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- Herausgeber: Old Street Publishing
- Kategorie: Geisteswissenschaft
- Serie: Shortest Histories
- Sprache: Englisch
- Veröffentlichungsjahr: 2024
'Humorous and accessible but never trivial... full of entertainment and insight' SUSAN QUILLIAM, co-author of The Joy of Sex How did sex begin? How did it evolve to be so varied in humans? What might sex look like in the future? The Shortest History of Sex traces the long evolution of human sexuality from the first microscopic couplings two billion years ago to today's somewhat baffling array of passions, impulses and fetishes. From the basic underlying chemistry to the tortuous complexities of the 21st-century human, David Baker lifts the lid on one of nature's primary forces. This is an erudite and entertaining book that tackles large questions with humour and insight – an essential guide for the curious reader.
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Contents
Foreword
by Simon Whistler
Sex. It’s the reason we’re all here, isn’t it? It’s a topic that captivates us all yet often remains shrouded in mystery and taboo.
For my generation, sex education was limited to a few lessons in biology class, with the girls separated from the boys and awkward discussions about our developing body parts and what we might one day do with them. “Uncomfortable” might be the best word to describe that experience. Perhaps if my teachers had communicated the facts with the ease and clarity of thisbook, I would have gotten better grades in those lessons.
In TheShortestHistoryofSex, Baker takes us on a journey that begins with the origins of life, travels through the chaotic evolution that created human sexual anatomy and instincts, and delves into every stage of human history, showing how deeply sex has shaped almost every aspect of our society. He then leads us to troubling questions about the state of sex and romance in the twenty-first century and some provocative questions about technology and sex in the not-so-remote future, painting scenarios in which we could be (a) sexless machines living in transhumanist “clouds,” (b) immortal studs and babes with enhanced genitals and perfect physiques, or (c) lonely, isolated people making love to intelligent robots designed purely for companionship and viiisex. The machines, at least, seem inevitable. Supply and demand, after all …
Here is a comprehensive, engaging story that will captivate readers from start to finish. This book is not afraid to tackle even the most unconventional aspects of sexuality, making it an eye-opening and informative read for anyone curious about sex—which, let’s face it, includes most of us—and its unique blend of humor and scientific rigor dispels many myths and misconceptions surrounding this complex and fascinating topic. In short, this book is sure to enlighten, entertain, and challenge our understanding of human sexuality. What we think we know about sex is just the tip of the iceberg. It opens up for the reader a much wider world concerning humanity’s most whispered-about and intimate subjects.
Introduction
The aim of this book is to explore sex from the “ground up” and hopefully give the audience a clear idea of where all the facets of human sexuality came from, and why humanity’s baffling array of passions, impulses, and fetishes are the way they are. We’ll start at the creation of sex approximately two billion years ago and chase it down our evolutionary family tree until we arrive at the present.
While thousands of books on sex have been written over the years, this is the first book that seeks to weave together the grand narrative of sex in its entirety. Its scope will go beyond that of most similar fare. There is an entire genre of history devoted to exploring the cultural expressions of human sexuality over the past 5,500 years, but this book isn’t so much about exploring in detail what the Ancient Greeks liked to do with their genitals so much as wheretheirgenitalscamefrom. Furthermore, there is a genre of natural history that explores our sexual instincts, but it usually starts with primates, where sex is already extremely complex, dropping us in the deep end, trying to figure out where the bizarre habits of chimps, bonobos, and gorillas came from in the first place. Moreover, these primate profiles are rarely linked to an in-depth historical exploration of sex in the 315,000 years of human history. Instead, this book attempts to convey the phenomenon of sex as a totality, from start to 2finish, from the basic chemical process of two microbes sharing DNA to things as bizarre and convoluted as foot fetishes or bukkake parties. Given where sex started, that is one hell of a transformation, and it is a story that deserves to be told in full.
As a result, the reader will hopefully emerge with a clear understanding of one of the deepest and most abiding forces of human nature. Zooming out to a bird’s-eye view has the function of giving us a new perspective on sex and society. We look at how sex changed for humans across the foraging, agrarian, and modern eras, and how we arrived at a period in history where the present nature of our sex lives has no historical or evolutionary precedent. We then briefly gaze at the horizon to try to figure out where current trends may lead us in the near future, as every human on the planet with a libido tries to navigate this brave new world. But instead of predicting one such future, we survey several.
Aside from telling a unified history of sex, this book has no gimmick or obnoxious thesis advocating for either the universal practice of promiscuity or a return to strict monogamy, like some other works on sex have done in the past. I have endeavored to present the chaotic mess of our sexual history, warts and all, so readers can reflect on what it means to them. To my mind, there are no easy conclusions. As such, you are cordially invited to draw your own conclusions from this story rather than be force-fed my own. In most places where my own perspective shines through the cracks, it is for humorous effect or to provoke independent thought, rather than to deliver a “moral to the story.”
Speaking of humor and provoking thought, this work is intended to be both informative and entertaining. There are a few cheeky jokes, a bit of foul language—for that, given the 3subject matter, I hope I will be forgiven. Furthermore, in every chapter I have attempted to convey some unusual information and burst a few popular myths, along with providing a few historical vignettes purely for the reader’s titillation.
The book’s structure is straightforward. Part I: Evolutionary Foreplay explores the slow construction of the fundamentals of sex, from the origin of life to the extinction of the dinosaurs. Part II: Primate Climax takes a long, hard look at the journey that led to the complex tangle of human sexual instincts. Part III: Cultural Afterglow examines how the evolutionary trends identified in the previous two sections interact with humanity’s tremendous capacity for creating a diversity of cultures and ideas, and how the dance of Nature and Nurture played out in the three major eras of human history: foraging, agrarian, and modern.
All of this serves to show how we got to where we are, before providing some provocative information about the current state of play. We then briefly turn to a survey of the potential utopias, dystopias, and doomsday scenarios of the future. From there, the reader will likely collapse into an exhausted heap, consumed by feelings of anxiety and foreboding. At which point, if possible, a bit of sex might not be a bad idea.
I very much hope you enjoy reading this book as much as I have enjoyed writing it.
Milestones in the Annals of Sex
PART ONE
Evolutionary Foreplay
13.8 BILLION TO 66 MILLION YEARS AGO8
CHAPTER 1
A Sexless Universe
13.8 billion to 2 billion years ago
Wherein the ingredients for life emerge from an inanimate cosmos • Those ingredients make their way to a newly formed Earth • Life evolves at the bottom of Earth’s oceans • DNA begins its endless quest to replicate itself • Numerous catastrophic disasters compel the evolution of an unlikely, inefficient, and slightly absurd process—sex
Despite its somewhat suggestive name, the Big Bang created a Universe that was both sexless and lifeless for most its history. As far as we know, for roughly 10 billion of the past 13.8 billion years, the cosmos was devoid of life and thus lacked any potential for sex. Yet all the ingredients for life were there at the very moment of the Big Bang 13.8 billion years ago. All the particles that make up every living thing that ever was—or will be—were trapped in the ultra-hot singularity that existed at the beginning of space and time. That fledgling matter has merely changed form since then, in a cascade of cosmic and biological evolution, with tiny particles coupling and decoupling, drifting across thousands of light years to become a part of a newly created Earth. And the cream of the crop of those lifeless elements, bubbling away in Earth’s early oceans, became the living, sexually intricate beings about which this story is written. It is in 8that sense that the matter in your body is 13.8 billion years old, whereas sex is a more recent invention.
Sexual selection, alongside natural selection, has played a pivotal role in the transformation of species in the past two billion years since it first evolved from microscopic asexual creatures, impregnating the natural world with its rich and brilliant diversity of forms, and making us humans the sexually complex (and confused) creatures that we are today. By traveling straight down our evolutionary lineage, we can find the origin of every blush, moan, and tingling sensation that reminds us we are alive, along with many of the instincts (both good and evil) that reside in the deepest, most innate parts of our being. By understanding how we transformed from such simple inorganic material into complex living beings, with convoluted body chemistry and fragile neurology, we can understand the heart and core of the overpowering human need for intimacy, love, and sex.
Intergalactic Aphrodisiac
At the core of all sex is DNA, an unassuming dollop of acid, a chemical that creates a panoply of instincts and peculiar bodies in its blind, single-minded effort to reproduce itself. And the core ingredients of DNA are the fundamental elements hydrogen, carbon, nitrogen, oxygen, and phosphorous, none of which existed at the start of the Universe. We begin our story by explaining how that innocuous glob of acid—which eventually became responsible for every breathtaking, body-spasming, toe-curling orgasm that has ever been experienced (or faked)—came to be.
A split second after the Big Bang, the first tiny pinpricks of matter that make up your entire body were created from pure energy, then mind-bendingly hot, at around 20.3 octillion degrees Fahrenheit. After three minutes, the Universe cooled to ten million degrees, producing clouds of hydrogen, the first ingredient of DNA and the simplest, most common element in the cosmos. In fact, hydrogen makes up approximately 75 percent of all matter in the Universe to this day.
Over the next fifty million years, the Universe grew dark and freezing cold. Wispy clouds of hydrogen slowly began to clump together into dense pockets, and the gas at the center of them began to generate a ferocious heat. The pressure became so intense that atoms started to smash together, letting off continuous nuclear explosions, creating brand new elements. Thus, the stars ignited and burst forth into existence, warming the Universe again for the first time in millions of years.
These stars were so massive that they burned extremely hot and quickly exhausted themselves, after only a few million years. In their cores, they used up all their fuel and began to fuse together to create heavier and heavier 12elements such as the carbon atoms, which are vital to every cell in your body, linking all other chemical combinations into a patchwork of bone, skin, and sinew. Also fused in the belly of the first stars, only a few million years after the Big Bang, were the oxygen, nitrogen, and phosphorous atoms that would one day complete the double helix of DNA. We now had all the ingredients for sex, in separate atoms at the core of a giant disorganized lump of gas we call a star. When these giant stars could no longer fuse any more atoms, they collapsed and exploded in blinding supernovas, flinging the ingredients for DNA across the Universe.
For countless eons, our atoms traveled across the vast stretch of space that, roughly ten billion years ago, became our Milky Way galaxy. About a light year away from where we are now, gravity sucked most of matter back into a dense cloud again, creating a second-generation star, seeded with the ingredients for future life. Then, roughly 4.6 billion years ago, that star also exploded in another furious supernova, converting even more hydrogen into heavier elements, and sowing them across the patch of space where our solar system now resides.
Approximately 4.567 billion years ago, the elements hurled into our solar system by the supernova rapidly got sucked together into a third-generation star: our Sun. As the dust of the solar system clumped together to form objects the size of rocks, then boulders, then mountains, their collisions became increasingly violent. Twenty-five million years later, the solar system had eight large planets, of which the newly formed Earth was third rock from the Sun. During these many apocalyptic collisions that created Earth, there was absolutely no way anything as fragile as life could have existed.13
So where were the ingredients of DNA? The hydrogen, carbon, oxygen, nitrogen, and phosphorous were heated by a molten Earth into the form of gases and ejected out of cracks in the frail surface of Earth as steam. This was because, as Earth differentiated and heavier elements sank through the molten sludge to the core, lighter elements like those that constitute DNA bubbled to the top. In other words, we began our history on Earth as clouds in a fire-soaked sky. We swirled around in Earth’s angry atmosphere, in a sky of blood red.
The Origin of Life
Around four billion years ago, the surface temperature of Earth fell below the boiling point of 212°F (100°C). The steam that had been belched out of Earth’s crust into the atmosphere began to fall back to Earth as rain, in a torrential downpour that continued for millions upon millions of years without cessation. The trenches and low-lying areas of Earth began to fill up with water, producing the world’s first oceans. Among the raindrops that fell to the surface at this time were the ingredients that would soon form into life: the same organic materials that have been recycled over billions of years and currently form your body. They found a home in the swirling chemical soup of Earth’s virgin seas.
At the bottom of Earth’s oceans were underwater volcanoes and piping hot sea vents, emitting extreme heat from a still newly molten planet. The surface of Earth was still grey, rocky, and lifeless. Not a single creature, not an inch of greenery. Nothing. It more closely resembled the Moon than the verdant, luscious Earth of today.14
Then, approximately 3.8 billion years ago, somewhere in the depths of the sea, the first life began to form. Organic chemicals clung together as they floated around in the swirling oceans of Earth’s primordial soup. Eventually, these chemicals began to form highly complex chemical configurations, taking the shape of microscopic cells, heated at the bottom of the oceans by underwater volcanoes.
These ancestral microbes were carbon-based, as all life on Earth still is today. Carbon is the most flexible of all elements, forming a vital link in the chain for about 90 percent of all chemical combinations that exist in the Universe. But these blobs also contained the elements of hydrogen, oxygen, nitrogen, and phosphorous, which were becoming woven together in increasingly tangled and complex chemical formulas. One of those configurations would spawn evolution and—after a spasm of transformation—sex.
The first self-replicating organic chemicals may not have used DNA itself, but may have had a more primitive, sloppier form of reproduction that has since been lost to the passage of time. But once DNA emerged, it quickly overtook all other forms of life on Earth. As a result, literally every living thing on Earth has DNA and has a common ancestry dating back to approximately 3.8 billion years ago. That is why you share 98.4 percent of your DNA with a chimpanzee and roughly 40 percent with a daffodil.
The organic soup that congealed at the edges of Earth’s underwater volcanoes was composed of atoms of hydrogen, carbon, oxygen, nitrogen, and phosphorous. As individual atoms, they were lifeless. But by pure physical chance, they began to arrange themselves into a kind of acidic sludge. History’s sexiest acid.15
ThedoublehelixofDNA
When different elements come together in different chemical combinations, they trigger some sort of chemical reaction. For instance, think of the elementary school “volcanoes” that result from mixing vinegar and baking soda, suddenly unleashing an eruption of foam. The arrangement of different chemicals into a double helix of DNA is a little more complex and tangled but essentially no different. And the chemical reaction that results from an arrangement of DNA is self-replication. In other words, the nucleic acid blindly copies itself like a mindless, eternally running fax machine. One living cell splits into two cells, and on and on it goes. This simple reaction is responsible for eons of evolution and sex: every sexual attraction, fetish, and orgasm you have is the end result of a chemical reaction that has been ongoing for billions of years.
A blob of DNA is built upon twin microscopic strands tied together in the shape of a double helix. Also, DNA has a companion solitary strand, called RNA, the “hardware” of the living cell. It unzips the double strands of DNA and “reads” it much like an Xbox reads a game disc. The RNA 16looks at the pattern of adenine, guanine, cytosine, and thymine in the same way computer hardware reads a binary code of ones and zeros. The precise arrangement of these chemicals in a strand of DNA tells the RNA what the living creature is supposed to be. The RNA then takes the instructions from DNA and delivers them to parts of the cell that produce proteins (tiny factories in the cell, called ribosomes). And these proteins carry out the grunt work of “building” the creature and imbuing it with certain traits and instincts.
Everything to do with life, evolution, and sex radiates out from the chemical process of self-replication. If the blind, automatic machinations of DNA can be likened to dumping vinegar into a bottle of baking soda, then the origin of species, the evolution of penises and vaginas, and the sensations one feels when confronted by a bit of lude sexual imagery are collectively the wild, messy foam that spurts forth.
The Heart of Evolution
Provided that the living creature survives, the DNA it carries will copy itself in order to continue giving “building instructions” to the rest of the body for the duration of its lifetime. When a cell copies itself, it splits in two. Most of the time the DNA replicates itself flawlessly. But one time in roughly a billion, there is a “copying error” or mutation, which slightly modifies the DNA’s instructions, and thus creates a slightly different living creature.
It is those accidental mutations that eventually, over many generations and hundreds of thousands of years, give rise to different species. Yes, it is actually an error that gives rise to all evolutionary history. If “copying errors” did not occur, there would be no evolution; life would have remained exactly as 17it was 3.8 billion years ago, huddling in microscopic blobs on the edges of undersea volcanoes.
Some of these random mutations are deadly to an organism—adversely affecting the creature’s health and cutting its life short. Some mutations don’t affect survival one way or another. And some prove quite useful for survival, providing an edge over competing organisms in a harsh environment where death is always just around the corner. Those mutations that work the best in a specific environment continue to exist. If not, they (and the organisms possessing those mutations) die out.
For instance, let’s say you have three wolves. One wolf has a random mutation that makes it born without legs. It will likely not survive and its DNA will no longer be able to copy itself. Another wolf has a tongue that is one centimeter longer than average. That mutation is unlikely to impact its survival one way or another. The third wolf has a mutation that makes its fur a greenish color, which turns out to be handy camouflage in the leafy forest where it lives. The third wolf will thrive. Yet, after several generations, if the environment changes and leafy forest gives way to snowy tundra, then being a “green” wolf would become a detriment to survival. Those wolves that evolved white fur would slowly outcompete the previously successful “green” wolves, driving them to extinction.
That is how DNA is the core of evolution: the random mutation of a creature’s genes and the natural selection of those mutations that allow DNA to survive and continue copying itself. In short, random mutation and non-random elimination. And as environments change, so do the mutations that work best.18
Thus, 3.8 billion years ago, microscopic blobs living on the warm edge of underwater volcanoes began to survive and evolve. They chomped down organic chemicals in the primordial sludge around them. And these microbes split themselves again and again and again, in an endless process as their DNA copied itself.
But these microbes did not fuck. They merely cloned themselves asexually.
The Disastrous Origins of Sex
The first life 3.8 billion years ago was relatively simple. They were creatures known as prokaryotes: single-celled microscopic organisms where DNA strands floated around openly within the cell walls, increasing the risk of it getting damaged. But they survived, and the bottom of Earth’s oceans became overcrowded with living little blobs.
To overcome the shortage of “real estate” 3.4 billion years ago, some prokaryotes evolved to live near the surface of the oceans, no longer keeping themselves warm with underwater volcanoes. Instead, these new microscopic blobs evolved to use the Sun’s energy. They used photosynthesis, converting water, sunlight, and carbon dioxide in the atmosphere to feed themselves. Just like plants today.
And just like plants today, they pumped oxygen (O2) into the atmosphere as a waste product. The problem is that oxygen is highly turbulent, can create violent chemical reactions, and in large quantities could kill fragile primitive life like those ancestral microbes that had evolved on an early Earth where there was very little oxygen in the atmosphere.
By 2.5 billion years ago, microscopic photosynthesizers had increased the level of oxygen in the atmosphere from 19next to nothing to 2.5 percent. This nasty chemical killed off scores of microbes in an event known as the Oxygen Holocaust, Earth’s first known mass extinction event and one of the only mass extinction events was kicked off by living organisms rather than an asteroid impact or a supervolcanic eruption.
The surviving microbes evolved an increasing tolerance for oxygen in the atmosphere. Some of them even evolved the ability to consume oxygen instead of carbon dioxide, reversing which chemical was food and which waste. These were the first aerobic species, microscopic creatures similar in that respect to humans and other animals. We inhale oxygen, we exhale carbon dioxide.
But photosynthesizers remained the majority of living things on Earth and continued to create unmitigated disasters by pumping out oxygen. About 2.2 billion years ago, enough O2 had gathered in the atmosphere that the oxygen atoms began to group together in threes, creating ozone (O3). The resulting ozone layer that blanketed Earth reflected a lot of the Sun’s rays back into space. While we desperately require the ozone layer to protect us from solar radiation today, in the short term 2.2 billion years ago, this was not a good thing. Photosynthesizing life continued to increase the thickness of the ozone layer. As a result, Earth got colder and colder. The oceans froze at the poles. Then the ice spread down toward the equator, encasing the entire Earth in a frozen prison, in the first “Snowball Earth” event that occurred roughly two billion years ago. The average global temperature would have been around –58°F (–50°C).
Snowball Earth imposed a strain on the microbes living in the now ice-covered oceans. As a result of the strain, a new 20kind of microbe evolved: the eukaryote. These are “beefier” cells, ten to a thousand times the size of prokaryotes, which also evolved to protect their DNA by keeping it in a central nucleus instead of letting the strands just float around within the cell. We humans are descended from these eukaryotes, as are all the ancestors and descendants in the evolutionary tree of the plant and animal kingdoms. And it is these tiny eukaryotic blobs that were the first creatures to have sex.
In the same disastrous Snowball Earth period, these microscopic eukaryotes began to engage in carnal relations with one another, as does 99.9 percent of all eukaryotic life today. The habit stuck and has grown only more thrilling and perplexing. But the question of how and why our microbial ancestors began to feel compelled to exchange genetic information in the same way two people might exchange phone numbers at a bar, remains shrouded in mystery.
Sex, Starvation, and Hannibal Lecter
There is very little question that sex first evolved around two billion years ago as a response to the pressures imposed on our tiny ancestors by the harsh and unforgiving environment of Snowball Earth. Or a similar catastrophe that has since been lost to the passage of time. Otherwise, sex makes very little sense for living things to do. From an outsider’s perspective, then as now, sex was a somewhat absurd and costly process.
Imagine that you are a strand of DNA. Your one goal in the Universe is to copy yourself relentlessly. Therefore, it makes very little sense for you to share space with a different strand of DNA from another organism. When you clone yourself asexually, as all living things did from 3.8 billion to 2 billion years ago, you copy 100 percent of your genetics. Well 21done. Mission accomplished. But once you combine your genes with those of another microscopic blob, you only successfully copy and pass on 50 percent of your genes. In other words, this is directly against DNA’s raison d’être. A living creature would not have evolved to behave that way unless it was forced to by outside circumstances.
Furthermore, as an asexual creature that just clones itself, you do not require a mate to produce offspring. You can just keep pumping out a huge number all by yourself, potentially creating a colony of hundreds or thousands of offspring in a matter of hours. Again, mission accomplished. However, once you throw sex into the mix, population growth inevitably slows down. It now requires two organisms to create offspring, and it takes time to locate such a mate and to exchange DNA with them. The first evolution of sex thus only makes sense in constrained and starving situations where having a large, fast-growing population is a negative thing and having too many offspring would risk starving everyone. Like a family of fifteen in a famine rather than a family of three. The act of sex managed to impose population control by slowing down the pace of reproduction in an environment where food and resources were scarce. Just the sort of conditions that would have prevailed on Snowball Earth.
A third problem arises from the fact that mixing the genes of two organisms in sex creates more genetic variation. This means a DNA copying error is more likely than in asexual cloning. And this means a microbe 2 billion years ago would have been at increased risk of being born with a mutation that would have killed it or reduced its chances of survival. Remember, not all genetic mutations are good. Many of them can kill you. Switching to sex and greater genetic variation 22would only have been an advantage in a disastrous situation such as Snowball Earth, where living things genetically needed to roll the dice as fast and as frequently as possible to evolve useful evolutionary traits that would allow their offspring to survive in a hellish, starving environment. To put it more crudely, 2 billion years ago our ancestors felt so much pressure from the environment that they needed to fuck in order to survive.
But how would the act of sex have physically emerged in the first place in a world where only microbes had existed, happily cloning themselves, for the previous 1.8 billion years? How and why did the first sexually charged eukaryotes have such a bright idea? The proposed answer may disturb you.
The most credible and compelling theory is that the first exchange of DNA between two living things may have been accidental. Snowball Earth may have reduced the food available to our eukaryotic ancestors to such an extent that some microbial blobs may have started to eat each other. In a word, cannibalism. When an asexual eukaryotic cell consumed another one, there may have been an accidental exchange of DNA. The strands of the devoured victim may have become intertwined with the DNA of the hungry predator.
The offspring of such a grisly union may well have possessed some slight advantage in a frozen environment. What that precise advantage was, we cannot be sure. But the process of sexually reproducing, thus producing more frequent mutations, allowed these eukaryotes to speed up evolution and adapt faster to their grim environment.
All that was required of these microbes was for the continued shortage of food and the grotesque cannibalistic exchange to occur several more times in a starving colony of microbes 23over a few short years before it became naturally selected. From there, the habit of sexually reproducing and combining two sets of DNA was no longer an accident but an evolutionary behavior that two organisms were driven to do. (Yes, dear reader, your most intimate and romantic experiences in life may in fact originate from a desperate act of cannibalism.)
Regardless of how the first sex act may have emerged, once it was naturally selected for in a small population of eukaryotic blobs, it took off like wildfire. Despite the numerous disadvantages in the short term, once sex got into our DNA (literally) its evolutionary advantages became immensely potent in the long term.
Sex Is Wonderful
The first major advantage to sex is the greater genetic variation that comes from having two parents, which can speed up the pace of evolution and adaptation. Once living things were forced to deal with the risk of passing on bad mutations and that pandora’s box was opened, they leaned hard into its potential advantages in order to compensate. When you combine two strands of DNA, you may get a combination of physical traits and instincts that would not have occurred by mere a copying error from cloning. To use a simplistic example, a child who inherits his father’s rakish good looks and his mother’s profound intelligence may well be more fit for survival and to have children of his own one day. If the child had merely been cloned from his father’s DNA, he would simply be a beautiful idiot.
A second advantage is that sex can increase the odds that unhealthy genes are eliminated. If an asexual creature has a mutation that endangers its survival, the trait may simply 24be cloned again and again and again, until the creature goes extinct. But if a sexually reproducing organism has a negative mutation and then a sexual partner imports more dominant and healthy genes, they may eliminate the “bad” set of genes. To use another simplistic example, let’s say a child’s father has a greater risk of heart disease in his family history. And let’s say what causes this malady is a recessive gene. Then a mother comes in with a more dominant gene from a family of healthier, more robust hearts, and the dominant gene replaces the recessive one, just like dark hair replaces red hair (no offense to my redheaded brethren, you are all beautiful and sexy, I am just using a common example of recessive genes). Again, there is a clear evolutionary advantage in combining two sets of genes rather than simply cloning oneself. In a nutshell, when it comes to sex, it pays to share.
A third advantage is that sex imposes moderation on evolution. Cloning can copy even the most wild, dramatic, and grotesque DNA mutations, whereas sex tends to filter these mutations out because sex requires a viable partner. For example, let’s say our poor hypothetical child was born with a mutation that gave him eight spider-like legs, eighteen yellow eyes, and a twenty-six-foot-long penis with a sharp dagger-like stinger at the end of it. If the child reproduced asexually, that dramatic mutation would be cloned. But being a sexually reproducing creature, it is unlikely that child will find a mate willing to risk having sex with him, so the wild mutations will die with him. In wider nature, mutations that are too dramatic generally don’t find compatible mates, which prevents a flood of dramatic and potentially deadly mutations from being thrown into the more gradual process of evolutionary change. 25
A fourth advantage is that sex between two creatures can confer greater resistances to viruses and diseases. An asexual organism is only capable of developing immune resistance to a disease by a random mutation during cloning. Two sexual organisms potentially bring different lineages with different resistances to disease and combine them, building upon them with each generation. Again, to use a simplistic example, dad brings with him a resistance to smallpox and mom brings with her a resistance to bubonic plague. Their child may potentially inherit resistances to both. As such, sex may provide an immense advantage in the evolutionary arms race between parasites and their potential hosts.
And so, once sex took off in our evolutionary timeline, it proved immensely useful for evolution. Sure, DNA had to make the sacrifice of only copying 50 percent of itself and combining with the genetics of another creature. But in exchange, it increased the odds of its own survival; you simply can’t keep copying yourself if your species goes extinct.
Furthermore, sex bequeathed to those hardy, horny eukaryotes the potential for rapid evolution into increasingly complex species—from tiny, microscopic blobs existing in Earth’s oceans to relatively gigantic multicelled creatures that evolved into fish, amphibians, reptiles, and mammals. In the next chapter we shall see how, alongside this greater biological complexity, sex also became increasingly intricate and bizarre. And amid the chaos of copulation, we can discern the lineage of our own sexual anatomy, physical sensations, and romantic instincts. The origins of these things are evolutionarily distant from us—on timescales of thousands and millions of years—but today they are unmistakably and unquestionably part of what makes us human.26
CHAPTER 2
Underwater Fumbles and Tumbles
2 billion to 375 million years ago
Whereinrecurrentfrozendisastersspurtheevolutionof multicelled life •In bodies composed of trillions of cells, sex specialistscalled“gametes”appear•Thehermaphroditicworm-likeancestorsofvertebratesbegin“69ing” •Thesewormsevolve intoCambrianfishwithprimitivebrains•Fishinourdirectline of ancestry evolve gonochorism•Our ancestors adopt the rather dull practice of external fertilization •Sexual competition and the “battleofthesexes”evolveinvertebrates •Theearliesttetrapods decidetocrawloutoftheoceansandhavesexonthebeach
The tyranny of the first Snowball Earth two billion years ago, which had compelled the evolution of our eukaryotic ancestors and the origin of sex, was eventually broken by the forces of geology. New volcanoes emerged out of Earth’s crust as a result of shifting plate tectonics. They pierced through the sheets of ice covering the planet and began pumping tons of carbon dioxide into the atmosphere. This reversed the process of oxygen-heavy cooling, and the gigantic ice sheets receded and then disappeared. Earth became warm and temperate once again.
Meanwhile, the existential threat of Snowball Earth loomed over our microscopic, single-celled ancestors, as the clash between carbon dioxide and oxygen for dominance 28in the atmosphere bounced the planet between phases of extreme cooling and temperate warming. Photosynthesizers still existed on the surface of Earth’s oceans, and periodically began guzzling carbon dioxide and emitting oxygen as a waste product, cooling the planet yet again. This process was exacerbated by regular Milankovitch cycles, when Earth tilts further away from the Sun, spurring along more moderate ice ages, just like the last one humans experienced 115,000 to 12,000 years ago. That ice age was bad but was nowhere near as devastating as a Snowball Earth.
As a result of cycles of extreme cooling, in the last billion years we have experienced two more Snowball Earth phases, when glaciation has met at the equator and entombed the planet. One occurred approximately 700 million years ago. Not long after Earth had recovered, a second one began 650 million years ago and ended 635 million years ago. This was the last Snowball Earth, thus far, in natural history. It provoked another profound change in the history of life, and irrevocably changed the nature of sex, transforming it beyond a mere exchange of DNA between two tiny blobs.
Friends with Benefits
For the past three billion years, microscopic life lived in colonies of thousands, even millions, of cells in the ocean. Each were separate and distinct organisms, but nevertheless thriving in a community. Some of these blobs even developed symbiotic partnerships with each other, to increase the odds of both surviving. This went double for sexually reproducing eukaryotes, who already depended on exchanging DNA with each other to perpetuate their various microbial species and keep the DNA replication process going.
When the last Snowball Earth phase struck 650 million years ago, these communities of symbiotic microbes became ever more dependent on one another in order to survive the sub-zero conditions. Time is fleeting for living creatures, and a single-celled organism only has enough energy to do a limited number of things in any given day. During Snowball Earth, different microbes began to fulfil different functions for each other. Some set about breaking down food, some focused on discarding waste products from that food, and others spent their time solely on the act of sex and the replication of their DNA.
This last (fortunate) group of cells specialized in the process of meiosis and fertilization, where the cell is initially split with half the chromosomes from its “mother cell” and then is fertilized with half the chromosomes of the “father cell” to complete the sex act. From there a new organism is born. Whereas in the previous 1.4 billion years all pairs of microscopic blobs performed the sex act, now, increasingly, only a select few cells operated in this sphere—canoodling while other microbes in the colony were busying themselves at less titillating work. These lucky reproductive blobs are called 30the gametes, otherwise known as the sex cells of the body. The microbial world’s courtesans and gigolos. In humans, these gametes are the sperm and the eggs. Not every cell in the human body can reproduce. Your hair follicles aren’t going to be impregnating anyone anytime soon. That is the specialist role of the gametes.
Ameetingofgametes
Thus, as symbiosis intensified under the pressures of Snowball Earth, it was as if all the tiny blobs were suddenly working in a giant office building. Some of them worked the mail room, some in accounting, some took out the trash, and some of them, to stretch the metaphor, focused solely on banging in the stationery closet or on the conference room table.
Eventually different cells became so intertwined and dependent on each other that if one group of specialists died, the rest would die. And it was through this excessive codependence, an immoderate amount of symbiosis, that the first multicelled organisms (the eukaryotic ancestors of plants, animals, and fungi) were born.31
You are a multicellular eukaryote. A giant corporation of thirty-seven trillion individual organic cells. That is roughly a hundred times the number of stars in the Milky Way galaxy. But these cells don’t just live in a giant colony where they act symbiotically toward one another. They cannot live without each other. Your liver doesn’t just have symbiosis with the rest of your body. It cannot act independently and crawl along behind you when you go to the shops. It is such an inextricable part of your being that you are, for all intents and purposes, one structure, one organism.
And so, between 650 million and 635 million years ago, multicelled creatures with sexual anatomy and the capacity for increasingly intricate sexual instincts emerged. Until now, sex represented little more than a stale chemical reaction between organisms that we cannot even see with the naked eye. But after the final Snowball Earth and the emergence of multicellularity, it was only a matter of time before penetration, masturbation, lust, jealousy, orgasms, oral sex, and (more distantly) bukkake parties, entered our evolutionary lexicon. But each of these evolved in stages and building blocks along our ancestral line.
Worming One’s Way into Sex
The Ediacaran era dawned 635 million years ago with a warm climate, thanks to volcanoes pumping CO2 into the atmosphere. At this time, all multicellular life existed in the oceans. And because multicelled beings were at this point evolutionarily untested, a bizarre array of forms emerged that would have done H. P. Lovecraft proud for their outlandishness. For instance, Aspidella were strange disc-like creatures that sat on the ocean floor and had no mouth 32or anus, instead absorbing food and shitting it out again through pores in their skin. Strange eukaryotic multicelled plants also began to make an appearance.
The ancestors of humans, and indeed all animals, in the Ediacaran era is currently thought to have been a worm-like creature less than a centimeter long: not much bigger than a grain of rice. These ancestral worms burrowed into the soft sand on the ocean floor and moved by contracting their muscles and stretching them out again as they slithered along. What scaffolding existed inside these worms were simply soft tubes filled with fluid. They also likely possessed a primitive mouth, anus, and digestive tract.
The bodies of these worms would have had sense receptors to detect nearby environmental stimuli, but because those nerves had not yet clustered into a brain at one end or another, they did not have an identifiable head. And because they lacked a brain, they had extremely limited self-awareness and next to no consciousness, and would have reacted only to immediate stimulation from the environment. Not unlike the single-celled creatures from which they were descended. This means that when our Ediacaran worm ancestors had sex, they were not able to contemplate it, let alone experience pleasure. And they had no sexual instincts to speak of. Their copulations were mechanical, knee-jerk, and thoroughly uninspiring. But we all have to start somewhere.
Ediacaran worms were soft-bodied, meaning they leave very little trace in the fossil record. This deprives us of a direct glimpse of their sexual anatomy. However, looking at their evolutionary precursors and descendants, it seems highly probable that each worm possessed both sperm and eggs, being capable of filling either reproductive role. In 33other words, they may well have been hermaphrodites; the common ancestor of the animal kingdom may have been both biological sexes at once. The worms would carry their eggs in a pouch located on their bodies, along with having an imperceptibly small hole or pore from which would ooze the equivalent of “worm sperm.” They had no penis to speak of.
After being born and passing the few weeks required to reach sexual maturity, these worms would have bumped into one of their compatriots somewhere in the ocean floor and mechanically begun the process of primitive copulation. The two worms would likely “69”: that is to say, line up alongside each other so that each partner’s mouth and anus were at opposite ends. The two lovers would press tightly up against each other, and the sperm would trickle out of one worm and enter the other via pores in its egg sack.
Worms69ing
In this way the eggs would be fertilized. All of this would take no more than a few seconds before each worm slithered along its merry way in search of the day’s food (tiny nutrients within the ocean floor). The impregnated worm would carry 34
