Guaranteed to Blow your Mind (Seriously)
Last edited Tue Oct 2, 2012, 12:58 PM - Edit history (3)
Species of birds have a few different ways of navigating during migration. Some have biological magnetic detectors. Some use culture—learning from the previous generation.
And some use the stars.
It appears that these birds are born knowing the stars, and how to determine north from them. But somebody very clever realized that birds cannot have evolved an innate star map of north and south because the Earth's axis has a large but very slow wobble that cycles every 26,000 thousand years.
Polaris, the star we call the north star, wasn't the north-most star 13,000 years ago. (The visible star that Earth's axis most closely points to.)
26,000 years is a mere blink in evolutionary time. The sky changes too fast for evolution to have created an instinctual knowledge of which star is the north star.
It was a genuine challenge to evolution. How can birds be born knowing which star to follow north?
When we got night vision cameras and such to study birds we found out what evolution had done. These birds are not born with an innate star map. They are born with an innate method for finding the north star!
These baby birds sit motionless in the nest, night after night, staring up at the sky. Over enough hours of observation there is one star in the sky that appears to move the least during the night, and that is the north-most star. And then they learn the pattern of stars around it so they can find that star from different orientations, and so on.
If that doesn't blow a person's mind then nothing will.
This is one of many things that animals appear to be born knowing, but actually have an instinct for learning. (Much like our language instinct. We are not born knowing chinese or english, but we are born with an instinctual method for learning the language we grow up hearing. And toddlers with no language taught to them will make up a language, in the way some identical twins create a language only they understand.)
On edit: I might as well include information about our changing north star. It's 26,000 years... I know it was 20-something.
The identity of the pole stars gradually changes over time because the celestial poles exhibit a slow continuous drift through the star field. The primary reason for this is the precession of the Earth's rotational axis, which causes its orientation to change over time. If the stars were fixed in space, precession would cause the celestial poles to trace out imaginary circles on the celestial sphere approximately once every 26,000 years, passing close to different stars at different times. However, the stars themselves exhibit motion relative to each other, and this so-called proper motion is another cause of the apparent drift of pole stars.
http://en.wikipedia.org/wiki/Pole_star
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I would love to share it with my kids and people I know...absolutely mind-blowing. As human beings with our big brains, we think other animals on this planet are so simple, so mindless; this certainly proves otherwise, and it also reminds us of our interconnectedness and oneness with the universe. Thank you for sharing. 
And you did a great job writing that from memory.
night after night, staring up at the sky.
Over enough hours of observation there is one star
that moves the least in the sky, and that is the
north-most star. And then they learn the pattern
of stars around it, and so on.
YAY *stars and birds*
I wonder if light-pollution can screw up their whole system.
She speaks herself to sleep too, just in conure.
Now that bird, like Alex, is using language in context.
And a sun on shoulder right now, and my quake detector at my feet.
I need to check supplies, he's accurate.
