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N for Nambia, The North and Navigation

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alicecd24
1149032.  Mon Sep 14, 2015 8:12 am Reply with quote

(Inspired by http://www.bbc.co.uk/programmes/b01pqmqq - definitely worth a watch)

Spanning hundreds of kilometers across the Namibian landscape is a phenomenon known as the “Namibian Fairy Circles”- often considered “nature’s greatest mystery”. These circles, which look almost like lunar craters, are rings of tall grass surrounding a disc of barren soil- and the regular size and distribution of these rings has had scientists baffled for years. Averaging about 7m in diameter, and having a close packed, even tessellation, they sparked several conspiracy theories: the Himba people believed that they were the footprints of their God, Mukuru, and local tour-guides would tell of an underground dragon, whose breath was so poisonous it killed all the plants in its path. The most accepted theory was suggested in 2013, when it was observed that the rings only formed from homogenous grasses in areas between arid grassland and desert; it posits that, due to the high competition for water in these areas, the grasses take on the most efficient design for nutrient uptake. Stronger grasses sap up all the water and nutrients, causing weaker neighbours to die and create a gap - these gaps then become reservoirs for nutrients, encouraging larger grasses to take root there - and this nucleates a stable circle formation. From above, these pattens are incredibly mathematically predictable; in 2015 Professor Robert Sinclair, a mathematical biologist from the Okinawa Institute of Science in Japan, observed that the mathematics behind the circles share a surprising similarity with the skin cells of a zebrafish - "It is still difficult to say why exactly they are similar, but the fact that they are similar is already very important," Sinclair said. "This is suggesting there may be such types of patterns that cover really different size scales”. It is thought that the fact that fairy circles and skin cells are competing for space may play an important part in this curious similarity, and scientists are keen to analyze their geometrics further in the hope that such patterns may help the search for life on other planets.

Talking of skin, did you know that there are about 1 billion tones of skin floating about in the atmosphere? Thankfully, there are about 5.15×1018 kg of atmosphere, which only puts skin at about 0.000000019% of the total weight. But it is true that up to 50% of your household dust will be made up of dead human skin cells.

Moving on from human skin cells, it turns out humans might actually be able to see magnetism! Humans have chryptochrome in our retinal cells, and magnetite in our brains- the two chemicals which result in magnetic sense in animals.
Chryptochrome is a flavoprotein (a protein which contains a nucleic acid derivative of ribolavin- part of the vitamin B group) which acts as a magnetoreceptor and is also found in the eyes of migratory birds and sea turtles - it’s believed to allow the animal to “see” the earth’s magnetic field lines, as well as acting as a receptor to blue tones of light, helping regulate the circadian rhythm. It has long been assumed that humans don’t posses any magnoreceptive abilities, but a recent experiment, which injected human chryprochromes into the eyes of flies, found that the human cryptochromes worked just as well as the fly’s own magnoreceptors. This evidence points to an evolutionary change, where at some time in our distant past the ability to interpret the information from these magnetic receptors was switched off in our brain. Incredibly, if this research can locate the “switched off” area of our brain, there is the possibility we could somehow switch it back on and “see” magnetic fields!
Biological magnetite is a little less well understood; discovered in 1992, it is found in most migratory animals, and in humans it exists in the cerebellum, cerebral cortex and lining of the brain and spinal chord as a magnetite-containing bacteria. These bacteria are effectively tiny living compass needles, which (thanks to their magnetic insides) orientate with the earth’s magnetic field in a process called “magnetoaxis”. Scientists don’t fully understand the mechanism by which these bacteria translate into an ability to sense direction in their host animal, but if we can unlock that secret we may be en-route to having our own in-built Sat-Navs.

On a final, fun, magnetic note: dogs poo facing north. Ok, so not 100% of the time, but after zoologist Dr. Sabine Begall (now holder of the Ig Nobel Prize) analysed over 2000 videos of doggies doing their business, she noticed a trend: dogs spin around in circles before emptying their tanks, and generally end up pointing north. This isn’t always the case- it’s believed that local magnetic fields from things like power lines disrupt the data- but cross-referencing the puppy poop positions against the times of medium to large solar flares (which induce storms in the earth’s magnetic field) uncovered a direct correlation. It’s believed that dogs do this so they can orientate themselves in unfamiliar environments, finding a landmark that correlates with polar north as a reminder, and maybe using their excrement as a little “Google Maps pin”; so if you’re ever lost, you may be able to follow your doggie’s dumps all the way home.


http://www.livescience.com/39401-fairy-circles-get-new-explanation.html
http://www.livescience.com/50426-namibia-skin-fairy-circles.html
https://en.wikipedia.org/wiki/Fairy_circle_(Africa)
http://www.telegraph.co.uk/news/worldnews/africaandindianocean/namibia/1461430/Fairy-circles-of-Africa-baffle-scientists.html
http://www.slideshare.net/getKlara/7-41409338
https://en.wikipedia.org/wiki/Atmosphere_of_Earth
http://www.nature.com/ncomms/journal/v2/n6/full/ncomms1364.html
https://en.wikipedia.org/wiki/Magnetoception
http://news.discovery.com/animals/pets/dogs-have-a-butt-compass-poop-facing-ns-pole-140102.htm


Last edited by alicecd24 on Wed Sep 16, 2015 5:03 am; edited 2 times in total

 
gruff5
1149039.  Mon Sep 14, 2015 9:06 am Reply with quote

have to say that dog poop story looked like a pile of (unsubstantiated) crap

 
alicecd24
1149075.  Mon Sep 14, 2015 11:53 am Reply with quote

It's definitely still unclear why animals exhibit magnetic-sensory behaviour in this way, but across species it does seem to be a common trend. Cattle appear to prefer a North-South orientation, and of course it's documented that migratory animals use the magnetic poles to navigate. It doesn't seem a huge stretch to me that there could be something similar, albeit obscure, in dogs- it's a shame there is a lack of more solid statistical data available. If you'd like to learn more about the substantiation, and similar cases in other animals, feel free to have a look at these links:

http://www.sciencebuddies.org/science-fair-projects/project_ideas/Zoo_p058.shtml?from=Pinterest
http://www.economist.com/node/12001823
http://healthypets.mercola.com/sites/healthypets/archive/2014/09/27/dogs-pooping-behavior.aspx?e_cid=20140927Z1_PetsNL_art_1&utm_source=petnl&utm_medium=email&utm_content=art1&utm_campaign=20140927Z1&et_cid=DM56333&et_rid=671426752
https://de.wikipedia.org/wiki/Sabine_Begall

 
Leith
1149295.  Tue Sep 15, 2015 6:19 pm Reply with quote

Welcome to the forums, Alice. Some interesting subjects there.

Further to Gruff's doubts, here's the original paper on the dog poo theory:
http://www.frontiersinzoology.com/content/10/1/80

... and a skeptical assessment of the findings:
http://skeptvet.com/Blog/2014/01/do-dogs-line-themselves-up-with-the-earths-magnetic-field-to-poop/

This appears to be from the same team of Czech and German researchers responsible for previous media stories on North-South orientation of cattle, and on directions of pouncing foxes (the latter featured in the QI J series) .

It seems the pattern they found in the dog experiment was only visible when they discounted recordings taken while the declination of the magnetic field was fluctuating, and they hypothesize that not accounting for this fluctuation may explain why results of previous experiments in this area have not proved replicable. Since this magnetic field fluctuation occurs most (70%?) of the time, this conclusion seems one to treat with a degree of caution.

It's a fascinating topic, nonetheless, particlarly the idea that humans may have some latent magnetosense. Just anecdotally, we briefly had a forum member whose claimed direction-finding abilities appeared consistent with an ability to sense magnetic field inclination:
post 1044493


Last edited by Leith on Tue Sep 15, 2015 6:23 pm; edited 1 time in total

 
Leith
1149296.  Tue Sep 15, 2015 6:22 pm Reply with quote

The elves looked into the 'human skin in household dust' claim for the D series, and found it difficult to support: post 180444

 
alicecd24
1149324.  Wed Sep 16, 2015 4:57 am Reply with quote

Hi Leith,

Thank you for the welcome! On reading the skeptics article, then going back to the original paper, it does seems to have highlighted some rather spurious interpretations that I hadn't picked up on. Despite having read broadly on the topic before posting, a certain degree of my confidence in their results comes from the knowledge that they don't award Ig Nobel Prizes to any old idiot with a microscope, and people much older and wiser than me must have believed their results represented something very interesting and encouraging.
While I can find very little data on canines and magnetite, it is clear that dogs have the same cryptochrome, CRY1, present in other migratory mammals, and that these crypochromes play a key part in magnetosense:
http://www.ncbi.nlm.nih.gov/gene/474528
https://en.wikipedia.org/wiki/Cryptochrome
http://www.novateinbio.com/en/dogcanine-elisa-kits/58331-dog-canine-cryptochrome-1-cry1-elisa-kit.html (for research)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2559964/

I actually don't take much issue with the lack of hugely correlative data - many, now respected, scientific theories began from slightly sceptical roots, and I think there is some interesting data in there - but given the variables (in her paper she mentions radiation from the Sun, unpredictable Earth magnetic fluctuations, localised magnetic fields, and many more) I think she should have conducted the experiment on a much larger sample and in a more controlled environment - it was her job to find the most reliable results possible, and i'm not sure she managed that. Personally what I find disappointing in Begall's research is that she seems content with finding a trend (albeit a bit of a wobbly one) and hasn't expressed much curiosity as to how or why the trend exists, and her paper makes no mention as to a suggested mechanism by which a dog could detect magnetic fields. Hopefully exploring the mechanism of how magnetosense works in mammals will be her next step, because, for me, that would be even more interesting!

 
gruff5
1149330.  Wed Sep 16, 2015 6:13 am Reply with quote

I seemed to have a sense of direction as a child (pre-teenager), in the literal meaning of 'sense', not just being good at knowing where I was. I seemed to be able to know where magnetic north was with no external references (eg within an unfamiliar room/building).

Course, it might have just been my imagination ...

 
Alfred E Neuman
1149333.  Wed Sep 16, 2015 6:29 am Reply with quote

I wonder if it's not something we stop using or even suppress as we get older? My memory is similar to Gruff's

 
alicecd24
1149341.  Wed Sep 16, 2015 7:40 am Reply with quote

The most suggestive data I've been able to find is an experiment conducted in 1979 by a Robin Baker from the University of Manchester (who has also written a couple of books on the subjects of humans and magnetic navigation) which shows some really interesting results (page 844):
https://books.google.co.uk/books?id=FMQQnijnhsUC&printsec=frontcover&rview=1#v=onepage&q&f=false

And this article follows on from it, seeming to suggest that we are, in fact, using our magnetic sense all the time, but more for spacial orientation than direction. http://www.nytimes.com/2011/06/28/science/28magnet.html?_r=0

But I'd be interested to find out if anything has been done more recently with humans to reach some more conclusive results.

 
gruff5
1149640.  Fri Sep 18, 2015 6:37 am Reply with quote

Fascinating articles there, alicecd24. Nice to see New Scientist back from 1980!

The study from 1979 looked fairly convincing, even if the numbers of subjects were somewhat small. But it seems that other researchers have not been able to reproduce these results. As a cheap and easy experiment to try to replicate, one would hope that researchers (even for an MSc/PhD dissertation) continue to try it - as the implications would be so profound.

It also says in that New Sci article that during the 19th Century it was a common view that magnetoception was active in aborigines and perhaps in children (as Alfred & myself may have experienced), but the sense atrophied in adults. This could influence the choice of subjects.

This is how wiki summarises the state of play for magnetoception in humans:

wiki wrote:
Magnetoception in humans is controversial ...

Magnetic bones have been found in the human nose, specifically the sphenoidal/ethmoid sinuses.[38] Beginning in the late 1970s, the group of Robin Baker at the University of Manchester began to conduct experiments that purported to exhibit magnetoception in humans: people were disoriented and then asked about certain directions; their answers were more accurate if there was no magnet attached to their head.[39] Other scientists have maintained they could not reproduce these results.[39][40] Some other evidence for human magnetoception was put forward in a 2007 study: low-frequency magnetic fields can produce an evoked response in the brains of human subjects.[41]

Additionally, a magnetosensitive protein, cryptochrome-2, has been found in the human eye.[42] Given the lack of knowledge as to how cryptochrome mediates magnetosensitivity in Drosophila, it is unclear whether the cryptochrome found in humans functions in the same way and can be used for magnetoception.

Magnetoception in humans has also been achieved by magnetic implants[43] and by non-permanently attached artificial sensory "organs"

The NY Times article has a suggestion that our modern electomagnetic environment may be interfering with our magnetoception abilities. Dear ol' Noel Edmunds might be onto something after all! ;-)

 
Jenny
1149795.  Sat Sep 19, 2015 12:04 pm Reply with quote

gruff5 wrote:

The NY Times article has a suggestion that our modern electomagnetic environment may be interfering with our magnetoception abilities.


That's why God allowed us to invent GPS.

 
gruff5
1159058.  Wed Nov 18, 2015 7:18 pm Reply with quote

Further new research on the cryptochrome proteins:

http://www.dispatchtribunal.com/researchers-finally-discover-biological-compass-of-organisms/7369/

The link says "finally discovered", though I'm not sure that this adds to existing knowledge?

 

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