direct definition of fitness is difficult to give. Fitness is not the number of offspring, because then a fitness-maximizing organism would accept the following trade: add one child and remove the reproductive ability of all your children. Similarly, fitness is not the number of grandchildren or grand-to-the-n-children, because if it was, the reproductive ability of the grandchildren would be traded away for one more grandchild. If fitness was the number of fertile offspring surviving to adulthood, this trade could be shifted by one generation: add one adult fertile child and remove the reproductive ability of grandchildren or all descendants in a more distant generation. Clearly one has to take into account all descendants in the infinite future in some way.

Fitness can be defined recursively: it is the sum of the fitnesses of the offspring (multiplied by some positive constant). The fitness of each child in turn is the sum of the fitnesses of that child’s offspring, their fitnesses are the sums of the fitnesses of their offspring, and so on to infinity.

Under this definition, the trade described initially would not be made: changing the fitnesses of all descendants in some generation to zero would not be accepted, no matter what is offered in return (increasing the fitness of more distant descendants cannot be part of the same trade). Increasing the summary fitness of descendants in some more distant generation, other things equal, is inconsistent with reducing the fitness of descendants in a nearer generation. This is because if the fitness of an organism increases, other things equal, then the fitness of all that organism’s ancestors increases.

Under multilevel selection, as in Reeve and Holldöbler 2007, there is more than one fitness concept. There is individual fitness and group fitness, if both individuals and groups reproduce. The definitions of these fitnesses are also recursive, but more complicated, since fitness at one level of reproduction will interact with the fitness at another.