Beauty in the right eye of the beholder – finch chooses better mates with its right eye


It’s said that beauty is in the eye of the beholder, but that’s only half-true for the Gouldian finch. Jennifer Templeton from Knox College, Illinois has found that these beautiful birds only display their famous fussiness over mates if they’re looking with their right eye. If the right is shut, and the left eye is open, the birds have more catholic tastes. As Templeton writes, “Beauty, therefore, is in the right eye of the beholder for these songbirds.”

The Gouldian finch, found in northern Australia, looks like a bird painted by Gauguin. Its palette includes a purple chest, yellow belly, green wings and cyan highlights. But it’s the head that really matters. They come in red or black (there’s a very rare yellow variant too, but we can ignore that here), and they strongly prefer to mate with partners of their own colours. This isn’t abstract fussiness – genetic incompatibilities between the black-heads and red-heads mean that their offspring are often infertile and feeble. Indeed, these two variants could be well on the way to becoming separate species.

Red and black finches are so easy to tell apart that scientists could be forgiven for neglecting how they do so. But Templeton suspected that the act of choosing a mate was more complicated that anyone had thought.

Another type of finch – the zebra finch – provided a clue. The males prefer to watch their intended females with their right eye. The right eye feeds information to the left half of the bird’s brain, and there the asymmetries continue. Genes that are switched on when neurons fire tend to be more active in the left half of a courting zebra finch’s brain than the right half. Maybe the left brain, and thus the right eye, dominates the selection of mates.

Templeton tested this idea with Gouldian finches. She covered the left or right eyes of black males (who show the strongest preferences for their own colours) and presented them with a choice of potential mates. If they could see through both eyes, or just the right one, they spent more time staring at black females than other finches. If they could only see through their left eye, this preference disappeared. Likewise, males were more likely to serenade black females, but only if they could see with their right eye.

Written By: Ed Yong
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  1. If the right is shut, and the left eye is open, the birds have more catholic tastes.

    If they have both eyes shut and heads bowed, do they have Roman Catholic vision and a taste for crackers?

  2. I’ve noticed when the sun is up and too bright I always shut my left eye. I wonder if this is a normal reaction that allows me to reduce the amount of irritating sunlight while remaining fully aware of my surroundings. Perhaps the right eye and left brain isn’t so much about being used to find mates but rather to discern details like colour, fast moving cars, shape. Try the same experiment with food source selection.

  3. Good grief ‘aqui’, we Darwinians really are “surfing the same waves”. You’ve just read my mind (again!). “. . .to discern details like colour, fast moving cars, shape. Try the same experiment with food source selection.” The Bottlenose dolphin of Sth Carolina USA, hunt in packs by herd ‘surfing’ then ‘beaching’ shoal-fish onto the mudflats shallows in an SC river estuary. There is a fascinating Ytube video of these dolphins in action, and the narrator even mentions that  ALL of the dolphins select and grab their prey by flipping onto their rightside!  “ALOHA” 😉   

  4. Dear ‘bluebird’. I think Charles Darwin gave us “a whole new meaning” to the origins of life on Earth just by keeping a ‘right’ good eye on his Galapagos finches! Heres a question for our RDF youngsters. I’m not entirely sure about this, but did Darwin survey and record 13 species of finch out of the 14 Galapagos Islands? If so, what happened to the 14th colony? “ALOHA” 😉 

  5. What is referred to as Catholic tastes? I know! “If thy right eye offend thy faith, pluck it out.” Catholic procreation MUST be conceived in the missionary position. The epitome of BLIND faith.


    I had no idea about the dolphins. Interesting. There looks to be something in it. If I look with my right eye, that is.

    Humans like many animals can be dominantly right handed and with a dominant right eye.  A minority are left handed.  Children can be disadvantaged if their dominant eye is not on the same side as the dominant hand, as this can make hand-eye co-ordination difficult.

    It can also have effect in sports where left-handers / left footers are better in some positions.

    Opponents often find it confusing in table tennis , that I can hold a bat and play with either hand.

  7. Yeah, I’m a bit of a blend on that front. I shoot (rifle, bow) with the right, throw naturally with the left (although I am about 85% equal with right), catch with the left (which makes me shite at baseball). I used to play tennis right and squash left but I have migrated all racket sports to the right (figured out my backhand). I can paint with both but do detail with the right. I write with the right but can write with my left with a little practice. Hockey and golf are both left. I kick left and can kick right when I’m not paying attention.

    When people ask me if I’m right handed I don’t know what to say. Sometimes, I guess.

  8. If the right is shut, and the left eye is open, the birds have more catholic tastes.


    What, you mean they fancy the eggs?

    No, they’re using the withdrawal method.

    I’m glad I met my wife before losing 80% of the sight in my right eye. That said, I don’t think the loss has affected me too much; I mean, Sarah Palin is quite the babe….. Isn’t she?

  9. Dear ‘Alan4’. Down in ‘tropical Torbay’, our Paignton Zoo has a beautiful flock of pink Chilean flamingoes. Out of about 30 birds, I noticed 3 where asleep standing on one leg – the left. Most of the rest where asleep, upright, on the right leg! From another visual clue, it dawned on me that perhaps 1 in 10 pCflams are natural ‘leftfooters’. The clue was the yellow ID tag-rings!   

  10. “From another visual clue, it dawned on me that perhaps 1 in 10 pCflams are natural ‘leftfooters’. The clue was the yellow ID tag-rings! “

    I don’t think they put those on themselves.

  11. Very trendy, those Paignton flamingoes. They like to look nice for the tourists.

    But seriously, flamingoes have the remarkable ability of shutting down only half the body at a time for sleep, so when the right foot is down the left side of the bird is asleep, and vice-versa. Had memetical gone back an hour later many of them would be stood on the other leg, so then 9 in 10 would be ‘left-peggers’.

  12. Presumably the survival rate in the muslim ones is lower as the males will murder their partners for not covering up their brightly coloured plumage & also murder their offspring ***  for talking to different kinds of finch.

    *** NB. Applies to female offspring only.

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