Cincy Science: It's not spring, it's oxytocin and vasopressin that turn our thoughts to love

HIGHLAND HEIGHTS, Ky. - It’s spring and love is in the air, or so we’ve come to believe. The famous poet Alfred Lord Tennyson once wrote, “In the spring a young man’s fancy lightly turns to thoughts of love.”

So is there something to the notion that more people actually fall in love in the springtime?

To unlock the mysteries of the heart, we turned to Mark Bardgett , Northern Kentucky University regents professor and director of the interdisciplinary minor in neuroscience , to shed some light on the brain chemistry involved in falling in love.

1. What is the physiological reason why we fall in love?

“For the most part, scientists have steered clear of this question because defining what one means by ‘love’ was seen as better left to poets and the Beatles. But in the late 1990s, neuroscientists decided to address this question from a very unorthodox perspective. It has been long known that one species of vole (voles are small hairy rodents that live in the wild) called the prairie vole lived in life-long, monogamous pairs, as opposed to other species of voles. It was found that these prairie voles had high amounts of two peptides called oxytocin and vasopressin in their brains, and that blocking receptors for these peptides caused the prairie voles to venture away from their life-long partners and ‘start playing the field’ (for example, explore unfamiliar, opposite sex voles), so to speak.”

2. So this same concept holds true in humans?

“Subsequent studies have explored the role of oxytocin and vasopressin in human romantic partnerships. Oxytocin levels are higher in people who have recently fallen in love versus unattached singles. Oxytocin administration to human males in a committed relationship causes them to rate their partner as more attractive and increases activity in brain reward centers when viewing their partner's face. On the other hand, slight dysfunctions or perturbations to brain vasopressin receptors have been associated with greater partner conflict in human males.”

“I'm not telling my wife that my attraction to her is all because of my oxytocin and vasopressin levels, but they may account for some proportion of why we (all humans) fall in love.”

3. Do we fall in love or desire companionship more in the spring?

“I am not sure what the answer is here. If falling in love or companionship is linked at an evolutionary level to fertility and reproduction, that it would make some sense that even humans would be more likely to express love or seek companionship during the spring, especially if in our history as a species, we, like other animals, used to spend our winter months in a dormant type of state.”

4. I've read melatonin levels (the hormone that helps regulate sleep) may increase during winter months, making us more tired and less concerned with romance. Is that true?

“Melatonin secretion has been implicated in seasonal affective disorder since its release from neurons in the brain appears to be regulated by the length of daylight. However, whether it plays a causal role in seasonal affective disorder has not been well established. I am unaware of research linking melatonin levels to romantic love or seasonal changes in attraction or even mating.”

5. I've also read animals are more likely to reproduce in spring. Is it the same in humans?

“It looks like there is some evidence that conception increases in humans in the spring, but also again in the fall.”

Bargett referenced a 1990 study published in the New York Times, which pointed to evidence of higher birthrates during ideal conception time which is “when the sun shines for about 12 hours and the temperature hovers between 50 and 70 degrees Fahrenheit.” The study showed birthrates remained constant in areas where the weather stayed consistently warm and sunny yearlong and higher birth rates during winter months in areas where seasons changed, indicating increased conception during the spring.

To see if the theory of amour in the springtime holds true for other species, we contacted Thane Maynard , executive director of the Cincinnati Zoo .

1. In regards to our friends in the animal kingdom, do you see romance increase during the spring at the Cincinnati Zoo?

"It’s an interesting thing, because different animals have different breeding cycles. It is true that many, many animals – say for example nesting birds that may be in your own backyard. They make it through the winter and they migrate back and in the spring depending on the species, that might be as early as February or as late as May. They establish their territory and build their nest, mate and have their young. That of course coincides with the seasons because of the availability of food going from a harsh winter to an abundant spring – so you have enough food to feed your young. So that is a natural cycle in this part of the world. But typically spring is the most abundant season for baby animals to be conceived in nature."


So has this been a busy spring for breeding?
This spring we have a bunch of babies here and on the way, no doubt about it for our zoo baby celebration we do in May.


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