Love has been a subject of interest ever since we arrived on this planet. Many modern studies are trying to understand why people fall in love and whether monogamy leads to better or worse relationships.
Some of these questions may have been answered by a new study that investigated why Zebra Finches fall in love. Zebra Finches are birds that generally practice monogamy and pair up for life. They form “marriages” not unlike those of humans and center them on the well being of their children.
But just like humans, not all Zebra Finches are sexually monogamous. Both male and female members of the species have been observed seeking out sex partners outside their “marriages”.
Another similarity between these birds and humans is that female Zebra Finches aren’t all drawn to the same male Zebra Finch because of his superior genes. Each female has a unique taste in men and will choose her partners based on traits that are important to her.
Malika Ihle, field expert from the Max Planck Institute for Ornithology, and her colleagues wrote in their study that “zebra finches choose mates on the basis of behavioral compatibility”.
In order to assess how successful or unsuccessful a bird couple’s relationship was, the research team first put several members of the species in a room so that they could mingle and pair up.
After the females chose their partners, the researchers split couples in two (2) groups. The couples in one group were kept intact, whereas the couples in the other group were split up and forced into arranged marriages with random suitors.
The researchers were not surprised to notice that Zebra Finches that were allowed to choose their own partner had better reproductive success. What’s more, the baby birds of these couples were 37 percent (37%) more likely to survive, compared to the baby birds of Zebra Finches in arranged marriages.
Another finding was that Zebra Finches in arranged marriages were much more likely to practice infidelity. The first ones to cheat on their partners seemed to usually be the female Zebra Finches, but the male Zebra Finches followed soon after their “wives”.
It’s worth mentioning that the male Zebra Finches in arranged marriages were just as loving with their partners as the ones in couples where the birds were allowed to choose each other.
The Zebra Finches forced to be together were less fertile and paid less attention to their children once they hatched, which resulted in many of them dying. These couples had about three (3) times more unfertilized eggs than the couples where the birds chose each other.
One theory as to why this happens is that the males and females in arranged marriages have a high behavioral incompatibility, rather than a genetic incompatibility. Female Zebra Finches simply didn’t respond to their “husband’s” affection when being forced to be with someone they weren’t attracted to, or when they suffered a trauma after being slip from a partner that they did care about.
The findings were published earlier this week, on Monday (September 14, 2015), in the journal PLOS Biology.
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