The human heart has long been the quintessential symbol of romantic love, but the relationship between this vital organ and one of the most profound human experiences appears to extend beyond mere symbolism and into the realm of biology, according to recent scientific investigations.
New research suggests that heart rate and skin conductance – a measure of the body’s ability to conduct electricity, reflecting nervous system activation – can predict romantic attraction between two people. A study by psychologist Eliska Prochazkova at the University of Leiden in the Netherlands explored these physiological indicators of connection during speed dating scenarios.
Prochazkova’s work centers on the idea that choosing a partner is often based on a “gut feeling,” a sense of connection experienced with only certain individuals. Her research investigated how this feeling of romantic connection arises during first encounters. The findings reveal that when heart rate and skin conductance synchronize naturally between two people, it indicates mutual attraction. This synchronization, the research suggests, explains why we feel a strong connection with some individuals and not others.
Like heart rate, skin conductance is a measure of nervous system activation. Prochazkova’s study marks the first demonstration that the ability to physiologically synchronize with a potential partner is a significant predictor of sexual attraction during initial meetings.
Researchers created “dating booths” at various events, including the Lowlands music festival, and invited 140 young, single individuals to participate in blind dates. Participants were randomly paired. Inside the booths, couples wore eye-tracking glasses to record their gaze patterns, and electronic devices measured their skin conductance, finger sweat, and heart rate.
“We found that if one person felt attracted to their date, their heart rate would synchronize with the other person’s,” Prochazkova explained. “If one person’s heart rate increased, the other’s would also increase. And if one person’s heart rate decreased, the other’s would do the same.” Skin conductance followed a similar pattern, with synchronization at a deeper level indicating increasing attraction between the participants.
The researchers at Leiden believe that the synchronization of heart rate and skin conductance in attracted individuals may be due to subtle, often imperceptible micro-expressions, such as slight blinks. When one person unconsciously perceives these micro-expressions in the other, they experience a sense of well-being because they feel emotionally understood, which in turn accelerates their heart rate. “What we have is likely what happens when you find someone attractive,” Prochazkova suggests.
The History of the Heart Symbol
While the biological connection to attraction is being mapped, the heart’s symbolic representation of love has a long and winding history. The artistic depictions of the heart, with its two curved lobes joined at the base, differ significantly from the actual anatomical shape of the organ – a cone positioned upside down with vessels at its broader upper end.
However, in the symbolic realm, artistic representations of the heart, and the gesture of offering or touching the left side of one’s chest, have become universally recognized icons of romantic love. The origins of this symbolism may trace back to ancient Greece, specifically to coins from Cyrene (modern-day Libya) dating between the 6th and 3rd centuries BC. These coins featured the seeds of the silphium plant, now extinct, which bore a shape remarkably similar to the heart symbol we use today.
The silphium plant, valued for its culinary, medicinal, and veterinary uses, was sometimes associated with the goddess Aphrodite, potentially linking the heart shape to the concept of love. The evolution of the heart as the primary symbol of love is complex, with theories spanning from ancient Greece and Egypt to Renaissance depictions of the Sacred Heart of Jesus and the popularization of Valentine’s Day cards in 19th-century Britain.
The First Valentine’s “Cardiac” Cards
“No tradition is more intimately associated with the heart than Valentine’s Day,” notes cardiologist and historian Vincent M. Figueredo, who has spent nearly three decades combining medical practice with scientific research. Figueredo’s work explores how the heart responds to stress, alcohol, and disease, and has contributed to improved diagnosis and treatment of cardiovascular illnesses.
“From the dawn of humanity, the heart has been much more than an organ: it has beat as an emblem of love, vitality, and wisdom in cultures around the world,” Figueredo states. “Although today we better understand its physiology and medical function, it continues to intrigue us as an eternal symbol of emotions and memories.”
Figueredo points to the contributions of Renaissance figures Leonardo da Vinci and Andreas Vesalius, considered the father of modern anatomy, who expanded our understanding of the body and created the first accurate depictions of the heart.
Regarding Valentine’s Day, Figueredo explains that the Christian priest Saint Valentine of Rome was martyred by the Romans on February 14, 269 AD, after secretly performing Christian marriages despite an imperial ban. In the 5th century, Pope Gelasius declared February 14th as Saint Valentine’s Day, which eventually became associated with the commemoration of romantic love.
By the 17th century, Valentine’s Day celebrations in England were largely limited to those who could afford them. Wealthy individuals would randomly draw the names of women to whom they would offer gifts. The earliest English, French, and American Valentine’s cards consisted of a few handwritten verses on a piece of paper. Over time, these cards were embellished with drawings and illustrations, often including the now-iconic heart symbol, sealed with wax, and placed on the doorsteps of their recipients.
