Chapter 9 Chapter VII Family Planning

It is not difficult to understand why some argue that parental care should be distinguished from other types of kin-selected altruism.Parental care appears to be integral to reproduction, whereas altruistic behavior such as that of a nephew is not.I think there is an important distinction hidden here, but people get it wrong.They lump together reproduction and parental care, and separate other kinds of altruism.But I wish to make a distinction like this: one is for producing new individuals, and the other is for raising existing ones.I call these two activities childbearing and childcare, respectively.An individual survival machine has to make two entirely different kinds of decisions, decisions about rearing and decisions about procreation.I use the word "decision" to mean an unconscious strategic action.A parenting decision is a decision of the form: "There is a young child; how close is it to me in kinship; if I don't feed it, what are its chances of dying; should I feed it?" On the other hand, the decision to reproduce is this: "Should I take all necessary steps in order to have a new individual? Do I reproduce?" To some extent, rearing and procreation are necessarily the occupation of an individual's time and Competing with each other for other resources, the individual may have to make a choice: "Should I raise this young child or create a new one?" Mixed strategies of rearing and reproduction, if adapted to the ecological specific conditions of the species, are evolutionarily is stable.Pure parenting strategies are unlikely to be evolutionarily stable.If all individuals devote all their energy to raising the existing young, so that no new individuals are born, such a population will soon be invaded by mutant individuals who are good at reproduction.Rearing is evolutionarily stable only as part of a mixed strategy—at least some amount of reproductive activity is required.

Species with which we are very familiar—mammals and birds—tend to be adept at parenting.Along with the decision to have a young child is often the decision to raise it.It is precisely because the two activities of procreation and rearing take place practically one after the other that people confuse the two events.But from the selfish gene's point of view, it makes no difference in principle whether the baby being reared is a brother or a son.We have mentioned this above. Both babies are equally related to you.If you had to choose between two young children to feed, there was no genetic reason why you should choose your own son.But on the other hand, by definition, you can't have a younger brother.You can only raise him after other people have born him.We have discussed in the previous chapter how an individual survival machine can make an ideal decision about whether to act altruistically towards other existing individuals.In this chapter we explore how an individual survival machine decides whether to produce a new individual.

I mentioned in the first chapter about the "group selection" debate, and this fierce debate revolves around this issue.This is due to the fact that Wynne-Edwards put forward his view of group selection based on the "Population regulation" theory, and he is the main proponent of this group selection theory. He believes that individual animals deliberately reduce their birth rate for the overall benefit of the group . This is a very attractive hypothesis because it fits well with the actions that individual human beings should take.There are too many human children.The size of the population depends on four events: births, deaths, immigration and emigration.If we take the world population as a whole, there is no immigration or emigration, only births and deaths.As long as each couple has an average of more than two children surviving to reproduce, the number of newborn babies will continue to increase linearly at a continuous acceleration.The population of each generation does not rise by a fixed amount, but is more likely to increase by a fixed rate based on what the growing population has already achieved.Since the population itself is also increasing, the increments of the population are also increasing.If this rate of growth were allowed to continue unchecked, the population would increase astronomically, at an astonishing rate.

Incidentally, population growth depends not only on how many children people have, but also on when they have them, and even people who care about population sometimes don't realize this.Because each generation tends to grow at a certain rate, if you make the distance between generations longer, the annual growth rate of the population will be lower.We can completely change the words "only two children" written on the banner to "start at thirty"!But in any case, the accelerated population growth will cause serious problems. We've all probably seen examples of this kind of calculated staggering number that speaks volumes.For example, Latin America currently has a population of about 300 million people, many of whom are already malnourished.But if the population continues to increase at the present rate, in less than five hundred years the result of the population growth will be such that people stand and squeeze together to form a line of human bodies covering the entire area of ​​the continent. carpet.This is true even if we assume that they are all skinny—an assumption that is not untrue.A thousand years from now, they will stand on each other's shoulders a height greater than a million men.In two thousand years, this mountain built by people will stretch upward at the speed of light, reaching the edge of the known universe.

No doubt you will notice that this is a figure calculated on assumptions!In fact, for some very practical reasons, it definitely won't happen: famine, plague, and war; or, if we're lucky, family planning, are some of the reasons.Invoking advances in agricultural science -- the "green revolution" and the like -- is of no avail.Increased food production may alleviate the problem temporarily, but it is mathematically certain that it cannot be a long-term solution; speed, exacerbating the problem.It is a simple logical fact that without rockets carrying millions of people per second into space on a mass scale, the uncontrolled birth rate must lead to a horrific rise in the death rate.It is unbelievable that even leaders who forbid their followers to use effective contraceptive methods do not understand such a simple fact.They showed that they preferred the "natural" method of population restriction, and it was this natural method which they were going to get: starvation.

But the unease caused by such long-term calculations is, of course, a concern for the future welfare of our species as a whole.Humans (some of them) have the conscious foresight to foresee the catastrophic consequences of overpopulation.Survival machines are generally operated by selfish genes. It is absolutely certain that selfish genes cannot predict the future, nor can they take the welfare of the entire species at heart. This is the basic assumption of this book.It is at this point that Wynne-Edwards parted ways with orthodox evolution theorists.He argues that there are ways in which truly altruistic birth control behaviors can take shape.

There is agreement, not disagreement, on a large part of the facts, but this is not emphasized in Wynne-Edwards's work, or in Ardley's essays on Wynne-Edwards' views. It is an obvious fact that wild animal populations are not increasing at astronomical rates, although such rates are theoretically achievable.Sometimes the numbers of wild animals are fairly stable, with births and deaths roughly equal.In many cases, their numbers fluctuate wildly, lemmings being a good example, which sometimes explode in large numbers and sometimes go extinct.Sometimes the result of fluctuations is the complete extinction of a population, at least in local areas.In the case of the Canadian lynx, the fluctuations in numbers seem to be rhythmic, as evidenced by the number of pelts sold by the Hudson's Bay Company over successive years.One thing is certain, that is, the number of wild animals will not continue to grow indefinitely.

Wild animals almost never die of old age: long before they die of old age, starvation, disease, or predators can kill them.The same was true of humans until recently.Most animals die in infancy, and many die while still in the egg stage.Starvation and other causes of death are fundamental reasons why wild animals cannot grow without limit, but as we have seen with our own species, there is no reason why our species should get to that point.As long as animals can regulate their birth rates, starvation never occurs.The Wynne-Edwards argument is that animals do just that.But even here there may not be as great a divide as you might imagine from reading his book.Advocates of the selfish gene theory will readily agree that animals do regulate their own birth rates.The clutch size, or litter size, of any particular species is fairly fixed: no animal can reproduce indefinitely.The disagreement is not whether birth rates are regulated, but how: by what process of natural selection did family planning come into being?In a nutshell, he said, the disagreement is: whether birth control in animals is altruistic, controlled for the good of the group as a whole, or selfish, controlled for the benefit of the breeding individual.I will discuss these two theories one by one.

Wynne-Edwards believed that individuals limit the number of children they have for the good of the group as a whole.He concedes that normal natural selection is unlikely to have evolved such altruistic behavior: natural selection for below-average reproductive rates is, on the face of it, an oxymoron.So, as we saw in Chapter 1, he turned to the theory of group selection.According to him, a group whose individual members can restrain their own birth rate is less likely to become extinct than a group whose individual members reproduce so rapidly that the food supply is endangered.The world would thus be occupied by groups whose individual members can restrain their own birth rates.Wynne-Edwards's self-regulating behavior is roughly equivalent to birth control, but he is more specific, and in fact he develops a very important concept, that the whole social life is a mechanism of population adjustment.For example, the social life of many animal species has two main features, territoriality and dominance hierarchies, which we mentioned in Chapter 5.

Many animals apparently devote a lot of time and energy to "guarding" an area that naturalists call a turf.This phenomenon is very common in the animal kingdom, not only in birds, mammals and fish, but also in insects and even sea anemones.This area may be a large area in the forest, which is mainly a natural feeding ground for breeding pairs.Such is the case with the bird. Or, as in the case of mackerel gulls (herring gulls), such a territory may be a small area devoid of food but with a nest in the middle.According to Wynne-Edwards, animals who fight for territory are fighting for a symbolic object, not an actual object like a bit of food.In many cases, females refuse to mate with males because they do not own a territory.Occasionally, a female animal, because her mate has been defeated and her territory is taken, quickly commits herself to the victor, and this does often happen.Even in apparently loyal monogamous species, females may mate to the male's territory rather than the male himself.

If there are too many members of the population, some individuals will not get territory, and they will not be able to reproduce.Thus, according to Wynne-Edwards, winning a territory is like winning a certificate or license to breed. Since the number of sites available is limited, it is as if the number of breeding licenses issued is limited.Individuals may fight to obtain these permits, but the total number of young that can be produced by the population as a whole is limited by the amount of territory available.Sometimes some individuals appear at first to be self-disciplined, as is the case with the red grouse, because those that cannot win territory not only do not reproduce, but seem to give up the struggle to gain territory again.They seem to accept the rules of the game: If you have not obtained an official permit to reproduce at the end of the competition season, you must consciously refrain from breeding, and do not disturb those lucky individuals during the breeding season so that They are capable of propagating species. Wynne-Edwards also illuminates the process of ruling group formation in a similar way.In many animal groups, especially captive animals, but sometimes wild animals as well, individuals remember each other's traits, and they also know who they can beat in a fight, and usually who can beat them.As we saw in Chapter 5, they "know" which individuals are likely to defeat them, and therefore tend to surrender without fighting when confronted with these individuals.As a result, naturalists have been able to describe ruling groups or "peck orders" (so named for the situation in which they were originally used to describe hens)--a hierarchical society in which each individual clearly One's own status, and therefore has no idea beyond one's own identity - pictured graphically.Of course, there are times when real all-out combat takes place, and there are times when individuals are able to win promotions and gain status over their immediate superiors.But, as we saw in Chapter 5, in general the consequence of the voluntary concessions of low-ranking individuals is that truly sustained fights rarely occur and serious injuries are rare. Many people who see the problem from some vague group selection point of view think that this is a "good thing".Wynne-Edwards' interpretation is even bolder.Higher-ranking individuals have a greater chance of reproducing than lower-ranking individuals, either because they are preferred by females, or because they violently prevent lower-ranking males from approaching females.Wynne-Edwards sees high social status as another ticket for the right to reproduce.Thus, individuals fight for social status rather than directly for females, accepting that they have no right to reproduce if they end up with a low social rank.Where females are directly involved, they are always self-restraining, but these individuals can from time to time try to win a higher social position, and so may be said to compete for females indirectly.But as with turf-related behavior, the "conscious acceptance" of the rule that only high-status males can reproduce has the consequence, according to Wynne-Edwards, that population numbers do not grow too rapidly.Populations don't start by having too many offspring and then learn the hard way that they were wrong.They encourage formal competition, in which their members compete for status and territory, as a means of limiting population size in order to keep it slightly below the level at which starvation itself would actually kill. Perhaps one of Wynne-Edwards' most surprising ideas is epideictic behavior, a term he coined himself.Many animals spend a lot of their time living in groups, gathering in groups and moving on land, in the air or in the water.Various reasons have been given for why natural selection should favor such collective life, and these reasons are more or less within the realm of common sense.I discuss some of these in Chapter 10.Wynne-Edwards took a very different view.He thinks that when flocks of plover birds congregate at night, or swarms of midges fly around gateposts, they are taking a "census" of their population.Because he made the point that individuals constrain their own birthrates for the overall good of the group, i.e., to have fewer animals when the density of individual animals is high, they should of course have some way of estimating the density of individual animals.A thermostat requires a thermometer as an integral part of its mechanism, and this is the case above.In Wynne-Edwards's view, displaying behavior is a well-organized group gathering to facilitate the estimation of animal populations.He did not consider animals' estimation of their own numbers to be a conscious behavior, but rather a neural or endocrine automatic mechanism linking individuals' intuitions about the individual density of their populations with their reproductive systems. My introduction to the Wynne-Edwards theory, though only a few words, tries to be fair.If I've managed to do this, you should now be convinced that the theory is at least plausible on the surface.But you say in a hesitant tone that although Wynne-Edwards's theory sounds plausible, it had better be well-founded, otherwise...  Your skepticism is the result of reading the earlier chapters of this book.Unfortunately, the basis is not sufficient.The large number of examples that make up this theory can be explained in his way, but they can also be explained in terms of the more orthodox "selfish gene" law. Although David Lack never used the term "selfish gene", he was the main founder of the selfish gene theory of family planning and was a great ecologist.He has conducted specialized studies on the number of broods per brood of wild birds, but his theories and conclusions have general applicability.Each species of bird tends to have a typical brood size.For example, gannets and guillemots incubate one egg at a time, swifts incubate three at a time, and great tits incubate six or more at a time.The number of eggs per incubation is not uniform: some East Asian swifts lay only two eggs at a time, and great tits may lay as many as twelve.It is reasonable to suppose that the number of eggs a female lays and hatches, like other traits, is at least partly controlled by heredity, that is to say, there may be genes that cause a hen to lay two eggs, competing genes for three, etc. alleles, the next four alleles, and so on. Although the actual situation may not be so simple, the theory of the selfish gene now requires us to ask which of these genes will be more and more in the gene pool. many.On the face of it, genes for laying four eggs would undoubtedly outperform genes for laying three or two.A little thought, however, reveals that the "more is merrier" argument is far from true.The result of this analogy will be that five is better than four, ten is better, one hundred is better, and an unlimited number is the best.In other words, by analogy like this, logic will fall into absurdity.Clearly, there are gains and losses in mass laying of eggs.Increased fertility necessarily comes at the cost of poor parenting.Lacker's basic argument is that any given species must have an optimum number of brooding eggs in any given environmental condition.The difference between him and Wynne-Edwards lies in how he answers the question: "From whose point of view is it the optimum?" Wynne-Edwards believes that this important The optimum is the optimum that all individuals strive to achieve.On the other hand, Lacker believes that each selfish individual's choice of the number of broods in each brood is based on the number that it can raise to the maximum.If the optimum number of eggs per colony for East Asian swifts is three, it means, from Lacker's point of view, that an individual that tries to produce four offspring will be more cautious than a competitor that tries to produce only three offspring. There may be fewer children.This situation is apparently due to the fact that the average of four young children gets so little food that few survive to adulthood.The yolk rationing of the initial four eggs, as well as the rationing of food to the young after they hatch, are equally responsible for this.Thus, Lacker argues, it is not altruistic motives for individuals to regulate their brood size.They do not practice birth control to avoid excessive consumption of the group's resources.They control births in order to maximize the number of surviving children they have, and their goals are the exact opposite of what we advocate birth control for. Raising chicks is an expensive affair.The mother bird has to invest a lot of food and energy in the process of making the eggs.In order to preserve the eggs it lays, it takes a lot of labor to build the nest, which may also be done with the assistance of its mate.The mother bird spends weeks patiently incubating the eggs.After the chicks hatch, the mother bird has to work hard to get food for them, with almost no time to breathe.We already know that great tit mothers reach for food on average every 30 seconds during the day.Mammals, like us humans ourselves, do it a little differently, but the basic concept of reproduction as a costly affair -- especially for mothers -- is the same.Obviously, if a mother distributes limited food and energy resources to too many children and ends up raising fewer children, it is better to be cautious in the first place and not to be greedy.She has to strike a reasonable balance between procreation and upbringing.The amount of food and other resources each female or pair can gather is the limiting factor in determining how many children they can raise.According to Lacker's theory, natural selection regulates the initial brood size (little size, etc.) per clutch in order to maximize the use of these limited resources. Individuals who have too many children are punished not because the population as a whole is going extinct, but simply because fewer and fewer of their own children survive.Genes that make for a large number of children simply do not pass on in large numbers to the next generation, because very few young children with such genes survive to adulthood. Now let's talk about wild animals.Rucker's argument about brood size can be generalized to other examples given by Wynne-Edwards: turf behavior, ruling groups, and so on.Take, for example, the research he and several colleagues conducted on the red grouse.The bird-eating heather divides the heath-grown wastes into patches which apparently provide their masters with more food than they actually need.Early in the estrus, they start fighting for territory, but before long the losers seem to throw in the towel and stop fighting.They become strays, never get a piece of territory, and by the end of the rut most of them starve to death.The only animals that get the chance to reproduce are territory-owning animals.If a territorial animal is shot, its place is quickly filled by a previous stray, and the new owner breeds. This fact suggests that animals that do not own territories are physiologically capable of reproduction.We have seen that Wynne-Edwards' explanation for such extreme behavior involving territories is that the vagrants "admitted" themselves a failure and could not get certificates or permits to reproduce; they did not want to reproduce. On the face of it, this example seems difficult to explain using the theory of the selfish gene.Why don't these vagabonds try again and again to drive out the occupants of the territory until they are exhausted?It appears that they have nothing to lose by doing so.But wait, maybe they do lose something.We have seen that if a territory-holder should die, there is an opportunity for wanderers to take his place, and thus to reproduce.If a wanderer is more likely to inherit a territory in this way than to gain it by fighting, then, as a selfish individual, he would rather wait in the hope that some individual will die than in a useless situation. Even a little bit of energy is wasted in fighting.For Wynne-Edwards, the role of the Rangers for the welfare of the group is to act as understudies, waiting on the sides of the stage, ready to take the place of the turf-holders who die on the stage of group reproduction.We can now see that, as purely selfish individuals, this approach may be their best strategy.As we saw in Chapter 4, we can think of animals as gamblers.For a gambler, sometimes the best strategy is not to take the initiative and take the initiative, but to wait for the opportunity. Likewise, the many other instances in which animals have shown docile "acceptance" of non-reproductive status can be explained without difficulty by the theory of the selfish gene.But the general form of explanation is always the same: the individual's best bet is to temporarily restrain himself and hope for better times to come.It is not out of the interest of the group that the seal does not disturb the dreams of the "wives" occupants, but is waiting for the moment, looking forward to a more suitable moment.Even if that moment never comes and ends up with no posterity.There was a possibility of winning this gamble, although in hindsight it was not a successful gamble for this seal.While millions of lemmings are fleeing the lemming-infested heartland in floods, their purpose is not to reduce the lemming density in that area!They're looking for a place that's not too crowded, as every selfish lemming is.If any of them might perish from not being able to find such a refuge, that is a fact that can only be seen with hindsight.It doesn't change the possibility that it's even more risky to stay. It is well documented that overcrowding sometimes reduces birth rates.This phenomenon is sometimes considered the basis for the Wynne-Edwards theory.That's not the case at all.This phenomenon is not only consistent with the Wynne-Edwards theory, but also completely consistent with the theory of the selfish gene.For example, in one experiment mice were kept in an open enclosure with lots of food and allowed to breed freely.Rat populations grow to a certain level and then stabilize.This stability turned out to be due to too many mice making the females less fertile: they had fewer pups.Such results are frequently reported.People often refer to the direct cause of this phenomenon as "stress", although such a name is not helpful to explain this phenomenon.In conclusion, whatever the proximate cause may be, we need to get to the root or evolutionary cause. Rat populations live in overcrowded environments, so why would natural selection favor females that reduce their own birth rates? Wynne-Edwards' answer was clear and to the point.Group selection favors groups of females who can size their own group and regulate their birth rates to avoid overburdening the food supply.Under the conditions of the above-mentioned experiment, it so happened that lack of food never occurred, but we cannot presume that the rats are able to recognize it.They are programmed for life in the wild, and under natural conditions, overcrowding may be a reliable harbinger of impending famine. What about the selfish gene theory?Almost identical, but with one very important difference. You may recall that, according to Lacker, animals tend to reproduce the optimum number of young from their selfish point of view.If they breed too few or too many, they end up raising fewer young than they should be producing optimally. The "optimum" may be a lower number in years when the species is overcrowded, and a larger number in years when the animal becomes rare.We all agree that a surplus of animals may portend famine.Obviously, if there are reliable indications to the female animal that a famine is imminent, it is in her selfish interest to reduce her birth rate.Opponents who do not act on the omens in this way will end up with fewer surviving, even if they actually produce more young.So we end up coming to conclusions that are almost identical to those of Wynne-Edwards, but we arrive at them by a completely different kind of evolutionary reasoning. The theory of the selfish gene can even explain "epideictic displays".You will recall that Wynne-Edwards postulated that some animals were deliberately gathered in herds in order to facilitate a "census" of all individuals, and to regulate their birth rates accordingly.There is no evidence that any such aggregations were in fact ostentatious, but we can assume that such evidence is found.Wouldn't this put the theory of the selfish gene in a bind?Not at all. Starlings live together in large groups.It may be assumed that their overpopulation in winter will reduce their reproductive capacity in the following spring;This fact can be proved by such an experiment.Two recordings were played to some starling individuals, one reproduced the dense habitat of the starling and the song was very loud, and the other reproduced the less dense habitat of the starling. The sound is relatively small.Compared with the two, the former starling lays fewer eggs.This suggests that the song of the starling constitutes a ostentatious display.The selfish gene theory explains this phenomenon in much the same way as it does with the mouse example. And we started with the assumption that if those genes make you have children you can't raise, those genes are automatically penalized and there will be fewer and fewer of them in the gene pool.It is the task of an efficient egg-laying animal, as a selfish individual, to foresee what the optimum clutch size will be in the coming breeding season.You may recall the special meaning we used of the word foresee in Chapter 4.So how does the mother bird predict her optimum amount for each clutch?What variables affect its predictions?The predictions made by many species may also be fixed, never changing from year to year.Therefore, the optimum amount of gannets per clutch is one egg.It is possible that the true optimum for an individual may be temporarily raised to two eggs in years of particularly abundant fish, and if the gannets cannot know in advance whether a given year will be a good one or not, we Female gannets cannot be expected to take the risk of wasting their resources by laying two eggs, as this risks compromising their normal reproductive success in the average year. In general, there may be other species—starlings may be one of them—that can predict in winter whether a particular food resource will have a good harvest in the following spring.Farmers in the countryside have many old proverbs, such as saying that a good harvest of holly fruits may be a good omen for the weather in the coming spring.Regardless of whether these statements are correct or not, logically speaking, omens are possible, and a good forecaster can theoretically adjust the number of eggs laid in each clutch according to his own interests year after year. .Holly berries may or may not be a reliable harbinger, but as in the case of the rat, the density of individual animals seems likely to be a correct predictor.Typically, he says, a female starling knows that when she finally feeds her chicks the following spring, she will be competing for food with rivals of the same species.If it can somehow estimate the local density of its own species during winter, it has a powerful means of predicting how difficult it will be to find food for chicks next spring.If it finds that the density of individuals is particularly high in winter, it is likely, from a selfish point of view, to adopt a prudent policy and lay relatively fewer eggs: its estimate of its optimum number per clutch will consequently be lowered. If it were true that individual animals would reduce their clutch size based on their estimate of individual density, then every selfish individual would immediately pretend to his opponent that the individual density was high, regardless of the fact that this was the case, by doing so. It is good for every selfish individual.If eucalyptus were judging individual density by the volume of sound in their winter flock roosts, each bird would sing as loudly as possible so that it sounded like two birds instead of one, which would be bad for them. is favorable.The practice of one animal dressing up as several animals at the same time, JRKrebs (JRKrebs) mentioned on another occasion, and called this phenomenon the "Beau Geste Effect" (Beau Geste Effect), this is a novel The title of the book tells of a similar tactic used by a unit of the French Foreign Legion.在我们所举的例子中，这种方法是用来诱使周围的欧椋鸟降低它们每窝的生蛋量，降低到比实际的最适量还要少。如果你是一个欧椋鸟而且成功地做到这一点，那是符合你的自私的利益的，因为你使不合有你的基因的个体减少了。因此，我的结论是，瓦恩-爱德华兹有关炫耀性行为的看法实际上也许是一个很正确的看法：除了理由不对之外，他所讲的始终是正确的。从更广泛的意义上来说，拉克所作的那种类型的假设能够以自私基因的语言，对看上去似乎是支持群体选择理论的任何现象，都能作出充分有力的解释，如果此类现象出现的话。 我们根据本章得出的结论是，亲代个体实行计划生育，为的是使它们的出生率保持在最适度……。 对于家庭的大小从数量上进行的探讨就讲这些。现在我们开始讲家庭内部的利害冲突。做母亲的对其所有的子女都一视同仁是否总是有利？还是偏爱某个子女有利？家庭该不该作为一个单一的合作整体发挥作用，还是我们不得不面对甚至在家庭内部存在有自私和欺骗这一现实？一个家庭的所有成员是否都为创造相同的最适条件而共同努力，还是在什么是最适条件这个问题上"发生分歧"？这些就是我们要在下面一章试图回答的问题。关于配偶之间是否可能有利害冲突这个问题，我们放到第九章去讨论。