Evolutionary Magic Tricks?

This is a photo of a Bower bird’s courtship layout of leaves, all shiney side up. I’m not sure if this bird uses the Ame’s room approach but the following description of the Bower Bird’s behaviour is fascinating to the extent that it makes me wonder, how does evolution come to that? I’m imagining some bird that is born with perceptual ‘dysfunction’ and begins this obsessive layering of leaves. But, hey, all insights appreciated.

So this from the CSIRO ‘Science by email’  “In 1934, the American ophthalmologist Adelbert Ames Jr. designed and created a strange room that would make Alice feel as if she was back in Wonderland. Its four walls were arranged as a trapezium and its floor painted as a warped checker-board. Yet from the perspective of an observer peeking in through a tiny window, it looked as if it was your average, square-shaped room. As a result of this illusion, two people standing in opposite corners would look to be very different sizes to anybody looking in. You can visit an ‘Ames room’ in many science centres and museums around the world. However, it seems Adelbert might have been beaten to the punch. By a bird, no less. Bower birds are famous for their architectural skills. While different species make their nests – or ‘bowers’ – in different ways, they’re all used by the male to attract a mate. One approach taken by some species is to bend the vegetation into a ‘U’ shape, creating a walled corridor in the undergrowth. Some even scatter bright ornaments on the ground, such as berries, flowers, shells or even pieces of plastic or other rubbish. The prettier the bower, the better he looks to a potential girlfriend. An evolutionary ecologist from Deakin University has recently noticed that the male of the species known as the great bowerbird arranges his ornaments according to size, placing smaller pieces at one end of the bower and larger pieces at the other. It’s not just a coincidence, either. If the pieces are moved, the bird tidies up and returns them back to the same spot. Given that the bird’s brain recognises visual clues in a similar way to our own, big objects in the distance and small ones up close would make the nest look smaller than it really was to those standing at one end. Expecting the female bird to approach from one side, the male might have evolved this unusual behaviour as it made him look larger than he really was, just as the Ames room makes people in it to appear bigger. “

I have visited an AMES room in New Zealand. It is truly a weird experience.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s