Birds And The Bees: Picky Mating Practices Of Zebra Finch Give Insight Into Evolutionary Advantage Of Human Dating
Humans are particularly picky when it comes to picking a mate, which is why dating often seems like a long and tedious process. However, there may be an evolutionary benefit to all of it, according to a recent study.
For the study, published Monday in the open access journal PLOS Biology , a team of researchers from the Max Planck Institute for Ornithology in Germany attempted to understand why we fall in love in the context of evolution, and why courtship and romance play such large roles in it. To do this, the team observed the mating rituals of the zebra finch, which, although it may not be noticeable at first glance, exhibit mating behavior that is very similar to humans. These tiny birds are monogamous for life , and share the burden of parental care. But perhaps the most notable similarity between humans and finch is that the females have their own unique criteria for traits they find particularly attractive in male partners.
“In that sense we could speculate that humans may also choose their partner based on behavioural compatibility criteria, either to match their personality or coordinate their behavior, or because individuals are specifically (idiosyncratically) attracted by a particular partner,” Dr. Malika Ihle, one of the researchers involved in the study explained to Medical Daily in an email.
In a population of 160 birds, the team allowed groups of 20 females to choose freely between 20 males. According to a press release , once the birds had paired off, half of the couples were mated happily while the other half was split up and forced to mate with a bird they had not purposely selected.
Results revealed that chicks born from finches that mated with their chosen partner had a 37 percent higher survival rate when compared to chicks from non-chosen pairs. In addition, the nests of the arranged pairs had three times more unfertilized eggs as well as a higher number of lost and buried eggs.
The team believes that part of the reason more of the arranged pairs’ chicks died was because of parental negligence . The highest number of chick deaths occurred during the first 48 hours of their lives, a time considered to be most crucial to their survival. The researchers found many of the males were less diligent in their nest-care duties during this time. However, female birds also played a part in having a lower number of surviving offspring, as they were far less receptive to the advances of other mates, and thus copulated less frequently. Infidelity was also markedly higher in male birds from the arranged pairs and an analysis of harmonious behavior revealed there was generally less affection between these pairs.
The team concluded that the “dating” and mate-selection process of the zebra finches led to increased parental commitment and female copulation rates — two factors that helped to maximize the couple's likelihood of successful breeding. Although the zebra finches are an entirely different species, the researchers believe these parallels in mating behavior reveal the evolutionary importance of dating and love in human relationships . Yet, despite the insight the findings might provide when it comes to dating behavior, the researchers said the results may not accurately reflect human behavior in an arranged marriage. This is because in the experiments the finches were forced to breed with partners they had already interacted with and rejected as a mate. This practice is not often seen in arranged marriages.
“In humans, I believe the family (who I assume care about the happiness of their children) choose [who] they think would be a best match for their child, and they might actually know who would be a good or compatible partner,” explained Ihle.
Source: Ihle M, Forstmeier W, Kempenaers B. PLOS Biology . 2015