Behaviors That Alter Your Genes to Improve Your Health & Performance | Dr. Melissa Ilardo

Andrew Huberman hosts geneticist Dr. Melissa Ilardo for the podcast's first deep dive into human genetics and epigenetics. They explore how behavior and environment can modify gene expression within a single lifetime and across generations, using Ilardo's fieldwork on breath-hold diving populations such as Indonesia's Bajau and Korea's all-female Haenyo divers. Key threads include the mammalian dive reflex and spleen contraction for an oxygen boost, the role of thyroid-linked genetic variants in producing larger spleens, and how diving through pregnancy may have driven blood-pressure adaptations. The conversation also covers mate selection via immune-system smell cues, hybrid vigor versus inbreeding, mindset effects on physiology, and the ethics of CRISPR gene editing and embryo sequencing.

• All blue-eyed people descend from a single common ancestor who first had the eye-color mutation.
  00:05:05
• In a sweaty-T-shirt study, humans were most attracted to the smell of people whose immune systems were most different from their own.
  00:13:58
• The Tibetan high-altitude adaptation is believed to have come from interbreeding with the archaic Denisovan hominids.
  00:19:08
• Ilardo was told one Bajau diver could hold his breath for 13 minutes (she emphasizes she did not verify it).
  00:28:25
• The mammalian dive reflex contracts the spleen to deliver about a 10% oxygen boost during a breath hold.
  00:36:42
• Bajau divers were found to have spleens about 50% larger on average, in both divers and non-divers, pointing to a genetic basis.
  00:47:29
• A Haenyo diver's heart rate dropped more than 40 beats per minute in under 15 seconds during a dive.
  01:05:38
• Ilardo notes that becoming very good at one trained skill also narrows the range of other things you can be good at.
  01:32:46

• Eyes darken with UV exposure, so a blue-eyed baby's eyes are bluer at birth than later in life.
  00:06:38
• Refugee populations can inherit epigenetic changes from parents even without experiencing the original trauma.
  00:11:19
• Most mutations are deleterious and kill embryos before they become fetuses; beneficial mutations are rare and slow to arise.
  00:24:17
• The spleen receives heavy neural innervation, raising the possibility of some conscious control over its contraction.
  00:39:18
• A thyroid-linked gene variant correlates with higher thyroid hormone, larger spleens, and higher red blood cell count, even in Europeans.
  00:49:33
• The Korean Haenyo are an all-female diving population with an average age around 70 who often dive into their 80s and beyond.
  00:55:48
• Haenyo carry a genetic variant that lowers diastolic blood pressure while diving, likely protective against pregnancy hypertension.
  01:08:12
• Mochin children see better underwater by constricting their pupils very small, not by having flatter eyes.
  01:21:21
• In a study, people merely told their genes favored fitness gains improved measurably more, despite no real genetic difference.
  01:33:48
• A Chinese scientist used CRISPR to edit the genomes of babies (the HIV receptor) and was reportedly imprisoned afterward.
  01:36:24

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