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.

Thank you to our sponsors

AG1: https://athleticgreens.com/huberman

LMNT: https://drinklmnt.com/hubermanlab

Waking Up: https://www.wakingup.com/huberman

Timestamps

00:00:00 Introduction  

00:00:30 AG1, LMNT & Waking Up  

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

00:08:00 Maximizing Learning from the Podcast  

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

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

00:14:15 Hormones Basics  

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

00:17:50 Y Chromosome Inhibition of Feminization  

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

00:19:45 Hormonal Sex, Morphological Sex  

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

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

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

00:27:03 Secondary Sexual Characteristics  

00:27:43 Penis Sprouting: Guevedoces  

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

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

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

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

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

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

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

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

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

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

01:06:39 Creatine & DHT/Hair Loss  

01:08:20 Predicting Aging Rates By Pubertal Rates  

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

01:14:26 Intersex Moles  

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

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

01:29:13 Brain Dimorphisms with Sexual Orientation  

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

01:35:06 The Path Forward & A Warning  

01:35:55 Support & Your Questions  

Disclaimer & Disclosures