The Evolution of Love

Zebra finches who mate for 'love' are better parents than those who don't...
17 September 2015




Scientists in Germany have shown that, for zebra finches, "falling in love" makes them more successful parents.

In a study published in the journal PLOS Biology, finches which chose their partner had 37% more surviving young.

It is possible that the study sheds some light on the human pursuit of love.

People can spend years looking for the perfect person to settle down with, there are endless dates; awkward encounters and miserable break-ups, all in the pursuit of love. But what is the point? If the purpose is ultimately to further our own species, why bother with love?

Now scientists at the Max Planck Institute for Ornithology have found what might be the true purpose of love, with the help of a special little bird.

Zebra finches share many dating similarities in common with humans. They have lifelong monogamous relationships, they divide up parental responsibilities, and their choice of mate isn't always predictable. 

And also like us, female finches don't always agree on what makes the perfect mate. Instead, they choose their lifelong partner based on behavioural compatibility, rather than the compatibility of their genes. 

Lead scientist Malika Ihle conducted the study on 162 zebra finches, which were allowed to mate freely.

During the finch 'speed dating' the birds were able to choose their own mates. Of those which formed partnerships, Ihle took half and switched the male partners, so that half of the females were paired with a partner they had not chosen.

The two groups of finches were then left to mate, and the scientists observed their behaviour and the fates of their eggs.

"The assigned pairs were less lovey-dovey... they were less close to each other... the females of the assigned pairs were less willing to copulate with their partners," Ihle explains.

The males of the assigned pairs also behaved differently. They were more promiscuous and less attentive of the nest.

Most significantly, 37% more chicks survived when their parents had chosen to be together. 

Ihle was able to conclude that the finches had chosen their partners based on behavioural compatibility not genetic.

This is because the survival rate of finch embryos did not differ between the two groups, whereas chick survival was much higher in the group who had chosen to be together.

Previous studies have shown that embryo mortality is a result of genetic incompatibility, whereas chick mortality is because parents have incompatible behaviour. 

This means the finches who chose each other did so based on behavioural compatibility. In other words, maybe they chose each other for "love", which ultimately made them more successful parents...


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