Y: The Descent of Men: Revealing the Mysteries of Maleness

1\ Nature's Sole Mistake\ Ejaculate, if you are so minded and equipped, into a glass of chilled Perrier. \ There you will see a formless object, but look hard enough — or at least so \ eighteenth-century biologists believed — and a baby appears: the male's \ gift to the female, whose only job is to incubate the child produced with so \ much labor by her mate. So central seemed a husband's role that his wife \ was a mere seedbed, a step below him in society, in the household, and, \ most of all, in herself.\ \ Foolish of course and quite wrong, for biology proves that man, \ and not woman, is the second sex. His sole task is to fecundate his \ spouse, but quite why he does it remains a mystery. To divide is more \ efficient than to unite, and everyone has a history of a single sexual event \ when sperm met egg, followed by billions of cell divisions without its benefit. \ Untold numbers of species manage without even that masculine moment and \ for most of the time do not seem to mourn its absence.\ Why men and why so many? Surely a few or even one would do, \ yet males are everywhere and do not always behave well. As Lady Psyche \ in Gilbert and Sullivan's operetta Princess Ida sings, "Man is coarse and Man \ is plain — /Man is more or less insane — /Man's a ribald, Man's a rake —\ /Man is Nature's sole mistake!" Much of modern biology is an affirmation of \ her claims.\ Man's state can be defined in several ways, but most are \ frivolous. Those who claim it are indeed plain, and coarse, and possessed \ of a penis. None of those qualities is very significant, giventhe bizarre \ appearance of half the members of many species and the many ways \ invented by evolution to deliver their sex cells. Men themselves have a \ special structure that shunts them toward their fate. As well as the twenty-\ two chromosomes shared by each sex, women have two large X \ chromosomes, while their partners have a single X chromosome paired with \ a smaller Y. Fundamental as it might seem, the Y is not the root of \ maleness, as other creatures gain the state without chromosomes at all. \ Even ribaldry and rakishness are not peculiar to one partner, for plenty of \ animals leave the husband to hold the baby while a wife searches for a new \ mate.\ To biologists, masculinity turns only on the size of the sex cells. \ Such things come in large and small varieties, and the males make the \ small ones. They put their bets on an outsider: on a single winner among \ billions at the post, each stripped down ready to face a risky gallop to the \ line. Their partners, in contrast, stake their all on a few more or less safe \ bets. Every egg has a fair chance of a plod around the sexual racecourse, \ but each carries, as a massive weight penalty, the goods needed to make an \ embryo. Those who make sperm take a free ride at the expense of their \ opposite numbers, for men do not — by definition — give birth. Instead, they \ use female flesh to copy their own DNA.\ Males act in their own interests but as an incidental perform a \ vital role in evolution, for they act as conduits through which genes move \ between females. Without their help, all new mutations would be confined to \ the direct descendants of the individual in which they arise and life would at \ once become a multitude of clones rather than a set of unstable biological \ alliances formed anew each time sperm meets egg.\ Men bring women together. They make links between families and \ allow genes to be tested against nature in new and perhaps fruitful \ coalitions. Expensive as they are, once evolved such creatures are almost \ impossible to get rid of. A certain group of tiny freshwater animals managed \ to do away with males a hundred million years ago, but for all others a burst \ of masculinity is needed now and again.\ Its humble task flies in the face of tradition, which has long seen \ man as the bearer of the human heritage and his mate as, at best, a \ tiresome detail. At Karnak, in Upper Egypt, the god Amun gave life to the \ world by masturbating over it. In a more decorous myth, Genesis allows \ Eve a mention, but by chapter five she too has gone: "And Adam lived an \ hundred and thirty years, and begat a son in his own likeness, after his \ image; and called his name Seth." After her moment of glory in the first book \ of the Bible (one of the few written before the emergence of an all-male \ priesthood), her sex fades away.\ Eve's consort could not, of course, reproduce without help, as he \ was (ribs apart) a blind alley. What makes Adam and his descendants what \ they are?\ Physics was transformed in 1905 with the theory of relativity. \ Everyone knows who thought of that idea, but Nettie Maria Stevens, the \ Albert Einstein of manhood, is forgotten. Like Einstein, she started outside \ science and turned late to research. In the year of relativity, when sex \ chromosomes seemed no more central to masculinity than a mustache, \ Miss Stevens explained how they work. Flour beetle sperm came, she \ found, in two types, one with a large version of a certain chromosome, and \ the other with a small, the famous Y. The truth about maleness was revealed.\ Two centuries earlier, the secretary of the Royal Society had \ recorded a remarkable case: "A country Labourer, living not far from Euston-\ Hall in Suffolk shewed a Boy (his Son) about fourteen Years of Age, having \ a cuticular Distemper. His mother had received no fright . . . his Skin was \ clear at birth — by degrees it turned black, and in a little time afterwards \ thickened, and grew into that State it appeared at present." The boy, \ Edward Lambert, exhibited himself in London: "To be seen at the George in \ Fenchurch Street a Man and his Son, that are cover'd from Head to Foot \ with solid Quills, except their Face, the Palms of their Hands, and Bottoms \ of their Feet." He had many children and grandchildren. They, too, were \ exhibitionists, although some found it necessary to decorate their story: \ "The young man is . . . covered with Scales . . . nearly half an inch long, and \ so hard and firm that with the touch of a finger they make a sound like stones \ striking together . . . the great-grandfather of the singular family to which \ this young man belongs, was found savage in the woods of North America."\ The Lamberts are much quoted as an example of a condition that \ passes from fathers to sons. Even Darwin mentions them. Sadly, the \ records reveal scaly daughters, too, as proof that their state was not in fact \ coded for on the Y chromosome.\ Several genes have professed that noble home, but not for almost \ a century after its discovery did one earn it. Some of the false claims arise \ because, in small families, a trait may appear by chance in sons alone. \ Others are due to mere bias, as a history of maleness has, for men, a great \ allure. In a certain Indian lineage, all the men — but none of the women — \ have points of hair (sometimes waxed by their proud bearers) on their ears. \ I once met a hairy-eared African who, when I asked whether any of his \ relatives shared it, told me his mother did. Most other supposed cases of \ Y-based inheritance also collapse on closer inspection.\ Now everything has changed. The Y has come into its own. \ Biology no longer needs freaks of nature to track down genes. Instead it \ can go straight to the DNA. The completion of the entire human gene \ sequence, with its great string of chemical bases of four distinct types, has \ transformed the image of men. Our biological heritage, the Human Genome \ Project showed, is filled with parasites, redundancy, and decay. The \ chromosome unique to men is a microscopic metaphor of those who bear it, \ for it is the most decayed, redundant, and parasitic of the lot.\ The male badge of identity is small indeed — just a fiftieth of the \ total genome, with 60 million or so of the 3.3 billion base pairs in the entire \ sequence. Three quarters of the double helix as a whole consists of spaces \ between genes, and the genes themselves contain hundreds of redundant \ sections. Much of the DNA exists as duplicates, multiplied again and \ again, with the copies diverged into families. It is also marked by innumerable \ segments of foreign material that have elbowed their way in. They are \ matched by internal hangers-on and by other great portions that have gone \ to rack and ruin. As a result, just a few parts in a hundred bear useful \ information.\ Masculine decadence is such that, on the Y chromosome, a \ mere one part in thousands does so. Every gene has a molecular signature \ that sets it apart from the material around it. The Y has but seventy or so \ elements that code for proteins, compared to ten times as many on the X. \ More than half consists of multiples of two uninvited guests, and most of its \ duplicated sections are no more than corpses. In spite of some local hints \ of order, man's defining structure is a haven for degenerates.\ It has a single redeeming feature. To half the human race the Y is \ the prince of chromosomes, for it gives the embryo a testis. There resides \ the noblest of all genes, the sine qua non of maleness. The crucial piece \ sits near the structure's tip, and in its absence a fertilized egg becomes a \ female. It is — at first sight — simple.\ The key to man's nature came from some unusual men. Armed \ with penises though they are, such people lack a discernible male \ chromosome and carry (like women) two copies of the X. Their predicament \ comes from a genetic accident. A tiny portion of their father's Y was broken \ off when his sperm was made, and became attached to his own X \ chromosome. Eggs fertilized by X-bearing sperm are expected to develop \ into girls, but in this case the uninvited passenger brought as a guest an \ extra length of DNA. It includes the gallant structure that impels a baby into \ boyhood.\ The SRY gene itself (the initials stand for Sex-determining Region \ of the Y) was tracked down in 1990 after a hunt through that nomadic \ fragment. It contains fewer than a thousand DNA bases, which code for a \ mere two hundred and four amino acids (the units bolted together \ end-to-end to build proteins). Unlike most genes it has no inserted \ sequences of useless material. SRY is small but potent. When a copy was \ injected into a normal XX mouse egg, the young animal that emerged (Randy, \ by name) was anything but female. His sisters gladly accepted him as a \ mate, to give a consumer's seal of approval for the power of that tiny gene.\ Modern genetics takes place not just in animals (in vivo, as \ biologists say), or even in vitro, in test tubes, but in silico, inside computers \ able to match DNA sequences with each other. A search for genes with \ some resemblance to the master of manhood reveals a host of relatives, \ with the most similar of all upon the X, where it is active in the young brain \ (which might have interested Freud).\ The monarch of maleness belongs, the computers show, to a \ large and diverse family. Its members do many things (they are, for \ example, in charge of the reproductive lives of mushrooms). Each controls \ some aspect of development, and all share a special sequence of eighty or \ so amino acids. This forms a groove in the molecule, which allows it to bind \ to a variety of DNA sequences. As it does, the double helix bends, and \ somehow the change in shape turns on a target gene. At once the machinery \ of growth springs into life.\ SRY is a switch that directs other genes onto their allotted path. \ Like the railway points outside a large terminus, the testis-determining \ element guides, with a single tiny shift, the sexual express train toward one \ destination rather than another. It is (with a few rare exceptions) the sole \ gene absolutely necessary for a testis to be made, although to construct \ the organ itself and the other useful structures that decorate all males needs \ hundreds of others, scattered all over the genome. SRY kicks into action \ four weeks or so after the egg is fertilized. In its brief moment of glory it \ sends billions of babies on a masculine journey. Quite how it does so, \ nobody knows, as its prime target — the leading wheel, as it were, of the \ embryonic locomotive — has not yet been found.\ Most of its fellow passengers are associated with maleness. In \ guppies the gaudiest animals attract the most mates — and the genes for \ bright color share a home with SRY. Our own version of the chromosome is \ involved in the manufacture of sperm, in the rate of growth, in the formation \ of teeth and of certain brain proteins, in left-handedness, and — if mice are a \ guide — in aggression. Its few other useful sections do the day-to-day jobs \ needed by all cells.\ Outside the segments devoted to these small tasks, most of the \ Y is filled with decay. It has degenerated because it abjures the messy \ business of sex.\ To biologists, that pastime is simple. It adds statistics to nature, \ for without it every child would be an exact copy of its parent. Copulation \ causes random noise in the world of the double helix, because it mixes up \ genes. Without it evolution could hardly happen.\ Chromosomes are present in double copy in most cells, but \ sperm and egg each contain just half the DNA of the person who made \ them. As a result, just one member of each chromosome pair can get in \ (which is why half of all sperm — made as they are by XY individuals — have \ an X and half a Y). By chance, a child may receive its mother's edition of \ some chromosomes and its father's of others. The process (recombination \ as it is called) goes further, as it reorders the very material of chromosomes. \ The members of each pair line up as sperm and egg are made and then \ intertwine, break, and rejoin in novel ways.\ From a gene's point of view, reshuffling of this kind is a great \ restorative, as it allows it to escape from its neighbors — and to move \ house can be a great help when the individual next door is a feeble character \ who might, when exposed to the rigors of the world, drag a whole block down \ to his own level. Recombination means that sex, not death, is the great \ leveler. It allows new and hopeful blends to appear each generation and can \ get rid of several damaged pieces of DNA at once if they get into the same \ sperm or egg. The recipient becomes a scapegoat, for his demise purges \ several inborn sins at the same time. In his lonely fate he rescues many of \ his fellows who might otherwise be condemned by inferior genes.\ The Y, in its solitary state, disapproves of such laxity. Apart from \ small parts near each tip which line up with a shared section of the X, it \ stands aloof from the great DNA swap. Its genes, such as they are, remain \ in purdah as the generations succeed. As a result, each Y is a genetic \ republic, insulated from the outside world. Like most closed societies, it \ becomes both selfish and wasteful. Every lineage evolves an identity of its \ own, which quite often collapses under the weight of its own inborn \ weaknesses.\ Celibacy has ruined man's chromosome. The Y is a dead end for \ DNA, as once on board, it is impossible to escape through the hatch \ marked "Sex." Most genes can use recombination as an emergency exit to \ flee, with a set of new companions, into the biological lifeboats known as \ sperm and egg. Only the Y lacks such a release. As a result, it has \ become confined to a single narrow interest: maleness. Any gene able to \ help in the task is welcomed, but all others (apart from those involved in its \ own internal economy) rot away. Males evolved to stop females from \ degenerating into clones, but in their own intimate selves have suffered the \ same fate.\ Where did the Y come from, and why is it so different from its \ fellows?\ It bears the scars of a complex and unexpected past. DNA hints \ that the crucial structure was once the equal of its larger associate, the X, \ which now contains far more genes. It has suffered many ups and downs \ since the break with its partner. Both halves of this odd couple have altered \ over time, but one version has changed at breakneck speed. It has lost \ thousands of genes and gained just a few. As a result, the Y is an arriviste \ on the evolutionary scene, with a unique identity.\ Fossils prove when, in the distant past, various groups of \ mammals split apart. The sex chromosomes of a series of our more and \ more distant relatives, from chimps to mice to wallabies, also show how \ they have changed through time. Their pattern of evolution is a hint of the \ active, bitter, and ancient battle of the sexes that has driven males since \ they began.\ When it comes to courtship or child care, the biological interests \ of the parents differ. The checkered history of a chromosome shows that \ the tension between them goes far deeper.\ Males are, in many ways, parasites upon their partners. Their \ interests are to persuade the other party to invest in reproduction, while \ doing as little as they can themselves. Like all vermin, from viruses to \ tapeworms, they force their reluctant landladies to adapt or to be \ overwhelmed. As the host evolves to cope with her unwelcome visitor, the two \ parties enter a biological dance. Each has its own agenda, and as one gains, \ the other fights back. Quite often, the evolutionary pas de deux takes up a \ frenzied pace.\ New parasites evolve all the time, and the older kinds often \ change their identity. Most of our diseases are recent and can be traced to \ an enemy that began in an animal (as is the case for the agent of AIDS, \ which came from apes, and of malaria, from birds). Whenever a new illness \ emerges or an old ailment flares up, those under attack must respond or \ die. The parasite, whatever it may be, constantly tests its host's fortifications \ with new mechanisms of virulence — which in turn are fended off. Neither \ party can afford to relax, and little by little a complex and rickety structure of \ defense and counterattack evolves.\ Like the front line in the First World War, the evidence of past \ assaults may make no apparent sense and can even sink from view. The \ foes may stay immobile for years until a sudden advance by one forces a \ response by the other. The battle of the parasites — and the sexes — \ anticipated the strategy of Generals Haig and Ludendorff by millions of \ years.\ Every year I take a group of undergraduates on a field course to \ Spain to study evolution in action. On the streams, water skaters swim in \ pairs, with the male on top. His embrace comes not from affection (as the \ old texts have it) but is a desperate attempt to keep off his rivals, with \ thousands of attacks before a second mate has any chance. As the struggle \ goes on, the object of his attentions begins to starve, but she cannot shake \ off her partner. In the meadows above, flowers attract insects to pollen — a \ male attribute — but the female parts of the plant abort almost all the seeds \ that result from their efforts. The students take notes and go to the bar.\ The strategies of water skaters and plants reflect the divergent \ interests of two factions. Monogamous creatures (and they are rare, and \ have become rarer as paternity tests reveal the sordid truth about nature) live \ in harmony, as any harm done to the prospects of one does the same \ damage to its partner. For all others, the interests of each player diverge. \ Males hope for another encounter, while their spouses must decide whether \ to nourish the results of an erotic fling or wait for a better chance. For one \ participant, success turns on how many individuals can be inseminated, \ while the other is best served by a choice of the finest mate. The antagonism \ sets off a conflict as bitter as that between the British and German armies \ and leads to the spectacular rows among sea elephants or peacocks beloved \ of filmmakers.\ Blubber, plumes, and the rest are mere vulgar brawls in a larger \ engagement. The image of males — once seen as the prime movers in the \ sexual universe — has faded in the face of the truth: that for much of the \ time their backs are to the wall. The dispute with those who copy their DNA \ forces their very being into flux.\ Pasiphaë, wife of Minos (who later gave birth to the Minotaur, a \ beast much painted by the spermatic enthusiast Pablo Picasso), was fed \ up with her husband's infidelity. She put paid to his mistress in an ingenious \ way. With a little necromancy she made Minos "pour forth in his semen a \ swarm of venomous snakes, scorpions and centipedes, which devoured the \ woman's intestines."\ The Minotaur's mother was ahead of her time. Biology reveals \ how males attack the molecular entrails of their mates and how their targets, \ as they try to escape, oblige them to update their armaments. Semen as \ both weapon and gift is a microcosm of the endless two-horse race that \ drives men and their machinery forward.\ Seminal fluid does many things. It carries sperm, of course, but \ can also compel those who receive it to invest more than they might like in \ those cells' success, whatever harm is done to their own prospects.\ Insect sperm comes in a poisoned chalice. Some of the \ ejaculate's chemicals resemble digestive enzymes. They disable foreign \ sperm and increase the penetrative power of those of the male who makes \ them. Other spermatic ingredients are subtler, for they act on females \ themselves. They plug her reproductive tract, force her to store the \ donation, reduce her desire to mate again, and oblige her to make more eggs \ than she might prefer. Some males are selfish enough to impose monogamy \ on their partners while staying promiscuous themselves. A female housefly, \ for example, is limited to a brief encounter, as her partner's poisons are so \ potent that after a single spermatic experience she can never mate again. \ Fruit flies are less efficient bullies, but can still damage their mates.\ The evolution of the hundred or so specialized proteins found in \ insect semen reveals a series of repeated engagements in which attack is \ countered by defense. Some males are ten times better than others at \ displacing foreign sperm. In the same way, animals with certain variants in \ the ejaculate can overcome the resistance mechanisms of particular mates, \ while other females can resist those individuals but yield to the assaults of \ another version of the seminal weapon.\ The balance of terror is fine indeed. When flies are allowed to \ mate just once in a lifetime over many generations, seminal fluid evolves to \ become more benign, as, without a chance at a second mate, it pays its \ makers not to harm those who receive it. Females in turn become less \ defensive about the crucial but risky liquid. Once removed from this Garden \ of Eden and returned to the real world, neither party can compete: the tamed \ males are less able to fertilize a partner, and their newly confident mates \ may be, like the victims of Pasiphaë, killed by foreign sperm.\ The divergent interests of those who manufacture and those who \ accept sperm make seminal proteins change far faster than molecules with \ a less salacious task. Closely related species of fruit fly differ more in their \ ejaculate molecules than in any other. Even humans and chimps, similar in \ most of their DNA, are distinct in the sections responsible for such \ proteins, a hint at a history of conflict between body fluids in our own recent \ past.\ Bitter as it is, the battle of the secretions is little more than a \ skirmish in the war that molds the essence of every male.\ Males look different. All cock birds go in for courtship, but they do \ it in their individual ways. Canaries sing, peacocks have great tails, ruffs \ dance in natural ballrooms in front of their mates, and bowerbirds build \ shelters to impress their opposite numbers. Even close relatives can be \ quite unalike. Female ducks all look rather similar, but their partners each \ have their own gaudy (and in the hunting season dangerous) displays. Their \ desires are unchanged, but each species advertises them in a unique and \ what seems an almost arbitrary fashion.\ The control of sex is much the same. On the larger scale of \ evolution, males are made with distinct, and at first sight unrelated, \ strategies. Some creatures depend on genes and some on whole sets of \ chromosomes, while others turn to environmental cues to decide which \ sexual identity to assume. In the grand reproductive handicap, stalemate is \ interrupted by change and, now and again, by a large and strategic shift \ that pushes matters into a new phase. Masculinity emerges as a fragile and \ uncertain thing, which is often forced to reinvent itself. Whatever is hijacked \ to its ends, from tails to genes, begins at once to crumble away.\ Parasites reduce themselves to a bare minimum as soon as they \ can. Faced with a host who shifts the goalposts each generation, they have \ to run to stay in the same place. In a race it pays to be as unhindered as \ possible, which often means reduction to a mere sack of genitals and guts. \ They may shrink at the molecular level, too; the leprosy bacillus, for \ example, has lost hundreds of genes in comparison to its free-living \ ancestor. Man's most basic attribute also has a strong tendency to wilt.\ Australian males are a model of virility, but the average native has \ a rather small version of what makes him what he is. Kangaroos split from \ our own ancestors a hundred and thirty million years ago, while the \ platypus made the breach even earlier. Both animals have tiny Y \ chromosomes, barely visible even under the microscope. Each has a mere \ ten thousand DNA bases (compared to sixty million on the human version), \ but minute as it is, the entire antipodean Y can be paired up with a small part \ of our own. It contains the local version of the SRY gene, a core of \ masculinity left from the days when mammals began. Outside this tiny \ sector the male trademark of the kangaroo has been whittled away.\ In parts of the Northern Hemisphere, the rot has gone further, for \ the mole vole attains masculinity without a Y chromosome or an SRY gene \ at all (how it does so, nobody knows). In a matching perversion of the rules, \ up to half the females of certain South American mice are XY — and they \ have more offspring than those who are satisfied to stick with two X's. \ Although few mammals have gone quite so far toward downgrading the Y \ chromosome, most have suffered repeated changes of masculine \ personality, with much divergence even between close relatives. The viruses \ on our own version — unlike those elsewhere in the genome, which are \ shared with mice or flies — are different even from those of chimpanzees. \ Given the rate of decay since it began, the Y might disappear altogether \ within a mere ten million years.\ The SRY gene itself has undergone many shifts of identity. It \ does the same job in platypuses and primates, but just a small part is \ conserved. The central piece — the length that binds to DNA — is the same \ in kangaroos and humans, but elsewhere evolution has been busy. Among \ the mammals, SRY evolves ten times faster than the other members of its \ gene family. The version found in mice, for example, is twice the size of the \ equivalent in Homo sapiens.\ About two thousand proteins have been read from end to end in \ both mice and men. When compared by computer, most differ by less than \ one in ten in the order of their building blocks. A hundred or so of the \ molecules stand apart, for they have diverged by half or more from their \ fellows. A substantial proportion of that group is involved in reproduction, \ while the rest is responsible for parts of the immune system and for the \ antiseptic protein found in teardrops, both of which are needed to deal with \ parasites.\ The grand falling-out of the sex chromosomes began long before \ the evolution of men or mice — or mammals — themselves, soon after the \ separation of our own ancestors from those of birds, three hundred million \ years before the present. The Y traces its origin to a time long before the \ death of the dinosaurs, when tree ferns and simple reptiles ruled the land.\ The DNA of one tip of the modern X resembles that of its partner, \ while the other end is quite distinct. Like a zipper as it opens, divergence \ has spread from one extremity of the two once equal structures. The rupture \ happened in fits and starts, and the male chromosomes of a range of \ mammals have a stepwise, rather than a gradual, pattern of separation from \ their opposite numbers. In addition, vast blocks of genes have reversed their \ order. The first reshuffle took place when the ancestors of birds and \ mammals separated, whereas the last did not happen until the appearance \ of the hominid line a few tens of millions of years ago. Such upheavals have \ moved the SRY gene to the far end of the chromosome from its relative on \ the X.\ The chromosome has had many other adventures on its journey \ into decline. Its DNA comes in two flavors. Certain sections have matches \ on its opposite number, but others find their kin elsewhere. The Y is a men's \ club for genes, and some of its members come from afar.\ Many men cannot make viable sperm (azoospermia, as the \ condition is known). The Y, like its owners, is fragile, and about one man in \ a hundred is infertile because of a new mutation, which can be seen as a \ small break in the chromosome. The genes involved give an insight into the \ history of maleness.\ Women, XX as they are, might seem more symmetrical than their \ XY partners, but in fact men are the more reflective party. The Y is, in parts, \ a great hall of molecular mirrors. Upon it live several vast palindromes: \ immense and much reversed lengths of DNA whose repeated and \ symmetrical sectors retain almost perfect matches across vast numbers of \ bases. "Madam, I'm Adam" is a gentlemanly enough phrase, but its eleven \ letters are dwarfed by their molecular equivalents, which may contain three \ million DNA units. Nobody knows what preserves these long segments from \ decay, but somehow males can keep them under control. The main genes \ involved in spermlessness sit within that region, and almost all men with the \ problem suffer a break in just the same place.\ A computer search reveals that some of the Y's twenty or so \ genes have equivalents on their ancestor, the X. Others do not. A few look \ like genes on other chromosomes, which is no surprise, for such structures \ often break and rejoin as evolution goes on. The migrants have suffered \ some sea changes since their arrival in the ocean of palindromes, but retain \ much of their identity. Other passengers, though, have reached their refuge in \ quite a different way.\ To make any protein, a long messenger molecule is first read off \ from the DNA. Within it are both useful sections and various bits that seem \ to contain no information. These redundant parts are cut out by a set of \ special enzymes, and the edited instructions (now without inserts) pass to \ the cellular factories. Why life is so profligate, nobody knows.\ One group of Y-chromosome genes lacks those superfluous \ pieces. Its members exist as abridged versions of a set of relatives found \ elsewhere in the genome. Their reduced state hints at an unexpected \ history.\ Mammalian DNA is besieged by viruses. Some hijack pieces of \ the revised messenger molecule on their way to the cellular factories. They \ insinuate themselves and their passenger into a new site. Several Y-based \ genes were delivered in this manner. The gene whose failure causes many \ cases of infertility is a recent arrival, for in lemurs, our distant primate \ relative, it is on another chromosome, while in monkeys, apes, and ourselves \ the structure has made its way to the master of maleness. The great leap \ took place after the split between the ancestors of lemurs and humans, fifty \ million years ago, which is, to an evolutionist, the day before yesterday.\ The Y, it seems, is a pragmatist, happy to welcome any \ immigrant — however it arrives — if it is useful but ready to ignore those \ who are not. Most of the settlers are unlucky. They make a protein of little \ value to the male and, without a job to do, decay.\ Such endless strife has pushed the masculine state into flux on a \ scale far greater than the Y chromosome. It is achieved in quite dissimilar \ — and at first sight unrelated — ways in different creatures. Such shifts hint \ at great strategic advances and retreats in the struggle for masculinity.\ In birds the world turns upside down. Males are, in effect, XX (with \ two large sex-determining elements) and their opposite numbers XY (with \ one large and one small). The bird "X" and "Y" do not match their human \ equivalents but are kin to a different chromosome (an ancestor of our own \ number nine), as proof of an independent origin. Snakes have a birdlike \ system, with XX males, but for them yet another chromosome pair has \ taken up the banner of virility.\ Fruit flies achieve the manly state in a different way. Males are \ XY, but a fly's identity depends not on a special gene but on a balance \ between the number of X's and all others. Children born with just a single X \ (and no Y) are girls because they have no SRY to put them on the \ alternative track, but flies in such a predicament are male, because they have \ half the number of X's as normal. Bees and wasps go even further in their \ definition of males as diminished females, for sons have half as many of all \ their chromosomes as do daughters.\ Some plants have Y chromosomes, which must have arisen \ independently from our own, and as a final twist to the tale, certain \ creatures use schemes which at first sight fly in the face of our own familiar \ rules. For them, identity comes not from within, but from the world outside.\ In the Middle Ages, life seemed simple: heat on the right side of \ the uterus gave a boy, on the left a girl. That eccentric notion is not \ altogether false, as in many fish and reptiles sex depends on the \ temperature at which an egg is incubated. The details, as so often, are filled \ with ambiguity. In alligators, heat makes sons and cold makes daughters. In \ most turtles the opposite is true. Hot eggs grow quicker and make larger \ young. Alligator males gather a harem, and it pays any male to be as big as \ possible — which is why they have sons in the warm. Many turtles (with \ sons in cooler nests) mate peaceably in the ocean, and large males do not \ gain much — but large females lay more eggs. To clinch the matter, \ snapping turtles (freshwater beasts who quarrel over females) return to the \ alligator pattern, with sons from warm eggs.\ Sex responds to many other pressures. In a certain marine snail \ of banal tastes, a young animal lucky enough to meet a female becomes \ male, and vice versa. In many insects, high density leads to sons, and fish \ have a whole gamut of gender shifts which depend on the emotional rather \ than the physical temperature, as a female changes sex when left alone \ with a group of her fellows anxious to find a mate.\ Although the end is reached with such a variety of means, \ maleness itself seems simple enough. Alligators, flies, peacocks, snails, \ and fish are, in their shared passion for sperm, not much different from men \ themselves. Why is their state defined in such disparate ways? Sex and \ males have been around for much longer than people or alligators, and it \ seems odd that their controls have changed so much.\ The genes in charge of the basic body plan — left or right, up or \ down, front or back — are shared not just by men and women but by \ alligators, flies, and worms. Different as such creatures might appear, all \ have the same basic layout. Once its foundations were hidden, overlaid by \ the diversity of shape and size conjured up by evolution. Not until biologists \ dug deep into DNA did those very divergent animals reveal their hidden \ likeness.\ Genetics has started to uncover the groundwork buried in the \ debris of sex. Because maleness changes at such speed, the rubble is \ piled higher over those ancient genes than in most places, but today's \ excavating machinery has begun to dig them out. They hint at what it really \ takes to be a man.\ Hermes — messenger of the gods, controller of dreams, and \ guardian of livestock — fell for Aphrodite, the goddess of love (who herself, \ as it happens, emerged from aphrodes, a sea of foaming semen flooding from \ her castrated father). Her first son, Priapus, was foul in appearance, but her \ second, Hermaphrodite, was a boy of matchless beauty. As he bathed one \ day in a fountain, he was seen by its nymph. She begged to be allowed to \ unite with him — and her wish was granted. Their metaphorical \ descendants hint at the deep secrets of the priapic state.\ One child in several thousand has both testes and ovaries (or, \ sometimes, tissues that mix the two). Some have a Y chromosome, but \ most do not. Like normal women, they have a pair of X's and, as a result, \ have no SRY gene. How can a fetus grow a testis when the crucial \ sequence of DNA is not there? SRY is not, it seems, quite such a sine qua \ non as it seems.\ Hermaphrodites are asymmetrical in their ambiguity. Something \ has pushed their manhood to one side, for most of them have a testis on \ the right matched with an ovary on the left, and just a few the opposite \ pattern. Such reproductive lopsidedness has to do with the rate of growth in \ the first days of development.\ The right half of an embryo grows faster than its mirror image. \ What once seemed no more than a curiosity was in fact a hint at a \ profound truth: that genes far older than SRY rule the world of maleness. The \ fetal testis is, from its earliest days — well before any Y-based gene kicks \ into action — twice as big as its female equivalent. The gonad is given an \ initial push toward its fate by an ancient and hidden mechanism, to which \ hermaphrodites in their asymmetry hold the key. The male sex-determining \ gene is, like the antlers of deer or the tails of peacocks, more a symptom of \ masculinity than its ultimate cause. SRY, like the mechanisms with which \ birds, bees, alligators, and the rest decide their state, stands on the \ shoulders of some earlier masters.\ Sex, like politics, depends on a hierarchy of command. Empires \ collapse and are superseded, and masculinity is much the same. Ancient \ controls have been overlaid by new devices, quite different in different \ creatures — but now and again the old rulers issue a reminder of their \ existence. They are the ghosts of a world of maleness which evolved long \ before the animals who indulge in the pastime today.\ Men, flies, and worms have all had their entire DNA sequences \ deciphered. Distinct as they appear, all three possess rare and shared \ mutations in certain groups of genes that lie close to the roots of manhood. \ When damaged, they cause males to develop as members of the opposite \ sex — and they can exert their transforming power even when moved by \ clever biologists from flies to worms. The existence of a shared set of \ errors, with an ability to work in such different creatures, hints at an ancient \ foundation of masculinity which, should it be damaged, causes the whole \ structure that rests upon it to fail. Then the other party hidden within can \ make an appearance.\ A few XY babies develop as girls. Most have a normal SRY and \ have — like flies and worms — been transformed through faults in some \ earlier step along the pathway to manhood that override the gene's effects. \ One of the guilty parties resembles a sex-determining element found in \ worms. It sits on our chromosome nine — whose ancestor also gave rise to \ the sex chromosomes in birds. It puts a stop to manhood if one of its two \ copies has been destroyed by mutation. In this, too, we resemble birds, \ whose males also need two copies of the structure.\ The gene involved makes — like SRY itself — a protein with a \ special segment able to bind to DNA. From worms to birds and people, the \ molecule is hard at work in the earliest stages of sexual development, well \ before the more obvious mechanisms kick into action. Manhood needs two \ functional copies of that ancient gene, and without them SRY is impotent. \ In birds the equivalent DNA sequence is on the "X" chromosome — found in \ double copy in males, but with just a single copy in their opposite numbers. \ Turtles and crocodiles, too, hint at its power, for in reptiles the hidden \ emperor of sex changes its activity with temperature.\ Males, that mysterious element shows, have a history that \ stretches back at least to the split between worms and mammals a billion \ years ago. On that ancient foundation is balanced the gothic complexity of \ today, with one switch replacing another in different groups as the millennia \ roll by. In their urge to escape the attentions of their partners, females have \ obliged males to redefine the very mechanism that makes them what they \ are.\ How did the endless race between the sexes begin? Some ideas \ about men are positive (even if few are as much so as those of the ancient \ Egyptians) and see them as a force for good, helping evolution on its way \ as they move genes between female lines. The evidence of universal conflict \ supports a grimmer view: that the parasitic habits of one party began as \ soon as the starting gun was fired.\ Life managed without males for its first billion years, much of \ which was passed as single cells in a series of warm ponds. Then, in some \ ancient and neutral Eden, the fruit of the tree of sexual knowledge — a new \ mutation — persuaded members of a particular clone to fuse with cells from \ another, and then to divide. That ingenious idea is good news for the novel \ gene, as it doubles its rate of spread, but is a lot less so for those who \ receive it, who are obliged to copy the extra DNA. At once, two factions \ emerge, one keen to force itself upon the other. Thus was sex invented.\ Soon one contestant began to cheat. Large cells are expensive, \ but are better at dividing because they have more food reserves. Small cells \ are cheaper to make, but cannot afford to split. Their sole chance of \ success hence lies in fusion with a large cell. The first males had appeared \ on the scene.\ Their state fed on itself. For the new small cells the pressure to \ fuse is intense, because they have no other hope of a genetic future. The \ more minute and more mobile they become, the more can be made and the \ better the prospects of finding a large partner are. Any that take extremism \ too far and become too small to swim fail. Natural selection pushes in \ opposite directions to make such structures tiny, or (as in females) huge. \ This inbuilt instability explains why there are only two — rather than \ dozens — of sexes; the male is reduced as far as is physically possible, \ and forces everyone else to put in whatever is needed for fusion.\ The tension between sperm and egg and between those who \ make them has gone on for at least two billion years. It has driven much of \ evolution. For one of the parties involved, the first fusion marked nature's \ greatest mistake. For males, on the other hand, it was a triumph.\ \ Copyright © 2003 by Steve Jones. Reprinted by permission of Houghton \ Mifflin Company.

Preface: The Diminished Female1Nature's Sole Mistake12The Common Man213Seven Ages of Manhood414Hydraulics for Boys625Man Mutilated816Bois-Regard's Worms1027Bend Sinister1218James James's Skull1429Polymorphous Perversity16410A Martian on Venus184Envoi: The Descent of Men205Sources225Index236

\ The Washington PostY melds a lively and lucid exploration of the genetics of maleness with some baser stuff -- the hydraulics of erection, the ethics of circumcision, the testosterone-baldness myth, to name some -- all in service of his central point, which is that men ain't what they used to be. But we already knew that, didn't we? — Gregory Mott\ \ \ \ \ Publishers WeeklyShriveled, decrepit and of little use except for sex, the Y chromosome is an apt metaphor for post-modern manhood in this eye-opening exploration of the biology of maleness. Jones, a geneticist and author of Darwin's Ghost, traces the development of maleness from its origins as a parasitic stratagem by which certain microbes forced others to replicate their genes for them, to the dawning age of cloning, which could, in theory, allow women to dispense with men's reproductive services altogether. Along the way he investigates the essentials of maleness, including baldness, the perverse, multi-faceted and never-ending competition for the favor of choosy females, and the many surgical, chemical and mechanical reinforcements men call on to stand firm in battle. Writing in a snappy, erudite style replete with droll euphemisms, Jones takes readers on an engaging tour of the Darwinian view of sex as the ultimately absurd outcome of natural selection and clashing reproductive strategies. But he is no essentialist defender of patriarchy. Indeed, in his treatment males emerge as the weaker sex-a complex and fragile variation on the sturdy female model, whose extra testosterone makes them shorter-lived, more prone to disease and suicide, less able than females to cope in contemporary society and doomed to descent in the coming "age of women." Men may find this book demoralizing, and Jones's case overstated, but women may take a certain grim satisfaction from it-and readers of both sexes will find it very educational. (May) Copyright 2003 Reed Business Information.\ \ \ Library JournalIn Darwin's Ghost, Jones provided an entertaining and informative update to Darwin's On the Origin of Species. Here he does the same for Darwin's The Descent of Man, with an added emphasis on man in the noninclusive sense. Although not closely following the structure of Darwin's book, Jones discusses many of the same issues-our evolutionary links with apes, the ties between human and animal behavior, the relations between the sexes, and specifically male characteristics. Because of new knowledge obtained through modern genetics, starting with the role of the Y chromosome, Jones is able to add much to Darwin's speculations on such topics as male development and physiology, genetic population mapping based on the Y chromosome, and even male "hydraulics." His lively and decidedly irreverent style makes even technical matters entertaining. Unlike Darwin, however, who was confident of male superiority, Jones is more pessimistic, pointing out such disadvantages as a shorter life span, weaker immune system, and susceptibility to stress. Recommended for popular science collections. [Previewed in Prepub Alert, LJ 1/03.]-Marit MacArthur Taylor, Univ. of Colorado at Denver Lib. Copyright 2003 Reed Business Information.\ \ \ \ \ Kirkus ReviewsMaleness as survival strategy seems increasingly unwise in this elaboration on the Y chromosome. As the old joke goes, referring to the two X chromosomes that determine female sex and the X-Y pair that confers maleness, everyone knows that women are cross (X) and men are wise (Y). Not in today’s world, laments the author, who counts the ways in which men are undone by forces genetic, behavioral, social, cultural, and environmental. To begin with, the Y is a very small chromosome that lacks counterparts of many genes on the X, so its bearer is heir to such diseases as hemophilia and muscular dystrophy that are carried on the X. But that’s just the beginning. Jones (Genetics/University College, London; The Language of Genes, 1994, etc.) deals with the origins of sexuality and Darwin’s notions of sexual selection: women choose, men compete. He then rings changes on sexual behavior across the animal kingdom, demonstrating just how wrong Darwin could be. Even the sex of offspring is not immutable but in some species can be altered at various stages in the life cycle. On the whole, Jones’s debunking is good and solid: no relation between baldness and virility, or an extra Y and criminality; no good reason for circumcision; no genes for homosexuality. He provides good information too on tracing human migrations using the Y chromosome. But arriving at these gems often means wading through masses of odd facts and tidbits Jones has collected, or (worse) suffering at length with coy references to the "member" in discourses on male anatomy, penile length, the nature of erections, and treatments for ED from time immemorial to Viagra. It seems that Jones is quite serious in bemoaning the dethroning ofmales in the third millennium, what with women outliving men, taking better care of themselves, and proving professionally competent. Informative but off-putting unless you agree that "ascent of women" implies "descent of men."\ \