Animal magnetism: Bacteria may help creatures sense Earth's magnetic fields
An intriguing theory explains animals' magnetic sense.
17 September, 2020
Credit: PedroNevesDesign/designer_an/Shutterstock/Big Think
- Some animals can navigate via magnetism, though scientists aren't sure how.
- Research shows that some of these animals contain magnetotactic bacteria.
- These bacteria align themselves along the magnetic field's grid lines.
<p>It's one of the more fascinating discoveries of the last several decades: the growing list of animals who can navigate the Earth's magnetic grid to get where they need to go. From <a href="https://www.nationalgeographic.com/news/2007/9/birds-can-see-earths-magnetic-field/" target="_blank">birds</a> to <a href="https://bigthink.com/surprising-science/magnetic-dog" target="_self">dogs</a>, from fruit flies to lobsters, a number of species are somehow hooked into the planet's magnetic field — maybe even <a href="https://www.sciencemag.org/news/2019/03/humans-other-animals-may-sense-earth-s-magnetic-field" target="_blank">humans</a>. The big unanswered question is how?</p><p>A new paper just published in <a href="https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0595" target="_blank">Philosophical Transactions of the Royal Society B</a> may have the answer: The creatures may have a symbiotic relationship with <a href="https://en.wikipedia.org/wiki/Magnetotactic_bacteria" target="_blank" rel="noopener noreferrer">magnetotactic bacteria</a> that orient them along global magnetic field lines.</p><p>While it's possible that the bacteria themselves are just one more magnetically sensitive organism, the paper presents evidence supporting the theory that their presence within other organisms endows their hosts with their magnetic navigational abilities.</p>
Magnetotactic bacteria hosts
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQyMTQ2Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2MDcwMTYxMn0.BZ-cpaTejm38_HCvVoSZ92k58dxnQETahNmKOmB14X4/img.jpg?width=980" id="c6097" class="rm-shortcode" data-rm-shortcode-id="a9f01b7583442ad92a05927c79754f50" data-rm-shortcode-name="rebelmouse-image" alt="whale mother and calf" data-width="1440" data-height="960" />A right whale mother and calf
Credit: wildestanimal/Shutterstock
<p>One of the paper's authors, Geneticist <a href="https://sciences.ucf.edu/biology/person/robert-fitak/" target="_blank">Robert Fitak</a>,<a href="https://sciences.ucf.edu/biology/person/robert-fitak/" target="_blank" rel="noopener noreferrer"></a> is affiliated with the biology department of the <a href="https://www.ucf.edu" target="_blank">University of Central Florida</a> in (UCF) Orlando. Prior to joining the department, he spent four years as a postdoctoral researcher at Duke University investigating the genomic mechanisms responsible for magnetic perception in fish and lobsters.</p><p>Fitak tells <a href="https://www.ucf.edu/news/animals-magnetic-sixth-sense-may-come-from-bacteria-new-paper-suggests/" target="_blank">UFC Today</a>, "The search for a mechanism has been proposed as one of the last major frontiers in sensory biology and described as if we are 'searching for a needle in a needle stack.'"</p><p>That metaphorical needle stack may well be the scientific community's largest database of microbes, the <a href="https://bmcgenomics.biomedcentral.com/articles/10.1186/1471-2164-9-75" target="_blank" rel="noopener noreferrer">Metagenomic Rapid Annotations using Subsystems Technology database</a>. It lists the animal samples in which magnetotactic bacteria have been found.</p><p>The primary use of the database, says Fitak, has been the measurement of bacterial diversity in entire phyla. An accounting of the appearance of magnetotactic bacteria in individual species is something that has previously be unexplored. "The presence of these magnetotactic bacteria had been largely overlooked, or 'lost in the mud' amongst the massive scale of these datasets," he reports.</p><p>Fitak dug into the database and discovered that magnetotactic bacteria have indeed been identified in a number of species known to navigate by magnetism, among them loggerhead sea turtles, Atlantic right whales, bats, and penguins. <em>Candidatus Magnetobacterium bavaricum</em> is regularly found in loggerheads and penguins, while <em>Magnetospirillum</em> and <em>Magnetococcus</em> are common among right whales and bats.</p><p>As for other magnetic-field-sensitive animals, he says, "I'm working with the co-authors and local UCF researchers to develop a genetic test for these bacteria, and we plan to subsequently screen various animals and specific tissues, such as in sea turtles, fish, spiny lobsters and birds."</p>The bacteria-host relationship
<p>While the presence of the bacteria in these particular species is intriguing, further study is needed to be sure they're responsible for other animals' magnetic navigation. Their presence in these species <em>could</em> be just a coincidence.</p><p>Fitak also notes that he doesn't know at this point exactly where in the host animal the magnetotactic bacteria would reside, or other details of their symbiotic relationship. He suggests that they might be found in nervous tissue associated with navigation, such as that found in the brain or eye.</p><p>If confirmed, Fitak's hypothesis could suggest that our own sensitivity to the Earth's magnetic field might one day be enhanced via magnetotactic bacteria in our own individual microbiomes, should they be benign to us as hosts.</p>
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For starlet sea anemones, more food means more arms
A new study finds that starlet sea anemones have the unique ability to grow more tentacles when they've got more to eat.
16 September, 2020
Credit: Smithsonian Environmental Research Center/Wikimedia
- These anemones belong to the Cnidaria phylum that continues developing through its lifespan.
- The starlet sea anemone may grow as many as 24 tentacles, providing there's enough food.
- When deprived of the chance to reproduce, they also grow more tentacles.
<p>By now, you've probably worked out your personal go-to strategy for those times when you discover — a little bit too late — that you've eaten too much. Maybe you're the proactive type, arriving at the table in sweatpants. Otherwise, maybe a quick postprandial nap or a loosened belt is your thing. A new paper published in the journal <a href="https://www.nature.com/articles/s41467-020-18133-0" target="_blank">Nature Communications</a> describes the unique way that starlet sea anemones deal with extra food: They simply grow a pair of new tentacles, as if to make room.</p>
Starlet sea anemone basics
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDM5Mzk3MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0Njc2MDk0OX0.q_e2-_VyGcBaOoGM53Uu1XZPaaVxsPhsn7shaxVGu1c/img.jpg?width=980" id="ac056" class="rm-shortcode" data-rm-shortcode-id="200a59225bbce7ddda78d80a20fc267d" data-rm-shortcode-name="rebelmouse-image" alt="sea anemone" data-width="1440" data-height="1422" />Credit: Smithsonian Environmental Research Center/Flickr
<p>The <a href="https://en.wikipedia.org/wiki/Starlet_sea_anemone" target="_blank">starlet sea anemone</a>, or <em>Nematostella vectensis</em>, lives burrowed into the mud and silt of coastal salt marshes. Research suggests it's originally native to the east coast of North America, although it can also be found along the continent's west coast, around Nova Scotia, and in U.K. coastal marshes.</p><p>Being stationary creatures, starlet sea anemones have to reach out and grab nutrition floating by. Their natural diet is mainly copepods and midge larvae, though they're also perfectly happy eating brine shrimp in a laboratory setting. The anemones grab food with their tentacles whose cilia then wiggle the meal down to their mouths.</p><p>In the larval stage, the anemones have a quartet of tentacles, though they may develop up to 24 of them. A more typical amount is 16.</p><p>While the starlet sea anemone may grow larger in a lab setting, in the wild its clear, worm-like body typically extends from 10 to 19 millimeters (about three quarters of an inch) in length. Tentacles may add another 8 mm.</p><p>Members of the phylum to which the starlet sea anemone belongs, the <a href="https://en.wikipedia.org/wiki/Cnidaria" target="_blank"><em>Cnidaria</em></a> phylum, have the unique ability to grow new body parts throughout their lives in response to environmental influences. Among these influences are fluctuations in the amount of available food. Nonetheless, no other animal has yet been seen growing new appendages when they get extra sustenance.</p>The study
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDM5NDAwOS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyOTMzMTcyMX0.aSMrGNPw3Hz_dAmy-PGe7sWHp-ePGZFhi4AT2M5zEfE/img.jpg?width=980" id="7f3ff" class="rm-shortcode" data-rm-shortcode-id="fb709c543b60912c99dc5ee9c2871d49" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="595" />Tentacles budding, or not, under different feeding conditions
Credit: Ikmi, et al./Nature Briefing
<p>Observations of starlet sea anemones in his lab prompted lead author of the paper, <a href="https://www.embl.de/research/units/dev_biology/ikmi/members/index.php?s_personId=CP-60026325" target="_blank">Aissam Ikmi</a> of the European Molecular Biology Lab Heidelberg, to undertake the new research. He'd noticed what seemed to be an association between the amount of brine shrimp being consumed and the sprouting of new tentacles.</p><p>Ikmi and his team raised over 1,100 starlet sea anemone polyps to which they fed brine shrimp. Some of them began with 4 tentacles while the rest already had 16.</p><p>For over six months, the researchers varied the animals' food supply at cyclical intervals, feeding the anemones for a few days and then stopping for a few days.</p><p>The scientists tracked tentacle growth throughout the experiment, creating a spatio-temporal map that identified periods of tentacle growth in relation to feeding cycles.</p><p>They found that the anemones grew new tentacle pairs during feeding periods, and new tentacle production did indeed stop when their food supply was temporarily cut off. Tentacle-pair budding occurred at the same time as an anemone also doubled its body size.</p><p style="margin-left: 20px;">"When food was available, however, primary polyps grew and sequentially initiated new tentacles in a nutrient-dependent manner, arresting at specific tentacle stages in response to food depletion." — Ikmi, et al.</p>Two ways to bud
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDM5NDA1NS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY2OTkwNjMzMX0.VN5Q8MFO7QnQRiBTVY4xg_hqMN-VvqBqDBLlNCb1mL0/img.jpg?width=980" id="5aff3" class="rm-shortcode" data-rm-shortcode-id="3ac439c1ad951d3a2aa2afa4b3a8a14b" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="470" />In this illustration from the paper, development from 4 to 12 tentacles is characterized by trans budding. Cis budding is present beginning with 16 tentacles.
Credit: Ikmi, et al./Nature Briefing
<p>The team identified two budding modalities, they named "cis" and "trans." In both modes, pairs of tentacles were produced, budding either simultaneously or consecutively. In:</p><ul><li><em>Trans budding</em> — the two new tentacles budded on opposite sides of the anemone.</li><li><em>Cis budding</em> — the two new tentacles budded from within the same segment.</li></ul><div>The experiments also suggest that the starlet sea anemone appears to have ability to make good use of available energy dependent on its situation. Being prevented from spawning, for example, prompted the anemones to grow more tentacles, as if they were rechanneling the energy they'd have otherwise directed to reproduction.</div>
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Study finds the real reason you get goosebumps
No, its not just to keep you warm with hair you don't have.
23 July, 2020
By Flystock/Shutterstock
- A new study suggests that goosebumps are part of a larger system that not only keeps us warm, but also helps hair to heal.
- The sympathetic nerve system reacts to cold air with goose skin. If it stays on long enough, it orders new hair growth.
- The authors note that other, currently unknown, connections between this system and other parts of the body are likely to exist.
<p>Everybody gets goosebumps, but have you ever wondered why? Until now, the leading hypothesis was that by elevating hair-follicles on the skin, goosebumps helped keep the body warm by providing more space for warm air to be collect near the body. However, many scientists have puzzled over this explanation, as the lack of body hair on modern humans leaves us with the ability to have goose skin but without the ability to benefit from it.</p><p> Evolutionarily, that makes little sense, if it really was that useless we'd expect more than a few people to not have the ability to get them by now. </p><p>A new <a href="https://www.cell.com/cell/pdf/S0092-8674(20)30808-4.pdf?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867420308084%3Fshowall%3Dtrue" target="_blank">study</a> published in <em>Cell </em>suggests a different reason for this reaction. Its authors argue that the same cells that cause goosebumps might be responsible for helping hair growth in the first place, giving a reason for evolution to retain this familiar phenomenon. </p>
A hair-raising study
<p>In animals, many organs are made of three kinds of tissue: epithelium, mesenchyme, and nerve. In the skin, which is an organ, a nerve connects to muscle in the mesenchyme. This nerve is part of the sympathetic nervous system and helps maintain homeostasis. The muscle itself is connected to stem cells in the epithelium that heal wounds and regenerate hair follicles.</p><p>The researchers focused on mice, as is typical in these studies, but suggest that the findings are also applicable to humans given the similarity between our skin and hair cells. </p><p>The researchers examined the behavior and structure of the nerve under an electron microscope. To their surprise, the nerve was not only attached to the previously mentioned muscle tissue but also wrapped around hair follicle stem cells. </p><p>In normal conditions, the sympathetic nervous system is always operating at a low level. This keeps the body functioning normally. When the researchers observed this behavior, they noticed signals being sent by the nervous system to the stem cells in the hair follicles. These signals seem to keep the stem cells at the ready for potential use. </p><p>However, when the researchers exposed the tissues to the cold, the activity ramped up. A flood of neurotransmitters was released, and the stem cells activated. This prompted new hair growth to begin. </p><p>Another experiment dove into how the nerve reached the stem cells in the first place. Co-Author Yulia Shwartz explained the findings in a press release:</p><p>"We discovered that the signal comes from the developing hair follicle itself. It secretes a protein that regulates the formation of the smooth muscle, which then attracts the sympathetic nerve. Then in the adult, the interaction turns around, with the nerve and muscle together regulating the hair follicle stem cells to regenerate the new hair follicle. It's closing the whole circle -- the developing hair follicle is establishing its own niche." </p><p>Putting this together, it appears that goosebumps are part of a two-phased response to cold. In the first, the muscle below the skin is stimulated to form goosebumps. If this stimulation lasts long enough, the second phase kicks in, with the sympathetic nervous system calling for new hair growth and repairs for the old ones to be made in response to the cold. </p>This is interesting and all, but what possible application could this information have?
<div class="rm-shortcode" data-media_id="a1mxkAJg" data-player_id="FvQKszTI" data-rm-shortcode-id="34227067ef7afd2e24cf95e8c455de17"> <div id="botr_a1mxkAJg_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/a1mxkAJg-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/a1mxkAJg-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/a1mxkAJg-FvQKszTI.js"></script> </div> <p>In their <a href="https://www.eurekalert.org/pub_releases/2020-07/hu-trr072020.php" target="_blank">press release</a>, the authors suggest that further research can focus on how the body repairs itself in response to environmental stimuli in various situations. The findings also imply that other currently unsuspected connections between the sympathetic nervous system and other parts of the body exist. These potential interactions will undoubtedly be searched for and examined.</p><p> Everybody gets goosebumps now and then. We've always assumed we knew why we still get them, even though the hypothesis had some holes. This study's findings show that the benefits of getting goosebumps are more complex than initially thought. It just goes to remind us that we still have much to learn about even the most mundane things.</p>
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New fossils reveal first known swimming dinosaur
Non-avian dinosaurs were thought terrestrially bound, but newly unearthed fossils suggest they conquered prehistoric waters, too.
01 May, 2020
<ul class="ee-ul"></ul>
<p>Despite being extinct for <a href="https://www.usgs.gov/faqs/when-did-dinosaurs-become-extinct?qt-news_science_products=0#qt-news_science_products" target="_blank">65 million years</a>, dinosaurs continue to <a href="https://qz.com/1579292/our-knowledge-of-dinosaurs-is-evolving-so-is-how-we-depict-them/" target="_blank">evolve in our imaginations</a>. Over the past two hundred years of research, these once terrible lizards have added a panoply of new adaptations, from brightly colored feathers to a <a href="https://www.cbc.ca/news/technology/dinosaur-sounds-honk-growl-torah-kachur-1.3803212" target="_blank">syrinx</a> more appropriate for mate-attracting honks than movie-monster roars.</p><p>Despite these many changes, one taxonomic rule seemed steadfast: <a href="https://bigthink.com/kevin-dickinson/what-makes-a-dinosaur-a-dinosaur" target="_self">Non-avian dinosaurs</a> lived terrestrial lives. If Mesozoic reptiles flew, like <a href="https://www.smithsonianmag.com/science-nature/why-a-pterosaur-is-not-a-dinosaur-87082921/" target="_blank"><em>Pterodactylus</em> and <em>Pteranodon</em></a>, then they were not dinosaurs. If they swam, like <a href="https://en.wikipedia.org/wiki/Ichthyosaurus" target="_blank"><em>Ichthyosaurus</em></a><em> </em>or <a href="https://en.wikipedia.org/wiki/Plesiosauria" target="_blank"><em>Plesiosaurs</em></a>, then they were not dinosaurs.</p><p>But new <em>Spinosaurus aegyptiacus</em> fossils excavated in the Kem Kem region of the Moroccan Sahara may have rewritten those rules and our understanding of the Mesozoic world. </p>
Unearthing a mystery in the desert
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzE4MDU1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNzI1NTExM30.1L90N5rrjAiYqBzRa72_b3hmP8Bq20MdZ3KtdfSgUTg/img.jpg?width=1245&coordinates=0%2C24%2C0%2C24&height=700" id="8e39f" class="rm-shortcode" data-rm-shortcode-id="45a87235d3fe79b339ade44f58f9818c" data-rm-shortcode-name="rebelmouse-image" data-width="1245" data-height="700" />Stromer's holotype of his original Spinosaurus specimen.
<p>Spinosaurus was a Cretaceous period therapod, a clade of dinosaurs that include <em>Velociraptor</em>, <em>Dilophosaurus</em>, <em>Giganotosaurus</em>, and of course, <em>Tyrannosaurus rex</em>. At nearly 40-feet long and weighing an estimated 6 tons, Spinosaurus is one of the largest predatory dinosaurs ever discovered, yet many of its characteristics have confounded paleontologists for decades.</p><p>The first Spinosaurus fossils were discovered in 1912 by <a href="https://blogs.scientificamerican.com/tetrapod-zoology/the-discovery-and-early-interpretation-of-spinosaurus/" target="_blank">Ernst Freiherr Stromer von Reichenbach</a>, a paleontologist and German aristocrat. Stromer's specimen mainly consisted of jaw fragments and neural spines, but that proved enough to convince him of his discovery's peculiarities. </p><p>Unlike T. rex's stout, powerful jaw, Spinosaurus had a slender yard-long snout more akin to a crocodile's. Its conical teeth were ill-suited to shearing and tearing like other therapods' serrated teeth; they were a better match for snapping the fish out of water. Then there was that characteristic spine sail.</p><p>Unfortunately, Spinosaurus would remain elusive to Stromer as his original specimen was destroyed in the Allied bombing raids on Munich. Over the decades, however, paleontologists would keep trying to solve the puzzle of Stromer's weird dinosaur.</p>A digital resurrection
<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzE4MDU1OS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY1ODQzMzExOX0.ejZrgtQkbRBP8jEsC4sH0WWmXoxcMHvrCltL3TyvWBc/img.png?width=1245&coordinates=92%2C0%2C92%2C0&height=700" id="0b87c" class="rm-shortcode" data-rm-shortcode-id="b58ca0abb324db9a0fd7851490615a89" data-rm-shortcode-name="rebelmouse-image" data-width="1245" data-height="700" />An illustration of a Spinosaurus skeleton with its thinner, more traditionally therapod-like tail.
<p>And Spinosaurus kept getting weirder. In addition to the back-sail and elongated jaw, further fossil discoveries elucidated a dinosaur that was incredibly front-heavy with dense bones and short back legs not tailored for running.</p><p>"I tried to see all the bones, the muscles, the connective tissue, everything," Nizar Ibrahim, a paleontologist at the University of Detroit Mercy, <a href="https://www.nationalgeographic.com/magazine/2014/10/" target="_blank">told <em>National Geographic</em></a><em>. </em>"Sometimes it was there for an instant, then it vanished, like a mirage. My brain couldn't quite compute all that complexity."</p><p>As <a href="https://www.nationalgeographic.com/news/2014/9/140911-spinosaurus-fossil-discovery-dinosaur-science/" target="_blank">reported in <em>National Geographic</em></a>, Ibrahim teamed up with Simone Magnuco at the Milan Museum and University of Chicago fossil preparator Tyler Keilor in 2014 to digitally resurrect Spinosaurus. </p><p>The team used a CT scanner to reconstruct <a href="https://www.nytimes.com/2014/09/12/science/a-nomads-find-helps-solve-the-mystery-of-the-spinosaurus.html" target="_blank">Spinosaurus bones</a> within a computer, including some unearthed by Ibrahim in Morocco. They rounded out their skeleton by assembling missing bones from images of museum specimens, Stromer's original photographs and sketches, and those from other therapod specimens.</p><p>When they saw Spinosaurus walk across its digital landscape, they realized the animal was better attuned for an amphibious lifestyle than a terrestrial one. It had nostrils at the tip of its snout. Its bones were dense like aquatic mammals, and its hind legs would not have been such a hindrance if submerged in buoyant hunting grounds.</p><p>Their hypothesis also fits with what we know about Spinosaurus's habitat. Today, the Sahara is one of the driest places on Earth, but in the Cretaceous period, vast waterways covered the land and sported giant fish to outsize the most unbelievable of fish stories. (Seriously though, they were <em>this big</em>.)</p>A study of lost tails
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="0530ef75d9bc4d29b2bc7c7802ba98e9"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/fDhofM81RQE?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>But something was missing: a means of propulsion. How did a giant like Spinosaurus catch slick and quick prey while paddling like a duck on two stumpy hind legs? It didn't add up.</p><p>"The big thing we were missing was a propulsive structure because you can't really be an aquatic predator unless you have some way to catch prey in the water and move through the water," <a href="https://www.youtube.com/watch?v=fDhofM81RQE&t=66s" target="_blank">Ibrahim told <em>Nature</em></a>. "That's what we now found."</p><p>Between 2015 and 2019, on a grant from the National Geographic Society, Ibrahim and his team traveled to the Kem Kem region of the Moroccan Sahara to unearth further Spinosaurus fossils. During their dig, they discovered Spinosaurus tail vertebrae that were "characterized by extremely long spines."</p><p>Ibrahim's previous reconstruction of Spinosaurus featured a thin tail borrowed from other therapods. But such a tail would make traveling through the water unwieldy—think paddling a canoe with a walking stick. The new vertebrae revealed a fin-like tail, similar in appearance to a newt's, and could more easily propel the dinosaur through the water.</p><p>To test his hypothesis, Ibrahim's colleagues at Harvard crafted plastic models of the Spinosaurus tail. They attached it to a robot system that mimics swimming and measured its thrust and efficiency. They then compared the Spinosaurus tail's performance against two other therapod tails and extant aquatic animals.</p><p>Spinosaurus's results were consistent with the aquatic animals and superior to the terrestrial therapods. Ibrahim and his team published their results in <a href="https://www.nature.com/articles/s41586-020-2190-3" target="_blank"><em>Nature</em></a>. </p><p>"This discovery is the nail in the coffin for the idea that non-avian dinosaurs never invaded the aquatic realm," <a href="https://www.eurekalert.org/pub_releases/2020-04/ngs-nfr042920.php" target="_blank">Ibrahim said in a release</a>. "This dinosaur was actively pursuing prey in the water column, not just standing in shallow waters waiting for fish to swim by. It probably spent most of its life in the water."</p><p>But as is the case in science, not everyone is yet convinced.</p><p>Donald M. Henderson, the curator of dinosaurs at the Royal Tyrrell Museum, believes Spinosaurus likely lived at the water's edge, scooping up fish as they swam by. As he told <a href="https://www.nytimes.com/2020/04/29/science/spinosaurus-dinosaur-tail-swimming.html" target="_blank">the <em>New York Times</em></a>, he does not believe Spinosaurus would be a powerful swimmer.</p><p>"My first thing is, they haven't actually demonstrated that this tail could produce enough force to propel a six-and-a-half-ton body through the water," Henderson said. He added that the researchers had yet to provide that Spinosaurus had enough muscle power to move such a tail or compensate for the drag of its sail.</p>Dinosaurs are alive! Here’s how we know, and why it matters
<div class="rm-shortcode" data-media_id="nTfwl0kS" data-player_id="FvQKszTI" data-rm-shortcode-id="67c76febbfb51d2231c6bcef00459388"> <div id="botr_nTfwl0kS_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/nTfwl0kS-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/nTfwl0kS-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/nTfwl0kS-FvQKszTI.js"></script> </div> <p>As new fossils are found and new ideas to test emerge, we'll see if Henderson's concerns capsize the aquatic hypothesis or not.</p><p>Even if Spinosaurus is thrown out of the pool, that doesn't mean dinosaurs will forever remain grounded. As <a href="https://www.nytimes.com/2017/12/06/science/duck-dinosaur-swim.html?action=click&module=RelatedLinks&pgtype=Article" target="_blank">reported by the <em>New York Times</em></a>, a dinosaur fossil called <em>Halszkaraptor escuilliei</em> has features that suggest a partial aquatic lifestyle. These include "a neck like a swan, a snout like a goose, and forelimbs like flippers," but the specimen is so unusual that its authenticity remains a matter of debate. </p><p>And what is revealed in these debates will change our understanding of dinosaurs—both those that are gone and those that are still with us.</p>
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Humans were born to run. Exoskeletons might make us better at it.
New research on ankle exoskeletons show promising results.
30 March, 2020
Photo: Getty Images
- New research from Stanford finds that motor-powered ankle exoskeletons conserve 15 percent of energy expenditure when running.
- Spring-powered exoskeletons without motors actually made running harder.
- The researchers hope to develop better spring-powered models moving forward.
<p>Humans were born to run, as journalist and running fanatic Christopher McDougall <a href="https://www.chrismcdougall.com/born-to-run/" target="_blank">phrased it</a>. Bipedalism offers many advantages over quadrupeds, including the ability to better communicate over longer distances and improved cardiovascular skills. Humans are relatively lackluster over short distances; since our organs don't crash into our lungs when we run, as they do with quadrupeds, we are master marathoners.</p><p>There are still trade-offs. Thanks to our upright posture, we have weak necks—misbalances in our ankles and knees often lead to neck problems. Further down the chain, running can lead to chronic knee problems and labrum tears; I've suffered both while training for half-marathons. The impact force of repetitive striking can result in chronic lower back problems, especially if runners don't stretch and practice mobility routines. We expend a lot of energy when running; our body pays the toll.</p><p>Still, running is a natural activity that, according to McDougall, excite evolutionary senses of fear and pleasure deeply embedded in our biology. Too bad our anatomy doesn't always agree.</p><p>Researchers have long sought new means for alleviating energy output while running. A fascinating <a href="https://robotics.sciencemag.org/content/5/40/eaay9108" target="_blank">new study</a> on exoskeleton emulators, published in the journal <em>Science Robotics</em>, might have gotten us one step closer.</p><p>When <a href="https://www.amazon.com/dp/0307279189?tag=bigthink00-20&linkCode=ogi&th=1&psc=1" target="_blank">McDougall's book</a> was published in 2009, more Americans were running. As the researchers (based at Stanford but including experts from Carnegie Mellon, Ghent University, and Nike) in this new study note, only 25 percent of Americans aged 18-29 reported running even once in 2018. Participation for adults aged 30-49 dropped 20 percent that year. They cite time commitments and negative associations to exercise as two leading causes. Given the high likelihood of injury due to running, it makes sense that there's hesitancy.</p>
Stanford researchers find ankle exoskeleton makes running easier
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="5e8f155585a0bd7d072b36b8b6a96c39"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/NEIHLfPd4gI?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>Mindset matters. Running is a birthright and offers great cardiovascular conditioning. Yet there has to be some excitement around it. As McDougall writes, "if you thought [running] was only a means to an end—an investment in becoming faster, skinnier, richer—then why stick with it if you weren't getting enough quo for your quid?"</p><p>You have to <em>love</em> running to dedicate yourself to it. If you're in pain, that's a tall order. </p><p>The researchers tested two modes of running assistance: motor-powered and spring-based exoskeletons. An exoskeleton is an external skeleton that supports an animal's body, such as insects and mollusks. In human terms, they are <a href="https://www.nextbigfuture.com/2018/05/suitx-lowers-cost-of-full-body-medical-mobility-exoskeleton-to-40000.html" target="_blank">expensive devices</a> designed to slow down fatigue. In this study, ankle exoskeletons were tethered to motors as volunteers ran on a treadmill. </p><p>Eleven competitive runners were divided into three groups: an "optimized power" group, the motor-based cohort that boosted the runners' strides; "optimized spring-like," the group wearing the exoskeleton sans motor power; and the control group, "zero torque mode," runners wearing an exoskeleton with none of the features initiated. A final control element was runners wearing a neutral running shoe with no exoskeleton.</p><p><br></p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwNDQ5MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNTg1MTI3MH0.v3l_H6u2dZ_6UYRfvmTJta3-y-WCMN2E69a9FgJh_XI/img.jpg?width=980" id="ffe4c" class="rm-shortcode" data-rm-shortcode-id="146c3927174d29797e82ab228f510044" data-rm-shortcode-name="rebelmouse-image" data-width="660" data-height="439" />
Optimized spring-like and Optimized powered assistance resulted in metabolic reductions of 2.1 and 24.7%, respectively, compared with zero-torque mode, while running at 2.7 m s−1. Optimized powered assistance resulted in an improvement in running economy of 14.6% compared with running in normal shoes, whereas Optimized spring-like assistance resulted in an 11.1% increase in the energy cost of running. Error bars indicate SD. *P < 0.05.
Kirby A. Witte, et al.
<p>The motors are an important component. Wearing an exoskeleton with the motor switched off actually increased physical demand by 13 percent. With the motors purring, the demand was 15 percent less than when running without an exoskeleton.</p><p>Spring-based exoskeletons did not fare nearly as well, as it increased energy output by 11 percent than running without the gear. Stanford's Steve Collins, lead author of the paper, was surprised by this result, <a href="https://techxplore.com/news/2020-03-ankle-exoskeleton-aids.html" target="_blank">noting</a>,</p><p>"When people run, their legs behave a lot like a spring, so we were very surprised that spring-like assistance was not effective. We all have an intuition about how we run or walk but even leading scientists are still discovering how the human body allows us to move efficiently."</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwMzMxNi9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMzUwOTE4Mn0.ykeISrsXzSgspJ_LgT28yxoVJGqkUa1-VZZ_ZALQrpM/img.jpg?width=980" id="80d01" class="rm-shortcode" data-rm-shortcode-id="86f5fb823d529a16cb07e2853a1aac49" data-rm-shortcode-name="rebelmouse-image" data-width="1050" data-height="706" />
(A) Exoskeleton emulator testbed. A participant runs on a treadmill while wearing bilateral ankle exoskeletons actuated by motors located off-board with mechanical power transmitted through flexible Bowden cables. (B) Ankle exoskeleton. The ankle exoskeleton attaches to the user by a strap above the calf, a rope through the heel of the shoe, and a carbon fiber plate embedded in the toe of the shoe. The inner Bowden cable terminates on a 3D printed titanium heel spur that is instrumented with strain gauges for direct measurement of applied torque. A magnetic encoder measures ankle angle. (C) Participant running on the treadmill with bilateral ankle exoskeletons. Metabolic data are collected through a respiratory system by measuring the oxygen and carbon dioxide content of the participant's expired gasses.
Kirby A. Witte, et al.
<p>On the plus side, spring-based exoskeletons are much cheaper than motor-based models. The researchers are hoping to design a more energy-efficient model. Motor-powered models work great when tethered to treadmills but are unrealistic for road and trail runners, so an affordable spring-based version would be a boon for outdoor runners. </p><p>Spring-based exoskeletons mimic the natural spring of running. As with our normal running pattern, it stores energy only to unleash it when pushing off from the toes. With the help of a motor, the foot is able to extend at the ankle at the end of the step. Not quite Iron Man, but as Stanford graduate student <a href="https://techxplore.com/news/2020-03-ankle-exoskeleton-aids.html" target="_blank">Delaney Miller says</a> of these trials, </p><p style="margin-left: 20px;">"Powered assistance took off a lot of the energy burden of the calf muscles. It was very springy and very bouncy compared to normal running. Speaking from experience, that feels really good. When the device is providing that assistance, you feel like you could run forever."</p><p>Collins says this is one of the biggest improvements in energy economy ever made in running. It will likely not affect pro marathoners that much, but for novice runners or those susceptible to injury, it could ease the pain and remove a few seconds from your mile time. </p><p>Yes, humans were born to run. As it turns out, some of us just do it a little better with assistance. If consumer-priced exoskeletons hit the market, the statistics on running enthusiasts might swing in an upward direction. If the result is decreased energy expenditure, which by extension lowers the risk of injury, it's a win for all of us bipeds.</p><p>--<br></p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a> and <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a>. His next book is</em> "Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</p>
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