The Science of Sexual Development

In this episode, I discuss how hormones such as testosterone and estrogen and their derivatives impact the early development of the brain and body and their maturation. I review published data on environmental factors shown to powerfully alter hormone pathways in animals and humans and the effects of cannabis, alcohol and cell phones on testes, sperm, ovaries and hormones. I describe the predictable relationship between genes, beard growth and balding patterns, and the importance of estrogen for brain development in people of all chromosomal sexes. Finally, I discuss how the hormones we are exposed to in the womb shape the relative length of our finger digits, the sounds our ears make (yes you read that correctly), and how those correlate with people's self-reports of their sexual preferences. As always, basic information and tools are discussed.

Read the full show notes for this episode at hubermanlab.com.

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Timestamps

00:00:00Introduction

00:00:30AG1, LMNT & Waking Up

00:06:47Announcement: Mood Meter App Works Again

00:08:00Maximizing Learning from the Podcast

00:10:00New Non-Sleep Deep Rest Protocol, Spanish Subtitles

00:11:35Sexual Differentiation: Hormones, Neurons & Behavior

00:14:15Hormones Basics

00:15:26Sperm Meets Egg, Chromosomal Sex, Gonadal Sex

00:17:50Y Chromosome Inhibition of Feminization

00:19:00Placenta Is An Endocrine (Hormone-Producing) Organ, Adrenal Testosterone

00:19:45Hormonal Sex, Morphological Sex

00:21:04Hormones Fast & Slow, Sex Steroids Can Turn On Genes

00:23:06Masculinization, Feminization, Demasculinization, Defeminization

00:23:42Primary Sexual Characteristics: DHT Drives Penis Development

00:27:03Secondary Sexual Characteristics

00:27:43Penis Sprouting: Guevedoces

00:31:25Estrogen, NOT Testosterone, Masculinizes The Brain

00:33:15Breast Development In Males: Aromatase; Puberty, & Steroids in Athletes

00:34:50Estrogen Powerfully Controls Brain Development In All Individuals

00:35:19Avoiding Hormonal Disruption In Children & Adults: Specific Oils, Creams, Etc.

00:39:00Environmental Endocrine Disruptors, Sperm Count Decline, Vincloziline

00:44:20Androgen Insensitivity Syndrome: Hormones Need Receptors, SARMS

00:48:41Estrogen Establishes “Masculine” Brain Circuits, Testosterone

00:49:42Cannabis, Alcohol: In Babies, Puberty & Adults

00:56:25Cell Phone Technology: Effects On Hormones, Ovaries, & Testicles

01:02:33Beards & Baldness Patterns Around the World, DHT, 5-alpha-reductase

01:06:39Creatine & DHT/Hair Loss

01:08:20Predicting Aging Rates By Pubertal Rates

01:10:04Hyenas, Baseball, & Jumbo Clitorises: Androstenedione

01:14:26Intersex Moles

01:15:40Marijuana Plants, Pollens: Plant-To-Animal “Warfare”

01:20:08Finger Length Ratios, Prenatal Hormone Exposure & Sexual Orientation

01:29:13Brain Dimorphisms with Sexual Orientation

01:32:00“Older Brother Effects”: Male Fetuses Might Change Mothers & Subsequent Brothers

01:35:06The Path Forward & A Warning

01:35:55Support & Your Questions

Disclaimer & Disclosures