The XX Lab

Your WHOOP recovery score dips, you slept fine, you did everything right, so why does the number look worse? What if that "bad" reading is your body working exactly as it should? In this episode of The XX Lab, Dr. Sarah Hill sits down with Dr. Kristen Holmes, Global Head of Human Performance and Principal Scientist at WHOOP, to explore what wearables really measure in women, resilience to hormonal change, sleep-wake regularity, mental health as the foundation of performance, and her new book, Aligned. Whether you are curious about what your wearable is telling you, navigating perimenopause, or rethinking how mental health, sleep, and recovery connect, this conversation offers a women-first lens on performance and resilience. KEY TAKEAWAYS: - A lower recovery score during your cycle is often normal biology, not a sign you did something wrong. - Women on hormonal birth control show fewer perturbations, and their data can resemble a man's. - Cardiovascular amplitude is a novel, patented marker of resilience that HRV and resting heart rate miss. - The resilience you build in your 20s and 30s shapes your perimenopause and menopause experience. - If your mental health is not right, top fitness and performance stop mattering very quickly. - Sleep-wake regularity predicts disease better than sleep duration and supports mental health too. Timestamps The Scientist Behind Your WHOOP Recovery Score (00:00) From Elite Coaching to Human Performance Science (02:25) Availability: The Metric That Predicts 86% of Success (04:45) Leaving Princeton to Scale Recovery at WHOOP (10:15) Why Your Cycle Changes Your Recovery Score (14:55) Resilience to Hormonal Change and Amplitude (18:10) Why Building Resilience Starts in Your 20s and 30s (24:15) The New Book Aligned and Losing Her Mother (32:45) Why Mental Health Is the Foundation of Performance (44:00) Sex Differences in Sleep and the Light Diet (55:25) The HEAL Framework and Sleep-Wake Regularity (1:11:55) Guest Bio Dr. Kristen Holmes is the Global Head of Human Performance and Principal Scientist at WHOOP, where she has led research on recovery, sleep, and women's health since 2016. A two-sport All-American at Iowa and seven-year US National Field Hockey Team member, she was one of the most successful coaches in Ivy League history at Princeton, winning 12 league titles in 13 seasons. A psychophysiologist, her work focuses on how psychology, physiology, sleep, and recovery shape human performance. She is the author of Aligned. - Aligned (book): https://a.co/d/aligned - Instagram: https://www.instagram.com/kristen_holmes2126 - WHOOP: https://www.whoop.com *** 📘 Go deeper with Dr. Sarah Hill's books, both science-backed guides to understanding your own biology: The Period Brain: the new science of why we PMS and PMDD, and how to feel your best all month long 👉 https://www.amazon.com/Period-Brain-Science-Manifesto-Women/dp/0063382474 This Is Your Brain on Birth Control: how the pill shapes mood, attraction, and behavior in ways most women are never told 👉 https://www.amazon.com/This-Your-Brain-Birth-Control/dp/0525536035

You did everything right, kale, running, annual blood tests, and still ended up with a mass in your lung. So why does the disease killing more young, healthy women than breast, ovarian, and colon cancer combined still carry the stigma of a smoker's disease? In this episode of The XX Lab, Dr. Sarah Hill sits down with Shira Boehler, lung cancer survivor, author of the New York Times bestseller One Scan Saved My Life, and founder of the Cancer Doesn't Care foundation, to explore why lung cancer is rising in young non-smoking women, sex differences in medicine, the toll on caregivers, and why a $200 scan could rewrite the guidelines. KEY TAKEAWAYS: - Lung cancer kills more young, healthy women than breast, ovarian, and colon cancer combined, yet gets a fraction of the awareness and funding. - "If you smoke, you get lung cancer" has curdled into "if you have lung cancer, you smoked", a stigma that keeps survivors silent. - The real truth is simpler and scarier: if you have lungs, you can get lung cancer. - Non-smoking women in parts of Asia get lung cancer at higher rates than smoking men, pointing to a female health crisis science hasn't explained. - Studying diseases separately in men and women may accelerate progress and reveal sex-specific risk factors. Timestamps 00:00 One Scan Saved My Life: Shira Boehler's Story 05:37 Pushing for the Low-Dose CT Doctors Dismissed 08:52 Why Lung Cancer Kills More Young Women Than Breast Cancer 14:08 The Myth That Only Smokers Get Lung Cancer 21:31 How Women's Heart Attack Symptoms Went Ignored for Decades 27:20 How She Told Her Kids She Had Cancer 39:32 Why Your Surgeon Should Warn You About Depression 43:52 The Ripple Effect: Susan Wojcicki and Hidden Costs 53:00 What to Say When Your Doctor Refuses the Scan 56:14 How to Get a Low-Dose CT for Under $500 1:04:36 If She Could Rewrite the Screening Guidelines 1:10:07 The One Thing She Wants Every Woman to Do Guest Bio Shira Boehler is a lung cancer survivor and author of One Scan Saved My Life, a New York Times bestseller chronicling her diagnosis as a healthy, non-smoking runner and mother of four. Diagnosed at 43 after a mass was caught incidentally, she had half her right lung removed and was declared cancer-free at stage one. She founded the Cancer Doesn't Care foundation, which funds low-dose CT screenings for those who cannot afford them, and focuses on early detection, dismantling stigma, and modernizing screening guidelines. - Book: One Scan Saved My Life https://a.co/d/006gnafi - Foundation: https://www.cancerdoesntcare.com - Instagram: https://www.instagram.com/shiraboehler/ *** Go deeper with Dr. Sarah Hill's books, both science-backed guides to understanding your own biology: The Period Brain: the new science of why we PMS and PMDD, and how to feel your best all month long https://www.amazon.com/Period-Brain-Science-Manifesto-Women/dp/0063382474 This Is Your Brain on Birth Control: how the pill shapes mood, attraction, and behavior in ways most women are never told https://www.amazon.com/This-Your-Brain-Birth-Control/dp/0525536035

Why does attraction change once you're in a long-term relationship? And could hormones, physical attractiveness, and even what happens after sex shape how satisfied couples remain over time? On this episode of The XX Lab , Dr. Sarah Hill sits down with Dr. Andrea Meltzer , Professor of Social Psychology at Florida State University, to explore the science of attraction, mate choice, sexual satisfaction, and long-term relationship health. Dr. Meltzer has spent years studying how individual differences and interpersonal dynamics shape romantic relationships. Her research uses longitudinal and experimental methods to examine newlywed couples, giving researchers a rare look at how attraction, stress, sexual satisfaction, and perceptions of partners influence relationship outcomes over time. Does physical attractiveness predict relationship satisfaction? The conversation begins with a surprising finding about physical attractiveness and relationship satisfaction. Dr. Meltzer explains why attractiveness can matter differently for men and women once a relationship becomes established, and why the person you find attractive from across the room isn't necessarily the same person you experience as attractive when they're your partner. Sarah and Andrea also discuss how people tend to see their romantic partners more positively than outside observers do. Relationship satisfaction and commitment can shape how attractive we perceive our partners to be, suggesting that attraction isn't simply a fixed reaction to someone's physical appearance. How can couples protect relationship satisfaction over time? Relationship satisfaction tends to decline on average over the course of marriage, but Dr. Meltzer emphasizes that couples differ considerably in how steep that decline is. Her research points toward factors that may help buffer against those changes. The conversation ends with practical ideas for maintaining strong relationships, including positive communication, supporting a partner's goals, and creating novel experiences together. Dr. Meltzer also highlights something couples may underestimate: the role that outside stress can play inside the relationship. This episode is for anyone curious about the science of attraction, hormones, sex, mate choice, marriage, and what actually helps romantic relationships stay satisfying over time. KEY TAKEAWAYS Relationship attraction is shaped by context , meaning a partner's personality, behavior, status, and relationship dynamics can matter alongside physical appearance. Sexual afterglow can last roughly 24 to 48 hours after sex , potentially helping couples maintain a sense of connection between sexual experiences. Stronger sexual afterglow has been associated with greater relationship satisfaction months later , suggesting that the effects of sex may extend beyond the sexual encounter itself. Sexual frequency appears to matter up to a point , while sexual afterglow may become particularly relevant once couples are already meeting their desired level of sexual frequency. Positive communication and novel experiences together may help protect relationship satisfaction , while outside stress is an often-underestimated influence on romantic relationships. GUEST BIO Dr. Andrea Meltzer is a Professor of Social Psychology at Florida State University whose research examines relationship development, maintenance, and well-being. Her work focuses on how individual differences, stress, sexual satisfaction, partner perceptions, and interpersonal dynamics shape romantic relationship outcomes over time. Follow The XX Lab for more science-based conversations about women's health, psychology, relationships, and human behavior.

What does your voice say before you even finish a sentence? Long before someone processes your words, their brain has already begun decoding your voice. In a fraction of a second, people can make surprisingly accurate judgments about your age, biological sex, emotional state, health, native language, and even aspects of your social relationships. The fascinating part? Most of this happens automatically. In this episode of The XX Lab , Dr. Sarah Hill sits down with cognitive scientist Dr. Greg Bryant , Professor and Chair of Communication at UCLA, to explore the hidden science of human vocal communication. Drawing from evolutionary psychology, cognitive science, and behavioral biology, Dr. Bryant explains why our voices evolved to carry so much information and how humans have become remarkably skilled at interpreting those signals. Sarah and Greg discuss how listeners detect subtle vocal cues associated with illness, strength, stress, confidence, and authenticity. They also explore why these abilities likely evolved to help humans navigate cooperation, competition, caregiving, and mate selection. Whether you're interested in psychology, neuroscience, communication, women's health, or human behavior, this conversation offers a fascinating look at one of the most overlooked aspects of everyday life: the science hiding inside every conversation. KEY TAKEAWAYS Your voice communicates far more than the words you speak, including biological and social information. Listeners can often estimate a person's age, biological sex, emotional state, and native language after hearing only a brief vocal sample. Subtle vocal characteristics can provide clues about illness, physical condition, and overall health. Humans evolved specialized abilities to rapidly interpret vocal signals because they support cooperation, survival, and social decision-making. Genuine laughter carries different acoustic characteristics than polite or socially motivated laughter. Vocal communication combines language, context, and sound into a remarkably rich social signal. Evolutionary psychology helps explain why humans are exceptionally tuned to vocal cues. Understanding how voices shape perception can improve communication, relationships, and social awareness. GUEST BIO Dr. Greg Bryant is a cognitive scientist who studies communication and cognition from an evolutionary perspective. He serves as Professor and Chair of the UCLA Department of Communication, where his research examines vocal communication, laughter, music perception, social cognition, cultural evolution, and behavioral biology. His work combines laboratory experiments, cross-cultural field research, acoustic analysis, and comparative studies across species. GUEST LINKS Spotify (Music) https://open.spotify.com/artist/7txtvHi6cCtJJRhZX2zBlJ HOST LINKS Website https://www.sarahehill.com Instagram https://www.instagram.com/sarahehillphd LinkedIn https://www.linkedin.com/in/sarahehillphd If you enjoyed this conversation, follow The XX Lab , leave a review, and share this episode with someone who's fascinated by the science of human behavior.

Are women really less competitive than men, or have we been measuring competition the wrong way? In this episode of The XX Lab , Dr. Sarah Hill sits down with Dr. Khandis Blake , PhD, evolutionary psychologist and researcher, to explore how hormones, competition, confidence, mate preferences, and modern environments shape women's behavior in ways that are often misunderstood. Why do women compete differently than men? Drawing on years of research in evolutionary psychology, Dr. Blake explains why women often compete through different strategies than men, how status and relationships influence those behaviors, and why common stereotypes fail to capture the full picture. Sarah and Khandis discuss the evolutionary pressures that shaped female competition and why cooperation has been just as important to women's success as competition itself. The conversation also explores how hormonal fluctuations across the menstrual cycle can influence confidence, ambition, social behavior, and partner preferences. Together, they unpack what researchers know, what remains uncertain, and why nuance matters when discussing sex differences. How do hormones shape everyday decisions? Sarah and Khandis examine research on hormonal contraception, workplace behavior, mate choice, and the gender pay gap, asking whether biology and modern culture interact in ways that help explain differences in outcomes without reducing them to simple cause-and-effect stories. Whether you're interested in women's health, psychology, relationships, or understanding the science behind human behavior, this episode offers an evidence-based conversation that challenges common assumptions while respecting the complexity of the research. Key Takeaways Women often compete through social and relationship-based strategies rather than direct physical competition. Cooperation and competition have evolved together as complementary survival strategies. Hormonal changes can subtly influence confidence, motivation, and social behavior. Confidence is influenced by both biology and environment rather than either factor alone. Hormonal contraception may affect some aspects of psychology differently across individuals. Mate preferences are flexible and can shift depending on context and life stage. Evolutionary psychology helps explain behavioral patterns without determining individual outcomes. Biological differences should inform research without reinforcing stereotypes. Understanding women's psychology requires considering both culture and biology. Scientific nuance is essential when discussing hormones, behavior, and sex differences. Guest Bio Khandis Blake is an evolutionary psychologist whose research examines female competition, hormones, mating psychology, status, and human behavior. Her work explores how evolutionary science can help explain modern social dynamics while challenging common misconceptions about women. Enjoyed this conversation? Follow The XX Lab and leave a review to help more people discover evidence-based conversations about women's health, psychology, and human behavior.

We have more health information than ever before, yet we're getting sicker, more stressed, and more overwhelmed. So what's missing? In this episode of The XX Lab , Dr. Sarah Hill welcomes Sarah Ann Macklin , registered nutritionist, former international model, host of Live Well Be Well , and author of Healthy Shouldn't Be This Hard . Together, they explore why today's $8.5 trillion wellness industry isn't delivering better health and why the missing ingredient may have less to do with information and more to do with how we relate to ourselves. Why isn't more health advice making us healthier? Sarah Ann shares her remarkable journey from the fashion industry to clinical nutrition, revealing how years of chasing perfection ultimately reshaped her understanding of health. She explains why fear-based wellness messaging often backfires, how self-worth influences health behaviors, and why sustainable habits begin with self-compassion rather than self-criticism. The conversation also explores mindset, stress, body awareness, food insecurity, nutrition science, and the fascinating ways our thoughts can influence our physiology. Sarah and Sarah discuss why understanding your body's signals is essential for making lasting lifestyle changes and why health doesn't have to be built on restriction or guilt. What does it really mean to work with your body? From the science of interoception to practical advice about whole foods, supplements, cooking, and behavior change, this episode offers an evidence-based roadmap for building a healthier relationship with food and with yourself. Rather than chasing perfection, Sarah Ann explains why learning to trust your body may be one of the most powerful health interventions available. Whether you're overwhelmed by conflicting nutrition advice, struggling to build healthier habits, or simply looking for a more compassionate approach to wellness, this conversation offers practical tools backed by science. Key Takeaways More health information doesn't automatically lead to better health outcomes. Self-compassion is a critical foundation for long-term behavior change. Fear-based wellness marketing often undermines healthy habits. Whole foods support healthier body signals than highly processed foods. Mindset can influence physiological responses to nutrition and exercise. Chronic stress affects both physical and mental well-being. Supplements should support, not replace, a nutrient-rich diet and should be guided by appropriate testing when possible. Sustainable health comes from working with your body instead of constantly trying to fix it. Guest Bio Sarah Ann Macklin is a registered nutritionist, former international model, founder of the Be Well Collective, host of the Live Well Be Well podcast, and author of Healthy Shouldn't Be This Hard . Her work focuses on evidence-based nutrition, behavior change, and helping people build healthier relationships with food and themselves. Guest Links Website: https://www.sarahannmacklin.com Live Well Be Well Podcast Instagram: @sarahannmacklin Book: Healthy Shouldn't Be This Hard Be Well Collective If you enjoyed this conversation, follow The XX Lab and leave a review to help more listeners discover science-backed conversations about health, psychology, and human behavior.

We're more connected than any generation in history, yet loneliness continues to rise. What happened? In this episode of The XX Lab , Dr. Sarah Hill sits down with Dr. Bill von Hippel , evolutionary psychologist and bestselling author of The Social Paradox , to explore why the very freedoms that define modern life may also be driving us further apart. Why does modern life leave so many people feeling isolated? Drawing from evolutionary psychology, Bill explains how humans evolved to depend on tight-knit communities for survival and why today's culture of independence, mobility, and individual achievement often clashes with those ancient social instincts. Together, he and Sarah unpack the surprising ways technology, urbanization, modern dating, and changing family structures have reshaped our relationships and our well-being. The conversation explores why autonomy and connection often pull us in opposite directions, how our brains respond to social isolation, and why loneliness isn't simply an emotional experience but a biological signal that evolved to keep us connected to others. Can we build happier lives by understanding our evolutionary past? Bill shares practical insights from The Social Paradox , discussing why meaningful relationships remain one of the strongest predictors of happiness, health, and longevity. He also explains how modern environments amplify stress, why friendship becomes harder in adulthood, and what individuals can do to cultivate stronger social networks despite the demands of contemporary life. Whether you're interested in psychology, relationships, health, or understanding why modern life often feels disconnected, this episode offers a thoughtful, science-backed perspective on one of the defining challenges of our time. Key Takeaways Human brains evolved for close-knit communities rather than large, anonymous societies. Loneliness functions as a biological signal that encourages social reconnection. Modern independence often comes with hidden psychological costs. Strong relationships consistently predict better physical and mental health. Evolutionary mismatch helps explain why modern environments can increase stress and isolation. Technology connects us efficiently but doesn't always satisfy our need for meaningful social bonds. Adult friendships require intentional effort because modern lifestyles reduce repeated social contact. Balancing autonomy with connection leads to greater long-term well-being. Understanding our evolutionary history provides valuable context for today's mental health challenges. Small, consistent investments in relationships can have an outsized impact on happiness. Guest Bio Dr. Bill von Hippel is an evolutionary psychologist, professor, and bestselling author of The Social Paradox . His research explores human behavior, social relationships, happiness, evolutionary psychology, and the ways modern environments shape our minds and well-being. Guest Links Website: https://billvonhippel.com Book: The Social Paradox Research publications University profile (if included in your transcript resources) If you enjoyed this conversation, follow The XX Lab and leave a review to help more listeners discover evidence-based conversations about women's health, psychology, and human behavior.

Dating apps promised more choice. But what if more choice is making relationships harder to build? In this episode of The XX Lab, Dr. Sarah Hill sits down with Dr. Cari Goetz, evolutionary psychologist and relationship researcher, to explore the psychology of mate switching, online dating, sexual exploitability, casual sex, and the hidden forces shaping modern relationships. Cari explains how humans evolved in environments with relatively small pools of potential partners, and why today's endless swiping culture may be activating psychological mechanisms that were never designed for thousands of options. The conversation dives into the paradox of choice, why people often become less satisfied when they have more alternatives available, and how dating apps may subtly encourage a constant comparison mindset. How does online dating affect long-term relationships? Sarah and Cari unpack research suggesting that the way people select partners online may differ dramatically from how humans historically chose mates. Instead of evaluating a few potential partners holistically, many daters begin filtering candidates by isolated traits, which can make commitment more difficult and increase the temptation to keep searching for someone better. The discussion also explores practical strategies for using dating apps without falling into a perpetual mate-switching mentality. If you've ever wondered why dating can feel so exhausting, why casual sex can be emotionally complicated, or why modern relationship advice often feels disconnected from human psychology, this episode offers a nuanced, research-based perspective. Key Takeaways The paradox of choice can make people less satisfied with a dating partner when they perceive endless alternatives. Limiting the number of dating profiles you evaluate may improve decision-making and reduce comparison fatigue. Early-stage dating is often when people are most vulnerable to a constant "someone better might be out there" mindset. Being intoxicated, fatigued, or appearing less aware can increase perceptions of vulnerability. Men who are low in agreeableness and highly interested in casual sex were more likely to perceive women as sexually exploitable. Sexual regret and sexual disappointment are distinct emotions and may be conflated in some research. Women's casual sex experiences are often shaped by potential costs such as pregnancy, STIs, and reputational concerns. Women's sexual motivation may increase during the years when fertility is beginning to decline, potentially reflecting an evolved reproduction-expediting mechanism. Guest Bio Dr. Cari Goetz is an evolutionary psychologist whose research focuses on mating psychology, mate switching, sexual exploitation, relationship dynamics, and reproductive behavior. She is a faculty member at California State University, San Bernardino and has published extensively on human mating strategies and social behavior. Guest Links CSUSB Profile: https://www.csusb.edu/profile/cgoetz LinkedIn: https://www.linkedin.com/in/cari-goetz-62725542/ Google Scholar: https://scholar.google.com/citations?user=BIKau3cAAAAJ&hl If you enjoyed this conversation, follow The XX Lab and leave a review to help more listeners discover evidence-based discussions about women's health and human behavior.

If a friend is gossiping to you, she's probably gossiping about you too. That's the unsettling rule of thumb Dr. Tania Reynolds lives by—and in this episode, she explains why. In this episode of The XX Lab, Dr. Sarah Hill sits down with Reynolds, a social psychologist and leading researcher on female friendship, cooperation, and competition, to unpack the evolutionary science behind how women build relationships—and why those relationships carry such high stakes. Bless Her Heart Dr. Reynolds explains the "bless her heart effect," the sneaky way concern-framed gossip lets women damage a rival's reputation while looking kind doing it, and why this strategy works especially well on other women. From there she tells us about the the evolutionary logic behind female-typical aggression—why it's indirect, deniable, and built around exclusion rather than confrontation—and how the same instincts that helped our ancestors protect their children now show up in group chats, PTA meetings, and office politics. Sexual Policing, Female Bosses, and Women’s Mental Health We also get into some of the more uncomfortable data: why women police other women's sexuality more than men do, why attractive or sexually open women tend to become targets, and why having a female boss is correlated with lower job satisfaction than having a male one (and what bosses can actually do about it). We close on the modern mental health paradox—why women report feeling worse than ever despite unprecedented material progress—and talk through practical ways to catch these instincts in ourselves before they run the show. Key Takeaways The "bless her heart effect" and concern-framed gossip Why women are better at detecting harm to their own reputation than harm they cause others The evolutionary logic of indirect aggression, exclusion, and female friendship jealousy Sexual double standards and who really enforces them Female bosses, workplace satisfaction, and status asymmetries between women The "Queen Bee" phenomenon and whether it's real Social comparison, social media, and the gender gap in anxiety and depression Practical strategies for catching competitive instincts and building better female friendships Guest Bio Dr. Tania Reynolds is a social psychologist whose research explores female friendships, cooperation, aggression, social relationships, and evolutionary psychology. Guest Links psych/tania-reynolds scholar.google/citations psychologytoday/tania-reynolds If you enjoyed this episode, follow The XX Lab and leave a review to help more listeners discover science-backed conversations about women's health and human behavior. Chapter Timestamps 02:08 Meet Dr. Tania Reynolds 07:24 Why Female Friendships Matter 16:18 The Evolution of Women's Social Bonds 27:41 Are Women Really More Competitive? 39:12 Gossip: Harmful or Helpful? 50:35 Understanding Relational Aggression 1:02:44 Cooperation vs. Competition 1:14:53 Friendship, Stress, and Mental Health 1:26:48 Why Belonging Is a Biological Need 1:38:56 What We Get Wrong About Women's Relationships

How much of your behavior is shaped by biology without you even realizing it? From the clothes you choose to the people you find attractive, your hormones may be influencing more than you think. In this episode of The XX Lab , Dr. Sarah Hill sits down with evolutionary psychologist Dr. Kristina Durante to unpack the fascinating science behind hormones, decision-making, consumer behavior, relationships, and social dynamics. Drawing on years of research, Kristina explains how subtle biological shifts can affect everyday choices while challenging many of the misconceptions that surround this work. Can hormones influence behavior without controlling it? Dr. Durante shares groundbreaking studies on ovulation, attraction, and purchasing decisions, discussing why women may behave differently across the menstrual cycle and how these patterns fit within an evolutionary framework. She also addresses the media firestorms that often erupt around this research and explains why nuance matters when interpreting scientific findings. What can evolutionary psychology teach us today? Sarah and Kristina dive into the challenges of communicating controversial science, the importance of replication and critical thinking, and the ways modern environments interact with ancient psychological adaptations. They also discuss social belonging, online behavior, and why our brains are still wired for close-knit communities despite living in a hyperconnected world. Whether you're interested in women's health, psychology, neuroscience, marketing, or human behavior, this episode offers a thoughtful look at how evolution continues to influence everyday life in ways both subtle and surprising. Key Topics Covered How hormones can shape everyday decisions and preferences The science behind ovulation and attraction research What evolutionary psychology says about human behavior Why consumer choices may shift across the menstrual cycle The difference between biological influence and biological determinism Media misconceptions surrounding hormone research How social belonging affects mental and emotional well-being The challenges of studying sex differences in science Why context matters when interpreting behavioral research Practical reasons to understand your own biology without fear or stigma Guest: Dr. Kristina Durante, evolutionary psychologist and researcher whose work explores hormones, decision-making, consumer behavior, and social psychology. If you enjoyed this conversation, follow The XX Lab and leave a review to help more listeners discover evidence-based discussions about women's health and human behavior. Chapter Timestamps 02:18 Meet Dr. Kristina Durante 07:12 What Evolutionary Psychology Gets Right 14:45 Why Hormones Influence Behavior 23:27 The Research on Ovulation and Clothing Choices 34:36 Attraction, Dating, and the "Sexy Guy" Studies 43:58 Consumer Behavior and Hormonal Shifts 51:24 The Media Firestorm Around Hormone Research 1:03:47 Why Science Needs Nuance, Not Headlines 1:16:18 Biological Differences Without Stereotypes 1:28:52 Modern Life vs. Ancient Psychology 1:40:11 Social Belonging and the Need for Community 1:51:23 Final Thoughts and Key Takeaways

Why are women told their hormones are essential at 45 — that losing them is a health crisis, that we must replace them to protect our brains and bones and hearts — while those same hormones are routinely shut down in women in their 20s with barely a second thought? That contradiction is at the center of today's conversation. And once you see it, you can't unsee it. On Today’s Episode, Dr. Sarah Hill welcomes Lara Briden, ND , internationally recognized naturopathic doctor and bestselling author specializing in women's hormonal health. Together they explore why menopause deserves to be viewed through an evolutionary lens rather than as a hormone deficiency, and how misconceptions about estrogen, progesterone, HRT, and menstrual cycles continue to shape women's healthcare. The discussion covers the surprising biology behind why humans experience menopause, what differentiates bioidentical progesterone from synthetic progestins, and why many women receive incomplete or misleading information about hormonal treatments. Lara also explains how cycle literacy can transform the way women understand their own bodies and make informed health decisions. Can evolutionary biology improve women's healthcare? Drawing from research and decades of clinical experience, Lara and Sarah unpack common misconceptions surrounding PCOS, endometriosis, ovulation, hormonal birth control, and the menstrual cycle itself. They discuss why symptoms shouldn't automatically be viewed as malfunctions, the importance of preserving ovulation when possible, and how clinicians can better support women through every reproductive stage. Whether you're approaching perimenopause, navigating menopause, working in healthcare, or simply trying to understand your hormones, this episode offers practical insights grounded in science instead of fear. Key Takeaways ● Menopause is a normal biological transition that may offer evolutionary advantages rather than representing hormone failure. ● Understanding bioidentical progesterone vs. synthetic progestins can improve conversations about hormone replacement therapy. ● Learning to recognize signs of healthy ovulation provides valuable information about overall hormonal health. ● Viewing the menstrual cycle as a vital sign can improve long-term women's health awareness. ● Many symptoms attributed solely to aging may have multiple biological explanations worth exploring. ● Evolutionary biology provides useful context for understanding why menopause exists in humans. ● Better education about PCOS management helps women pursue individualized treatment strategies. ● Improved awareness of endometriosis symptoms and diagnosis can shorten delays in receiving care. ● Evidence-based discussions around hormonal birth control help women make informed personal decisions. ● Increasing hormone literacy empowers women to advocate for themselves throughout every life stage.

Why is making friends as an adult so difficult—and why are female friendships often both deeply supportive and unexpectedly complicated? Friendship may be one of the most overlooked public health assets we have. Yet it's also one of the least studied areas of psychology. In this episode, Dr. Sarah Hill sits down with UCLA friendship researcher Dr. Jaimie Krems to unpack the science behind why friendships matter, why women experience friendship differently than men, and what we can do to build stronger, healthier connections in modern life. Why Are We Living Through a Friendship Recession? Dr. Jaimie Krems is a social and evolutionary psychologist at UCLA, where she directs the Social Minds Lab and the UCLA Center for Friendship Research. Her work explores one of the most important yet overlooked questions in psychology: why humans make friends, how friendships evolve, and why they profoundly shape our physical and mental health. Together, Dr. Sarah Hill and Dr. Krems explore how friendship protects us against anxiety, depression, cardiovascular disease, and even premature death. They discuss why lacking close friends can have health consequences comparable to smoking 15 cigarettes per day, and why researchers now consider friendship a major public health issue. The conversation also dives into what many women secretly experience but rarely discuss: why female friendships can feel both extraordinary and emotionally complicated. Can You Actually Make Friends as an Adult? The answer is yes—but it requires intentionality. In a culture optimized for convenience and productivity, we've accidentally eliminated many of the moments that once helped friendships grow naturally. This episode offers practical ways to bring those moments back. KEY TAKEAWAYS Strong friendships improve mental health, cardiovascular health, and longevity. Friendship is one of the strongest predictors of happiness across adulthood. Repeated interactions are one of the simplest ways to build meaningful adult friendships. Technology has unintentionally removed many opportunities that once helped friendships deepen naturally. Women often prioritize fewer, deeper friendships, while men tend to maintain larger social networks. Friendship deserves the same intentional investment we typically give to careers and romantic relationships. GUEST BIO Dr. Jaimie Krems is a social and evolutionary psychologist at UCLA, where she directs the Social Minds Lab and the UCLA Center for Friendship Research. Her research examines friendship, cooperation, social support, and the evolutionary forces that shape human relationships. Connect with Sarah: Website https://www.sarahehill.com/ Instagram https://www.instagram.com/sarahehillphd/ LinkedIn https://www.linkedin.com/in/sarahehillphd Connect twith Jamie: UCLA Faculty Page https://www.psych.ucla.edu/faculty-page/jkrems/ LinkedIn https://www.linkedin.com/in/jaimie-krems Instagram https://www.instagram.com/jaimie.krems/

Female sexuality is far more complex and fascinating than we’ve been taught. In this episode of The XX Lab with Sarah Hill , Sarah sits down with pioneering sexuality researcher Dr. Cindy Meston to unpack the science of female desire, arousal, orgasm, menopause, antidepressants, birth control, and the psychology behind what actually creates satisfying sex for women. From groundbreaking lab research measuring physiological arousal to redefining female orgasm for the World Health Organization, Dr. Meston shares decades of discoveries that challenge outdated assumptions about women’s sexuality and reveal just how much context, emotion, hormones, stress, and self-perception shape desire. In this conversation, they explore: Why women’s desire works differently than men’s How stress, exercise, and novelty can increase arousal The hidden sexual side effects of hormonal birth control and antidepressants Why orgasm becomes easier for many women with age and experience How sexual schemas and body image influence intimacy across the lifespan This episode is science-driven, deeply validating, and packed with insights every woman should hear. If you’ve ever wondered whether your experience is “normal,” this conversation will completely change the way you think about sex, desire, and pleasure. About this guest: Dr. CINDY M. MESTON, PhD is a Professor of Clinical Psychology and the Director of the Sexual Psychophysiology Laboratory at the University of Texas at Austin. She has received numerous international awards and accolades for her ground-breaking research on the consequences of childhood sexual abuse on adult sexuality and on the psychophysiology of women’s sexual arousal. In 2016 Meston was named one of the 100 most influential and inspirational women in the world by the BBC. Her book Why Women Have Sex (co-authored with Dr. David Buss) has been translated into twelve languages and has received extensive media coverage. Meston has published over 200 peer-reviewed academic publications, is the past president of the largest professional society for women’s sexuality, the International Society for the Scientific Study of Women’s Sexual Health, and is an endowed Fellow of the Wayne H. Holtzman Regents Chair in Psychology at the University of Texas at Austin. She has served as a consultant to the U.S. Food and Drug Administration and the World Health Organization. Awards for Meston’s research include a fellowship from The Ford Foundation, NY, an International Research Award from the Athena Institute for Women’s Wellness, a Distinguished Professor Award from the Canadian Research Foundation, the Raymond Dickson Centennial Endowed Teaching Fellowship, the Wulf H. Utian Endowed Lecturer Award from the North American Menopause Society, the Career Service Award from the International Society for the Study of Women’s Sexual Health, and the International Society of Sexual Medicine Research Contribution to Sexual Medicine Award. Connect with Dr. Meston’s work here: www.mestonlab.com

What if infertility is not just about getting pregnant, but one of the earliest warning signs that something deeper is happening in the body? In this episode of The XX Lab with Dr. Sarah Hill , Sarah sits down with double-board certified fertility specialist Dr. Natalie Crawford to unpack the science of ovulation, egg quality, chronic inflammation, stress, PCOS, endometriosis, and the hidden factors affecting women’s reproductive health. Together, they challenge the outdated idea that fertility only matters once you’re trying to conceive and explain why your menstrual cycle may be one of the most important indicators of overall health. They explore why so many women are dismissed when something feels “off,” how lifestyle and stress impact fertility in real time, and what women in their 20s and 30s should know about fertility testing and egg freezing. In this episode: Why regular periods do not always mean healthy ovulation How stress and inflammation can interfere with fertility The truth about egg quality, aging, and fertility testing Why endometriosis is still so underdiagnosed What women can actually do to support fertility naturally Whether you want children someday or simply want to better understand your body, this conversation will change the way you think about reproductive health. About this guest: Natalie Crawford, MD is double board certified in both Obstetrics and Gynecology + Reproductive Endocrinology and Infertility and author of the bestselling book, The Fertility Formula . She is co-founder of Fora Fertility, a boutique fertility practice in Texas and CEO + co-founder of Learn at Pinnacle, a medical education network. Connect with Sarah: http://www.sarahehill.com Books: The Period Brain (on sale now!) | This is Your Brain on Birth Control Social: Facebook | Instagram | X https://www.youtube.com/@TheXXLab Connect with Natalie: Link to The Fertility Formula Link for more info about The Fertility Formula: nataliecrawfordmd.com/book IG: @nataliecrawfordmd TikTok: @nataliecrawfordmd LinkedIn: Natalie Crawford, MD YouTube: Natalie Crawford, MD Podcast: As a Woman

What if the life you’re chasing is already inside you? In this episode of The XX Lab , Dr. Sarah Hill sits down with Gabby Reece to explore how self-trust, curiosity, and resilience shape a meaningful life. From growing up “feral” to navigating elite sports, modeling, motherhood, and marriage, Gabby shares how tuning out noise and listening inward became her greatest advantage. They unpack the difference between pressure and purpose, how to handle setbacks without spiraling, and why most of us are living in imagined futures instead of reality. In this episode: Why self-trust beats external expectations How to reframe failure and stop catastrophic thinking The key to lasting relationships, attraction, and personal growth This conversation is a powerful reminder that your path isn’t something you find, it’s something you build by trusting yourself along the way. Connect with Sarah: http://www.sarahehill.com Books: The Period Brain (on sale now!) | This is Your Brain on Birth Control Social: Facebook | Instagram | X https://www.youtube.com/@TheXXLab

What if the thing you’re craving most isn’t happiness, but feeling truly loved? In this deeply honest conversation, Dr. Sarah Hill sits down with happiness researcher Dr. Sonja Lyubomirsky to unpack the science of happiness, connection, and why so many people feel unseen even when surrounded by others. From gratitude practices and social comparison to the hidden psychology of relationships, this episode explores what actually creates a meaningful life. They also dive into Sonja’s newest work on love and connection, including the “relationship seesaw,” why vulnerability matters, and how being truly known changes everything. In this episode: Why your brain keeps chasing “I’ll be happy when…” The surprising habits that actually increase happiness How to feel more loved in your relationships Why being seen matters more than being admired The mindset shifts that deepen human connection If you’ve ever felt lonely, emotionally disconnected, or stuck chasing happiness, this conversation will make you feel deeply understood. Follow Sarah and The XX Lab for more conversations on psychology, relationships, sex differences, and human behavior. Connect with Sarah: http://www.sarahehill.com Books: The Period Brain (on sale now!) | This is Your Brain on Birth Control Social: Facebook | Instagram | X https://www.youtube.com/@TheXXLab

What if the reason so many women feel anxious, burned out, and disconnected isn’t personal failure… but a misunderstanding of what women actually need? In this inaugural episode of The XX Lab , Dr. Sarah Hill shares the deeply personal story behind the show and the science that transformed the way she understands herself, relationships, motherhood, ambition, and modern womanhood. Drawing from more than 25 years of research on women’s psychology, hormones, evolution, and behavior, Sarah explains why women today are struggling to “do it all” and why science alone is not enough to help us heal. This is not another optimization podcast. It’s a place for real conversations about what it actually means to be a woman today. In this episode: Why women are experiencing burnout at unprecedented rates How evolutionary psychology changed Sarah’s understanding of herself The missing connection between science, storytelling, and meaningful living Whether you’re navigating career, motherhood, relationships, identity, or simply trying to make it through the day feeling whole, this podcast is here to help you feel more understood and less alone. Welcome to The XX Lab . Connect with Sarah: http://www.sarahehill.com Books: The Period Brain (on sale now!) | This is Your Brain on Birth Control Social: Facebook | Instagram | X https://www.youtube.com/@TheXXLab

June 1st