Episode Details

You've been told the pill and the hormonal IUD act "locally," that they barely touch the rest of you. What if science says almost the opposite? Most of us treat hormones as background chemistry for periods and pregnancy, when they are really broadcast signals traveling everywhere blood goes, switching genes on and off in the brain, the muscles, and far beyond the reproductive organs.

In this episode of The XX Lab, Dr. Sarah Hill sits down with Dr. David Puts, evolutionary anthropologist and neuroendocrinology researcher at Penn State, to explore what hormones actually are, how they shape the brain before birth, the myth of "locally acting" hormones, what the menstrual cycle does to attraction, and how the birth control pill nudges desire and partner choice.

KEY TAKEAWAYS:

- Hormones act by binding a receptor that regulates gene expression, changing what a cell makes.

- A purely "locally acting" hormone does not hold up; if it reaches the bloodstream, it travels.

- Most women on the hormonal IUD stop ovulating, evidence the hormone reaches systemic levels.

- Sex hormones shape the brain, not only the reproductive organs, from before birth.

- CAH and IHH serve as natural experiments for studying prenatal hormone effects on behavior.

- The "masculine voices when fertile" preference is weaker and less consistent than popular science suggests.

Timestamps

Why Men And Women Are So Different (00:00)

What Hormones Actually Do In Your Body (08:43)

Is There Really A Locally Acting Hormone (11:07)

What Sex Hormones Do Besides Reproduction (13:55)

How Hormones Shape The Developing Brain (18:00)

CAH And IHH: Nature's Hormone Experiments (33:55)

What The Menstrual Cycle Does To Attraction (40:09)

How The Pill Changes Attraction And Libido (49:45)

How Low Estrogen Affects Attraction (57:32)

What Anogenital Distance Reveals About You (01:11:52)

Does Puberty Rewire The Brain (01:19:13)

Why Disease Hits Men And Women Differently (01:25:25)

Why We Choose Mates With Good Genes (01:33:10)

Guest Bio

• Explore David Puts’ research, publications, and academic work: https://www.researchgate.net/profile/David-Puts
• Google Scholar:  https://scholar.google.com/citations?user=fZ_ZqrMAAAAJ&hl=en

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Guest Bio

Dr. David Puts is Professor of Anthropology and Psychology at Penn State and Co-Director of the Center for Human Evolution and Diversity, where he directs the Behavioral Endocrinology and Evolution Lab. His work bridges the "why" of evolutionary theory with the "how" of hormones and gene expression, studying the sexual differentiation of the brain and behavior, mating psychology, and sex differences.

• Explore David Puts’ research, publications, and academic work: https://www.researchgate.net/profile/David-Puts
• Google Scholar:  https://scholar.google.com/citations?user=fZ_ZqrMAAAAJ&hl=en