If you could be one age for the rest of your life, what would it be?

Would you choose to be nine years old, spending your days playing with friends and practicing your times tables?

Or would you choose your early 20s, when time feels endless and the world is your oyster with friends, travel, pubs, and clubs?

Western culture idealizes youth, so it may come as a surprise to learn that in a recent poll asking this question, the most popular answer wasn’t 9 or 23, but 36.

Yet as a developmental psychologist, I thought that response made a lot of sense.

adulthood, turning 36, developmental psychology, life satisfaction, emotional maturity, career crunch, parenting, aging, 30s life, peak happiness
36 is the magic number. Canva

For the last four years, I’ve been studying people’s experiences in their 30s and early 40s, and my research has led me to believe that this stage of life, while full of challenges, is much more rewarding than most might think.

The career and care crunch

When I was a researcher in my late 30s, I realized that no one was doing research on people in their 30s and early 40s, which puzzled me. So much often happens during this time: Buying homes, getting married or getting divorced; building careers, changing careers, having children or choosing not to have children.

self-confidence, mental health, midlife, adult friendships, work-life balance, life stages
According to one respondendant things Canva

To study something, it helps to name it. So my colleagues and I named the period from ages 30 to 45 “established adulthood” and then set out to try to understand it better. While we are still collecting data, we have interviewed over 100 people in this age cohort and collected survey data from more than 600 additional people.

We went into this large-scale project expecting to find that established adults were happy but struggling. We thought there would be rewards during this period of life, perhaps being settled in career, family, and friendships, or peaking physically and cognitively, but also some significant challenges.

The main challenge we anticipated was what we called “the career and care crunch.”

This refers to the collision of workplace demands and the demands of caring for others that occurs in one’s 30s and early 40s. Trying to climb a ladder in one’s chosen career while also being increasingly expected to care for kids, tend to the needs of partners and perhaps care for aging parents.

Yet when we started to look at our data, what we found surprised us.

Yes, people were feeling overwhelmed and talked about having too much to do in too little time. But they also talked about feeling profoundly satisfied. All of these things that were bringing them stress were also bringing them joy.

For example, Yuying, 44, said, “Even though there are complicated points of this time period, I feel very solidly happy in this space right now.” Nina, 39, simply described herself as being “wildly happy.” (The names used in this piece are pseudonyms, as required by research protocol.)

When we took an even closer look at our data, it started to become clear why people might wish to remain age 36 over any other age. People talked about being in the prime of their lives and feeling at their peak. After years of working to develop careers and relationships, people reported feeling as though they had finally arrived.

Mark, 36, shared that, at least for him, “things feel more in place.” “I’ve put together a machine that’s finally got all the parts it needs,” he said.

A sigh of relief after the tumultuous 20s

As well as feeling as though they had accumulated the careers, relationships and general life skills they had been working toward since their 20s, people also said they had greater self-confidence and understood themselves better.

Jodie, 36, appreciated the wisdom she had gained as she reflected on life beyond her 20s:

“Now you’ve got a solid decade of life experience. And what you discover about yourself in your 20s isn’t necessarily that what you wanted was wrong. It’s just you have the opportunity to figure out what you don’t want and what’s not going to work for you. So you go into your 30s, and you don’t waste a bunch of time going on half dozen dates with somebody that’s probably not really going to work out, because you’ve dated before and you have that confidence and that self-assuredness to be like, ‘Hey, thanks but no thanks.’ Your friend circle becomes a lot closer because you weed out the people that you just don’t need in your life that bring drama.

Most established adults we interviewed seemed to recognize that they were happier in their 30s than they were in their 20s, and this impacted how they thought about some of the signs of physical aging that they were starting to encounter. For example, Lisa, 37, said, “If I could go back physically but I had to also go back emotionally and mentally no way. I would take flabby skin lines every day.”

Not ideal for everyone

Our research should be viewed with some caveats.

The interviews were primarily conducted with middle-class North Americans, and many of the participants were white. For those who are working class, or for those who have had to deal with decades of systemic racism, established adulthood may not be so rosy.

It is also worth noting that the career and care crunch has been exacerbated, especially for women, by the COVID-19 pandemic. For this reason, the pandemic may be leading to a decrease in life satisfaction, especially for established adults who are parents trying to navigate full-time careers and full-time child care.

[You’re smart and curious about the world. So are The Conversation’s authors and editors. You can get our highlights each weekend.]

At the same time, that people think of their 30s and not their 20s or their teens as the sweet spot in their lives to which they’d like to return suggests that this is a period of life that we should pay more attention to.

And this is slowly happening. Along with my own work is an excellent book recently written by Kayleen Shaefer, “But You’re Still So Young,” that explores people navigating their 30s. In her book she tells stories of changing career paths, navigating relationships and dealing with fertility.

My colleagues and I hope that our work and Shaefer’s book are just the beginning. A better understanding of the challenges and rewards of established adulthood will give society more tools to support people during that period, ensuring that this golden age provides not only memories that we will fondly look back upon but also a solid foundation for the rest of our lives.

Clare Mehta is an Associate Professor of Psychology, Emmanuel College. This article originally appeared on The Conversation. You can read it here.

This article originally appeared last year.

  • Spanish zoo study suggests that giraffes can do basic math
    Photo credit: CanvaA study is showing giraffes could be using math.
    ,

    Spanish zoo study suggests that giraffes can do basic math

    These hoofed mammals can understand addition.

    The results of an experiment done in a Barcelona zoo suggest that giraffes are capable of doing basic mathematics.

    A group of researchers from the University of Leipzig, the Max Planck Institute for Evolutionary Anthropology, and the University of Barcelona published their study observing four giraffes at the Barcelona Zoo. The experiment involved the giraffes observing containers that had different amounts of carrot pieces inside.

    How did this experiment work?

    The researchers showed each giraffe the two yellow containers and the amount of carrots within each one. After a few seconds, they closed the containers, keeping the carrots out of sight. They then showed each giraffe a green container which had extra carrots inside. Researchers took the carrot pieces from the green container and placed them into one of the closed yellow containers. They then let each giraffe independently choose which of the two closed yellow containers they preferred, without them seeing the total number of carrot pieces within each box.

    The results found the giraffes would choose the container that had the most carrot pieces around 68% of the time. This suggests to the scientists that the giraffes were mentally adding the carrots up in each container before making their choice. After all, there have been past studies suggesting that other hoofed mammals, such as horses, had similar capability of basic quantity tracking.

    The researchers did the experiment again. Only this time they subtracted the amount of carrots in each container. The giraffes were mostly unsuccessful at finding the container with the most pieces. So while giraffes showed signs of knowing addition, they don’t quite process all forms of arithmetic.

    Math = Survival

    Scientists believe that this understanding of addition helped giraffes survive in the wild. They cite that acacia trees, a dietary staple for wild giraffes, can be spread far apart in Africa. Being able to figure out which area has the most trees and the most leaves can help them decide where to graze next.

    Giraffes also live in flexible groups that often change in size. One grouping can mix in with another group and then branch off or away. This means that the giraffes often have to keep track of those currently within their group and surroundings to survive.

    Can other animals do math?

    Giraffes are just the latest animal species known to have some form of mathematical skill. Chimpanzees displayed similar abilities to count as giraffes in a similar experiment that involved them picking the bowl with the most chocolate pieces rather than carrots. Chickens and black bears also showed aptitude in quantity tracking, too. 

    Scientists theorize that most of the animals that can do this basic math through evolutionary survival. After all, the animal that can deduce where more food is tends to live longer.

    One species that displays remarkable mathematical ability are Tunisian desert ants. An observation of their navigational skills of finding their way to food and back to their nest suggests they use the sun as a compass in combination with mentally keeping track of the number of steps they take in a three-dimensional space. In short, these desert ants possess basic geometric and trigonometry skills.

    While you wouldn’t want wild animals to calculate your taxes, it’s interesting to see how rudimentary math is a language that goes beyond species.

  • A bonobo’s make-believe tea party has scientists rethinking whether imagination belongs only to humans
    Photo credit: CanvaAn adorable baby bonobo.

    Childhood activities like playing house, superheroes and villains, the floor is lava, and the classic tea party all involve imagination. We create stories and worlds with rules and roles to play.

    Humans want to believe that our creativity and art make us unique. But a bonobo named Kanzi was part of research that has scientists wondering how different we really are. In three evolving experiments, Kanzi correctly identified pretend objects, demonstrating that he could understand and engage in make-believe situations.

    primate research, behavior, bonobo study
    Kanzi associates words and symbols with Sue Savage-Rumbaugh.
    Photo by William H. Calvin, Phd/ Wikimedia Commons (Cropped)

    Kanzi has a make-believe tea party

    Researchers developed a simple setup using cups, a pitcher, and actions that began as real pouring and gradually shifted into pretend play. The first experiment used real liquids. The second had a combination of real and pretend liquids. The final scenario had no real liquids and relied entirely on imagination.

    The scientists used gestures and make-believe to see if Kanzi would react differently depending on what he was being shown. He didn’t react the same way in each setup. His responses showed he was paying attention to more than just the objects, but also to the way the situation was presented.

    bonobo play, animal imagination, Kanzi bonobo, apes
    Kanzi participates in an indoor test.
    Photo by William H. Calvin, Phd/ Wikimedia Commons (Cropped)

    Animals engaging in fantasy

    The experiment revealed that non-human animals can understand and follow along with imaginary situations.

    “[It] shows that animals are capable of understanding pretence in a controlled experimental setting, which hadn’t been done before,” Dr. Amalia Bastos, first author of the research from the University of St Andrews, told The Guardian.

    Scientists involved in the research are careful about how they describe it. They don’t treat it as proof that bonobos imagine things the same way humans do. Instead, they suggest that animals are capable of responding to situations where meaning is implied rather than directly shown.

    Why scientists care about pretend play

    Albert Einstein, one of the greatest scientific minds in history, is often credited with the idea that logic gets you from A to B, but imagination can take you everywhere. This study suggests that the more we learn about animals, the more it seems the difference between us may not be as great as we once thought.

    Developmental research credits early social and cognitive growth in human children to imagining situations that aren’t physically present. A 2024 meta-analysis found that make-believe is not just entertainment but also directly linked to social understanding and real-world interpretation.

    Researchers now describe animal play as more flexible than once believed. A 2025 study of ravens revealed that play included the manipulation of sticks, stones, and other items, suggesting social awareness and responsiveness to context rather than simple instinctive behavior.

    Play and imagination may be versatile behaviors no longer seen as uniquely human traits. A broader cognitive toolkit shared across multiple species suggests the gap between humans and animals may be smaller than it once seemed. Things we’ve long believed to be uniquely human may instead exist along a spectrum of abilities expressed in different ways.

  • Humans nearly vanished 800,000 years ago, revealing a quiet truth: most family lines disappear
    Photo credit: CanvaA group of people hiking in the mountains.

    There was a moment in human history when our entire existence may have desperately clung to a thousand or so people. A DNA-based study found that between 800,000 and 900,000 years ago, our ancestors experienced a severe population crash.

    This wasn’t humans dealing with a giant meteor like the one that wiped out the dinosaurs. It was a much slower stretch during which humanity teetered on the brink of disappearing completely. This bottleneck in the human gene pool, comprising roughly 1,280 breeding individuals, lasted about 117,000 years.

    population, genomes, Ice Age, Early-Middle Pleistocene
    Removing representation of a human population group.
    Photo credit: Canva

    Human population levels plummet

    According to Scientific American, the study analyzed modern human genomes to piece together what the early human population looked like. By constructing a complex family tree of genes from present-day humans, researchers were able to identify important evolutionary events.

    During the Early-Middle Pleistocene, a period within the Ice Age, humans faced severe weather and intense glacial cycles. Most human ancestors may have died out, clearing the path for a new human species to take their place.

    Focusing on Africa, the study showed that 813,000 years ago, human populations began to recover and grow again. With an estimated two-thirds of genetic diversity potentially lost, traits like brain size appear to have been among the important features that survived. “It represents a key period of time during the evolution of humans,” population geneticist and study co-author Ziqian Hao said. “So there are many important questions to be answered.”

    DNA, genomes sequence, human existence, heredity
    DNA genome sequences.
    Photo credit: Canva

    Understanding evolution and ancestry

    What we know about evolution reveals a different story than a simple, continuous line of human improvement. Over time, genetic lines disappear—not dramatically all at once. It’s a slow and steady change, generation after generation.

    Human existence isn’t inevitable. Species strength or technical advancement doesn’t guarantee the future or explain our past. It’s contingent on narrow, accidental circumstances. A 2021 study showed that human evolution is better seen as a continuous flow of incremental fragments over time. Categorizing people into races and groups oversimplifies human history.

    species strength, evolutionary improvement, genetic lines, technical advancement
    A diverse group of wooden figures.
    Photo credit: Canva

    What does the bottleneck study say about us?

    The study reveals humanity didn’t simply decline; it nearly collapsed. With over 98% of our genetic diversity erased, entire branches of the human family tree permanently ceased to exist.

    It’s quite possible that if even a few more of those genetic lines had ended, human history could have vanished with them. Most branches of life don’t continue. What we witness today reflects biological persistence and countless moments that could have gone another way.

    A 2024 study conducted five billion simulations, revealing that as a species’ population shrinks, its risk of extinction rises. Even stable groups can quickly collapse if their numbers suddenly drop low enough.

    A 2025 study found that small populations erode genetic diversity. Isolation increases inbreeding and elevates the risk of extinction. Once a lineage shrinks, recovery becomes vastly more challenging over time. Long-term survival is an exception, not the guiding rule.

    Humanity likes to think of itself as the result of an incredibly unique progression. Perhaps studies like these suggest that we are actually what remains when everything else disappears. The reason any of us live today comes down to a small group of ancient outlasters: persevering individuals whose genetic lines are the building blocks of every human living today.

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