What does science actually say about monogamy, desire, and long-term love?

Evolutionary biologist Dr. Justin Garcia joins co-host Sue Marriott to deepen our understanding of the myths and realities of modern relationships. From monogamy to consensual non-monogamy, we explore how jealousy and trust function – not as flaws – but as deeply human signals shaped by biology and attachment. Dr. Garcia breaks down how relationships shift over time, especially as we age, and why sexual satisfaction isn’t just about frequency – it’s about novelty, meaning, and connection. We dive into the neuroscience of intimacy, including the roles of dopamine and oxytocin, and revisit the Kinsey scale to better understand the fluidity of sexual orientation. This conversation is a grounded, nuanced look at how passion evolves, and how couples can intentionally cultivate desire, curiosity, and emotional safety over the long haul.

“Humans, the most intimate animal, will always live and die for love. Understanding why gives us the power to find and maintain the loves worth living for.” – Dr. Justin Garcia, a quote from The Intimate Animal

Time Stamps for Why Long-Term Love Gets Complicated: A Scientific Approach with Dr. Justin Garcia (291)

00:57 Understanding social vs. sexual monogamy
04:32 The evolutionary perspective on relationships
08:26 Jealousy and relationship dynamics
20:25 Sexuality and aging: A new perspective
28:44 The power of eye gaze and oxytocin
30:30 Understanding aggression: Oxytocin and vasopressin dynamics
39:01 Exploring sexual diversity and the Kinsey scale

About Our Guest – Dr. Justin Garcia

Dr. Justin Garcia is an evolutionary biologist and international authority on the science of sex and relationships. Since 2019, he has served as the Executive Director of the world-renowned Kinsey Institute, where he is also a Senior Scientist. He holds an appointment as the Ruth N. Halls Professor in the College of Arts and Sciences at Indiana University and is a Founding Co-Director of Human Sexuality and Health at the IU School of Medicine. Dr. Garcia holds a Ph.D. in evolutionary biology and M.S. in biomedical anthropology from Binghamton University and an Executive Certificate in Public Leadership from Harvard Kennedy School.An award-winning researcher and educator, Dr. Garcia has consulted with a variety of industry partners, and he is currently the Chief Scientific Advisor to Match where he provides expertise for the annual Singles in America study. His research has been featured widely in the media and focuses on people’s romantic and sexual lives throughout the life course, especially on integrative biopsychosocial models of variation in courtship, intimacy, and sexual behavior.

Resources for Why Long-Term Love Gets Complicated: A Scientific Approach with Dr. Justin Garcia (291)

Justin Garcia – The Kinsey Institute: Biography and other information

The Intimate Animal – Dr. Garcia’s new book, order here!

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