
Birds can see Earth's magnetic fields because of cryptochromes in their eyes - startupflix
https://www.sciencealert.com/birds-see-magnetic-fields-cryptochrome-cry4-photoreceptor
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pknopf
I'm not sure why, but the few times in high-school that I took acid, I could
see lines in the night sky going north to south. It was deterministic, like
clock work.

Does anybody have an ideas why? I mean, I wasn't really hallucinating, I
didn't take too much. I could always truely find north or south. I couldn't
tell what was north or south, but I could draw the line, always.

Am I crazy? I mean, I'm not saying I'm a bird, but...

~~~
caf
Even if you could see magnetic fields, it wouldn't look like lines in the sky
running north to south, so this does sound like an hallucination.

~~~
taneq
So what would a magnetic field look like (to the naked eye, not just a
visualisation of field lines with iron filings or similar) if you could see
it?

~~~
allthenews
Well, I imagine the crystals can only perceive single vector values of the
magnetic field at the position of the eye. Imagine each censor returning a
vector defining the magnetic field at a point on the eye. There probably
wouldn't be any way to focus or change depth of perception like one could with
light. You'd have to move your eyes through space to get more than a localized
snapshot.

But, you can probably predict what a magnetic field looks like away from the
point of measurement, I.e. the eye. What is fascinating to me is that they
could potentially be learning to deal with manmade magnetic fields, adapting
to human culture in a possibly novel way.

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eganist
_grep "power line"_

...am I really the only one who thought about whether this might contribute to
why power lines are so attractive for birds to perch on?

~~~
pjpor
I suspect the magnetic field around a power line is thousands of times more
powerful than earth's magnetic field.

It would likely overload the birds senses and not be a pleasant experience.

~~~
jakubp
Their perception could be non linear, much like our perception of light
intensity. Or it might be adjusted automatically to a higher value, dimming
the earth's field but making power lines "bright" but not blinding.

What a cool possibility overall!

~~~
goalieca
There’s a difference with power lines because it runs an AC current. The
earths magnetic field is static for all intents and purposes.

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tzs
I wonder if they would perceive unnatural magnetic fields, particularly small,
strong fields as something strange enough to avoid?

If so, I wonder if one could discourage birds from hitting windows by
arranging for a strong magnetic field outside the window?

There are ways to discourage birds from flying into windows, but they often
make the window less useful to humans.

~~~
mdesq
Or keep them away from airports.

~~~
pjmlp
Eagles are very good avoiding planes and working as airport security buddies.

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ChuckMcM
This raises some interesting questions for me.

First since I've been doing some Software radio stuff of late, I'm wondering
if there is a way to build a chemical detector for magnetic fields that would
allow one to pick up signals without a giant magnetic loop antenna. The paper
(linked in another comment) suggests that the frequency response is low (1uS
to 100uS) so it would not be a high bandwidth link :-).

The other is what happens when the poles swap?[1] Do the birds commit mass
suicide as they fly north for the winter and south for the summer?

[1] [https://www.extremetech.com/extreme/192522-earths-
magnetic-f...](https://www.extremetech.com/extreme/192522-earths-magnetic-
field-could-flip-within-our-lifetime-but-dont-worry-we-should-be-ok)

~~~
basementcat
Geomagnetic reversal is not some atomic event but a gradual process lasting
for several kY. Different parts of the Earth are in different stages of of the
reversal, some further along than others.
[https://en.wikipedia.org/wiki/South_Atlantic_Anomaly](https://en.wikipedia.org/wiki/South_Atlantic_Anomaly)

~~~
ChuckMcM
"Atomic" no, but there is evidence it isn't kY either. The article I linked
was one of many that discussed the implications of the paper "Extremely rapid
directional change during Matuyama-Brunhes geomagnetic polarity reversal" [1]
published in 2014. In that paper, the authors studied different Lava flows
that suggested a reversal can happen in a single human lifetime, with a change
as rapid as 6 degrees per day.

I believe that a polarity change in fewer than 100 generations would be
challenging for most species that see or use the magnetic field to adapt.

[1]
[https://academic.oup.com/gji/article/199/2/1110/618671](https://academic.oup.com/gji/article/199/2/1110/618671)

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lurquer
Is there practical expirementsl evidence demonstrating birds can sense
magnetic fields? That is, can you train a bird to select between two boxes,
one of which contains a strong magnet?

Just wondering. I'd read about theories regarding iron in the beaks and
whatnot. Sounds cruel, but why not (a) train the bird to select the magnet,
then (b) remove beak and check if it can still do the trick, or (c) remove
eyes and see if it can still do the trick.

I'm not entirely sure, though, that (a) has been accomplished. Can't find
anything on it.

~~~
piptastic
maybe just blindfold the bird, instead of removing the eyes

~~~
jrimbault
Don't most bird just go to sleep when blindfolded ? Or is it just an idea that
got in my mind ?

~~~
SAI_Peregrinus
They don't tend to actually sleep. They do become more docile, because they
can't see to fly without risking hitting something.

~~~
jrimbault
Thinking about it, it was pretty dumb on my part. I know about hunting birds,
I should have thought about that.

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everyone
I wonder if the Earths magnetic field flipping every half a Million years
affects birds untowardly? Or have they evolved to deal with it?

~~~
gilgoomesh
If the images in the article are accurate, the birds don't really see the
polarity of the field, merely the alignment, so they don't really see "north",
"east", "south" and "west", merely "latitudinal" or "longitudinal".

They would probably combine with sunlight to get the real orientation – an
approach which would continue to work with a flipped magnetic field.

~~~
andai
If you have 3D polarized glasses from the cinema you can go outside on a sunny
day see this alignment in the sky. It's really cool, highly recommended.

~~~
spacehome
You can see it with the naked eye, too, near the center of your vision.

[https://en.wikipedia.org/wiki/Haidinger%27s_brush](https://en.wikipedia.org/wiki/Haidinger%27s_brush)

------
fmntf
If you liked this story, I recommend you "Life on the Edge: The Coming of Age
of Quantum Biology".

[https://www.amazon.com/Life-Edge-Coming-Quantum-
Biology/dp/0...](https://www.amazon.com/Life-Edge-Coming-Quantum-
Biology/dp/0307986829)

------
jugg1es
This is really hard to understand in terms of how the eye works. Conventional
sight works by detecting photons hitting the retina. But "seeing" a magnetic
field seems like it would only work when the eye is literally inside of the
field. Magnetic fields don't project or reflect off of things, they are where
they are. The eye would have to be directly affected by the field to see it.

And then they wouldnt be able to see parts of the field they are not currently
in. Magnetic fields don't radiate anything, they ARE the radiation. It's like
trying to see a laser that is not pointed at your eye. It's there, but it cant
be detected because no photons from it are hitting your eye.

~~~
mygo
you can see a laser that is not pointed at your eyes. Use fog.

The atmosphere is known to diffuse the vectors of electromagnetic radiation.
That’s how we get blue skies and red sunsets. Who says it’s not having the
same effect on earth’s magnetic fields

~~~
jugg1es
You are kind of proving my point though. With fog, you can see the laser
because photons are bouncing off the fog and hitting your eye. This article
isn't saying that photons are bouncing the magnetic fields and then hitting
their eyes, they are saying the eyes can literally detect magnetic fields. If
the birds were seeing magnetic fields via how they interact with photons, then
everyone would be able to 'see' magnetic fields because we can all see
photons. This is saying that the magnetic fields are directly visible by
birds.

~~~
mygo
I’m aware that photons have to physically interface with the retina to be
seen. You’re missing my point. Earth’s atmosphere acts like the fog as a laser
travels through it — it diffuses the vectors, making them visible to an
observer not along the path from the light source. When you look up at the
clear sky during the day you don’t see the sun and then pure black space (and
stars).

Likewise the effects of the magnetic field interface with earth’s atmosphere.

For example Earth's magnetic field deflects solar wind. The solar wind
interacting with the magnetic field transfers some of its energy into earth’s
atmosphere.

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JumpCrisscross
Could someone please explain the physics in respect of how blue light and
magnetic fields measurably interact with this protein?

~~~
CitizenKane
It's actually linked in the article, this explains more about the working
theory they have [https://physicsworld.com/a/birds-measure-magnetic-fields-
usi...](https://physicsworld.com/a/birds-measure-magnetic-fields-using-long-
lived-quantum-coherence/)

------
gcb0
title was not click bait. they can actually see it. nice. can't wait for the
bodymod crowd to catch up on that one

~~~
piracykills
They've already managed to use CRISPR to give color blind primates their full
vision back...

[http://www.neitzvision.com/research/gene-
therapy/](http://www.neitzvision.com/research/gene-therapy/)

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unit91
> Whoa, evolution. Just... whoa.

At some point this really starts to sound ridiculous.

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hyperpallium
What is it like to see a magneric field?

Because it's in their eyes, it would have a visual interpretation. And some
evolutionary advantage to that visual advantage, else the cells could be
anywhere (unless there's a biochemical similarity to cones?)

However, a field isn't like photons hitting the retina. It would probably be a
new colour, which we can't imagine, but I'm asking where that colour would
appear, to indicate the field.

Perhaps a faint fog, varying in strength with direction - like the sky at dusk
and dawn.

~~~
caf
There are some speculative illustrations at the bottom of the article.

------
andai
If you have 3D polarized glasses from the cinema you can go outside on a sunny
day see this alignment in the sky. It's really cool, highly recommended

~~~
caf
That's not a magnetic field, that's polarisation of the light in the sky due
to scattering.

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volkk
Slightly off topic, but I am so thankful for firefox's reader. The amount of
annoying ads blinking/flashing is enough to drive me up a wall

~~~
abrowne
You should try Firefox's tracking protection. This was actually one page I
_didn 't_ use reader view for!

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tahw
Can anyone explain in layperson terms how this is different from regular old
polarization?

~~~
iaw
Light travels from one point to another in a direction.

Perpendicular to that direction light "wiggles" on it's way from origin to
destination.

The direction of the 'wiggle' is the polarization of the light.

Unpolarized light wiggles in every direction while polarized light only
wiggles in one.

Certain things (like how the sun shines on the sky) creates polarized light
naturally.

The earth's magnetic field DOES NOT polarize light.

Birds have a protein in their eyes that uses blue light + the earths magnetic
field to visualize the magnetic field around them.

Similar to visualizing the polarity of light, we lack the ability to visualize
magnetic fields, making both foreign concepts.

------
jasonkostempski
I've heard people can too if they look at the sky under the right conditions.

~~~
tangent128
[https://en.wikipedia.org/wiki/Haidinger%27s_brush](https://en.wikipedia.org/wiki/Haidinger%27s_brush)
is a real and really cool phenomenon, but it detects light polarization, not
magnetic orientation.

~~~
jasonkostempski
Does the polarization of the light in sky correspond with the poles of the
earth? If so, since the effect has direction, wouldnt you have a compass in
the sky?

I was just able to see the effect for the first time using this image [1] full
screen on my phone :) Brightness up, screen rotation off, hold out the phone
and turn it like your steering a car. Jumped right out at me. It's always at
the center of my vision, so if I look around the screen as I'm turning, it
follows. The yellow always points to the longer edges of my phone. It's hard
to hold it in view when not turning though.

[1]
[http://www.solidbackgrounds.com/images/2560x1600/2560x1600-v...](http://www.solidbackgrounds.com/images/2560x1600/2560x1600-vivid-
sky-blue-solid-color-background.jpg)

~~~
jasonkostempski
Looks like the polarization in the sky coresponds to the sun, not the poles.
[https://mysite.du.edu/~jcalvert/optics/haiding.htm](https://mysite.du.edu/~jcalvert/optics/haiding.htm)

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neom
So couple this with evolution and you have migration, no?

~~~
mywittyname
Probably migration existed first, but those with the ability to see the
magnetic field were much more successful at migrating, probably due to
expending less energy during.

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ada1981
If birds can figure out how to have blockchain based browsers embedded in
their eyes to help with navigation, why can't we just copy that tech for our
own uses?

Can we do an Initial Cryptochrome Offering?

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smrtinsert
I would love to add this ability.

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iaw
Flagging for a title change, perhaps:

"Birds can see Earth's magnetic fields due to protein in their eyes"

or the original, more clickbait-y title:

"Birds Can See Earth's Magnetic Fields, And We Finally Know How That's
Possible"

~~~
dang
Seems to me the first part of the title makes a reasonable whole title, so
let's go with that for now.

Also, we changed the URL from
[http://archive.is/SlcSL](http://archive.is/SlcSL). archive.is is an excellent
site for archiving, but not for HN submitting, because it's important for
readers to see the actual domain. For the same reason, we don't allow link
shorteners.

~~~
stan_rogers
The eye link to magnetic field navigation has been known for years; the
mechanism has not been.

~~~
dang
Ok, we've put some cryptochromes in the title.

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tzahola
Cryptochromes? Will there be an ICO?

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rs86
Crypto birds? I'm in

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phasnox
Cryptoc.. what? Crypto?! Sir when ICO?

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askafriend
Is it bad that I first thought of the electric scooter company Bird?

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John_KZ
If the cryptocrome mechanism is real, that's pretty spectacular. I thought
that the idea of magnetoreception was mostly abandoned in favor of visual
navigation, but I was wrong.

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digitalshankar
Cryptochromes? That sounds like Google launched a cryptocurrency. These birds
are mining Cryptocurrency using Magnetic fields. LOL!

