AP Biology class blog for discussing current research in Biology

Tag: love

The Science of Love

The neurobiology of love is not as simple to figure out as one may think. Throughout time, researchers have studied the prairie vole when looking to discover more about what exactly is going on in our brains when we fall in love. The prairie vole is used because they form monogamous relationships, in which they show empathy for and display actions that we would describe as love. The monogamy of prairie voles was tested and proven nearly 50 years ago, and since then, we have been researching prairie voles to discover the neurobiology of their love.

Prairie vole.gif
When first looking at exactly what happens in a prairie vole’s head when they “fall in love” the hormones oxytocin and vasopressin were found to play a key role in the bonding of prairie voles. These hormones work just as any hormone we have learned about in this AP Biology class does, they are peptides that bind to receptors, resulting in the change of the shape of the receptor, resulting in a change within the cell. This signal caused by oxytocin and vasopressin has been shown have the ability to change a solitary or polygamous prairie vole, into one that forms a monogamous bond with another prairie vole. This is unique to other voles, as the receptors for these hormones in prairie voles are in a separate location to those within other types of voles. This discovery opened up a doorway into understanding how the location and abundance of hormones receptors can affect the bonding of animals or even ourselves. In order to truly understand this though, researchers had to find a way to manipulate the ways that genes encode these receptors.

Vasopressin labeled  Oxytocin

Vasopressin                                               Oxytocin

Although this phenomenon has been well studied in the past,  the invention of CRISPR technology has opened many more doors into studying the ways that these hormone receptors work. Throughout time, it has been accepted that oxytocin in the true hormone that controls the bonds of these prairie voles. But, after a research team used CRISPR to “delete the gene that encodes the oxytocin receptor in prairie vole embryos,” it was found that the genetically modified prairie voles were still able to form bonds as easily as their non-modified brethren. Scientists are now trying to really figure out what the biology of the love of these voles is, as their original hypothesis that oxytocin controls it has been found incorrect. Scientists are now looking to hormones such as vasopressin, to see if that was the missing part of the puzzle they need. This discovery that oxytocin is not the entire basis of the bonding of prairie voles does show that as usual, love is less complex than we may think, and that they must look at the neurobiology of love as having a much bigger scale than before thought of.


Currently, scientists are aiming to look at the activity of genes in the brain to further look to what causes love bonds. Recent studies like this have shown that after the voles have mated, genes important to memory and learning are turned on, and that their brain’s reward structure turns on after a stable amount of time with a bond. These studies have also proven that the voles brains become “activated,” once they have created a bond, as their neural activity “lights up” and their brains “re-wire themselves.”

“How does this relate to us humans?” you may ask. Well, the ways that prairie voles react to their bonds can show us what an evolved brain, which neurologically is wired to have a partner. The studies done on prairie voles inspired scientists to look back closer at the reward structures pf the brain looked at in studies for prairie voles, and it was found that humans had similar responses to the voles. Overall, with much more time to let research and technology develop, studies on prairie voles have definitely taken us one step closer in understanding the science of love.

Can Science Explain Love?

Sometimes it’s the greatest feeling in the world. Sometimes it hurts. Although we may never derive a fundamental recipe for it, much of love can be explained by chemistry and biology.

The brain (not the heart!) is responsible for romantic love, which, according to Dr. Helen Fisher at Rutgers University and Katherine Wu at Harvard University, can be broken down into three categories: lust, attraction, and attachment.

Credit: “Hearts” by eflon on Flickr.

Lust is our yearning for “sexual gratification.” This facet of love is grounded in our evolutionary, inherent need to reproduce. Lust is stimulated when the hypothalamus releases “sex hormones (testosterone and estrogen) from the testes and ovaries.”

Whereas lust concerns merely “sexual gratification,” another aspect of love, attraction, encompasses a variety of emotions with regard to a specific person. Attraction leads to the release of the chemicals dopamine and norepinephrine. As anyone whose ever been attracted knows, these chemicals make us “giddy, energetic, and euphoric.” Attraction also stimulates the brain’s reward center, which fires “like crazy when people are shown a photo of someone they are intensely attracted to.” Another hormone, serotonin, is found in low levels in both people with obsessive-compulsive disorder and people those who are experiencing attraction. As a result, scientists have theorized that attraction, and the ensuing low level of serotonin, is responsible for the obsessive infatuation so common in love.

The third aspect of love, attachment, is responsible for intimacy, is a key factor in long-term relationships, and is, of course, mediated by hormones.  The two hormones responsible for attachment, oxytocin and vasopressin, “are found in large quantities during sex, breastfeeding and childbirth,” all activities that are “precursors to bonding.” From this, it is easier to understand the concept of three different aspects of love: the “love” parents feel towards their children is merely the attachment aspect of it, but neither the lust nor the attraction aspect.

Although science can give us a biological basis for it, love, and all of its intricacies, can never be fully explained.

Learning to Love

Photo Credit: Victoria Made Flickr

For years, scientists have believed that the nurture and love we receive from our parents when we are an infant, determines how we are when we are older. We learn very early on to trust and love and the relationship you have with your parents when you are a baby can affect relationships you have later in life. For example, researchers say that a mistreated infant may turn argumentative in stressful situations, while nurtured babies tend to deal with stress more skillfully.

Researchers Simpson, Collins, and Salvatore put babies and their mothers in high-tension situations and then years later researched the babies’ relationships. The researchers found that there is a link between the situations babies are put in and the relationship to the mother, and later relationships and stress management. However, they also found that although there is a link, it is not an extremely strong factor. You can learn to love, trust, and throughout your life, even if something traumatic did happen in your infancy.

Dear Darwin: What Makes Ryan Reynolds “Sexy”?

Photo Credit: Paco Paco Flickr

Now we all know that a big jaw, prominent brow, and bulging muscles are conventionally thought of as attractive features in a man and that large breasts, an hour-glass figure, and big eyes are attractive in women, but have you ever wondered why?

Well the answer lies in an unexpected place: science. According to the Evolutionary Theory of Attraction, what men and women  perceive to be attractive is actually based on adaptational behaviors that traditionally helped survival. Studies show that women look for masculine features such as a defined jaw, prominent brow, and muscular build because these often to reflect physiological and behavioral traits such as strength, aggression, virility, and a strong immune system, which would be advantageous to pass on to offspring and would mean that the man can provide and protect his family.

So while women’s attraction is rooted in a man’s ability to provide for his family, men on the put more emphasis on signs of fertility and youth. The hour-glass figure: large breasts and “child-bearing” hips, and youthful features such as plump lips, a hip-to-waist ratio of 0.7, a face with a high forehead, good skin, and big eyes are signs to men that the prospective mate is fertile and young. Such features helped ensure the male that his genes would be passed on to his offspring. Other factors such as symmetry, especially facial symmetry, is attractive because it means that there are strong genetics at work according to researchers and experts.

Recent studies show that when a woman chooses a mate, often times she must subconsciously choose between a macho man and his more wimpy counterpart depending on her situation. While the macho man has preferential genes to pass on to offspring, these traits often mean tendency to abandon, hostility, and promiscuity. The less masculine man is more likely to provide the stability, love, and care for a family. In fact, according to expert, Dr. DeBruine’s study, a woman’s environment greatly plays into her attraction between these two types of men. In her study on women in countries with poor health standards, women preferred men with more masculine features more than those who lived in more stable and healthy societies. This is a classic example of natural selection because the women look for healthier genes often associated with masculine, macho attractive men.

So that is why we find movie stars like Angelina Jolie, Brad Bitt, and Ryan Reynolds are attractive: evolutionary adaptations meant to help ensure our survival and the successful passing on of genes to offspring. Do you agree with this theory of attraction? And which category would you put yourselves in ladies, those who go after Mr. Sensitive or those who go after Mr. Dangerous?


For more on this go to:—Evolutionary-Theory&id=2236366

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