23 and We? Mating for Life Could Be Genetic

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Spending Valentine’s Day with your sweetheart might just take on a new meaning … an evolutionary one. Even though we live in an era in which endless opportunities for a mate are just a swipe left or right, science suggests that maybe we all have that one special someone out there.

Social monogamy is the practice of forming pair bonds in a two-partner relationship. One explanation for monogamy is to protect offspring—one partner takes care of the baby while the other hunts for food. Another more gruesome theory is that animals living in pairs evolved to prevent rival males from killing a female’s baby in order for the male to then sire his own. But why many different species became monogamous remained unanswered. For a long time, all scientists knew was that certain brain regions and hormones (like the “love hormone” oxytocin) played a role.

A new study suggests that there may be a genetic explanation for why animals and people evolved to mate in pairs. Researchers from the University of Texas at Austin explored the monogamous behaviors of various animals on a molecular level and how their behavior differs from non-monogamous species. The researchers studied genes that play a role in certain animal behavior development and traits. These genes are called candidate genes. A candidate gene that occurs more frequently in monogamous animals could mean it plays a role in why that species is monogamous.

The researchers found 24 different candidate genes associated with a monogamous mating system. These genes are also involved in functions such as development of the nervous system, cell signaling, learning and memory. They probably also allow animals to recognize and remember their mate.

Animals may share a common genetic formula for monogamy, highlighting that this behavior is advantageous and rewarding in some species. Natural selection would have conserved these genes in some species over thousands of years of evolution while “turning them off” in other, more promiscuous species.

Scientists don’t know if humans express these same genes, but the fact that similar patterns of gene expression are seen in all sorts of different monogamous species suggests we might. So, even in a society where monogamy is thought to be culturally reinforced, a genetic element might also explain why we choose to say “till death do us part.”

Brady Holmer HeadshotBrady Holmer is a PhD student in exercise physiology at the University of Florida. His lab focuses on cardiovascular physiology; mainly how exercise can play a role in health, disease and aging. 

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