Key Moments
Jonathan Reisman: The Human Body - From Sex & Sperm to Hands & Heart | Lex Fridman Podcast #297
Lex FridmanKey Moments
Dr. Jonathan Reisman discusses the human body's design flaws, wonders, and the doctor's journey.
Key Insights
The human body is an evolutionary marvel, yet exhibits design flaws (like the throat) alongside brilliant designs (like the hand and opposable thumb).
Sex and death are fundamental drivers of evolution, shaping biological adaptation and the continuous renewal of life.
Taboos around universal bodily functions (bathroom, bedroom activities) are a strange social construct despite their commonality.
Organs like the kidneys and liver are unsung heroes, performing complex, energy-intensive functions vital for life, often without public appreciation.
The doctor's journey involves confronting death, human vulnerability, and psychological challenges, requiring a blend of scientific expertise and compassionate human interaction.
Advances in medicine, partly accelerated by war and scientific curiosity, continuously challenge past dogmas, highlighting the humbling imperfection of current medical knowledge.
EVOLUTION'S DESIGN: FEATURES AND FLAWS
Jonathan Reisman, a physician and author, explores the human body's evolutionary design, highlighting both its brilliance and its inherent flaws. The human hand, with its dexterity and the foundational role of the thumb, is presented as an optimal solution for interaction with the world. In contrast, the throat's proximity of food and air passages, leading to choking hazards, is considered a significant design flaw, though potentially unavoidable given early embryonic formation. This juxtaposition underscores the improvisational nature of evolution rather than perfect engineering.
SEX, DEATH, AND THE DRIVERS OF LIFE
Reisman emphasizes that sex and death are the fundamental activities driving human evolution. Sex ensures reproduction and genetic variability, while death acts as a selection process, weeding out less adaptable genes and making room for new adaptations. This continuous cycle of creation and elimination is seen as foundational to life and intelligence, potentially extending to alien civilizations adapting to changing environments. Immortality, while seemingly desirable, would pose significant challenges for adaptation and renewal.
THE BIOLOGICAL TABOOS AND UNIVERSAL MYSTERIES
One of the human body's strangest aspects is the social taboo surrounding universal bodily functions like going to the bathroom and sexual acts. Reisman notes the irony that what all humans share in common is often deemed private and unspoken. He speculates that society's love for rules and the forbidden might contribute to these taboos. Different cultures possess varying taboos, often rooted in practical public health measures, such as the Indian cultural distinction between the right and left hands for different functions, even as modern hygiene makes some original reasons less critical.
UNSUNG HEROES: KIDNEYS AND LIVER
While the brain often receives the most awe for its complexity, Reisman champions organs like the kidneys and liver as underappreciated heroes. Kidneys are incredibly active, consuming vast energy to meticulously regulate the bloodstream throughout life. The liver, described as 'fifteen organs in one,' acts as the body's primary gatekeeper, processing nutrients, detoxifying substances like alcohol and drugs, and producing essential blood components. Its regenerative capacity, similar to the myth of Prometheus, makes it unique among internal organs and a powerhouse of metabolic activity.
THE DOCTOR'S JOURNEY: COLD HONESTY AND HUMANITY
Reisman recounts his first encounter with cadaver dissection in medical school, describing it as a moment of 'cold honesty' about the human story's end. This immediate immersion into human anatomy led him to decide to donate his own body to science. He observes that cadavers reveal personal histories—lifestyle choices, past injuries, and surgeries—written in scars and internal conditions. The medical profession, especially in the emergency room, exposes doctors to humanity at its most raw and vulnerable, requiring them to navigate scientific expertise with profound human compassion amidst chaos and diverse life stories.
UNDERSTANDING THE 'TUBE' AND ITS MULTIFUNCTIONALITY
Reisman explains the human body as an elaborate tube that develops from a microscopic disc, eventually sprouting various holes and specialized organs. The throat, a critical junction, highlights the challenge of multifunctionality, with air and food passages millimeters apart. Despite potential for error leading to choking, the body has evolved complex compensatory mechanisms, including gag reflexes, coughs, and a 'mucus elevator' in the lungs, along with an intricate swallowing mechanism, to ensure survival. This design, while seemingly flawed, is a testament to evolutionary adaptation.
THE HEART: A MECHANICAL PUMP, NOT LOVE'S ABODE
The heart, often associated with love and emotion, is, from a biological standpoint, a 'simple mechanical pump.' Its primary function is to circulate blood, delivering oxygen and nutrients to every cell while removing waste. This vital, non-stop operation begins in the womb and continues until death, contrasting sharply with poetic interpretations. Blood itself is portrayed as the body's most crucial fluid, serving as a delivery system for nutrients and waste, a diagnostic tool for doctors, and a primary attack vector for diseases entering through the respiratory or gastrointestinal tracts.
GENITALS: IRATIONALITY, ADAPTATION, AND THE FUTURE OF REPRODUCTION
Genitals are unique organs, not essential for moment-to-moment survival, and often drive irrational human behaviors. Reisman discusses the female reproductive system's peculiar monthly cycle that starts late in life and ceases with pregnancy, symbolizing life's central purpose. Male testicles, hanging externally for optimal sperm production temperature, exemplify a design that might be 'improved' if sperm could thrive at body temperature. The discussion extends to future reproductive technologies like artificial wombs, which offer hope for premature babies but raise significant ethical questions about human intervention in natural processes.
FECES: THE GROSS, THE FUNNY, AND THE INTELLIGENT
Feces, often considered vile and taboo, holds surprising biological fascination. Reisman highlights its role in the fecal-oral route of infection, explaining diarrhea as an 'intelligent' microbial mechanism to spread. The social awkwardness around discussing waste contrasts with its constant presence in medical conversations, where doctors become 'poop detectives.' This interaction often involves addressing psychological fears and insecurities, underscoring the deep human connection involved in medical practice, which blends scientific inquiry with therapeutic communication.
THE ER: A WINDOW INTO THE HUMAN CONDITION
The emergency room (ER) provides a profound glimpse into the human condition, exposing doctors to extremes of suffering, psychological distress, and societal challenges. Reisman observes that while intense, the human capacity for adaptation can normalize even the most shocking experiences for medical professionals. He views medical problems as a 'great equalizer,' stripping away superficial differences of class or background, revealing universal anxieties about mortality and bodily function. The ER is a space where professional demeanor meets raw humanity, fostering unique insights into life and death.
CULINARY EXTREMES AND THE WISDOM OF NATIVE DIETS
Reisman's extensive travels, often as a doctor in remote regions, have exposed him to diverse culinary practices. He recounts his fascination with the high-fat diets of indigenous communities in the Arctic, such as raw whale blubber (mukluk) and fermented whale meat. These diets, driven by the harsh environment and scarcity of cooking fuel, demonstrate profound adaptation to local resources and cultural identity. His experiences highlight the deep connection between geography, climate, and human survival strategies, offering a different perspective on fat, often maligned in modern society, as a symbol of health and pride.
LESSONS FROM THE PAST: SHACKLETON'S MEDICAL KIT
Comparing his fully equipped medical station in Antarctica to Ernest Shackleton's sparse 1910s medical kit, Reisman emphasizes the immense progress in medicine. Shackleton's kit, with laxatives for various ailments, reflects the humoral theory of medicine, where balancing bodily fluids was paramount. The evolution of germ theory, antibiotics, and advanced surgical techniques has, in just over a century, transformed medical possibilities. This contrast underscores the unforgiving nature of remote environments and the critical need for advanced medical preparedness in extreme conditions, such as future space missions.
THE HUMILITY OF MEDICAL KNOWLEDGE
Reisman reflects on the humbling truth that much of current medical knowledge will eventually be proven wrong, a concept illustrated by the adage that "half of what you learned in med school is wrong." He points to the historical shift from bloodletting to modern, evidence-based practices, acknowledging that even today, seemingly logical treatments are often disproven by rigorous placebo-controlled studies. This imperfection in scientific understanding underscores the need for continuous research, critical thinking, and a humble perspective from medical professionals, who can still inadvertently cause harm, despite good intentions.
THE MEANING OF LIFE: A GAME THE BRAIN PLAYS
Reisman grapples with profound philosophical questions about life and death, particularly the existential terror of consciousness ending. He suggests that the question 'why' might be an evolutionary adaptation, useful for practical survival in hunting and gathering, but extrapolated into unanswerable existential inquiries. While acknowledging the suffering and hopelessness many face, he posits that focusing on connections with others and contributing to their well-being can distract from personal existential anxieties. For him, the meaning of life, or the 'why,' might be a trick of the human brain, rather than an external universal truth.
ADVICE FOR A MEANINGFUL LIFE AND CAREER
Reisman advises young people to cultivate passion and follow it wherever it leads, emphasizing that early exploratory journeys, like his time in Russia, can be profoundly shaping experiences. He advocates for careers that blend intellectual problem-solving with hands-on work, using his medical career as an example where observation, instinct, knowledge, and compassion converge. He stresses the importance of humility in medicine, recognizing that despite scientific advancements, human intuition and the ability to connect with patients remain crucial. His journey underscores that a fulfilling life often involves embracing adventure, learning, and service, driven by genuine curiosity and a desire to make a difference.
Mentioned in This Episode
●Supplements
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●Books
●Concepts
●People Referenced
Common Questions
The human hand features muscles located in the forearm, with tendons acting like puppet strings to provide exceptional dexterity. This design allows for a wide range of activities, from holding objects to playing musical instruments. The thumb is particularly crucial for daily life and occupation, with surgeons prioritizing its repair over other digits in cases of severe injury.
Topics
Mentioned in this video
Jonathan Reisman's book about the human body, its messy, weird, beautiful, and fascinating details.
Book by Tracy Kidder about Paul Farmer, which Jonathan Reisman recommends for understanding the humanitarian aspects of medicine.
An underappreciated organ that constantly tinkers with the bloodstream, consuming a lot of energy and acting as an 'unsung hero' of the body. Also, it's an organ which can be replaced relatively easily.
Considered the most obvious fascinating part of the body but is still poorly understood in how it creates subjective experience.
Hormone that, like estrogen, can be absorbed orally, making it available in pill form.
A type of whale, whose heart was observed by Jonathan Reisman to be the size of a yoga ball, and its aorta the size of his thigh, during a whaling trip.
Hormone that is metabolized in the liver, hence its administration via injection or topical foam, not pills. It is also responsible for libido in women.
Future potential location for human colonization, where medical considerations for pioneers, such as preventative organ removal, would be extreme.
Figure in Greek myth whose liver regenerated daily after being eaten by a bird, reflecting the biological reality of the liver's regenerative abilities.
Indigenous people, similar to the Iñupiat, in their diet and life ways.
Eskimo culture in the Arctic whose diet traditionally consisted of over half of all calories from marine mammal fat, often eaten raw, indicating health and survival.
Described as the body's 'gatekeeper' for what we eat and absorb, a powerhouse with about 15 functions, and the biggest internal organ. It also has a mythological ability to regenerate.
Indigenous people of northern Kamchatka known for seal hunting, whose diets and life ways have changed dramatically over the last century.
A medical procedure for Parkinson's disease where devices electrically stimulate parts of the brain, showing dramatic effectiveness and potential for other conditions.
A bacterial infection discussed as an example of microbes that infect lungs and spread through coughing, similar to coronavirus.
Raw whale blubber, a traditional Iñupiat food, described as surprisingly pleasant with a sea smell, often sliced thin and eaten cold.
Neurological disorder for which deep brain stimulation is a dramatically effective treatment, illustrating advances in brain intervention.
Hormone that, unlike testosterone, can be absorbed orally, making it available in pill form.
Regime whose scientists performed horrific medical experiments during wartime.
A virus mentioned as an example of a microbe that infects lungs and spreadsthrough coughing, similar to tuberculosis.
Guest and author of 'The Unseen Body,' a physician who has practiced medicine in remote places.
Russian author whose works were loved by an elderly blind Koryak woman in Kamchatka, highlighting the surprising range of education even in remote areas.
Explorer whose medical kit from his 1910s Antarctic expedition is contrasted with modern medical resources, highlighting the harshness of his journey.
Pioneer of global health and co-founder of Partners In Health, a huge inspiration due to his dedication to bringing healthcare to the poorest people in the world.
Psychologist whose perspective is evoked to explain why universal human actions might become social taboos.
Russian president mentioned in the context of Russian history, societal upheaval, and the current war in Ukraine.
Late actor mentioned as an example of someone externally successful but internally struggling, illustrating that outward appearance doesn't reflect internal suffering.
A doctor and writer who observed that people from all social classes have the same 'ugly bodies', highlighting the great equalizer of medical problems.
Nurse during the Civil War, possibly quoted as saying 'war is the best medical school' due to advancements in medicine that come from conflict.
Philosopher whose 'question of why live' is referenced in the discussion about existential struggles and the commonality of contemplating suicide.
Filmmaker who voices the documentary 'Happy People: A Year in the Taiga'.
Public figure mentioned as also loving bone marrow, connecting it to its appreciation as a delicious food.
Founder of Theranos, whose goal of using less blood in tests was worthy, despite the company's eventual downfall.
Russian author whose works were loved by an elderly blind Koryak woman in Kamchatka, demonstrating the high level of education from the Soviet era.
Author of 'Mountains Beyond Mountains,' a book about Paul Farmer's life and work.
Arctic island in Russia also visited by Jonathan Reisman as a ship doctor, known for its wildlife.
Location in the Arctic Ocean where Jonathan Reisman went on a whale hunting trip and observed the cultural significance of whale blubber and its use.
Strait located between Russia and Alaska, through which Jonathan Reisman sailed on a wildlife cruise.
A city created by the Soviets near Novosibirsk specifically for scientific study, mentioned as an example of Russia's unrealized scientific potential.
Region in Russia where Jonathan Reisman worked as a ship doctor on a wildlife cruise, visiting villages and trying whale meat, noting similarities to Iñupiat culture.
Country where Jonathan Reisman worked, experiencing its unique geography and culture and practicing high altitude medicine.
Location of Shackleton's expedition and where Jonathan Reisman worked as a ship doctor, contrasting the limited medical supplies of the past with modern capabilities. Described as one of the most picturesque places.
Region in Russia where Jonathan Reisman traveled twice, including northern Kamchatka, noting the indigenous Koryak people's seal hunting and changing diets.
Country where Jonathan Reisman's grandmother was from, who contracted typhus during World War II.
Country where Partners In Health, co-founded by Paul Farmer, originally operated, demonstrating his commitment to providing healthcare in impoverished regions.
Country where cultural taboos, like the use of the left hand for personal hygiene, serve a public health measure.
City where Jonathan Reisman worked, experiencing its unique geography and culture.
City in Russia where the Soviets created Akademgorodok, an entire city dedicated to science.
Country that Moldova was part of during World War II, where Jonathan Reisman's grandmother contracted typhus.
City where Jonathan Reisman spent six months at a research center, studying the international environmental movement, and subsequently learned Russian.
Location in South Dakota where Jonathan Reisman has practiced medicine, noting its unique geography and culture.
Location where Jonathan Reisman worked in an emergency room, experiencing the Arctic diet and the cultural significance of fat.
Region where Jonathan Reisman currently works, finding its geography and culture unique and exotic.
Country whose destruction is considered tragic and a place from which many brilliant scientists and engineers have emerged, holding unrealized potential.
Country mentioned as having a strategy of anticipatorily removing gallbladders from people going to Antarctica to prevent medical emergencies.
An organization whose representatives have reached out to Lex Fridman to give lectures, indicating a scientific connection between Russia and the globe.
International financial institution mentioned in the context of pushing Russia's timber industry toward sustainable practices after the fall of the Soviet Union.
Environmental organization mentioned in the context of pushing Russia's timber industry toward sustainable practices after the fall of the Soviet Union.
International health organization founded by Paul Farmer, providing healthcare primarily in Haiti and Rwanda.
Country where Partners In Health operates, mentioned as an example of global health initiatives.
Defense Advanced Research Projects Agency, part of the U.S. military budget, that funds moonshot experiments pushing scientific frontiers.
Environmental organization mentioned in the context of pushing Russia's timber industry toward sustainable practices after the fall of the Soviet Union.
Civilian space program that originated from military efforts, leading to advances in health understanding on Earth and in space.
AI company mentioned for its work in computational biology and genetics, simulating parts of the body.
Pharmaceutical company that developed a COVID vaccine purely computationally from the virus's genome without ever having the virus in their lab.
Company focused on brain-computer interfaces, whose efforts are deemed feasible but require more understanding of brain connection.
Company started to revolutionize medical blood tests by using a single drop of blood to gather extensive information about a person's body.
Technology company whose CEO's advice to 'always have a plan' is contrasted with Jonathan Reisman's approach of following passion with no fixed plan.
Infectious disease that causes outbreaks during war, highlighting that infection is a huge problem historically in wartime.
Drug used for pain control in battlefield medicine, highlighted as an advancement stemming from war.
A pain medication included in Shackleton's 1910s medical kit, representing the limited pharmaceutical options of the era.
An inexpensive antibiotic that could save lives of children dying from bacterial pneumonia in developing countries, highlighting the disparity in access to basic medication.
Infectious disease that causes outbreaks during war, as experienced by Jonathan Reisman's grandmother during World War II.
Common painkiller mentioned as being toxic to the liver in overdose, due to the liver's role in metabolizing drugs.
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