Behaviors That Alter Your Genes to Improve Your Health & Performance | Dr. Melissa Ilardo
Dr. Melissa Ilardo, professor of biomedical informatics at the University of Utah, discusses how behavior and environment modify gene expression. She explains the mammalian dive reflex, its impact on oxygen availability via spleen function, and the genetic basis of mate selection and human evolution.
Deep Dive Analysis
17 Topic Outline
Introduction to Dr. Melissa Ilardo and Human Genetics
Nature vs. Nurture, Gene Expression, and Eye Color
Epigenetics, Trauma, and Intergenerational Changes
Hybrid Vigor and Immune System in Mate Attraction
Human Evolution, Globalization, and Inter-species Mating
The Bajau Sea Nomads and Breath-Hold Diving
Mammalian Dive Reflex: Spleen Contraction and Oxygen Boost
Genetic Adaptations in Free Divers: Spleen Size and Thyroid Hormone
The Haenyeo Female Free Divers of Korea and Cold Water Adaptations
Human Evolution and Diet: Lactase Persistence and Lipid Metabolism
Cardiovascular Adaptations and Pregnancy in Haenyeo Divers
Miscarriages and Natural Genetic Selection
Underwater Vision and Human Super-Performance
Genetics and Cognitive Abilities: Autism and Creativity
Genetic Determinism and Mindset Effects
Ethics of Gene Editing and Embryo Genetic Screening
Admixture and the Definition of Human Species
5 Key Concepts
Epigenetics
Epigenetics refers to modifications to the genome, such as molecules attaching to DNA, that change how genes express without altering the underlying DNA sequence. These changes can be influenced by environmental factors and can be passed down through generations, affecting traits like trauma response or famine survival.
Mammalian Dive Reflex
This is a physiological response triggered by breath-holding and cold water immersion on the face. It causes the heart rate to slow, blood vessels in the extremities to constrict, and the spleen to contract, releasing oxygen-rich red blood cells into circulation to boost oxygen availability to vital organs.
Lactase Persistence
Lactase persistence is the ability of humans to continue digesting lactose (milk sugar) past infancy. This trait is a strong example of rapid natural selection driven by diet, evolving quickly and independently in multiple human populations in Africa and Europe.
Genetic Determinism
Genetic determinism is the idea that an individual's genes solely determine all their traits and capabilities. However, current understanding indicates that traits are a complex combination of genetic factors, environmental influences, and individual choices, rather than being solely predetermined by genes.
Admixture
Admixture describes the mixing of different ancestry populations, resulting in individuals with genetic material from multiple ancestral groups. This phenomenon is becoming more common with globalization and creates new genetic combinations, though it can complicate genetic analyses.
8 Questions Answered
While some traits are genetically predetermined, a significant and increasing amount of gene expression is understood to be modifiable by environmental stimuli and chosen behaviors, including epigenetic changes that can be passed across generations.
Humans are often drawn to potential mates whose immune systems are genetically very different from their own, a preference unconsciously detected through body odor, which is thought to ensure offspring have a broader array of immune genes to combat pathogens.
The mammalian dive reflex is a physiological response to breath-holding and cold water immersion that slows heart rate, constricts peripheral blood vessels, and contracts the spleen, releasing oxygen-rich red blood cells to boost oxygen availability for safer, longer dives.
Yes, populations like the Bajau sea nomads have evolved to have significantly larger spleens (about 50% larger on average) and higher-than-average thyroid hormone levels, which contribute to increased red blood cell count and oxygen availability for diving.
Through a lifetime of training, Haenyeo divers exhibit a dramatic slowing of heart rate during dives, and they also possess a genetic adaptation that lowers their diastolic blood pressure while diving, protecting against hypertensive disorders, especially during pregnancy.
Yes, humans are continuously evolving as long as factors affect their ability to reproduce, with globalization introducing new genetic combinations that can lead to new adaptations and resilience, such as the Tibetan high-altitude adaptation from Denisovan genes.
Most mutations create non-viable embryos, and these genetic problems are thought to be a primary driver of early miscarriages, acting as a natural selection mechanism to prevent the development of non-viable offspring.
Key concerns include the current imprecision of gene-editing tools like CRISPR, which can lead to unintended 'off-target' edits, and the difficulty in defining the line between correcting a 'defect' and 'enhancing' a trait, raising questions about who decides these distinctions.
16 Actionable Insights
1. Safe Breath-Hold Diving Practice
Never attempt to test your breath-hold limits or free dive without expert instruction and supervision. Pushing past the natural urge to breathe underwater can lead to sudden unconsciousness and death due to unreliable oxygen sensors.
2. Prioritize Healthy Nighttime Breathing
Be aware of the dangers of sleep apnea, which involves holding your breath during sleep and can lead to low oxygen levels (hypoxemia) and other health complications. Ensure you are breathing properly at night, especially if you snore or have a large neck.
3. Leverage Mindset for Performance
Understand that your mindset significantly impacts your health and performance. Believing that stress is beneficial, or that you are capable of improving, can lead to better health outcomes and measurable biological changes, regardless of actual genetic predispositions.
4. Activate Mammalian Dive Reflex
To potentially boost oxygen availability, hold your breath and immerse your face in cold water (around 10°C/50°F). This triggers a physiological response that slows heart rate, constricts blood vessels, and contracts the spleen, releasing oxygen-rich red blood cells into circulation for an oxygen boost of about 10% during the breath hold.
5. Unconscious Mate Selection via Smell
When choosing a partner, be aware that your attraction to their natural body odor may unconsciously signal genetic compatibility. Humans tend to be drawn to mates whose immune system composition is most different from their own, which is beneficial for offspring diversity.
6. Prevent Disease Through Diverse Mating
Avoid reproduction with closely related individuals (e.g., siblings, cousins) to prevent the increased risk of offspring inheriting deleterious genetic variants and developing diseases.
7. Embrace Swimming for Health
Consider incorporating swimming or other water-based activities into your routine, especially as you age. It is a low-impact and natural way to move and exercise, contributing to overall fitness and health.
8. Darken Eyes with Sunlight Exposure
Eyes can darken with increased sunlight exposure, particularly to ultraviolet light, due to changes in pigmentation.
9. Understand Skill Specialization Trade-offs
Recognize that dedicating intense focus and training to become highly proficient in one specific skill or area often means less development in other potential abilities due to neuroplasticity’s inherent trade-offs.
10. Reject Genetic Determinism
Do not subscribe to the belief that your genes alone predetermine all aspects of your capabilities, potential, or life outcomes. Human traits are a complex interplay of genetic, environmental, and behavioral factors.
11. Personal Intelligence Not Inherited
Do not let the perceived intelligence of your family members dictate your own intellectual potential. Current scientific evidence suggests that intelligence is not highly heritable.
12. Redefine Evolutionary Fitness
Shift your understanding of ‘fitness’ in an evolutionary context from being ’the most capable’ to being ’the best adapted to your specific environment.’ Evolution favors the best fit, not necessarily the strongest or fastest.
13. Understand Epigenetic Inheritance
Be aware that significant environmental stressors, such as trauma or starvation, can induce epigenetic changes (modifications to gene expression) that may be passed down through generations. These changes can be adaptive in the original environment but potentially maladaptive in new conditions.
14. Recognize Diet’s Evolutionary Impact
Understand that diet is a powerful driver of natural selection. Historical dietary patterns have led to rapid genetic adaptations in human populations, influencing metabolic abilities and overall health over generations.
15. Acknowledge Genetic Mixing Effects
Recognize that increased globalization and inter-population mating are leading to novel genetic combinations in humans. This can result in both enhanced resilience and the emergence of new disease susceptibilities in offspring.
16. Grasp Mutation’s Deleterious Nature
Understand that the vast majority of genetic mutations are harmful or neutral, with beneficial mutations being rare and taking a very long time to become established within a population.
7 Key Quotes
Everyone with blue eyes descends from the same person.
Dr. Melissa Ilardo
Evolution doesn't care how fit you are in the way we think of fitness. It only cares how you fit with your environment.
Dr. Melissa Ilardo
If you're a sea nomad diving in the middle of the ocean with no one nearby, nobody's going to pull you out of that water. And so you've just removed yourself from the gene pool completely.
Dr. Melissa Ilardo
The spleen certainly wasn't the first organ that I thought about when thinking about diving.
Dr. Melissa Ilardo
The average age of the henyo currently is around 70 years old. So that's when I think of robustness with age, I think of the henyo.
Dr. Melissa Ilardo
Just because you can train someone to be at the same level, you know, as someone else doesn't mean that that person didn't have an advantage.
Dr. Melissa Ilardo
If you tell a child what they should or shouldn't do based on, you know, their genes, I think that's a really dangerous thing or, or potentially you could motivate them through that.
Dr. Melissa Ilardo