Planet Earth

What Would Life Be Like Without Sex?

We didn't know, so we asked the experts.


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Frankly, I suspect that if there had never been sex, life would have been stuck at the single-cell level. So I am assuming that for some reason sex has been abolished. The conscious mind boggles at the possibilities and ramifications. Therefore, I am reporting on what my unconscious had to say about this a few years ago. 

I had a dream once when I was writing about orangutans. It was set in the future (somehow I knew that), and I was all keyed up in a fantastic state of expectation. It was that time of month, and I was about to have a week’s leave from work to go to the hotel. This was the time everyone lived for, the frosting on a very workaday cake. The world had achieved peace, at a price, and the price had been so apparently cheap. The solution to the problem of human aggression had been to alter the genetic development of people so that females, like our ape cousins, spent a week a month in estrus. Males likewise had a week of sexual excitation. When the time arrived, women, like me, simply checked into the hotel of our choice and entertained. We could choose to be monogamous and have our cycle coincide with our mate’s, or we could just take the luck of the draw. Reproduction, which was kept low, was apparently in vitro. This seemed to solve everything. For three-quarters of the time, women and men worked side by side without any sexual tension, between the sexes or among themselves. Sex simply didn’t exist, and without sexual tension and overtones, a lot more work got done. On the other hand, the weeks at the hotel were splendid--honeymoon or orgy or whatever seemed fun at the time. So this was not a world without sex exactly, but one where sex was certainly pushed to the margin, where it was pleasant and helped perpetuate the species, but where it no longer played an integral part in the texture of daily life.

Before I woke up, the dream me went to comb her hair. Looking in the mirror, I saw that I had fur on my face. I woke up laughing. The genes that controlled estrus were evidently linked to the genes for a furry pelt, and there I was, not very unlike the orangutans I was writing about.

-Bettyann Kevles

Author of Females of the Species 

According to the Bible, God had (at least) three goals in mind when He created Adam and Eve with their sexual capacities.

First, POPULATE the world with their species (Genesis 1:28).

Second, VALIDATE that sacred institution of marriage, thereby continuously bonding husband and wife in their devotion and faithfulness to each other (Genesis 2:18, 23, 24).

Third, ILLUSTRATE that sacrificial love Christ would have for His church (Ephesians 5:22-23).

What would life be like without sex? In a nutshell, very impersonal and mechanical, to say the least.

SOCIALLY, the family unit, that backbone of society itself, would never have been brought about.

THEOLOGICALLY, both Jewish and Christian faiths would have changed beyond recognition.

-Jerry Falwell

Chancellor, Liberty University

We are there already! If a woman wants to be a mother without having to put up with a partner, all she has to do is visit a sperm bank and select the characteristics she would like her child to have from its list of donors.

If her tubes are blocked, her fertilized egg can be implanted and the pregnancy can continue in the conventional way.

More than half the households in the United States today are headed by a single parent. What has it meant? The parent is torn between spending time with the child to nurture it and earning enough to support and educate it.

-Abigail Van Buren (Dear Abby)

Syndicated columnist

What would life be like without sex? It would be boring. What we’d miss, besides the obvious, is the glorious diversity of shapes, colors, and sizes we see among individuals in sexual species, including of course human beings. Mutation and environmental factors cause some variation in asexual species, but nothing like the tremendous variety produced by genetic recombination in sexual species.

So let me change the question and ask you to consider what life would be like if our species required three sexes to reproduce. Never mind the anatomy, because I have no idea how it would work (make it up yourself). But one happy certainty is that relationships between any two of the sexes would be free of the worry of unintended pregnancy. On the other hand, three-way dating would be very complicated. Imagine the difficulties involved in finding three mutually attracted people and getting them together. Does a couple made up of sex 1 and sex 2 first get together and then jointly ask sex 3 to join? Or does sex 1 invite sex 2, and then 2 invites 3? Or maybe 1 invites both 2 and 3 independently and hopes they hit it off. And then somehow all three have to agree on a restaurant and a movie. Good luck.

More seriously, we cannot expect that dating, or any norm or institution drawn from this (or any other) culture of a two-sex species, would occur in a triple-sex species. Nor can we predict triple-sex sexual, parental, or larger-scale social arrangements with any confidence. Too much depends on the vagaries of history and culture (which would probably account for all the differences in social organization within the species), on the pattern of inheritance in reproduction, and on relative degrees of parental investment. However, we can make a couple of generalizations based on theory.

First, the inheritance pattern ought to have some consequences for parent-offspring ties. A parent has--evolutionarily speaking--an interest in each offspring that is proportional to the degree of kinship. In a two-sex species, the biological contribution of each parent is one- half, on average. In a three-sex species, if each parent contributes only a third, we might expect natural selection to produce a bond that is less strong between parent and offspring.

Second, sex-role differences will depend partly on the division of reproductive labor among the sexes. The evolutionary principle is this: the sex that invests less in the offspring will tend to make that investment more casually (more promiscuously) and will compete for sexual access to the sex that invests more. In ordinary two-sex mammals, females typically invest much more. Females produce larger sex cells, carry the offspring during pregnancy, and provide nourishment after birth. Males, in species that fit this pattern, typically compete for females. (In our own species and in some others, male investment is significant both during pregnancy and after birth, which changes the calculus considerably.) Likewise, the expected sex-role differences in triple-sex species would depend heavily on who does what. I leave it to you to fill in the specifics.

Suggesting a three-sex world naturally raises the question of what life would be like in a four-sex world. In a word, unmanageable.

-Daniel W. McShea

Assistant Professor, Museum of Paleontology and Department of Geology, University of Michigan

There has already been one relevant experiment. On this planet. Early in evolution. Millions of millennia ago.

When did life originate? Earlier than 3.5 billion years ago. But the earliest known fossils are non-nucleated prokaryotes (namely, bacteria and possibly cyanobacteria), microbes that were incapable of advanced sexual reproduction.

What about the nucleated (eukaryotic) cell--cells of the type that make up higher plants and animals? When did it evolve? At least as early as 1.75 billion years ago. Were the earliest forms sexual? No. Evidently they were simple phytoplankton that reproduced by asexual body cell division (mitosis). Offspring were exact copies of the parent cell. Genetic variation was minimal, provided only by chance mutations.

When did sex evolve? It’s not known with certainty, but perhaps about 1.1 billion years ago, when phytoplankton are first seen to become diverse in the fossil record. How did sex originate? With the invention of two new processes: meiosis (derived from mitosis), the reduction cell division that gives rise to spores in algae and plants, and sex cells in animals; and syngamy, the fusion of sex cells to complete the life cycle. Why does sex matter? Because sexually produced offspring combine traits from two parental stocks. Genetic variation is vastly increased. Evolution accelerates. Diversity markedly expands.

So there was life without sex on this planet for well over 2 million millennia, some two-thirds of the total history of life. What was it like? A world of pond scum and microbes. Not much diversity. Not much change over time. Humdrum verging on boring. But it was also enormously important. Without that asexual world and its evolutionary inventions (among others, photosynthesis, the ability to breathe oxygen, and sexual reproduction), you and I would not be here to ponder life, sex, or anything else!

-J. William Schopf

Director, Center for the Study of the Origin of Life, University of California, Los Angeles

What would life be like without sex? Besides a lot less interesting, you mean?

Look, sex doesn’t exist just to make advertisers’ lives easier. It has played (and continues to play) a crucial role in the development of life on our planet.

You don’t need sex to reproduce--one-celled organisms can just replicate their DNA and split. What’s important about sexual reproduction is that the offspring are different from each other and from their parents. In the normal course of affairs some of those offspring will have traits that will help them survive a little longer than their brethren--a curve of the fin that helps a fish swim faster, a change in the eye that helps a bird spot its food. The lucky ones will, on average, produce more offspring themselves, and the advantageous trait will come to dominate in the population. This, you will recognize, is what Darwin called natural selection, and it’s the way life diversifies.

If it wasn’t for sex, there would be almost no differences between parents and offspring, and evolutionary change would be very slow. I doubt, for example, if Earth would boast any multicellular life without it.

So without sex there’d be no birds, no whales, no elephants, and no readers of DISCOVER magazine. Not to mention perfume, candlelight dinnersŠ

Hell, the whole thing is just too depressing to think about.

-James Trefil

Clarence J. Robinson Professor of Physics. George Mason University

You might think life would be dull without sex, but not so. Sex is only one of nature’s several ways of shuffling genes so that there’s plenty of variability among organisms. Variations improve the likelihood that at least some organisms can survive in shifting, uncertain environments. The generation of diversity is so vital to survival that if sex were gone, the other ways would come to the fore. As the French say, Vive la différence!

Besides sex, other ways of generating variability include parasitism and symbiosis. For example, cows and termites carry microorganisms that are crucial to digestion, and these microorganisms are passed from generation to generation. When a cow nuzzles her calf, she’s saying: Here, baby, are the rumen ciliates you’ll need to grow up healthy and strong! Or consider the nuclear genes of the cells of advanced organisms (eukaryotes): At some early point in their evolution, these cells gained the help of the genes of a parasite or symbiont that became the mitochondrion, an organelle necessary for energy production. The combination was so effective that it is now virtually universal among eukaryotic cells. Similarly, plant cells probably acquired chloroplasts, which capture the energy of sunlight, from some early parasite or symbiont.

To be sure of achieving mix-and-match genetics, natural selection would inevitably generate the psychological phenomena we now associate with sexual longing. Just imagine: A stranger walks into a saloon. A head at the bar turns to observe and gives a low whistle, thinking: Wow! Imagine the E. coli in that beauty’s gut!

Perhaps Walt Whitman said it better in To a Stranger:

Passing stranger! you do not know how longingly I look upon you,

You must be he I was seeking, or she I was seeking, (it comes to me, as of a dream,) 

I am not to speak to you, I am to think of you when I sit alone or wake at night alone,

I am to wait, I do not doubt I am to meet you again,

I am to see to it that I do not lose you.

As long as natural selection is at work, life would still be fun.

-Joel E. Cohen

Professor of Populations. Rockefeller University 

Allow me to answer the question with this, the fable of the Whiptail Lizard Kingdom.

Once upon a time, long before there were desert cactuses to be found in Arizona, all was serene in the lizard kingdom under the rule of Whiptail the Tenth, the lizard god-king, and his queen, Cnemetail. There was sustenance for the entire lizard population. The king used his secret power each breeding season to guarantee that exactly the right number of eggs would hatch as males and exactly the right number as females. The queen, however, even though she had the duty to supervise all egg laying, was not let in on the king’s secret.

Imagine the queen’s consternation when, for the first season ever, no males hatched out. Then season after season the same thing happened. Without males, of course, the entire species would become extinct. To head off that catastrophe, the king was obliged to reveal his secret: for eggs to hatch into females, he had to find a warm place in the sand for them. Only in cold sand would eggs hatch into males. Now there were no cold places left. The greenhouse effect was taking hold on Earth, and Arizona was warming into a desert. The king was in despair. How could the species survive without sex?

A miracle was needed, and lo and behold, a miracle occurred. Yunitail, a newly hatched royal lizard, came forth, its belly filled with unformed eggs, every one of them carrying all the chromosomes needed to be fertile. They would not need to be fertilized by a male. They were the eggs of a virgin sovereign who would rule over an entirely new race of whiptails, a race in which there would be neither male nor female, only unisex members. No sooner had the new sovereign ascended the whiptail throne than the first proclamation was issued: All egg laying will be preceded by a ceremonial pairing with another lizard. Henceforth and forever all whiptails will honor the memory of Whiptail the Tenth and Queen Cnemetail. We are the heirs to their kingdom. We shall never forget how it used to be in the days of our forebears, when every whiptail lived with sex.

P.S. The name of the species from which this fable derives is Cnemedophorus uniparens.

-John Money

Director, Psychohormonal Research Unit. The Johns Hopkins Hospital

The sex drive, of course, is a biological necessity for sexual reproduction. People innately have this energy for copulation, and it requires some avenue of release. In opposition to biology, however, are our cultures, which curtail the direct and unrestricted expressions of our libido. Moreover, even under conditions in which sex is socially acceptable, humans still face obstacles from potential partners. The ability of either a woman or a man to both sexually attract and reject, plus the competition for desirable mates, creates a great deal of dynamic tension between the people of any given society. The restrictions placed on copulation, combined with the sexual tensions in human interactions, result in our sexual energies being redirected into other activities that generally have a sensual nature, such as art, music, sports, and theater.

Without sex, then, life would be less creative and dynamic than it is today.

Mark Mansperger

Department of Anthropology, Washington State University

The problem with sexual reproduction today is that there are only two partners involved. You have to choose so carefully.

But even with careful selection of mates, we’re all still part of a lottery. The genetic construction of each individual is based on the genes contained in 46 chromosomes--each of which is selected at random from either the child’s father or its mother. But soon--though no one can say yet how soon--there will be no reason at all why those chromosomes could not be selected from 46 different people. To accomplish this we need only a little technology, just enough to enable a technician (or more likely, a tiny and efficient machine) to extract a particular chromosome from one cell and properly install it in another.

Well, then, in that future, you’ll be able more literally to conceive your next child--if the adjective your any longer makes sense. Because you--or rather, your conception committee--will be able to debate the merits of various chromosomes. Of course, that will be far from simple. For one thing, each chromosome contains tens of thousands of different genes (or rather, alleles of different genes), and it will still be quite a few years before you can specify each single gene. Besides, in most cases it will not be at all obvious which gene-alleles are to be preferred--so you’ll have to wade through vast numbers of magazines with articles debating the virtues of various traits. And after all that, you’ll still be working mainly in the dark, because there will remain hundreds of thousands of virtually unpredictable interactions among the chosen genes. So there really won’t be any way to know whether any particular composition is really good--whatever that might mean--until those babies have matured. And even then it won’t be clear. But that’s no worse than the way things are now.

We’ll hear grumbling from every political quarter. Racism incarnate, some will wrongly say, not comprehending how this might equally mean the end of the very concept of race. Eugenics à la carte, others will moan, and wonder who will hold the patents and collect what sorts of royalties on sets of genes alleged to embody longevity. We must preserve our diversity, other neoconservationists will cry, banding against the new armies of clones. The end of Olympics, yet others will groan, facing the prospect of ounce-brained athletes entirely muscled by fast-twitching myosins.

The future lies ahead, as Mort Sahl said.

-Marvin Minsky

Professor of Computer Science, Artificial Intelligence Laboratory, Massachusetts Institute of Technology

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