by Matt Ridley
Read between November 17 - December 30, 2017
True enough, but reproduction is the sole goal for which human beings are designed; everything else is a means to that end.
Likewise, if an animal is brilliant at survival, has an efficient metabolism, resists all diseases, learns faster than its competitors, and lives to a ripe old age, but is infertile, then its superior genes are simply not available to its descendants. Everything can be inherited except sterility. None of your direct ancestors died childless. Consequently, if we are to understand how human nature evolved, the very core of our inquiry must be reproduction, for reproductive success is the examination that all human genes must pass if they are not to be squeezed out by natural selection.
Human nature was as carefully designed by natural selection for the use of a social, bipedal, originally African ape as human stomachs were designed for the use of an omnivorous African ape with a taste for meat.
If this is so, then the study of human nature must have profound implications for the study of history, sociology, psychology, anthropology, and politics. Each of those disciplines is an attempt to understand human behavior, and if the underlying universals of human behavior are the product of evolution, then it is vitally important to understand what the evolutionary pressures were.
Then Richard Dawkins of Oxford University effectively invented the notion that because bodies do not replicate themselves but are grown, whereas genes do replicate themselves, it inevitably follows that the body is merely an evolutionary vehicle for the gene, rather than vice versa. If genes make their bodies do things that perpetuate the genes (such as eat, survive, have sex, and help rear children), then the genes themselves will be perpetuated. So other kinds of bodies will disappear. Only bodies that suit the survival and perpetuation of genes will remain.
For a start, 100,000 years is only three thousand generations, a mere eye blink in evolution, equivalent to a day and a half in the life of bacteria. Moreover, until very recently the life of a European was essentially the same as that of an African. Both hunted meat and gathered plants. Both lived in social groups. Both had children dependent on their parents until their late teens. Both used stone, bone, wood, and fiber to make tools. Both passed wisdom down with complex language. Such evolutionary novelties as agriculture, metal, and writing arrived less than three hundred generations ago, ...more
A mere thirty generations back—in, roughly, A.D. 1066—you had more than a billion direct ancestors in the same generation (2 to the power of 30). Since there were fewer than a billion people alive at that time in the whole world, many of them were your ancestors two or three times over. If, like me, you are of British descent, the chances are that almost all of the few million Britons alive in 1066, including King Harold, William the Conqueror, a random serving wench, and the meanest vassal (but excluding all well-behaved monks and nuns), are your direct ancestors. This makes you a distant ...more
According to one estimate, only 7 percent of the genetic differences between two individuals can be attributed to the fact that they are of different race; 85 percent of the genetic differences are attributable to mere individual variation, and the rest is tribal or national. In the words of one pair of scientists: “What this means is that the average genetic difference between one Peruvian farmer and his neighbor, or one Swiss villager and his neighbor, is twelve times greater than the difference between the ‘average genotype’ of the Swiss population and the ‘average genotype’ of the Peruvian ...more
Sex is merely the dealer, generating unique hands from the same monotonous deck of genetic cards shared by the whole species.
There is a little wasp that injects its eggs into whitefly aphids, where they grow into new wasps by eating the whitefly from the inside out. Distressing but true. If one of these wasps, upon poking its tail into a whitefly, discovers that the aphid is already occupied by a young wasp, then she does something that seems remarkably intelligent: She withholds sperm from the egg she is about to lay and lays an unfertilized egg inside the wasp larva that is inside the whitefly. (It is a peculiarity of wasps and ants that unfertilized eggs develop into males, while all fertilized ones develop into ...more
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Why has that man fallen in love with that woman? Because she’s pretty. Why does pretty matter? Because human beings are a mainly monogamous species and so males are choosy about their mates (as male chimpanzees are not); prettiness is an indication of youth and health, which are indications of fertility. Why does that man care about fertility in his mate? Because if he did not, his genes would be eclipsed by those of men who did. Why does he care about that? He does not, but his genes act as if they do. Those who choose infertile mates leave no descendants. Therefore, everybody is descended ...more
Progress and success are always relative. When the land was unoccupied by animals, the first amphibian to emerge from the sea could get away with being slow, lumbering, and fishlike, for it had no enemies and no competitors. But if a fish were to take to the land today, it would be gobbled up by a passing fox as surely as a Mongol horde would be wiped out by machine guns. In history and in evolution, progress is always a futile, Sisyphean struggle to stay in the same relative place by getting ever better at things.
In the world of the Red Queen, any evolutionary progress will be relative as long as your foe is animate and depends heavily on you or suffers heavily if you thrive, like the seals and the bears. Thus the Red Queen will be especially hard at work among predators and their prey, parasites and their hosts, and males and females of the same species. Every creature on earth is in a Red Queen chess tournament with its parasites (or hosts), its predators (or prey), and, above all, with its mate.
But what is the relationship between a woman and her husband? It is cooperation in the sense that both want the best for the other. But why? In order to exploit each other. A man uses his wife to produce children for him. A woman uses her husband to make and help rear her children. Marriage teeters on the line between a cooperative venture and a form of mutual exploitation—ask any divorce lawyer. Successful marriages so submerge the costs under mutual benefits that the cooperation can predominate; unsuccessful ones do not.
This is one of the great recurring themes of human history, the balance between cooperation and conflict. It is the obsession of governments and families, of lovers and rivals. It is the key to economics. It is, as we shall see, one of the oldest themes in the history of life, for it is repeated right down to the level of the gene itself. And the principal cause of it is sex. Sex, like marriage, is a cooperative venture between two rival sets of genes. Your body is the scene of this uneasy coexistence.
Its principal insight is that the goal of an animal is not just to survive but to breed. Indeed, where breeding and survival come into conflict, it is breeding that takes precedence; for example, salmon starve to death while breeding. And breeding, in sexual species, consists of finding an appropriate partner and persuading it to part with a package of genes. This goal is so central to life that it has influenced the design not only of the body but of the psyche. Simply put, anything that increases reproductive success will spread at the expense of anything that does not—even if it threatens ...more
Virgin greenfly give birth to virgin young that are already pregnant with other virgins.
Genes are biochemical recipes written in a four-letter alphabet called DNA, recipes for how to make and run a body. A normal human being has two copies of each of 30,000 genes in every cell in his or her body. The total complement of 60,000 human genes is called the “genome,” and the genes live on twenty-three pairs of ribbonlike objects called “chromosomes.” When a man impregnates a woman, each one of his sperm contains one copy of each gene, 30,000 in all, on twenty-three chromosomes. These are added to the 30,000 single genes on twenty-three chromosomes in the woman’s egg to make a complete ...more
A few more technical terms are essential, and then we can discard the whole jargon-ridden dictionary of genetics. The first word is “meiosis,” which is simply the procedure by which the male selects the genes that will go into a sperm or the female selects the genes that will go into an egg. The man may choose either the 30,000 genes he inherited from his father or the seventy-five thousand he inherited from his mother or more likely, a mixture. During meiosis something peculiar happens. Each of the 23 pairs of chromosomes is laid alongside it opposite number. Chunks of one set are swapped ...more
A creature could borrow another’s genes at any stage in its life. Indeed, that is exactly what bacteria do. They simply hook up with each other like refueling bombers, pass a few genes through the pipe, and go their separate ways. Reproduction they do later, by splitting in half.
Evolution is something that happens to organisms. It is a directionless process that sometimes makes an animal’s descendants more complicated, sometimes simpler, and sometimes changes them not at all. We are so steeped in notions of progress and self-improvement that we find it strangely hard to accept this. But nobody has told the coelacanth, a fish that lives off Madagascar and looks exactly like its ancestors of 300 million years ago, that it has broken some law by not “evolving.” The notion that evolution simply cannot go fast enough, and its corollary that a coelacanth is a failure ...more
When the fittest are struggling to survive, with whom are they competing? With other members of their species or with members of other species?
We use our intellects not to solve practical problems but to outwit each other. Deceiving people, detecting deceit, understanding people’s motives, manipulating people—these are what the intellect is used for. So what matters is not how clever and crafty you are but how much more clever and craftier you are than other people. The value of intellect is infinite. Selection within the species is always going to be more important than selection between the species.
Throughout the world of animals, individuals are fighting individuals, whether of the same species or of another. And indeed, the closest competitor a creature is ever likely to meet is a member of its own species. Natural selection is not going to pick genes that help gazelles survive as a species but hurt the chances of individuals—because such genes will be wiped out long before they can show their benefits.
Animal altruism is a myth. Even in the most spectacular cases of selflessness it turns out that animals are serving the selfish interests of their own genes—if sometimes being careless with their bodies.
Within a few years of Williams’s book, Wynne Edwards was effectively defeated, and almost all biologists agreed that no creature could ever evolve the ability to help its species at the expense of itself. Only when the two interests coincided would it act selflessly.
The traditional explanation for sex, the Vicar of Bray theory, was essentially group selectionist. It demanded that an individual altruistically share its genes with those of another individual when breeding because if it did not, the species would not innovate and would, a few hundred thousand years later, be outcompeted by other species that did. Sexual species, it said, were better off than asexual species.
Imagine a Stone Age cave inhabited by two men and two women, one of them a virgin. One day the virgin gives birth “asexually” to a baby girl that is essentially her identical twin. (She becomes, in the jargon, a “parthenogen.”) It could happen in several ways—for example, by a process called “automixis,” in which an egg is, roughly speaking, fertilized by another egg. The cave woman has another daughter two years later by the same méans. Her sister, meanwhile, has had a son and a daughter by the normal method. There are now eight people in the cave. Next, the three young girls each have two ...more
For many generations in a row water fleas are asexual: They are all female, they give birth to other females, they never mate. Then as the pond fills up with water fleas, some start to give birth to males, which mate with other females to produce “winter” eggs that lie on the bottom of the pond and regenerate when the pond is flooded again.
Scientists used to think of mutations as rare events. But in recent years they have gradually come to realize how many mutations happen. They are accumulated at the rate of about one hundred per genome per generation in mammals. That is, your children will have one hundred differences from you and your spouse in their genes as a result of random copying errors by your enzymes or as a result of mutations in your ovaries or testicles caused by cosmic rays. Of those one hundred, about ninety-nine will not matter: they will be so-called silent or neutral mutations that do not affect the sense of ...more
The sickle cell anemia mutation, for example, can be fatal to those who have two copies of it, but the mutation has actually increased in some parts of Africa because it gives immunity to malaria.
One of the reasons the common mushroom has changed very little over the three centuries that it has been in cultivation is that mushrooms are asexual, and so no selective breeding has been possible.
The chessboard is the world; the pieces are the phenomena of the universe; the rules of the game are what we call the laws of Nature. The player on the other side is hidden from us. We know that his play is always fair, just, and patient. But also we know, to our cost, that he never overlooks a mistake or makes the smallest allowance for ignorance. —Thomas Henry Huxley
Even for microscopic animals, the bdelloid rotifers are peculiar. They live in any kind of fresh water, from puddles in your gutter to hot springs by the Dead Sea and ephemeral ponds on the Antarctic continent. They look like animated commas driven by what appear to be small waterwheels at the front of the body, and when their watery home dries up or freezes, they adopt the shape of an apostrophe and go to sleep. This apostrophe is known as a “tun,” and it is astonishingly resistant to abuse. You can boil it for an hour or freeze it to within I degree of absolute zero—that is, to -272 degrees ...more
The common analogy for what Williams was describing is a lottery. Breeding asexually is like having lots of lottery tickets all with the same number. To stand a chance of winning the lottery, you need lots of different tickets. Therefore, sex is useful to the individual rather than the species when the offspring are likely to face changed or unusual conditions.
Giant sequoias, the biggest plants, have tiny seeds, so small that the ratio of their weight to the weight of the tree is the same as the ratio of the tree to the planet Earth.
A gradual drifting away of a species from its previous form happens on small islands or in tiny populations precisely because of effects somewhat analogous to Muller’s ratchet: the chance extinction of some forms and the chance prosperity of other, mutated forms. In larger populations the process that hinders this is sex itself, for an innovation is donated to the rest of the species and quickly lost in the crowd. In island populations sex cannot do this precisely because the population is so inbred.
The discovery was that the probability a family of animals would become extinct does not depend on how long that family has already existed. In other words, species do not get better at surviving (nor do they grow feeble with age, as individuals do). Their chances of extinction are random.
The struggle for existence never gets easier. However well a species may adapt to its environment, it can never relax, because its competitors and its enemies are also adapting to their niches. Survival is a zero-sum game. Success only makes one species a more tempting target for a rival species.
The things that kill animals or prevent them from reproducing are only rarely physical factors. Far more often other creatures are involved—parasites, predators, and competitors. A water flea that is starving in a crowded pond is the victim not of food shortage but of competition. Predators and parasites probably cause most of the world’s deaths, directly or indirectly. When a tree falls in the forest, it has usually been weakened by a fungus. When a herring meets its end, it is usually in the mouth of a bigger fish or a in a net. What killed your ancestors two centuries or more ago? Smallpox, ...more
Just as every plant is perpetually under attack from insects, so every animal is a seething mass of hungry bacteria waiting for an opening. There may be more bacterial than human cells in the object you proudly call “your” body. There may be more bacteria in and on you as you read this than there are human beings in the whole world.
The bacteria in your gut pass through six times as many generations during your lifetime as people have passed through since they were apes.
In about ten years, the genes of the AIDS virus change as much as human genes change in 10 million years. For bacteria, thirty minutes can be a lifetime. Human beings, whose generations are an eternal thirty years long, are evolutionary tortoises.
The advantage of sex can appear in a single generation. This is because whatever lock is common in one generation will produce among the parasites the key that fits it. So you can be sure that it is the very lock not to have a few generations later, for by then the key that fits it will be common. Rarity is at a premium.
The immune system is a fairly recent invention in geological terms. It started in the reptiles perhaps 300 million years ago. Frogs, fish, insects, lobsters, snails, and water fleas do not have immune systems.
The immune system consists of white blood cells that come in about 10 million different types. Each type has a protein lock on it called an “antibody,” which corresponds to a key carried by a bacterium called an “antigen.” If a key enters that lock, the white cell starts multiplying ferociously in order to produce an army of white cells to gobble up the key-carrying invader, be it a flu virus, a tuberculosis bacterium, or even the cells of a transplanted heart.
And in an extraordinary discovery made by Wayne Potts of the University of Florida at Gainesville, house mice appear to choose as mates only those house mice that have different histocompatibility genes from their own. They do this by smell. This preference maximizes the variety of genes in mice and makes the young mice more disease-resistant.
Disease might almost put a sort of limit on longevity: There is little point in living much longer than it takes your parasites to adapt to you.
Hamilton and others did not pluck the idea of parasites and sex from thin air. They are the beneficiaries of three separate lines of research that have only now converged. The first was the discovery that parasites can control populations and cause them to go in cycles. This was hinted at by Alfred Lotka and Vito Volterra in the 1920s and fleshed out by Robert May and Roy Anderson in London in the 1970s. The second was the discovery by J. B. S. Haldane and others in the 1940s of abundant polymorphism, the curious phenomenon that for almost every gene there seemed to be several different ...more
Sex is about disease. It is used to combat the threat from parasites. Organisms need sex to keep their genes one step ahead of their parasites. Men are not redundant after all; they are woman’s insurance policy against her children being wiped out by influenza and smallpox (if that is a consolation). Women add sperm to their eggs because if they did not, the resulting babies would be identically vulnerable to the first parasite that picked their genetic locks.