July 27, 2024 • 1hr 39min
#817 - Dr Anna Machin - The Evolutionary Psychology Of Love, Lust & Cheating
Modern Wisdom
Key Takeaways
- Love evolved as a form of "biological bribery" to motivate and reward humans for forming and maintaining critical relationships for survival and reproduction
- Love involves a complex interplay of neurochemicals including oxytocin, dopamine, beta-endorphin, and serotonin that create feelings of attachment, reward, addiction, and obsession
- Romantic love differs from lust - attraction is based on oxytocin and dopamine while lust is driven by s*x hormones
- Women can unconsciously detect genetic compatibility through smell due to genes that affect immune system diversity
- Long-term love is underpinned by beta-endorphin, which creates an addictive bond that can last for decades
- Culture strongly influences how love is experienced and expressed, though the underlying biology is similar across humans
- Dating apps have not fundamentally changed love and attraction, but have altered how people meet and assess potential partners
- Parasocial relationships with celebrities or fictional characters activate similar brain regions as real relationships
- Religious love for a deity can provide similar psychological and health benefits as human relationships
Introduction
Dr. Anna Machin is an evolutionary anthropologist at Oxford University and author of books on love and fatherhood. In this episode, she discusses the science behind love - why it evolved, how it works in the brain, and how it manifests in human relationships. Drawing on her research and expertise, Dr. Machin provides insights into the biological, psychological and cultural factors that shape how humans experience and express love.
Topics Discussed
The Evolution and Purpose of Love (5:47)
Dr. Machin explains that love evolved as a form of "biological bribery" to motivate humans to form and maintain critical relationships:
- Humans are an extremely cooperative species, but living in groups is stressful and costly
- Love provides neurochemical rewards that make cooperation feel good and worthwhile
- It underpins relationships critical for survival and passing on genes
She notes that while many animals experience basic forms of love and attachment, human love is more complex, involving:
- Attachment
- Neurochemistry including beta-endorphin
- Grief at loss of love
- Friendships beyond reproduction
- Cognitive empathy
The Neuroscience and Stages of Romantic Love (12:50)
Dr. Machin breaks down the stages and neurochemistry of romantic love:
- Lust - Driven by s*x hormones, separate from attraction
- Attraction - Initial stage of all relationships, driven by oxytocin and dopamine
- Romantic love - Involves additional neurochemicals like beta-endorphin for long-term bonding
She explains that attraction starts as an unconscious process:
- The brain takes in sensory information about a potential mate
- This goes through an unconscious "mate value" algorithm
- If deemed valuable, oxytocin and dopamine are released
- This then moves into conscious assessment
Genetic Compatibility and Mate Selection (17:05)
An interesting finding is that women can unconsciously detect genetic compatibility through smell:
- Genes that affect immune system diversity also affect sense of smell
- Women can smell how similar a man's immune genes are to their own
- They prefer men with more different immune genes for offspring diversity
- This may explain inexplicable lack of attraction to seemingly suitable partners
Long-Term Love and Relationships (21:30)
Dr. Machin discusses how love maintains long-term relationships:
- Oxytocin alone is not enough for decades-long bonds
- Beta-endorphin is key for long-term human love
- It is addictive and we don't develop tolerance to it
- Released through social activities like laughter, touch, exercise
- Underpins all types of long-term human relationships
She notes human love also involves psychological elements like attachment, trust, and reciprocity.
Cultural Influences on Love (25:39)
While the biology of love is similar across humans, culture strongly shapes how it's experienced:
- Some cultures don't believe in concept of romantic love
- Love may be seen as spiritual, familial, or even negative in some societies
- Western cultures are "enthralled" with idea of romantic love
- Culture can overwhelm biological drives in how love is expressed
Gender Differences in Love (27:01)
Dr. Machin explains there are more differences within sexes than between them in how love is experienced:
- Brain scans show no clear differences between men and women in love
- Individual genetics, attachment style, and upbringing have more influence
- Cultural gender norms shape how love is expressed externally
Genetics, Upbringing and Attachment (30:24)
There is a complex interplay between genetics and environment in shaping how individuals experience love:
- Many genes influence social cognition and love-related neurochemistry
- Early childhood strongly shapes brain development for social relationships
- Some genes make people more or less susceptible to environmental influences
- This explains why some thrive despite difficult childhoods
The Dark Side of Love (1:04:16)
Dr. Machin discusses how love can be used to manipulate and control:
- Humans are the only species to use love for manipulation
- The addictive nature of love can keep people in abusive relationships
- Some stay hoping their love will change an abusive partner
- Male victims of abuse often stay out of love for children
Female Friendships vs Romantic Relationships (1:12:11)
An interesting finding is that women are often more emotionally intimate with female friends than romantic partners:
- Women share deeper vulnerabilities with friends
- Female friendships becoming primary relationships for some women
- Provides similar benefits to romantic relationships
- Cultural shift as women have more independence
Impact of Dating Apps (1:25:13)
Dr. Machin argues dating apps haven't fundamentally changed love, but have altered how people meet:
- Apps should be seen as "introduction apps" not dating apps
- Can't fully assess attraction through photos/texts alone
- Brain evolved for in-person assessment of potential mates
- Apps create illusion of efficiency in an inherently inefficient process
Parasocial Relationships (1:33:31)
Dr. Machin explains parasocial love for celebrities or characters:
- Brain can form attachment to someone never met in person
- Activates similar regions as real relationships
- Not pathological - most have normal social lives too
- Can be developmentally important, especially for marginalized youth
Religious Love (1:36:25)
Love for a deity activates similar brain regions as human love:
- Religious followers report full reciprocal loving relationships with God
- Personal prayer provides similar health benefits to human relationships
- Shows human capacity to form deep attachments beyond physical world
Conclusion
Dr. Machin provides a fascinating overview of the science of love, from its evolutionary origins to its neurochemical underpinnings to its cultural expressions. She emphasizes that while we can measure certain aspects of love objectively, much remains subjective and ineffable. Love's complexity and power stem from the intricate interplay of biology, psychology, and culture. Understanding the science can provide insights, but doesn't diminish love's profound impact on the human experience. As Dr. Machin concludes, love in its many forms is "possibly the cornerstone of being human" and living without it means living "very much half a life."