Huberman Lab Podcast Summary

Episode Title: Behaviors That Alter Your Genes to Improve Your Health & Performance
Host: Andrew Huberman, Ph.D.
Guest: Dr. Melissa Elardo, Professor of Biomedical Informatics at the University of Utah
Release Date: May 26, 2025

In this groundbreaking episode of the Huberman Lab podcast, neuroscientist Andrew Huberman engages in a compelling conversation with Dr. Melissa Elardo, a renowned expert in human genetics and epigenetics. The discussion delves deep into how human behavior and environmental factors can modify gene expression, impacting health, performance, and even influencing genetic traits across generations.

Nature vs. Nurture: The Modifiability of DNA

The episode kicks off with a fundamental question surrounding human genetics: "How much of our DNA is modifiable by our environment and what we choose to do?" (03:19). Dr. Elardo emphasizes the burgeoning understanding in the field of epigenetics, highlighting that "we're still learning with epigenetics and all of these new fields just how much we can actually change things" (03:45). This sets the stage for exploring the dynamic interplay between our genes and our behaviors.

Eye Color and Genetic Heritage

Huberman and Elardo revisit the classic example of eye color inheritance, discussing how everyone with blue eyes can trace their lineage back to a single individual who first exhibited this trait. "Everyone with blue eyes descends from the same person," Elardo notes (05:20). They also touch upon the rarity of green eyes and the historical predominance of brown eyes in human populations (05:52).

Huberman brings up an intriguing point about environmental influence on eye color: "We know that as you get more sunlight exposure, in particular ultraviolet light exposure, that eyes will darken" (06:49). This underscores the concept that certain genetic expressions can be subtly altered by external factors.

The Mammalian Dive Reflex: A Deep Dive into Physiology

One of the episode's standout topics is the mammalian dive reflex, a physiological response triggered by breath-holding in cold water. Elardo explains how this reflex can significantly increase red blood cell count and enhance oxygen availability to the brain and body: "Through that contraction, those oxygen-rich red blood cells are now pushed into circulation and you get an oxygen boost" (36:41).

They discuss studies on populations like the Bajau people of Indonesia, who are exceptional free divers. These individuals exhibit significantly larger spleens—about 50% larger on average—compared to nearby non-diving populations (47:16). Elardo highlights that this increase in spleen size is likely genetic rather than purely a result of training, as non-diving individuals with similar genetics do not display the same trait (48:13).

Genetic Adaptations in Diver Populations

Elardo shares fascinating insights into how behaviors such as free diving can drive genetic adaptations. For instance, in the Korean Haenyeo, female divers who have practiced breath-hold diving for generations show genetic variants associated with higher thyroid hormone levels. This adaptation not only supports their diving capabilities but also offers protection against hypertensive disorders during pregnancy (49:15).

“These higher than average thyroid hormone levels... increase hemoglobin, increase hematocrit, increase red blood cell count,” explains Elardo, linking these genetic traits to enhanced physiological performance (49:15).

Evolutionary Perspectives: Admixture and Species Integrity

The discussion broadens to encompass evolutionary biology, particularly the concept of admixture—where different ancestral populations interbreed. Elardo affirms that "as long as there are things that are affecting our ability to reproduce, we're going to continue to evolve" (18:56). She elaborates on historical admixture events, such as the interbreeding between Homo sapiens and Neanderthals or Denisovans, which introduced advantageous genes into the human gene pool (20:50).

Implications for Human Performance and Health

Huberman draws parallels between the genetic adaptations observed in diving communities and elite athletic performance. He references marathon runner Eliud Kipchoge as an example of extraordinary human performance potentially rooted in genetic advantages (84:11). Elardo concurs, suggesting that physiological traits like those seen in Kenyan and Ethiopian runners may offer significant competitive edges in endurance sports (85:28).

Ethical Considerations in Genetic Engineering

Toward the episode's conclusion, the conversation shifts to the ethics of genetic engineering. Huberman raises concerns about the use of CRISPR technology to modify human embryos, citing the controversial case in China where a scientist altered the genomes of babies (98:17). Elardo responds by highlighting the current technological limitations and ethical dilemmas surrounding such interventions, emphasizing that "CRISPR is still a little bit of a blunt tool" (104:05). She underscores the importance of distinguishing between therapeutic gene corrections and enhancements, noting the slippery slope this presents (104:05).

Final Thoughts: The Interconnectedness of Genes and Behavior

Throughout the episode, both Huberman and Elardo underscore the intricate relationship between genetics, behavior, and environment. They advocate for a nuanced understanding of genetics—not as a deterministic blueprint but as a dynamic interplay of inherited traits and adaptive behaviors.

“It's a combination of genetic factors, environmental factors, all of these different things,” Elardo summarizes, reinforcing the complexity of genetic expression (93:39).

Notable Quotes

• Dr. Melissa Elardo [05:20]: "Everyone with blue eyes descends from the same person."
• Andrew Huberman [03:19]: "How much of our DNA is modifiable by our environment and what we choose to do?"
• Dr. Melissa Elardo [36:41]: "Through that contraction, those oxygen-rich red blood cells are now pushed into circulation and you get an oxygen boost."
• Dr. Melissa Elardo [49:15]: "These higher than average thyroid hormone levels... increase hemoglobin, increase hematocrit, increase red blood cell count."
• Dr. Melissa Elardo [104:05]: "CRISPR is still a little bit of a blunt tool."

Conclusion

This episode of the Huberman Lab podcast illuminates the profound ways in which human behavior can influence genetic expression and, consequently, health and performance. Dr. Melissa Elardo's expertise provides listeners with a deeper understanding of the genetic underpinnings of extraordinary human abilities and the ethical considerations that accompany advancements in genetic engineering. The conversation serves as a compelling exploration of the mutable nature of our genes, shaped by both our choices and our environments.

Note: This summary excludes all advertisement segments and non-content sections to focus solely on the substantive discussions between the host and guest.