Adaptable

1. Our Bodies Are Evolutionary Masterpieces, Designed for a Past World

Your body will break down and fail because it is evolved to thrive in an environment that’s radically different from the one in which you live.

Evolutionary blueprint. Our bodies are intricate protein robots, products of millions of years of evolution, primarily as hunter-gatherers. This deep history is etched into our anatomy and physiology, from our teeth adapted for diverse diets to our endurance-focused hearts and muscles built for constant movement. We are designed for a physically demanding life, constantly seeking food and navigating diverse environments.

Ancient adaptations. Many of our fundamental biological features reflect this ancestral past.

• Digestive system: Our acidic stomachs are like those of scavengers, adapted to handle varied, sometimes putrid, foods. Our shorter intestines reflect a diet richer in meat and cooked foods than other primates.
• Thermoregulation: Our naked, sweaty skin evolved to keep us cool during active days in equatorial Africa, while our large noses help conserve water in dry climates.
• Endurance: Our long legs, fatigue-resistant muscles, and efficient hearts are all adaptations for covering vast distances daily, a hallmark of hunter-gatherer life.

Mismatch with modernity. The rapid shift to industrialized, sedentary lifestyles and processed foods has created a profound "evolutionary mismatch." Our bodies, optimized for a past environment, now struggle with the abundance and inactivity of the present. This fundamental conflict is the root cause of many modern health crises.

2. Human Diversity Is Profound, Yet Race Remains a Social Construct

Races are made-up social categories, not biological groups.

Diversity is real. Humans exhibit incredible biological diversity, evident in traits like height, body proportions, and skin color. This variation is shaped by a complex interplay of genetics, environment, and local adaptation. For example, populations in hot climates tend to be tall and thin (Allen's and Bergmann's rules), while those at high altitudes have unique blood adaptations (like the Denisovan EPAS1 allele in Tibetans).

Race is not biology. Despite visible differences, the concept of "race" as a biological category is a cultural invention, not a scientific reality.

• Clinal variation: Traits like skin color vary continuously across geographic gradients, not in discrete racial categories.
• Genetic overlap: All humans share over 99.9% of their DNA, and any two populations share over 90% of their genetic variants.
• Independent traits: Genes for skin color are independent of genes for other traits like blood type or intelligence, meaning racial groupings based on one trait don't predict others.
• Constant mixing: Human populations have been migrating and intermarrying for hundreds of thousands of years, leading to thoroughly mixed gene pools.

Racism makes race biological. While race isn't biological, racism—the systemic differential treatment based on perceived race—creates biological disparities. Chronic stress from discrimination, unequal access to nutritious food, and poorer healthcare lead to higher rates of heart disease, diabetes, and other illnesses in marginalized communities. These health outcomes are a consequence of social inequality, not inherent genetic differences.

3. Modern Life Creates a Mismatch, Fueling Chronic Disease Epidemics

Today’s weight problems can’t be due to lower daily energy expenditures from our less active, modern lifestyles.

The silent killers. Heart disease, diabetes, and certain cancers have become leading causes of death in industrialized societies, a stark contrast to traditional communities where these "mismatch diseases" are rare. This shift is not due to a decline in daily calorie burning. Studies show that active hunter-gatherers burn the same total calories daily as sedentary Westerners; our bodies simply reallocate energy from other physiological tasks.

Dietary culprits. The primary driver of modern health crises is our diet.

• Ultra-processed foods: These are engineered to be hyper-palatable, energy-dense, and low in protein and fiber, leading to overconsumption. Studies show people eat 500 more calories daily on ultra-processed diets.
• Nutrient imbalance: Modern diets are often high in added sugars, unhealthy fats, and salt, while lacking essential proteins and fiber.
• Obesity: This is fundamentally a "calories in" problem, driven by our modern food environment interacting with genetic predispositions that were once neutral but now promote weight gain.

Beyond diet and exercise. While diet and exercise are crucial, other modern factors contribute to disease. Chronic stress, poor sleep, and reduced exposure to diverse microbes (the "hygiene hypothesis") can lead to chronic inflammation and autoimmune disorders. Our bodies, evolved to cope with acute threats, struggle with the persistent, low-grade stressors of modern life.

4. Intelligence and Talent Are Dynamic, Shaped by Environment More Than Genes

IQ tests and educational attainment probably measure a range of traits that have nothing to do with the ability to remember or process information, develop creative ideas, or any of the other things we associate with being smart.

Intelligence is multifaceted. What constitutes "intelligence" is often culturally defined. Hadza tracking skills, for instance, are a form of intelligence not captured by Western IQ tests. Our brains are born "unfinished," designed for extensive learning and adaptation, making them highly plastic and responsive to environmental input.

The myth of fixed intelligence. The history of IQ testing is fraught with misuse, particularly by eugenicists who claimed intelligence was innate and fixed, leading to racist policies.

• Environmental impact: Landmark studies, like those on the Davenport orphans, demonstrated that a nurturing environment can dramatically increase IQ scores. The "Flynn effect" shows global IQ scores rising over decades, further proving environmental influence.
• Content, not hardware: IQ tests primarily measure cultural knowledge and learned problem-solving strategies, not innate brain "hardware." Comparing IQs across different cultural or socioeconomic groups reveals environmental disparities, not genetic ones.

Talent is cultivated. While genetics play a small role in predisposing individuals to certain abilities (e.g., ACTN3 for power, ACE for endurance), "talent" is largely a product of dedicated practice and opportunity.

• 10,000-hour rule: Elite performance across diverse fields consistently requires thousands of hours of deliberate practice with good instruction.
• Environmental advantage: Access to coaching, resources, and cultural encouragement (e.g., specific sports in certain countries) are far more predictive of athletic success than genetics.
• No racial advantage: The dominance of certain groups in specific sports is due to cultural and environmental factors, not inherent genetic superiority.

5. Sex Is Biological, Gender Is Cultural, and Both Are More Nuanced Than Binary

The distinction between sex and gender is relatively recent, largely a product of feminist scholarship in the 1960s and ’70s.

Biological sex is complex. Our bodies begin sexless, with female development as the default. The SRY gene on the Y chromosome triggers male development. However, variations in chromosomes (e.g., XXY, XYY) or hormone production/reception (e.g., androgen insensitivity, congenital adrenal hyperplasia) can lead to intersex anatomies, demonstrating that biological sex exists on a spectrum, not a strict binary.

Gender is identity and culture. Gender refers to how individuals identify and how society ascribes masculinity or femininity.

• Identity: While most people identify with their biological sex (cisgender), a small but significant percentage identify as transgender or nonbinary. These identities are deeply personal and not fully explained by biology or socialization alone.
• Socialization: Cultural norms heavily influence gender expression and roles. Historically, these norms have been rigid and often oppressive, but they are dynamic and evolving.

Sex differences in physiology. There are clear average differences between biological males and females, largely driven by testosterone.

• Physical attributes: Males, on average, are 10-30% stronger and faster due to higher testosterone levels post-puberty. These "organizational" effects are not easily reversed.
• Brain differences: Small average differences exist in brain anatomy and cognitive performance (e.g., spatial reasoning), but with significant overlap. The precise impact of hormones versus socialization on these differences is still debated.

Navigating the debate. The ongoing discussion about "what is a woman" highlights the tension between biological definitions and identity. Acknowledging the spectrum of biological sex, the profound impact of gender identity, and the cultural construction of gender allows for a more inclusive and nuanced understanding, moving beyond rigid binaries.

6. Our Immune System Is a Double-Edged Sword, Overwhelmed by Modernity

In a bit of cosmic irony, our immune systems, evolved to keep us alive, are killing us.

The body's army. Our immune system is a sophisticated defense network, with billions of specialized white blood cells born in the bone marrow. It identifies invaders via MHC complexes, mounts inflammatory responses, and develops "acquired immunity" through B and T cells that produce tailored antibodies. This system also targets rogue cancer cells.

Modern immune challenges. While modern medicine has drastically reduced infectious disease, our immune systems face new threats from evolutionary mismatch.

• Chronic inflammation: Modern diets, sedentary lifestyles, and obesity promote persistent, low-grade inflammation, damaging blood vessels and contributing to heart disease, diabetes, and other chronic illnesses.
• Hygiene hypothesis: Our increasingly sterile environments, with reduced exposure to diverse microbes, may lead to an overactive immune system. This misfiring manifests as:
  • Allergies: Overreactions to harmless substances like pollen or food.
  • Autoimmune diseases: The immune system mistakenly attacks the body's own healthy cells.

Vaccines: a triumph of science. Vaccines are a cornerstone of public health, training our immune system to fight specific pathogens without actual infection. From Pasteur's rabies vaccine to modern mRNA technology, they leverage our body's adaptive immunity to prevent disease. Despite their proven safety and effectiveness, vaccine skepticism, fueled by misinformation and poor risk assessment, remains a dangerous challenge, leading to resurgent outbreaks of preventable diseases.

7. Longevity Is a Team Sport, But Immortality Remains Beyond Our Grasp

Longevity is a measure of how well we’re doing.

Extending health span. We've added decades to human life expectancy in the past century, largely by conquering infectious diseases and developing treatments for chronic conditions. Lifestyle choices—regular physical activity, a balanced diet, adequate sleep, and stress management—are crucial for extending "health span," the years lived free of disability. New medications for obesity and cancer immunotherapies offer further hope.

The inevitability of aging. Despite these advances, our bodies are "evolved to wear out." Aging is a complex, polygenic process where investment in repair and maintenance declines after our reproductive years.

• Cellular decline: DNA errors accumulate, telomeres shorten, and cellular machinery falters.
• Organ senescence: Organs shrink and function declines, leading to "natural causes" of death.
• Menopause: A unique human adaptation, allowing grandmothers to support offspring, but marking the end of reproductive capacity.

Anti-aging frontier. Research into slowing aging focuses on cellular pathways (e.g., AMPK, mTOR) influenced by calorie restriction. Drugs like Metformin and Rapamycin show promise in extending lifespan in other species, but human efficacy is unproven. No current treatment can reverse aging or make cells truly "younger." While some optimistically predict humans living to 150, achieving such a lifespan would require a quantum leap in biological understanding, akin to engineering humans to be twelve feet tall.

8. Understanding Our Biology Is Key to a Healthier, More Equitable Future

If we want our children to live longer and healthier lives we will need to come together, to understand ourselves and our diversity, and finally come to grips with the reality that we’re all one species, our fates tied inexorably to one another.

Empowerment through knowledge. A foundational understanding of human biology is essential for navigating our complex world. It empowers individuals to make informed health choices, resist misinformation (from detox fads to anti-vax propaganda), and appreciate the intricate workings of their own bodies. This knowledge helps us see beyond superficial differences and recognize our shared humanity.

Building a better society. Our biological understanding has profound social implications.

• Challenging prejudice: Recognizing that race is a cultural construct, and that most human variation is neutral, dismantles the scientific basis for racism and eugenics.
• Addressing disparities: Understanding how social stressors like racism impact biology (e.g., elevated cortisol, reduced life expectancy) highlights the need for systemic change to achieve health equity.
• Inclusivity: A nuanced view of sex and gender, acknowledging both biological realities and identity, fosters more inclusive and compassionate communities.

Collective responsibility. The major challenges of our time—climate change, chronic disease epidemics, social division—are too vast for individual solutions. They demand collective action, rooted in a shared understanding of our species' biology and our interconnectedness. By embracing our diversity and recognizing our common evolutionary heritage, we can cooperate to engineer social and physical environments that are fair, sustainable, and conducive to longer, healthier lives for all.

Last updated: November 13, 2025