Hunger. Thirst. Sleep. Sex. The motivation to satisfy these physiological needs are what propels humans forward as a species. These are called “physiologic motivators,” which are primal instincts that continuously drive our behavior. Emotions like anger, sadness and happiness are fleeting—they only last a few seconds to a few minutes. Their role in evolution is debated, and they are largely influenced by the world around us. Society readily accepts these differences between physiologic needs and emotions. However, love remains an outlier. Love is both primal—like a motivator—and volatile—like an emotion. What then is love? Motivator or emotion?

Enrique Burunat, an evolutionary biologist and neuroscientist from Universidad de la Laguna in Spain says love is a physiological motivator. Burunat’s research on the psychology and biology of love focuses on a specific type of love—not the feeling you get from smelling freshly brewed coffee or the impulse to paint your face for a professional sports team. He is interested in old-fashioned, human-centered love that’s essential for the growth of the species. Parental love. Generational love. Romantic love.

Declaring love as a physiologic motivator is challenging because we are not bombarded with physiologic motivators all the time. We only register hunger and thirst when we need food or water. Sexual reproduction does not occur until years after our birth. Sleep is cyclical, but the amount we sleep changes over time. The uniting thread through these is how our bodies respond when we’re deprived of any of these things. We can survive at low levels of physiologic motivators. But deficiencies—of food or sleep, for example—can cause changes to our physical bodies or our neurocircuitry that may be irreversible. Burunat argues that similarly, love—and its absence—can also have permanent effects.  

Love is nonexistent in clinical terms. There are eating, drinking, sleep and sexual dysfunction disorders, but there is no diagnosis called “lovesickness.” Love is never mentioned in the manual of codes that doctors use to describe diseases. Although we might want one sometimes, there is no love potion.

Perhaps from a biologic view, “all you need is love” is a lacking sentiment. But according to Burnuat, “In the same way that human beings are always accompanied by the need for food and water, for sleep … they are also accompanied by the need for love.”

Salvatore Aiello is pursuing a combined MD/PhD degree at Rosalind Franklin University in Chicago. His research focuses on resuscitation and translating laboratory work into clinical practice. Outside of research, Aiello leads the Medical Humanities group on campus with the hopes of finding ways to better integrate the arts into the education of health care professionals.