Wednesday, August 11, 2021

Metal Heads and Canine Compasses

scooby dooAs the title of the animated American TV series Scooby-Doo, Where Are You! suggests, getting lost was a frequent premise. From 1969 to 1985, the cadre of teen gumshoes spent about half their time looking for young Shaggy, who always disappeared to smoke a joint (so it was implied), and then to satisfy his raging munchies afterward. His dog Scooby-Doo of course tagged along for the food. I recall one episode where Shaggy attempts to navigate a forest by looking for moss on the north sides of trees. He should have just asked Scooby to point North.

A 2013 paper published in Frontiers in Zoology suggests that dogs line up with Earth’s North-South axis when they defecate. Researchers took two years to observe 1,893 poop events, somehow accounting for a range of weather factors, before concluding that the number one element that influenced how dogs did a Number Two was Earth’s magnetic field. Perhaps the hound-winding pre-poop turning dance most dogs perform is to calibrate their internal compass.

We all assume that many, if not most, non-human animals can find their way around without asking directions or checking their phones, but science has proven that we have innate homing abilities as well. The mechanisms are not as yet entirely understood, but one thing which may be helping humans to navigate is the fact we have metal in our heads. That’s right – move over, Magneto. Some people have more brain-iron than others, and most of us know at least one individual we suspect of having rust between their ears. The truth is that we all have ferrous-rich cells located in our cerebellums and brain stems which can help us orient to North.

Without question, other animals are much better at non-GPS navigation than humans. When we talk about critters which can expertly find their way around, the homing pigeon probably comes to mind. Homers have an uncanny ability to accurately find their way back to their owners even when taken more than a thousand miles away. True story: in New Zealand, a “Pigeongram” service ran from 1898 to 1908, complete with special stamps. Homing pigeons were also vital leading up to the Normandy invasion when radio silence was essential.

Bird navigation has been well-studied, but much is still a mystery. Although birds use a variety of mechanisms to find their way around the planet, such as landmark recognition and solar orientation, sensitivity to Earth’s magnetic field is critical. Many bird species migrate only at night, so landmarks and solar position can’t help.

Luckily for us, Earth is a kind of induced magnet thanks to its rotating core of molten iron. If it weren’t a giant magnet, we’d all be fried to a crisp by solar radiation. Recently it has come to light that animals employ a protein molecule called a cryptochrome to sense the planetary magnetic field. This involves being attuned to blue light wavelengths, those between 400 and 480 nanometers. A corollary to this fact is that cryptochromes only function during the day. So what about those night owls?

Birds, it turns out, are serious metal-heads, having (as one researcher elegantly put it) “iron-containing sensory dendrites in the inner dermal lining of the upper beak.” There you have it, clear as a bell.

Ferrous-rich nerve cells were detected first in homing pigeons, but all bird species are thought to have them. Long-distance migrants need these most, but even poultry and resident birds are known to be endowed with an inner compass. In a research paper published in the journal PLOS One in February 2012, principal author G. Falkenberg writes “Our data suggest that this complex dendritic system in the beak is a common feature of birds, and that it may form an essential sensory basis for the evolution of at least certain types of magnetic field guided behavior.”

Heavy metal is not just for the birds. Bacteria, slugs, amphibians and loads more species are unconscious collectors of iron as well. A recently published study on human responses to magnetic fields found most subjects reacted to lab-generated magnetic fields. As observed on real-time functional brain scans, subjects could even detect when the polarity was reversed as part of the study. In the March 18, 2019 issue of the journal eNeuro, lead author Connie Wang writes “We report here a strong, specific human brain response to ecologically-relevant rotations of Earth-strength magnetic fields. Ferromagnetism…provides a basis to start the behavioral exploration of human magnetoreception.”

What really caught my attention is a new study out of South Korea. In a paper published in PLOS One in April 2019, Kwon-Seok Chae et al. found that male subjects who had fasted for an entire day seemed to orient themselves in a direction they keenly correlated with food, even when blindfolded and wearing ear plugs. That I can believe.

As a last resort we can always ask “In which direction would Scooby-Doo doo?”

Paul Hetzler wanted to be a bear when he grew up, but failed the audition. Having gotten over most of his self-pity concerning that unfortunate event, he now writes about nature. Including bears, once in a while. His book “Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World,” is available on Amazon

Photo: Still frame from the debut episode of Scooby-Doo, Where Are You!: “What a Night for a Knight”. (original airdate: September 13, 1969). Copyright © 1969 Hanna-Barbera Productions, Inc.

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Paul Hetzler has been an ISA Certified Arborist since 1996. His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine.You can read more of his work at or by picking up a copy of his book Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World


5 Responses

  1. Richard Monroe says:

    One late fall in the mid ’70’s,my Dad & I were deer hunting together high up on the ridges around Ampersand Mountain after a pretty good snowfall. We got turned around & misoriented tracking some deer through dense conifers, so my Dad, a Wanakena grad Forest Ranger, pulled out his compass to get us back on track so we could find the trail to make our way back down the slope before dark. He kept reshooting his azimuth as we walked, and walked, and walked…until we realized that his compass was just taking us in a circle around the summit. Finally, he stopped, made me climb a tall tree to get above the canopy, spot Middle Saranac, “Just look for the the big clear white spot down there somewhere below us, son.” Once we found that and got re-oriented, we walked out to Route 3 and back to our car. Dad later learned from another one of his Forest Rangers that the summit of Ampersand was (iron ore? loadstone?) and threw compasses off.
    I wonder which direction Scooby -Do would face to poop up on Ampersand Mountain. A mystery. Would he turn & face Middle Saranac? Or just poop his way around the summit in a big circle while the rest of the gang worked to solve it?
    Thanks for a great article! It made me both think and smile. I loved it.

  2. Randy Fredlund says:

    What about woodpeckers in particular? Are they metal heads? They’re certainly head-bangers.

  3. Boreas says:

    I am with Scooby – I always face north when eliminating. But then, my toilet doesn’t swivel…

  4. Jim S. says:

    I have to remodel my bathroom, my commode faces south.

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