Your Cheating Heart

Image – Keith Gerstung

Zebra finches are very pretty birds that live happily in large colonies. They are monogamous – well, usually. In the wild, they cheat on their mate occasionally. It is worth noting, though, that when held in a large aviary, the cheating increases markedly. Aviaries are not so exciting as the wider world out there, I suppose.

The “flighty” nature of the females in a large captive colony has been investigated and reported on by Fortsmeier et al (1). Free males and females went through a speed-dating event to gauge the perky nature of the females and the lotharioc nature of the males. The bedroom habits of a subset of pair-bonded individuals were carefully recorded.

The question to be answered here was “was the reason for their infidelity, nature or nurture?” The results showed a strong tendency for daughters of promiscuous males to be promiscuous in turn. So, they couldn’t help it. But that wasn’t the total reason. There were some errant daughters from fine upright males, so a really good line from a particularly good looking and smooth singing young male could overcome the poor young female’s better judgment.

You may think that the private life of zebra finches should be no ones business but theirs, but it confirms some studies on promiscuity among young adult humans (2).  In their study, Garcia et al showed that the dopamine D4 receptor gene was a good indicator of promiscuous tendency. If there are seven or more repeat alleles in their D4’s, then they are likely to be experienced with “one night stands” and  also more likely to dabble in infidelity.

This is bringing us right back to the good feelings we have of sex, drugs and rock and roll, which, of course, we all imagine that we discovered for ourselves and wouldn’t want to think that we inherited it directly from Mom and Dad.


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