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Animals' / Humans' Magnetic Sensory Abilities

ramonmercado

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Will the pigeons get lost?

Hard-Wired for Home
By John Bohannon
ScienceNOW Daily News
14 February 2007

Take a pigeon hundreds of kilometers from its home, and it has no problem finding its way back. For years, scientists have suspected that the bird's stellar navigation has to do with its ability to read Earth's magnetic fields. Now, thanks to a geomagnetic anomaly in New Zealand, researchers have the strongest evidence yet that this is indeed the case.
Until now, support for a pigeon's internal compass has been mostly anecdotal. The birds tend to fly in erratic patterns during electrical storms, for example. The first hard evidence for the geomagnetic theory came from a study showing that pigeons could detect a magnetic field in a wind tunnel (ScienceNOW, 24 November 2004), but that field was many times more intense than Earth's. Also, because the field was either completely on or off, it left the question open of how exactly pigeons might use subtle magnetic differences in the wild to correct their trajectories.

Taking a more natural approach, a team led by Todd Dennis, a behavioral ecologist at the University of Auckland in New Zealand, released pigeons close to a place called the Auckland Junction Magnetic Anomaly. Here, a cluster of massive rock slabs deep below the surface causes a detectable spike in the geomagnetic field. Dennis reasoned that if the pigeons were released here, they would reveal how they were using geomagnetic information as they struggled to get clear of the anomaly. To keep track of their trajectories, the researchers strapped global positioning system (GPS) devices to the birds' backs.

The geomagnetic anomaly threw the pigeons for a loop. Of the 92 pigeons released around the anomaly, 59 clearly flew relative to the direction of the local field--not Earth's field. As soon as they got beyond the anomaly, however, the pigeons corrected their direction and headed right home. Dennis concludes that the birds are keeping track of gradients in the field to navigate.

The study is "fantastic," says Joe Kirschvink, a biophysicist at the California Institute of Technology in Pasadena. "Now we have the data to convert the speculation" about pigeon navigation "into reality." The next key experiment, says Cordula Mora, a biologist at Duke University in Durham, North Carolina, who led the magnetic wind tunnel study, "will be to see whether this observation holds true at other sites in Europe and North America" and to find out how the pigeon's magnetic organ--thought to reside in the beak--is wired to its brain.

http://sciencenow.sciencemag.org/cgi/co ... 2007/214/3
 
mmm, ok?

More at link
http://www.rawstory.com/rs/2014/01/02/dogs-poop-in-line-with-earths-magnetic-field-says-study/

"A study published this week in the journal Frontiers in Zoology suggests that dogs choose to relieve themselves along a north-south axis in line with Earth’s magnetic field. The Motherboard blog reported on the study’s findings, saying that the research was carried out by a team of Czech and German scientists.

“Dogs are sensitive to small variations of the Earth’s magnetic field,” said the research team. “Dogs preferred to excrete with the body being aligned along the North-south axis” rather than the East-west axis.

The study examined the daily habits of 70 dogs during 1,893 defecations and 5,582 urinations over the course of two years. Consistently, during times of calm electromagnetic “weather,” the dogs chose to eliminate while facing north or south. "
 
Electric fields could help us wage war on destructive feral pigs

Which way does a pig point? The answer, it turns out, is north – or south.

Many organisms ranging from birds and bees to bacteria are known to have a magnetic sense that helps them navigate. But now it seems swine sense Earth’s magnetic field too – a finding that could help us win the fight against out-of-control feral pigs.

Pascal Malkemper at the University of Duisburg-Essen, Germany, and his colleagues made this discovery by observing more than 1600 wild boar in the Czech Republic, and more than 1300 warthogs in six African nations. Estimating the direction each animal was pointing in, the biologists found that, on average, they lined up closely with the north-south axis.

And it’s not just how they stand – they also found that wild boar beds face north or south, with a ridge at one end for it to rest its head. Altogether, the team suggests this shows these swine species have a strong sense of Earth’s magnetic fields.

“The fact that the animals align with the field lines suggests that they have a magnetic compass which they might use to navigate,” says Malkemper. Wild pigs can migrate over 50 kilometres between grazing areas. Perhaps a magnetic map of the landscape helps them find their way, he says. ...

https://www.newscientist.com/articl...campaign=hoot&cmpid=SOC|NSNS|2016-GLOBAL-hoot
 
Electric fields could help us wage war on destructive feral pigs

Which way does a pig point? The answer, it turns out, is north – or south.

Many organisms ranging from birds and bees to bacteria are known to have a magnetic sense that helps them navigate. But now it seems swine sense Earth’s magnetic field too – a finding that could help us win the fight against out-of-control feral pigs.

Pascal Malkemper at the University of Duisburg-Essen, Germany, and his colleagues made this discovery by observing more than 1600 wild boar in the Czech Republic, and more than 1300 warthogs in six African nations. Estimating the direction each animal was pointing in, the biologists found that, on average, they lined up closely with the north-south axis.

And it’s not just how they stand – they also found that wild boar beds face north or south, with a ridge at one end for it to rest its head. Altogether, the team suggests this shows these swine species have a strong sense of Earth’s magnetic fields.

“The fact that the animals align with the field lines suggests that they have a magnetic compass which they might use to navigate,” says Malkemper. Wild pigs can migrate over 50 kilometres between grazing areas. Perhaps a magnetic map of the landscape helps them find their way, he says. ...

https://www.newscientist.com/article/2094733-electric-fields-could-help-us-wage-war-on-destructive-feral-pigs/?utm_source=NSNS&utm_medium=SOC&utm_campaign=hoot&cmpid=SOC|NSNS|2016-GLOBAL-hoot
All very well, but how does one magnetise a boar? Rub it with a piece of iron? Seems risky. :)
 
Rather than lining up with the Earth's magnetic field, might the boars not simply turn their sides to east or west to catch the sunlight on it? Warm up a bit?
 
Humans able to detect magnetic fields? Farmers will want grants for those fields.

A study published today offers some of the best evidence yet that humans, like many other creatures, can sense Earth’s magnetic field.

But it doesn’t settle other questions that have swirled around this contentious idea for decades: If we do have a subconscious magnetic sense, does it affect our behavior? And does it arise from an iron mineral found in our brains, as the authors believe?

“I think this paper will make quite a splash,” says Peter Hore, a physical chemist at the University of Oxford in the United Kingdom. But, he adds, “Independent replication is crucial.”

A variety of species—bacteria, snails, frogs, lobsters—seem to detect Earth’s magnetic field, and some animals, such as migratory birds, rely on it for navigation. But testing for the sense in humans has been tricky. Experiments in the 1970s that asked blindfolded participants to point in a cardinal direction after being spun around or led far from home yielded inconsistent results.

https://www.sciencemag.org/news/201...ly_2019-03-18&et_rid=394299689&et_cid=2721870
 
Humans able to detect magnetic fields? Farmers will want grants for those fields.

A study published today offers some of the best evidence yet that humans, like many other creatures, can sense Earth’s magnetic field.

But it doesn’t settle other questions that have swirled around this contentious idea for decades: If we do have a subconscious magnetic sense, does it affect our behavior? And does it arise from an iron mineral found in our brains, as the authors believe?

“I think this paper will make quite a splash,” says Peter Hore, a physical chemist at the University of Oxford in the United Kingdom. But, he adds, “Independent replication is crucial.”

A variety of species—bacteria, snails, frogs, lobsters—seem to detect Earth’s magnetic field, and some animals, such as migratory birds, rely on it for navigation. But testing for the sense in humans has been tricky. Experiments in the 1970s that asked blindfolded participants to point in a cardinal direction after being spun around or led far from home yielded inconsistent results.

https://www.sciencemag.org/news/201...ly_2019-03-18&et_rid=394299689&et_cid=2721870
Interesting.
 
It's only 34 people. I'll withhold judgment.
 
It's only 34 people. I'll withhold judgment.
Well, that and that they only detected a change in brain waves in the presence of magnetic fields of a type the earth naturally has (in about a third of the subjects). You'd hardly expect anything else, as the brain, the little we know about it, is quite electrical.

There's no suggestion the subjects could really tell that anything had happened. Plus what's the margin of error on the measurements...?

I don't see a control group...

I'd imagine his audience of sceptics scientists will pull the protocol to bits.
 
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Well, that and that they only detected a change in brain waves in the presence of magnetic fields of a type the earth naturally has (in about a third of the subjects). You'd hardly expect anything else, as the brain, the little we know about it, is quite electrical.

There's no suggestion the subjects could really tell that anything had happened. Plus what's the margin of error on the measurements...?

I don't see a control group...

I'd imagine his audience of sceptics scientists will pull the protocol to bits.
I dashed that smart-arsed reply off, with a slice of toast in one hand and the laptop-bag in the other...

I decided to spend my lunchtime reading the paper - it's a topic that interests me as I’m something of ‘super navigator’ and can find my way about with seldom erring accuracy although my own observations are, that this is based on visual cues and to a limited extent, knowing which (compass) direction I’m going in.

Kudos to the authors for making the paper freely available and also the results/data. It very complete. You could recreate this experiment from the paper and the analysis from the data. That in itself is far less common that you might suppose.

I’ve not seen many so well constructed experiments of this type, that is physical phenomena interacting with people. They’ve really done a pretty good job and have bothered to understand the physics and the maths as well as the neuroscience. Coupla you guys can check the maths better than I, comparatively weak there myself ;)

The tone is little too sure of itself. For example, the significance statement; “Either we have lost a shared, ancestral magneto sensory system, or the system lacks a conscious component with detectable neural activity but no apparent perceptual awareness by us” doesn’t include a condition that the experiment itself may be a type one error and that a third option is that there is no such mechanism. I’m also worried when one of the experimenters in an evangelist for the cause – far too easy for bias to creep in then, even with the best of intentions. The conclusion is also ‘too sure’ and should perhaps use wording like "supports the hypothesis that...”.

'Because it's people’, a completely double blind methodology would have been appropriate. Participants were blind to Active vs. Sham mode, trial sequence and trial timing; this is good, I’d like all experimenters to have been in the same boat. This is not stated to be the case.

I note the participant briefing is not in the paper nor was there any suggestion of a debriefing. What were the participants told to avoid priming effects? All experiments with people as subjects generally have to mis-lead (although ethically) as to the true nature of the experiment to avoid priming effects skewing the results. In the interest of good ethics, one then de-briefs participants, telling the truth, at which point consent may be withdrawn and the data destroyed. This concerns me, it’s a big omission.

I’d prefer the study to have been between groups, that is a dummy/control group that were sat in the same room and subjected to the same protocol, but a static field consistent with the earth’s local magnetic field, turned on an off between runs. I’d prefer if the switch positions were automated (from ‘real’ to ‘sham’) and the experimenters never knew which was which until the results are collated. We also don’t want EEG ‘adjustment’ going on while the field is changing or not, notwithstanding those changes required to even out response between participants, hence ‘double blind’.

Overall, I’d say they may well be onto something, fascinating and IMO this result supports the hypothesis that changes in the magnetic field can affect aspects of the brains electrical behaviour. I’d draw the line at saying the experimental results ‘strongly supports’, until the experiment is repeated with:
  • Totally double blind protocols AND a control group.
  • A larger sample size for completed runs, 50 is a good number as dissertation studies (for example) are considered in a far more positive light once N >50 for good reason.
  • A briefing statement that negates priming effects and an appropriate de-briefing.
  • I’d consider hearing tests for the participants, especially is the age range is large, this would be to rule out the effects of auditory cues verses age.
  • A couple of the P values are in the range ‘so good they’re suspect’. I don’t suggest this is something one might use to invalidate the study, rather that the study must be repeated double blind and with no priming to ensure that the result is repeatable and real.

Coupla other things:

Sensible dummy objects used as controls for the EEG.

Samples size small, but typical for this type of paper.

Downward field sensitivity has a precedent in robins - they've been show to navigate using the angle on the magnetic field to the ground.

Some participants didn’t have SHAM data and were excluded. So even smaller sample's data was actually analysed.

Fascinating possibility that clockwise and counter-clockwise give different results in declination. I’d hypothesise that the east to west movement of the sun or the earth’s rotation might be a factors - assuming the effect is really there.
 
Kirschvink has published on dogs' magnetic sensitivity and also the idea of earthquake precursors.
 
Kirschvink has published on dogs' magnetic sensitivity and also the idea of earthquake precursors.
Yeah, that's why I noted he was a zealot for the idea.
The tone is little too sure of itself. For example, the significance statement; “Either we have lost a shared, ancestral magneto sensory system, or the system lacks a conscious component with detectable neural activity but no apparent perceptual awareness by us” doesn’t include a condition that the experiment itself may be a type one error and that a third option is that there is no such mechanism. I’m also worried when one of the experimenters in an evangelist for the cause – far too easy for bias to creep in then, even with the best of intentions. The conclusion is also ‘too sure’ and should perhaps use wording like "supports the hypothesis that...”.

Always iffy and especially if double blind protocols are not observed. But I've seen a lot worse.
 
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Here are the bibliographic particulars and abstract for the published research article. The full article is accessible at the link.

Hart et al. Frontiers in Zoology 2013, 10:80 http://www.frontiersinzoology.com/content/10/1/80
Abstract

Introduction: Several mammalian species spontaneously align their body axis with respect to the Earth’s magnetic field (MF) lines in diverse behavioral contexts. Magnetic alignment is a suitable paradigm to scan for the occurrence of magnetosensitivity across animal taxa with the heuristic potential to contribute to the understanding of the mechanism of magnetoreception and identify further functions of magnetosensation apart from navigation. With this in mind we searched for signs of magnetic alignment in dogs. We measured the direction of the body axis in 70 dogs of 37 breeds during defecation (1,893 observations) and urination (5,582 observations) over a two-year period. After complete sampling, we sorted the data according to the geomagnetic conditions prevailing during the respective sampling periods. Relative declination and intensity changes of the MF during the respective dog walks were calculated from daily magnetograms. Directional preferences of dogs under different MF conditions were analyzed and tested by means of circular statistics.

Results: Dogs preferred to excrete with the body being aligned along the North–South axis under calm MF conditions. This directional behavior was abolished under unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the MF.

Conclusions: It is for the first time that (a) magnetic sensitivity was proved in dogs, (b) a measurable, predictable behavioral reaction upon natural MF fluctuations could be unambiguously proven in a mammal, and (c) high sensitivity to small changes in polarity, rather than in intensity, of MF was identified as biologically meaningful. Our findings open new horizons in magnetoreception research. Since the MF is calm in only about 20% of the daylight period, our findings might provide an explanation why many magnetoreception experiments were hardly replicable and why directional values of records in diverse observations are frequently compromised by scatter.

Keywords: Magnetoreception, Magnetosensitivity, Magnetic field, Magnetic storm, Magnetic alignment, Dog, Canid, Mammal
FULL ARTICLE: https://frontiersinzoology.biomedcentral.com/track/pdf/10.1186/1742-9994-10-80
 
An inner compass.

Dogs are renowned for their world-class noses, but a new study suggests they may have an additional—albeit hidden—sensory talent: a magnetic compass. The sense appears to allow them to use Earth’s magnetic field to calculate shortcuts in unfamiliar terrain.

The finding is a first in dogs, says Catherine Lohmann, a biologist at the University of North Carolina, Chapel Hill, who studies “magnetoreception” and navigation in turtles. She notes that dogs’ navigational abilities have been studied much less compared with migratory animals such as birds. “It’s an insight into how [dogs] build up their picture of space,” adds Richard Holland, a biologist at Bangor University who studies bird navigation.

There were already hints that dogs—like many animals, and maybe even humans—can perceive Earth’s magnetic field. In 2013, Hynek Burda, a sensory ecologist at the Czech University of Life Sciences Prague who has worked on magnetic reception for 3 decades, and colleagues showed dogs tend to orient themselves north-south while urinating or defecating. Because this behavior is involved in marking and recognizing territory, Burda reasoned the alignment helps dogs figure out the location relative to other spots. But stationary alignment isn’t the same thing as navigation.

https://www.sciencemag.org/news/2020/07/dogs-may-use-earth-s-magnetic-field-take-shortcuts
 
An inner compass.

Dogs are renowned for their world-class noses, but a new study suggests they may have an additional—albeit hidden—sensory talent: a magnetic compass. The sense appears to allow them to use Earth’s magnetic field to calculate shortcuts in unfamiliar terrain.

The finding is a first in dogs, says Catherine Lohmann, a biologist at the University of North Carolina, Chapel Hill, who studies “magnetoreception” and navigation in turtles. She notes that dogs’ navigational abilities have been studied much less compared with migratory animals such as birds. “It’s an insight into how [dogs] build up their picture of space,” adds Richard Holland, a biologist at Bangor University who studies bird navigation.

There were already hints that dogs—like many animals, and maybe even humans—can perceive Earth’s magnetic field. In 2013, Hynek Burda, a sensory ecologist at the Czech University of Life Sciences Prague who has worked on magnetic reception for 3 decades, and colleagues showed dogs tend to orient themselves north-south while urinating or defecating. Because this behavior is involved in marking and recognizing territory, Burda reasoned the alignment helps dogs figure out the location relative to other spots. But stationary alignment isn’t the same thing as navigation.

https://www.sciencemag.org/news/2020/07/dogs-may-use-earth-s-magnetic-field-take-shortcuts
 
An inner compass.

Dogs are renowned for their world-class noses, but a new study suggests they may have an additional—albeit hidden—sensory talent: a magnetic compass. The sense appears to allow them to use Earth’s magnetic field to calculate shortcuts in unfamiliar terrain.

The finding is a first in dogs, says Catherine Lohmann, a biologist at the University of North Carolina, Chapel Hill, who studies “magnetoreception” and navigation in turtles. She notes that dogs’ navigational abilities have been studied much less compared with migratory animals such as birds. “It’s an insight into how [dogs] build up their picture of space,” adds Richard Holland, a biologist at Bangor University who studies bird navigation.

There were already hints that dogs—like many animals, and maybe even humans—can perceive Earth’s magnetic field. In 2013, Hynek Burda, a sensory ecologist at the Czech University of Life Sciences Prague who has worked on magnetic reception for 3 decades, and colleagues showed dogs tend to orient themselves north-south while urinating or defecating. Because this behavior is involved in marking and recognizing territory, Burda reasoned the alignment helps dogs figure out the location relative to other spots. But stationary alignment isn’t the same thing as navigation.

https://www.sciencemag.org/news/2020/07/dogs-may-use-earth-s-magnetic-field-take-shortcuts

'old on, we've 'ad this before. According to zoologist Hynek Burda, dogs' ability to detect the Earth's magnetic field is demonstrated by their careful positioning before defaecation, choosing a north or south-facing direction.
 
'old on, we've 'ad this before. According to zoologist Hynek Burda, dogs' ability to detect the Earth's magnetic field is demonstrated by their careful positioning before defaecation, choosing a north or south-facing direction.

Shih Tzu studies have discredited that hypoothesis.
 
Ramon's news item has been copied to that dedicated thread, for the sake of completeness.
 
Dogs are renowned for their world-class noses, but a new study suggests they may have an additional—albeit hidden—sensory talent: a magnetic compass. The sense appears to allow them to use Earth’s magnetic field to calculate shortcuts in unfamiliar terrain. ...

The published research study can be accessed at eLife:

https://elifesciences.org/articles/55080
 
This 2017 paper proposed the radical idea that animals' magnetic sensory capabilities (magnetoreception) might be the result of symbiotic cooperation with magnetism-sensitive (magnetotactic) microbes within their bodies.

The symbiotic magnetic-sensing hypothesis: do Magnetotactic Bacteria underlie the magnetic sensing capability of animals?
Eviatar Natan and Yoni Vortman
Movement Ecology 2017; 5: 22.
Published online 2017 Oct 23.
doi: 10.1186/s40462-017-0113-1

Abstract
The ability to sense Earth’s magnetic field has evolved in various taxa. However, despite great efforts to find the ‘magnetic-sensor’ in vertebrates, the results of these scientific efforts remain inconclusive. A few decades ago, it was found that bacteria, known as magnetotactic bacteria (MTB), can move along a magnetic field using nanometric chain-like structures. Still, it is not fully clear why these bacteria evolved to have this capacity. Thus, while for MTB the ‘magnetic-sensor’ is known but the adaptive value is still under debate, for metazoa it is the other way around.

In the absence of convincing evidence for any ‘magnetic-sensor’ in metazoan species sensitive to Earth’s magnetic field, we hypothesize that a mutualism between these species and MTB provides one. In this relationship the host benefits from a magnetotactic capacity, while the bacteria benefit a hosting environment and dispersal. We provide support for this hypothesis using existing literature, demonstrating that by placing the MTB as the ‘magnetic-sensor’, previously contradictory results are now in agreement. We also propose plausible mechanisms and ways to test the hypothesis. If proven correct, this hypothesis would shed light on the forces driving both animal and bacteria magnetotactic abilities.

SOURCE / FULL ARTICLE: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5651570/
 
Thie new Science Alert article reviews the reception and ongoing development of this symbiotic magnetic sensing hypothesis.
Wild Hypothesis Says Animals Sense Magnetic Fields Thanks to Microbes in Their Bodies

We don't know exactly how they do it, we just know it's an amazing gift. For decades, evidence has shown that all sorts of animals can sense magnetic fields and even use them to navigate their way around the planet.

This mysterious ability, called magnetoreception, is something that helps animals to make long-haul migrations, or even just find their way home, and it's a sense that's apparent in numerous species, whether feathered, furry, or finned.

As for humans, well, we might also have the capability of perceiving magnetic fields, although the evidence so far is scant – and even in animals, the precise origins of this magnetic awareness remain fuzzy and enigmatic. ...

"The search for a mechanism has been proposed as one of the last major frontiers in sensory biology," explains wildlife genomicist Robert Fitak from the University of Central Florida.

In a new study, Fitak and his co-authors reviewed the evidence for one potential basis of animal magnetoreception, although it's worth noting that the proposed idea remains largely hypothetical.

The most established explanations for how animals might detect magnetic fields revolve around two central hypotheses. One of these is cryptochromes, a class of proteins that are sensitive to light, and which are thought to help certain animals see magnetic fields.

The second hypothesis is magnetite-based magnetoreception, in which crystal clusters of iron in animals' bodies enable them to detect magnetic fields.

However, despite much research, neither of these answers appears to be entirely conclusive, and as Fitak and his co-authors suggest, there's another possibility altogether: a compass made of microbes.

According to the researchers, it's possible that animals can detect magnetic fields symbiotically via bacteria living inside them – specifically, magnetotactic bacteria (MTB), which orient themselves along magnetic field lines due to a chain of magnetic structures inside their bodies called magnetosomes. ...

FULL STORY: https://www.sciencealert.com/animal...o-something-living-inside-them-scientists-say
 
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