This One's a Tear Jerker

Episode Summary

Executive Summary: This episode explores why humans cry emotional tears, a phenomenon unique to humans. The hosts discuss the evolution of crying from babies' distress calls to adult emotional tears, the chemistry and social signaling involved, and whether crying is voluntary. They also examine animal mourning behaviors and the cultural role of tears as a signal of vulnerability and connection.

Main Topics: Uniqueness of Human Emotional Tears (Priority: 5/5): Discussion of whether other animals cry emotional tears. While animals like elephants and whales show mourning behaviors, there is no definitive evidence of emotional tears in non-human species. Evolution and Development of Crying (Priority: 4/5): Trace of crying from infant distress calls (vocal) to emotional tears in older children and adults, referencing Darwin's observations of his own children. Physiological and Hormonal Aspects (Priority: 4/5): Chemical composition of emotional tears vs. lubricating tears, role of prolactin, effects of hormones on crying threshold (e.g., androgen suppression causing increased crying). Social Signaling and Cultural Context (Priority: 4/5): Crying as a signal of vulnerability, honesty, or manipulation; cultural variations; the 'crying room' trend in Japan; phatic communion. Crying as a Release and Catharsis (Priority: 3/5): The psychological and physiological benefits of crying, including the release of oxytocin and endorphins, and the feeling of relief after crying. Animal Behavior and Mourning (Priority: 3/5): Mourning behaviors in elephants and whales, including the tragic playback experiment with elephant names. Crying in Solitude (Priority: 2/5): The story of Juana Maria, who lived alone for 18 years, raising questions about whether crying serves a social function or occurs in complete isolation.

Key Arguments: Emotional tears are chemically distinct from lubricating or reflex tears and contain hormones like prolactin, which may help the body remove stress-related substances. Crying likely evolved from vocal distress calls in infants to a visual signal of vulnerability in adults, reducing noise that could attract predators. Crying is not fully voluntary; it can be suppressed or triggered by hormonal and environmental factors (e.g., fatigue, altitude). Crying serves a social function: it signals vulnerability, de-escalates conflict, and can bond people together, but can also be perceived as manipulative. Darwin believed crying was a 'practiced' behavior that could be culturally suppressed and may be a non-adaptive byproduct of other muscular developments.

Data Points: Age for emotional tears in infants: 139 days (4.57 months) - Darwin's observation of his own child Age for reflex tears in infants: 77 days - Darwin's child accidentally brushed with coat cuff Number of cancer types: More than 200 - Cancer Research UK ad Survival rate improvement: Doubled cancer survival in UK over 50 years - Cancer Research UK ad Years alone for Juana Maria: 18 years (1835-1853) - Story of the last Nicoleño speaker

Pivotal Quotes: "There's the sort of lubricating tears that just stop your eyeballs from drying out, turning into brazins. There's the reflex, if you get something in your eye, it needs to water and flush it out. And then the third one is the emotional tears, which supposedly has all kinds of hormones inside of it, which make it chemically distinct from the previous two." — Hannah Fry: Introduction to the three types of tears "Crying equals meaning plus vulnerability divided by sensory threshold." — Hannah Fry (quoting research from Alabama): Presenting the 'crying equation', then critiquing its validity "I think that, yeah, we are a social species. So her story makes me wonder about the social niche of humans. Because no one ever seems content to say, well, we're the thinking ape or whatever. I guess we are literally called Homo sapiens, the wise ape. But the social aspect of it, I think, is kind of explained through tears." — Michael Stevens: Reflecting on the story of Juana Maria and the social function of crying

Implications: Crying is a powerful, involuntary social signal rooted in human evolution. Understanding its biological and cultural roles helps destigmatize emotional expression and emphasizes our species' deep need for connection and vulnerability. This can inform mental health practices and workplace policies.