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if evolution didn’t determine human behavior, what did? The most common explanation is the effect of cultural norms. That, for instance, society tends to view promiscuous men as normal and promiscuous women as troubled outliers, or that our “social script” requires men to approach women while the pickier women do the selecting. Over the past decade, sociocultural explanations have gained steam.

In her study, when men and women considered offers of casual sex from famous people, or offers from close friends whom they were told were good in bed, the gender differences in acceptance of casual-sex proposals evaporated nearly to zero.

Everyone has always assumed — and early research had shown — that women desired fewer sexual partners over a lifetime than men.

In 2009, another long-assumed gender difference in mating — that women are choosier than men — also came under siege

in 2003, two behavioral psychologists, Michele G. Alexander and Terri D. Fisher, published the results of a study that used a “bogus pipeline” — a fake lie detector. When asked about actual sexual partners, rather than just theoretical desires, the participants who were not attached to the fake lie detector displayed typical gender differences. Men reported having had more sexual partners than women. But when participants believed that lies about their sexual history would be revealed by the fake lie detector, gender differences in reported sexual partners vanished. In fact, women reported slightly more sexual partners (a mean of 4.4) than did men (a mean of 4.0).

the fact that some gender differences can be manipulated, if not eliminated, by controlling for cultural norms suggests that the explanatory power of evolution can’t sustain itself when applied to mating behavior.

“Some sexual features are deeply rooted in evolutionary heritage, such as the sex response and how quickly it takes men and women to become aroused,” said Paul Eastwick, a co-author of the speed-dating study. “However, if you’re looking at features such as how men and women regulate themselves in society to achieve specific goals, I believe those features are unlikely to have evolved sex differences. I consider myself an evolutionary psychologist. But many evolutionary psychologists don’t think this way. They think these features are getting shaped and honed by natural selection all the time.” How far does Darwin go in explaining human behavior?

Why does it happen? Some say that by mating with a “passive” male and transferring sperm, that sperm then gets passed over to the female when the passive male mates. Sneaky. But does it really happen?

If it is mistaken identity, as the authors hypothesize, it certainly happens a lot. Why could you get so many cases of false identity

In many observed cases, the males being mated with attempted to fight off the attackers. In others, they may emit pheromones of their own that let the males know that nope, this isn’t what you’re looking for. In some cases, the targeted male just runs away. But it’s hard to tell how often this happens, as no one has ever really studied it.

t very few of the hypotheses have been tested. Most of the insect orders in which male same-sex behavior has been documented have at most one or two studies. And of those, most are not focused on same-sex mating behavior; they just list it as a by-product

So it would be interesting to test these hypotheses, and to figure out what is really driving the guy-on-guy bug action. Is it pheromones? Desperation? Safety in numbers? Or something else? Science in the future will have to tell. 

this might explain why it is relative, rather than absolute, inequality that matters so much to people today. In modern Western society, when even relatively poor people have access to transport, refrigeration, entertainment, shoes and plentiful food, you might expect that inequality would be less resented than a century ago—when none of those things might come within the reach of a poor person. What does it matter if there are people who can afford private jets and designer dresses? But clearly that isn't how people think. They resent inequality in luxuries just as much if not more than inequality in necessities. They dislike (and envy) conspicuous consumption, even if it impinges on them not at all. What hurts is not that somebody is rich, but that he is richer.

research elsewhere has found that people are less satisfied when choosing from a larger group: in one study, for example, subjects who selected a chocolate from an array of six options believed it tasted better than those who selected the same chocolate from an array of 30.

evidence shows that the perception that one has appealing alternatives to a current romantic partner is a strong predictor of low commitment to that partner.

people who are in marriages that are either bad or average might be at increased risk of divorce, because of increased access to new partners. Third, it’s unknown whether that’s good or bad for society. On one hand, it’s good if fewer people feel like they’re stuck in relationships. On the other, evidence is pretty solid that having a stable romantic partner means all kinds of health and wellness benefits.” And that’s even before one takes into account the ancillary effects of such a decrease in commitment—on children, for example, or even society more broadly.

he phenomenon extends beyond dating sites to the Internet more generally. “I’ve seen a dramatic increase in cases where something on the computer triggered the breakup,” he says. “People are more likely to leave relationships, because they’re emboldened by the knowledge that it’s no longer as hard as it was to meet new people. But whether it’s dating sites, social media, e‑mail—it’s all related to the fact that the Internet has made it possible for people to communicate and connect, anywhere in the world, in ways that have never before been seen.”

eople seeking commitment—particularly women—have developed strategies to detect deception and guard against it. A woman might withhold sex so she can assess a man’s intentions. Theoretically, her withholding sends a message: I’m not just going to sleep with any guy that comes along. Theoretically, his willingness to wait sends a message back: I’m interested in more than sex.

But the pace of technology is upending these rules and assumptions. Relationships that begin online, Jacob finds, move quickly. He chalks this up to a few things. First, familiarity is established during the messaging process, which also often involves a phone call. By the time two people meet face-to-face, they already have a level of intimacy. Second, if the woman is on a dating site, there’s a good chance she’s eager to connect. But for Jacob, the most crucial difference between online dating and meeting people in the “real” world is the sense of urgency. Occasionally, he has an acquaintance in common with a woman he meets online, but by and large she comes from a different social pool. “It’s not like we’re just going to run into each other again,” he says. “So you can’t afford to be too casual. It’s either ‘Let’s explore this’ or ‘See you later.’ ”

As online dating becomes increasingly pervasive, the old costs of a short-term mating strategy will give way to new ones. Jacob, for instance, notices he’s seeing his friends less often. Their wives get tired of befriending his latest girlfriend only to see her go when he moves on to someone else. Also, Jacob has noticed that, over time, he feels less excitement before each new date. “Is that about getting older,” he muses, “or about dating online?” How much of the enchantment associated with romantic love has to do with scarcity (this person is exclusively for me), and how will that enchantment hold up in a marketplace of abundance (this person could be exclusively for me, but so could the other two people I’m meeting this week)?

“Historically,” says Greg Blatt, the CEO of Match.com’s parent company, “relationships have been billed as ‘hard’ because, historically, commitment has been the goal. You could say online dating is simply changing people’s ideas about whether commitment itself is a life value.” Mate scarcity also plays an important role in people’s relationship decisions. “Look, if I lived in Iowa, I’d be married with four children by now,” says Blatt, a 40‑something bachelor in Manhattan. “That’s just how it is.”

“I think divorce rates will increase as life in general becomes more real-time,” says Niccolò Formai, the head of social-media marketing at Badoo, a meeting-and-dating app with about 25 million active users worldwide. “Think about the evolution of other kinds of content on the Web—stock quotes, news. The goal has always been to make it faster. The same thing will happen with meeting. It’s exhilarating to connect with new people, not to mention beneficial for reasons having nothing to do with romance. You network for a job. You find a flatmate. Over time you’ll expect that constant flow. People always said that the need for stability would keep commitment alive. But that thinking was based on a world in which you didn’t meet that many people.”

“You could say online dating allows people to get into relationships, learn things, and ultimately make a better selection,” says Gonzaga. “But you could also easily see a world in which online dating leads to people leaving relationships the moment they’re not working—an overall weakening of commitment.”

Explaining the mentality of a typical dating-site executive, Justin Parfitt, a dating entrepreneur based in San Francisco, puts the matter bluntly: “They’re thinking, Let’s keep this fucker coming back to the site as often as we can.” For instance, long after their accounts become inactive on Match.com and some other sites, lapsed users receive notifications informing them that wonderful people are browsing their profiles and are eager to chat. “Most of our users are return customers,” says Match.com’s Blatt.

The market is hugely more efficient … People expect to—and this will be increasingly the case over time—access people anywhere, anytime, based on complex search requests … Such a feeling of access affects our pursuit of love … the whole world (versus, say, the city we live in) will, increasingly, feel like the market for our partner(s). Our pickiness will probably increase.” “Above all, Internet dating has helped people of all ages realize that there’s no need to settle for a mediocre relationship.”

When it comes to commonly held modern ideals — of gender egalitarianism, individualism, the assumption that men might seek to improve themselves even without outside prodding — his response is skepticism bordering on exasperation. “In the domain of sex and relationships, men will act as nobly as women collectively demand,” he writes. “This is an aggravating statement for women to read, no doubt. They do not want to be responsible for ‘raising’ men. But it is realistic.”

Throughout his book, Regnerus prods the reader to be skeptical of utopianism and see the world as it is. It’s a useful, if unpleasant, reminder for an era in which our goals seem both loftier and further out of reach than ever

Discokeryx xiezhi was an early relative of today’s giraffes, but more like a cousin and not a direct ancestor.

“To the best of our knowledge, D. xiezhi exhibits the most optimized head-butting adaptation in vertebrate evolution,” the researchers write in the paper.

The discovery of Discokeryx xiezhi suggests this fighting style and competition for mates may be a contributing factor in their long-neck evolution.

“In reality, it was likely a combination of natural selection ... for a particular dietary preference and sexual selection in that lineage that drove the evolution of modern giraffe necks and limbs,” Advait Jukar, a paleobiologist at Yale University who was not involved in the study tells Scientific American’s Rachel Nuwer.

In short, a complex and evolving system — whether that’s a flock of gold finches or a nebula or the English language — will produce ever more diverse and intricately detailed states and configurations of itself.

Some of these more diverse and intricate configurations, the scientists write, are shed and forgotten over time. The configurations that persist are ones that find some utility or novel function in a process akin to natural selection, but a selection process driven by the passing-on of information rather than just the sowing of biological genes

Have they finally glimpsed, I wonder, the connectedness and symbiotic co-evolution of their own scientific ideas with those of the world’s writers

Have they learned to describe in their own quantifying language that cradle from which both our disciplines have emerged and the firmament on which they both stand — the hearing and telling of stories in order to exist?

Have they quantified the quality of all existent matter, living and not: that all things inherit a story in data to tell, and that our stories are told by the very forms we take to tell them? 

“Is there a universal basis for selection? Is there a more quantitative formalism underlying this conjectured conceptual equivalence—a formalism rooted in the transfer of information?,” they ask of the world’s disparate phenomena. “The answer to both questions is yes.”

In her Pulitzer-winning “Pilgrim at Tinker Creek,” nature writer Annie Dillard explains plainly that evolution is the vehicle of such intricacy in the natural world, as much as it is in our own thoughts and actions. 

The principle of complexity evolving at its own pace when left to its own devices, independent of time but certainly in a dance with it, is nothing new. Not in science, nor in its closest humanities kin, science and nature writing. Give things time and nourishing environs, protect them from your own intrusions and — living organisms or not — they will produce abundant enlacement of forms.

This is how poetry was born from the same larynxes and phalanges that tendered nuclear equations: We featherless bipeds gave language our time and delighted attendance until its forms were so multivariate that they overflowed with inevitable utility.

Yes. They’ve glimpsed it, whether they know it or not. Sing to me, O Muse, of functional information and its complex diversity.

“The stability of simple forms is the sturdy base from which more complex, stable forms might arise, forming in turn more complex forms,” she explains, drawing on the undercap frills of mushrooms and filament-fine filtering tubes inside human kidneys to illustrate her point. 

“Utility to the creature is evolution’s only aesthetic consideration. Form follows function in the created world, so far as I know, and the creature that functions, however bizarre, survives to perpetuate its form,” writes Dillard.

Or, as the Mishna would have it, “the creations were all made in generic form, and they gradually expanded.” 

She notes that, of all forms of life we’ve ever known to exist, only about 10% are still alive. What extravagant multiplicity. 

“Intricacy is that which is given from the beginning, the birthright, and in the intricacy is the hardiness of complexity that ensures against the failures of all life,” Dillard writes. “The wonder is — given the errant nature of freedom and the burgeoning texture of time — the wonder is that all the forms are not monsters, that there is beauty at all, grace gratuitous.”

“This paper, and the reason why I'm so proud of it, is because it really represents a connection between science and the philosophy of science that perhaps offers a new lens into why we see everything that we see in the universe,” lead scientist Michael Wong told Motherboard in a recent interview. 

Wong is an astrobiologist and planetary scientist at the Carnegie Institute for Science. In his team’s paper, that bridge toward scientific philosophy is not only preceded by a long history of literary creativity but directly theorizes about the creative act itself.  

“The creation of art and music may seem to have very little to do with the maintenance of society, but their origins may stem from the need to transmit information and create bonds among communities, and to this day, they enrich life in innumerable ways,” Wong’s team writes.  

“Perhaps, like eddies swirling off of a primary flow field, selection pressures for ancillary functions can become so distant from the core functions of their host systems that they can effectively be treated as independently evolving systems,” the authors add, pointing toward the elaborate mating dance culture observed in birds of paradise.

“Perhaps it will be humanity’s ability to learn, invent, and adopt new collective modes of being that will lead to its long-term persistence as a planetary phenomenon. In light of these considerations, we suspect that the general principles of selection and function discussed here may also apply to the evolution of symbolic and social systems.”

The Mekhilta teaches that all Ten Commandments were pronounced in a single utterance. Similarly, the Maharsha says the Torah’s 613 mitzvoth are only perceived as a plurality because we’re time-bound humans, even though they together form a singular truth which is indivisible from He who expressed it. 

“Of the multiplicity of forms, I know nothing. Except that, apparently, anything goes. This holds for forms of behavior as well as design — the mantis munching her mate, the frog wintering in mud.” 

Like swirling eddies off of a primary flow field.

“O Lord, how manifold are thy works!,” cried out David in his psalm. “In wisdom hast thou made them all: the earth is full of thy riches. So is this great and wide sea, wherein are things creeping innumerable, both small and great beasts.” 

Because, whether wittingly or not, science is singing the tune of the humanities. And whether expressed in algebraic logic or ancient Greek hymn, its chorus is the same throughout the universe: Be fruitful and multiply. 

In all things, then — from poetic inventions, to rare biodiverse ecosystems, to the charted history of our interstellar equations — it is best if we conserve our world’s intellectual and physical diversity, for both the study and testimony of its immeasurable multiplicity.

Both intricate configurations of art and matter arise and fade according to their shared characteristic, long-known by students of the humanities: each have been graced with enough time to attend to the necessary affairs of their most enduring pleasures. 

Blame the much-documented rise of the “hookup culture” among young people, characterized by spontaneous, commitment-free (and often, alcohol-fueled) romantic flings. Many students today have never been on a traditional date,

Hookups may be fine for college students, but what about after, when they start to build an adult life? The problem is that “young people today don’t know how to get out of hookup culture,”

In interviews with students, many graduating seniors did not know the first thing about the basic mechanics of a traditional date. “They’re wondering, ‘If you like someone, how would you walk up to them? What would you say? What words would you use?’ ”

Traditional courtship — picking up the telephone and asking someone on a date — required courage, strategic planning and a considerable investment of ego (by telephone, rejection stings). Not so with texting, e-mail, Twitter or other forms of “asynchronous communication,” as techies call it. In the context of dating, it removes much of the need for charm; it’s more like dropping a line in the water and hoping for a nibble.

Online dating services, which have gained mainstream acceptance, reinforce the hyper-casual approach by greatly expanding the number of potential dates. Faced with a never-ending stream of singles to choose from, many feel a sense of “FOMO” (fear of missing out), so they opt for a speed-dating approach — cycle through lots of suitors quickly.

“I’ve seen men put more effort into finding a movie to watch on Netflix Instant than composing a coherent message to ask a woman out,” said Anna Goldfarb, 34, an author and blogger in Moorestown, N.J. A typical, annoying query is the last-minute: “Is anything fun going on tonight?” More annoying still are the men who simply ping, “Hey” or “ ’sup.”

The mass-mailer approach necessitates “cost-cutting, going to bars, meeting for coffee the first time,” he added, “because you only want to invest in a mate you’re going to get more out of.”

in  a world where “courtship” is quickly being redefined, women must recognize a flirtatious exchange of tweets, or a lingering glance at a company softball game, as legitimate opportunities for romance, too.

THERE’S another reason Web-enabled singles are rendering traditional dates obsolete. If the purpose of the first date was to learn about someone’s background, education, politics and cultural tastes, Google and Facebook have taken care of that.

Dodgy economic prospects facing millennials also help torpedo the old, formal dating rituals. Faced with a lingering recession, a stagnant job market, and mountains of student debt, many young people — particularly victims of the “mancession” — simply cannot afford to invest a fancy dinner or show in someone they may or may not click with.

“Maybe there’s still a sense of a man taking care of a woman, but our ideology is aligning with the reality of our finances,” Ms. Rosin said. As a man, you might “convince yourself that dating is passé, a relic of a paternalistic era, because you can’t afford to take a woman to a restaurant.”

“A lot of men in their 20s are reluctant to take the girl to the French restaurant, or buy them jewelry, because those steps tend to lead to ‘eventually, we’re going to get married,’ ” Mr. Edness, 27, said. In a tight economy, where everyone is grinding away to build a career, most men cannot fathom supporting a family until at least 30 or 35, he said.

Even in an era of ingrained ambivalence about gender roles, however, some women keep the old dating traditions alive by refusing to accept anything less. Cheryl Yeoh, a tech entrepreneur in San Francisco, said that she has been on many formal dates of late — plays, fancy restaurants. One suitor even presented her with red roses. For her, the old traditions are alive simply because she refuses to put up with anything less. She generally refuses to go on any date that is not set up a week in advance, involving a degree of forethought. “If he really wants you,” Ms. Yeoh, 29, said, “he has to put in some effort.”

If replication is what separates the rigor of science from the squishiness of pseudoscience, where do we put all these rigorously validated findings that can no longer be proved? Which results should we believe?

Schooler demonstrated that subjects shown a face and asked to describe it were much less likely to recognize the face when shown it later than those who had simply looked at it. Schooler called the phenomenon “verbal overshadowing.”

The most likely explanation for the decline is an obvious one: regression to the mean. As the experiment is repeated, that is, an early statistical fluke gets cancelled out. The extrasensory powers of Schooler’s subjects didn’t decline—they were simply an illusion that vanished over time.

yet Schooler has noticed that many of the data sets that end up declining seem statistically solid—that is, they contain enough data that any regression to the mean shouldn’t be dramatic. “These are the results that pass all the tests,” he says. “The odds of them being random are typically quite remote, like one in a million. This means that the decline effect should almost never happen. But it happens all the time!

this is why Schooler believes that the decline effect deserves more attention: its ubiquity seems to violate the laws of statistics

In 2001, Michael Jennions, a biologist at the Australian National University, set out to analyze “temporal trends” across a wide range of subjects in ecology and evolutionary biology. He looked at hundreds of papers and forty-four meta-analyses (that is, statistical syntheses of related studies), and discovered a consistent decline effect over time, as many of the theories seemed to fade into irrelevance.

Jennions admits that his findings are troubling, but expresses a reluctance to talk about them

publicly. “This is a very sensitive issue for scientists,” he says. “You know, we’re supposed to be dealing with hard facts, the stuff that’s supposed to stand the test of time. But when you see these trends you become a little more skeptical of things.”

Sterling saw that if ninety-seven per cent of psychology studies were proving their hypotheses, either psychologists were extraordinarily lucky or they published only the outcomes of successful experiments.

Jennions, similarly, argues that the decline effect is largely a product of publication bias, or the tendency of scientists and scientific journals to prefer positive data over null results, which is what happens when no effect is found. The bias was first identified by the statistician Theodore Sterling, in 1959, after he noticed that ninety-seven per cent of all published psychological studies with statistically significant data found the effect they were looking for

While publication bias almost certainly plays a role in the decline effect, it remains an incomplete explanation. For one thing, it fails to account for the initial prevalence of positive results among studies that never even get submitted to journals. It also fails to explain the experience of people like Schooler, who have been unable to replicate their initial data despite their best efforts.

One of his most cited papers has a deliberately provocative title: “Why Most Published Research Findings Are False.”

suspects that an equally significant issue is the selective reporting of results—the data that scientists choose to document in the first place. Palmer’s most convincing evidence relies on a statistical tool known as a funnel graph. When a large number of studies have been done on a single subject, the data should follow a pattern: studies with a large sample size should all cluster around a common value—the true result—whereas those with a smaller sample size should exhibit a random scattering, since they’re subject to greater sampling error. This pattern gives the graph its name, since the distribution resembles a funnel.

after Palmer plotted every study of fluctuating asymmetry, he noticed that the distribution of results with smaller sample sizes wasn’t random at all but instead skewed heavily toward positive results. Palmer has since documented a similar problem in several other contested subject areas. “Once I realized that selective reporting is everywhere in science, I got quite depressed,” Palmer told me. “As a researcher, you’re always aware that there might be some nonrandom patterns, but I had no idea how widespread it is.”

Palmer summarized the impact of selective reporting on his field: “We cannot escape the troubling conclusion that some—perhaps many—cherished generalities are at best exaggerated in their biological significance and at worst a collective illusion nurtured by strong a-priori beliefs often repeated.”

Palmer emphasizes that selective reporting is not the same as scientific fraud. Rather, the problem seems to be one of subtle omissions and unconscious misperceptions, as researchers struggle to make sense of their results. Stephen Jay Gould referred to this as the “sho

horning” process.

“A lot of scientific measurement is really hard,” Simmons told me. “If you’re talking about fluctuating asymmetry, then it’s a matter of minuscule differences between the right and left sides of an animal. It’s millimetres of a tail feather. And so maybe a researcher knows that he’s measuring a good male”—an animal that has successfully mated—“and he knows that it’s supposed to be symmetrical. Well, that act of measurement is going to be vulnerable to all sorts of perception biases. That’s not a cynical statement. That’s just the way human beings work.”

One of the classic examples of selective reporting concerns the testing of acupuncture in different countries. While acupuncture is widely accepted as a medical treatment in various Asian countries, its use is much more contested in the West. These cultural differences have profoundly influenced the results of clinical trials.

John Ioannidis, an epidemiologist at Stanford University, argues that such distortions are a serious issue in biomedical research. “These exaggerations are why the decline has become so common,” he says. “It’d be really great if the initial studies gave us an accurate summary of things. But they don’t. And so what happens is we waste a lot of money treating millions of patients and doing lots of follow-up studies on other themes based on results that are misleading.”

In 2005, Ioannidis published an article in the Journal of the American Medical Association that looked at the forty-nine most cited clinical-research studies in three major medical journals.

the data Ioannidis found were disturbing: of the thirty-four claims that had been subject to replication, forty-one per cent had either been directly contradicted or had their effect sizes significantly downgraded.

the most troubling fact emerged when he looked at the test of replication: out of four hundred and thirty-two claims, only a single one was consistently replicable. “This doesn’t mean that none of these claims will turn out to be true,” he says. “But, given that most of them were done badly, I wouldn’t hold my breath.”

According to Ioannidis, the main problem is that too many researchers engage in what he calls “significance chasing,” or finding ways to interpret the data so that it passes the statistical test of significance—the ninety-five-per-cent boundary invented by Ronald Fisher.

For Simmons, the steep rise and slow fall of fluctuating asymmetry is a clear example of a scientific paradigm, one of those intellectual fads that both guide and constrain research: after a new paradigm is proposed, the peer-review process is tilted toward positive results. But then, after a few years, the academic incentives shift—the paradigm has become entrenched—so that the most notable results are now those that disprove the theory.

The problem of selective reporting is rooted in a fundamental cognitive flaw, which is that we like proving ourselves right and hate being wrong.

“It feels good to validate a hypothesis,” Ioannidis said. “It feels even better when you’ve got a financial interest in the idea or your career depends upon it. And that’s why, even after a claim has been systematically disproven”—he cites, for instance, the early work on hormone replacement therapy, or claims involving various vitamins—“you still see some stubborn researchers citing the first few studies

That’s why Schooler argues that scientists need to become more rigorous about data collection before they publish. “We’re wasting too much time chasing after bad studies and underpowered experiments,”

The current “obsession” with replicability distracts from the real problem, which is faulty design.

“Every researcher should have to spell out, in advance, how many subjects they’re going to use, and what exactly they’re testing, and what constitutes a sufficient level of proof. We have the tools to be much more transparent about our experiments.”

Schooler recommends the establishment of an open-source database, in which researchers are required to outline their planned investigations and document all their results. “I think this would provide a huge increase in access to scientific work and give us a much better way to judge the quality of an experiment,”

scientific research will always be shadowed by a force that can’t be curbed, only contained: sheer randomness. Although little research has been done on the experimental dangers of chance and happenstance, the research that exists isn’t encouraging.

The disturbing implication of the Crabbe study is that a lot of extraordinary scientific data are nothing but noise. The hyperactivity of those coked-up Edmonton mice wasn’t an interesting new fact—it was a meaningless outlier, a by-product of invisible variables we don’t understand.

The problem, of course, is that such dramatic findings are also the most likely to get published in prestigious journals, since the data are both statistically significant and entirely unexpected

This suggests that the decline effect is actually a decline of illusion. While Karl Popper imagined falsification occurring with a single, definitive experiment—Galileo refuted Aristotelian mechanics in an afternoon—the process turns out to be much messier than that.

Many scientific theories continue to be considered true even after failing numerous experimental tests.

Even the law of gravity hasn’t always been perfect at predicting real-world phenomena. (In one test, physicists measuring gravity by means of deep boreholes in the Nevada desert found a two-and-a-half-per-cent discrepancy between the theoretical predictions and the actual data.)

Such anomalies demonstrate the slipperiness of empiricism. Although many scientific ideas generate conflicting results and suffer from falling effect sizes, they continue to get cited in the textbooks and drive standard medical practice. Why? Because these ideas seem true. Because they make sense. Because we can’t bear to let them go. And this is why the decline effect is so troubling. Not because it reveals the human fallibility of science, in which data are tweaked and beliefs shape perceptions. (Such shortcomings aren’t surprising, at least for scientists.) And not because it reveals that many of our most exciting theories are fleeting fads and will soon be rejected. (That idea has been around since Thomas Kuhn.)

The decline effect is troubling because it reminds us how difficult it is to prove anything. We like to pretend that our experiments define the truth for us. But that’s often not the case. Just because an idea is true doesn’t mean it can be proved. And just because an idea can be proved doesn’t mean it’s true. When the experiments are done, we still have to choose what to believe. ♦

Today, people are constantly told that we must be flexible and adaptable in order to succeed. Is it surprising that these values are reshaping how many of us approach sex and love?

part-timers, contractors and other contingent workers — who constitute some 40 percent of the American work force — are more inclined to text one another “u still up?” than to make plans in advance

Smartphones have altered expectations about when we are “on” and “off,” and working from home or from cafes has blurred the lines between labor and leisure.

The 2013 and 2014 Work and Education Poll conducted by Gallup found that the average full-time American worker reported working 47 hours per week. Moreover, 21 percent of the people surveyed reported working 50 to 59 hours per week; and another 18 percent said they worked 60 or more hours a week.

marriage rates have declined significantly since 1960. The median age of first marriage has risen to a record high: 27 for women and 29 for men.

“Knot Yet: The Benefits and Costs of Delayed Marriage in America” observed that young adults have gone from seeing marriage as a “cornerstone” of adult life to its “capstone,” something you enter only after you complete your education and attain professional stability

DATING itself is a recent invention. It developed when young people began moving to cities and women began working outside private homes. By 1900, 44 percent of single American women worked. Previously, courtship had taken place under adult supervision, in private places: a parlor, a factory dance or church social. But once women started going out and earning wages, they had more freedom over where and how they met prospective mates. Because men vastly out-earned women, they typically paid for entertainment.

In the 1920s and ‘30s, as more and more middle-class women started going to college, parents and faculty panicked over the “rating and dating” culture, which led kids to participate in “petting parties” and take “joy rides” with members of the opposite sex.

By the 1950s, a new kind of dating took over: “going steady.

by the post-war era of full employment, this form of courtship made perfect sense. The booming economy, which was targeting the newly flush “teen” demographic, dictated that in order for everyone to partake in new consumer pleasures — for everyone to go out for a burger and root beer float on the weekends — young people had to pair off

The generation of Americans that came of age around the time of the 2008 financial crisis has been told constantly that we must be “flexible” and “adaptable.” Is it so surprising that we have turned into sexual freelancers? Many of us treat relationships like unpaid internships: We cannot expect them to lead to anything long-term, so we use them to get experience. If we look sharp, we might get a free lunch.

this kind of dating isn’t any more transactional than it was back when suitors paid women family-supervised visits or parents sought out a yenta to introduce their children at a synagogue mixer.

Courtship has always been dictated by changes in the market. The good news is that dating is not the same thing as love. And as anyone who has ever been in love can attest, the laws of supply and demand do not control our feelings.