What bowerbirds, a 1920 love manual, and brutal modern advice reveal about trust
A 1920 dating manual, a book about animals having sex in a zoo, and a profane modern self-help book walk into a library, and somehow all say similar things about why dating feels so broken today.
That’s the experiment I ran. I randomly chose three books written roughly fifty years apart from my archive and read them through the lens of costly signaling theory—the evolutionary idea that the most believable signals of quality or commitment are those that are genuinely expensive to fake.
What emerged was surprising. Whether the subjects are bowerbirds or humans swiping on apps, the rules of honest mating signals haven’t changed in a hundred years, but the way we understand them has.
The power of costly displays in courtship
Betty Van Deventer’s slim 1920 guide How to Conduct a Love Affair arrived during the Jazz Age, when women were entering the workforce and courtship was moving from parlors to dance halls. She urged readers to treat their appearance, manners, and availability with deliberate strategy. Dress well, carry yourself with poise, and maintain independent interests. She also urged women to never place themselves fully “at a man’s disposal.”
Van Deventer never used the word “signal,” but her advice was pure costly signaling. In the roaring twenties, these behaviors might include investing time and money in stylish drop-waist dresses with rising hemlines, cloche hats, silk stockings, bobbed hair, and polished grooming with subtle makeup. Poise and restraint were also visible, expensive-to-fake demonstrations of value.
Fifty years later, June Johns’ The Mating Game: Sex, Love and Courtship in the Zoo (1970) described male bowerbirds spending months building elaborate nests decorated with shells, flowers, and feathers arranged by color. This bower has no practical purpose at all. Just like the 1920s bachelorette applies Maybelline mascara to signal desirability in the new public dating scene, the bower exists only as a display. Only a healthy, high-energy male can produce one. The female inspects it, watches his dance, and decides. The signal is honest precisely for the male bird because it is biologically expensive.
Gary John Bishop’s more recent Love Unfu*ked: Getting Your Relationship Sh!t Together (2019) takes a different angle for the dating-app era. He argues that most people don’t even know what they value, so they drift through low-effort situationships. Whether people need to be clearer about their “non-negotiables” (e.g., monogamy, ambition levels, desire for children, or how to spend their free time), the solution to finding a quality mate is more about internal signaling—or perhaps signaling to the self. Rather than seeking solutions through better presentation, he advocates ruthless self-honesty and alignment of values and behavior.
Three books, written across three very different eras. Each highlights a similar underlying mechanism: high-value mating requires displays that cost something real.
Strategic restraint: why playing hard to get still works
Across all three texts, the most consistent advice is that some form of withholding access until real effort has been shown pays off.
Van Deventer told 1920s women to maintain mystery and independence—not as games, but as strategic protection in a rapidly changing “dating” culture. In the book she explicitly advises: “even if you have to go to the movies alone, be out occasionally so he cannot take your availability for granted.” She urges women to “be reserved enough to protect your primary interest which is yourself,” and, in terms of attraction, it’s important to remember that most men and women like “an element of mystery.”
Johns observed a similar pattern of female restraint and selectivity throughout Chester Zoo. Female tigers tease and attack before finally allowing copulation. Female snakes reject males who skip the full courtship ritual. Among primates, females control access at peak fertility, granting it primarily to dominant males who have proven their quality through costly competition.
Bishop’s book flips the script to the post-commitment stage. He sees the traditional marriage vow as a once-powerful costly signal—a public, socially enforced promise with real consequences if broken. In today’s world of no-fault divorce and casual arrangements, that cost has evaporated. The vow became cheap, so it stopped meaning anything.
Costly signaling theory explains why this matters: a signal that costs nothing conveys almost nothing—at least in terms of quality in dating, mating, and relationships.
The honesty of animal signals, compared with human ones
This is where the zoo book becomes most illuminating.
In nature, widespread deception is rare because biology enforces honesty. The bowerbird either builds the bower or it doesn’t. The dominant baboon either wins the fights or it doesn’t. Gibbons (one of the few genuinely monogamous apes) either maintain their dawn duets or the pair bond weakens. Science is replete with experiments where signals have been artificially manipulated, be that the lengthening of barn swallow tails, the decorating of peacock trains (the extended, fanned-out feathers on the tail), or the altering of bower decorations, showing in each case that females often adjust their preferences in ways that confirm the underlying cost of the original signal.
That’s not to say that deception doesn’t exist. Male cuttlefish, for example, will display female coloring on one side of their body to fool a dominant rival while simultaneously courting a female with the other side. Sneaker male sunfish dart in to fertilize eggs while the dominant male is distracted by his own courtship display. Satellite frogs position themselves near calling males and intercept incoming females without ever producing the costly call themselves.
In all of these cases, however, the deception is frequency-dependent: it only works because most animals are signaling honestly. If every cuttlefish adopted the sneaker strategy, there would be no dominant males to deceive, and the tactic would collapse. Biology, in a sense, self-corrects.
Humans have no such built-in ceiling. Language, culture, and technology let us fake signals at a massive scale. Anyone can learn to write the perfect dating profile, curate an Instagram aesthetic, or say the right things in the talking stage. When signals become cheap and easy to imitate, trust collapses.
Van Deventer gave practical tools for navigating a more flexible signaling environment. Bishop described what happens when that environment becomes completely degraded: people stay in relationships that “leak air like a flat tyre” because there are no longer strong, enforceable signals of commitment.
How to apply costly signaling in your own dating life (2026 edition)
The only truly credible signal of quality and commitment is investment that cannot be faked cheaply—from the bowerbird’s months-long construction of its ornate bower to the sustained, respectful attention urged by Van Deventer or the deeply binding personal cost that Bishop believes a meaningful vow should once again carry.
So how do you actually use costly signaling in your own life? Here are five practical ways to create stronger, harder-to-fake signals in the 2026 dating market.
1. Create your own “high-value” signals. This might involve enhancing your physical fitness, acquiring new skills, refining how you communicate, expanding your social circles, or improving emotional regulation. Each of these pursuits can also contribute to a personal growth story, showcasing your path toward becoming a better version of yourself.
2. Demand genuine effort from others before you offer them your time and attention. Some refer to this as testing; for others, it means ensuring they meet certain criteria to warrant your emotional investment or intimacy. Endless messaging without any dates is a superficial signal, just as a quick sexual encounter devoid of meaningful conversation can reflect a different kind of neediness.
3. Reestablish the value of your commitments. Hold yourself accountable in public, ensure your actions reflect values, and be willing to risk your reputation.
4. Cease rewarding minimal effort—those who are most prepared to leave hold undue influence. Use this understanding judiciously.
5. Focus on settings where it’s difficult to fake intentions. Engaging in real-life activities, allowing for longer courtship durations, and navigating shared social networks necessitate effort.
The animals at Chester Zoo don’t need dating books. Their signals stay honest because dishonesty is too expensive. Humans have built a world where dishonesty is cheap—which is exactly why we keep writing (and reading) books trying to solve the resulting mess.
The solution has always been the same: look for the cost. Require the cost. Pay the cost yourself.
Everything else is just decoration on someone else’s bower.
For a more detailed discussion of how costly signaling theory relates to not only modern dating advice and relationships but also politics, popular culture, communication, and even parenting, be sure to check out my upcoming book, Costly Signals: The Evolution of Dating Advice.
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