Latest news with #Haridy
Yahoo
6 days ago
- Health
- Yahoo
Have Sensitive Teeth? Scientists Say They May Have Evolved to Feel—Not Chew
"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." Here's what you'll learn when you read this story: A new study from the University of Chicago suggests our sensitive teeth may be an evolutionary leftover that once helped our fishy ancestors sense their surroundings. Researchers studied modern fish with dermal teeth and determined they are innervated, meaning they deliver sensory signals through nerves like our own teeth would. The study supports the 'outside-in' theory which suggests sensitive 'teeth' developed on exoskeletons before they appeared in mouths. Some would say there's nothing better than taking a big ol' bite out of an ice cream cone—but that's not necessarily a popular opinion. If the thought of sinking your pearly whites into a frozen dessert makes you cringe, then you probably have something in common with our earliest fishy ancestors. According to a new study published in Nature, teeth may have originated as sensory organs that helped ancient fish navigate murky waters. 'When you think about an early animal like this, swimming around with armor on it, it needs to sense the world,' senior author of the new study Neil Shubin said in a press release. 'This was a pretty intense predatory environment and being able to sense the properties of the water around them would have been very important. So, here we see that invertebrates with armor like horseshoe crabs need to sense the world too, and it just so happens they hit on the same solution.' Lead researcher on the study Yara Haridy wasn't always looking for ancient smiles—she made the discovery while trying to find the oldest vertebrate in the fossil record. Haridy identified armor bumps called odontodes on samples of the Cambrian fossil Anatolepis. It seemed like there were dentine tubules just beneath the odontodes—a hallmark sign of a vertebrate. Upon further inspection, Haridy realized the tubules were more akin to the sensory organs on crabs' shells called sensilla, although the pockets did contain dentin (A.K.A. the hard tissue that makes up the teeth in your mouth). The discovery sparked a new hypothesis for Haridy and the rest of the team: teeth may be sensory even when they're not in the mouth. 'We've been wondering 'why would we chew with these painful things? Why are they so sensitive in the first place?' Haridy said in a video. 'And it turns out, maybe this is a leftover from one of our most ancient ancestors.' Surprisingly, external teeth aren't uncommon in the animal kingdom today. Sharks, skates, and catfish all have tiny tooth-like structures called denticles lining their skin, making them feel like sandpaper. To better understand whether these external teeth were innervated (connected to nerves), Haridy studied some modern fish with denticles. She determined that the denticles were, in fact, connected to nerves like human teeth would be. Haridy said in the press release that the resemblance between armored fish's denticles and the sensilla of arthropods (like the ones seen in the Anatolepis samples) was striking. 'We think that the earliest vertebrates, these big, armored fish, had very similar structures, at least morphologically.' she said. 'They look the same in ancient and modern arthropods, because they're all making this mineralized layer that caps their soft tissue and helps them sense the environment,' According to Shubin, these early sea creatures would have existed in a 'pretty intense predatory environment,' so the ability to sense the world swimming around them would have been extremely important. The team's findings support what is known as the 'outside-in' hypothesis, or the theory that sensitive structures developed on exoskeletons first and then sensitive teeth followed. This contradicts the 'inside-out' hypothesis that assumes teeth arose first and were later adapted for exoskeletons. 'The more we look at the fossil record, the more we put those fossils in an evolutionary sequence, the more that we see the 'outside-in' hypothesis is likely correct,' Shubin said in the video. 'Our teeth originally evolved as the armor on the outside of the body of the earliest fish.' Moral of the story is: next time an annual cleaning leaves you with a toothache, don't blame the dental hygienist—blame your gilled ancestors! You Might Also Like The Do's and Don'ts of Using Painter's Tape The Best Portable BBQ Grills for Cooking Anywhere Can a Smart Watch Prolong Your Life?
Observer
24-05-2025
- Science
- Observer
Teeth hurt? It could be because of a 500-million-year-old fish
Ever wondered why our teeth are so sensitive to pain or even just cold drinks? It might be because they first evolved for a very different purpose than chewing half a billion years ago, a study suggested Wednesday. The exact origin of teeth -- and what they were for -- has long proved elusive to scientists. Their evolutionary precursors are thought to be hard structures called odontodes which first appeared not in mouths but on the external armour of the earliest fish around 500 million years ago. Even today, sharks, stingrays and catfish are covered in microscopic teeth that make their skin rough like sandpaper. There are several theories for why these odontodes first appeared, including that they protected against predators, helped with movement through the water or stored minerals. But the new study published in the journal Nature supports the hypothesis that they were originally used as sensory organs which transmitted sensations to nerves. At first, the study's lead author Yara Haridy was not even trying to hunt down the origins of teeth. Instead the postdoctoral researcher at the University of Chicago was probing another major question puzzling the field of palaeontology: what is the oldest fossil of an animal with a backbone? Haridy asked museums across the United States to send her hundreds of vertebrate specimens -- some so small they could fit on the tip of a toothpick -- so she could analyse them using a CT scanner. She began focusing on dentine, the inner layer of teeth that sends sensory information to nerves in the pulp. - Things get fishy - A fossil from the Cambrian period called Anatolepis seemed to be the answer she was looking for. Its exoskeleton has pores underneath the odontodes called tubules that could indicate they once contained dentine. This has previously led paleontologists to believe that Anatolepis was the first known fish in history. But when Haridy compared it to the other specimens she had scanned, she found that the tubules looked much more like sensory organs called sensilla of arthropods, a group of animals that includes crustaceans and insects. The mighty Anatolepis was therefore demoted to the rank of an invertebrate. For modern arthropods such as crabs, scorpions and spiders, sensilla are used to perceive temperature, vibration and even smell. How little these features have changed over time suggests they have been serving these same functions for half a billion years. The researchers said they found "striking" similarities between these features in Anatolepis and vertebrate fish from around 465 million years ago -- as well as some better-known fish. "We performed experiments on modern fish that confirmed the presence of nerves in the outside teeth of catfish, sharks and skates," Haridy told AFP. This shows that "tooth tissues of odontodes outside the mouth can be sensitive -- and perhaps the very first odontodes were as well," she added. "Arthropods and early vertebrates independently evolved similar sensory solutions to the same biological and ecological problem." Senior study author Neil Shubin, also from the University of Chicago, said that these primitive animals evolved in "a pretty intense predatory environment". "Being able to sense the properties of the water around them would have been very important," Shubin said in a statement. Haridy explained that over time, fish evolved jaws and "it became advantageous to have pointy structures" near their mouth. "Little by little some fish with jaws had pointy odontodes at the edge of the mouth and then eventually some were directly in the mouth," she said. "A toothache is actually an ancient sensory feature that may have helped our fishy ancestors survive!" —AFP
Yahoo
23-05-2025
- Science
- Yahoo
Human Teeth Evolved From Body Armor of Extinct Species
A new study, published on May 21 in the journal Nature, has revealed surprising information about the origins of human teeth. Our teeth evolved from the piercing 'body armor' of extinct fish, which existed about 465 million years ago. The study explained how sensory tissue found within the exoskeletons of the fish can be tied to the same "genetic toolkit" that comprises human teeth. "This shows us that 'teeth' can also be sensory even when they're not in the mouth," Yara Haridy, the study's co-author, said in a information came as a surprise to Haridy and her fellow researchers, who initially wanted to find the oldest vertebrate fossil ever recorded. Vertebrate fossils can typically be identified because they contain internal tubules which store dentine, the calcified tissue which is found under the enamel of human teeth. Dentine is also found inside the external bumps on the armor of ancient fishes. While analyzing the 'first fish' species, Anatolepis heintzi, scientists found what appeared to be large pores filled with dentine. They compared the fossil to several ancient and modern animals, but upon further inspection, they found the pores to be more similar to the sensory organs which crabs have on their shells. That means Anatolepis heintzi is an invertebrate arthropod rather than a vertebrate were astonished to discover that fish and ancient arthropods produce the same type of mineralized tissue. They believe that human teeth began evolving into their modern form around 460 million years ago after animals utilized the same "genetic toolkit" to make their teeth. "Viewed through this evolutionary lens, the fact that teeth in the mouth are extremely sensitive is less of a mystery, and more a reflection of their evolutionary origins within the sensory armor of early vertebrates," the study Teeth Evolved From Body Armor of Extinct Species first appeared on Men's Journal on May 23, 2025
Yahoo
22-05-2025
- Science
- Yahoo
Tooth pain's origins traced to 465-million-year-old armored fish with sensors
Ever wonder why teeth hurt? Blame it on a prehistoric armored the outer layer of our teeth is coated in hard enamel, it's the inner layer, called dentine, that feels pain. Dentine carries signals to the nerves when we bite into something hard, or feel the sting of ice cream or sweetness. Scientists have long debated where teeth came from. One idea was that they evolved from small bumps on the tough outer shells of ancient fish. These bumps, known as odontodes, were once a mystery. But now, a new study confirms that these structures in an early vertebrate fish from the Ordovician period, about 465 million years ago, contained dentine. Using 3D scans on fossils of the fish, researchers discovered that these bumps were sensitive and were likely used to sense their environment, like detecting cold water or pressure from nearby objects. While studying the fossils, the team also found that odontodes in ancient fish looked a lot like sensilla — tiny sensory organs found in the shells of animals like crabs and shrimp. Sensilla are also seen in fossils of ancient invertebrates. Surprisingly, these two features evolved in completely different animal groups: fish, which have backbones, and arthropods, which don't. According to Dr. Yara Haridy, who led the study, this is a classic case of evolutionary convergence — when different species develop similar traits on their own. 'These jawless fish and Aglaspidid arthropods (extinct marine arthropods) have an extremely distant shared common ancestor that likely had no hard parts at all,' Haridy said. 'We know that vertebrates and arthropods evolved hard parts independently and amazingly they evolved similar sensory mechanisms integrated into their hard skeleton independently.' The findings also help explain a long-standing mix-up in the fossil record. For decades, a Cambrian-era fossil called Anatolepis was thought to be one of the earliest vertebrates, thanks to tooth-like bumps on its surface. But when the researchers closely examined the fossil using high-resolution CT scans, they realized those bumps didn't contain dentine after all. Instead, they looked just like the sensory structures — sensilla — seen in arthropods. That meant Anatolepis wasn't a vertebrate fish, but likely an ancient arthropod. The confusion, it turns out, is understandable. Sensory armor evolved in both vertebrates and invertebrates, and it often looks strikingly similar under the microscope. That's because both groups developed ways to sense their environment using nerve-connected structures embedded in hard outer coverings — whether it was fish skin or crab shell. To compare these features more broadly, the team scanned fossils and modern specimens ranging from snails and barnacles to sharks and catfish. One discovery stood out: suckermouth catfish raised in Haridy's own lab had small tooth-like scales on their skin — called denticles — that were directly connected to nerves. These denticles, like the ancient odontodes and arthropod sensilla, weren't just armor — they were sensory tools. 'We think that the earliest vertebrates, these big, armored fish, had very similar structures,' Haridy said. 'They look the same in ancient and modern arthropods because they're all making this mineralized layer that caps their soft tissue and helps them sense the environment.' This research also adds weight to a key theory in evolutionary biology. Called the "outside-in" hypothesis, the theory suggests that teeth evolved from external sensory structures like these. In other words, long before animals had mouths full of teeth, they had sensitive armor that helped them survive. While they didn't pin down the earliest vertebrate fish, Neil Shubin, the senior author of the study, said this discovery was more than worth the effort. 'For some of these fossils that were putative early vertebrates, we showed that they're not. But that was a bit of misdirection,' he said. 'We didn't find the earliest one, but in some ways, we found something way cooler.' The study has been published in the journal Nature.
Yahoo
21-05-2025
- Science
- Yahoo
Bumps on ancient, armored fish may have given rise to teeth in animals, study finds
Sign up for CNN's Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. The sensitive interior of human teeth might have originated from a seemingly unlikely place: sensory tissue in fish that were swimming in Earth's oceans 465 million years ago. While our teeth are covered in hard enamel, it's dentine — the tooth's inner layer responsible for carrying sensory information to the nerves — that reacts to the pressure of a hard bite, pain, or changes like extreme cold or sweetness. When trying to determine the origins of teeth, one of the many possibilities considered by researchers over the years was that teeth may have evolved from bumps on the armored exoskeletons on ancient fish. But the true purpose of the structures, called odontodes, was unclear. Now, a new study and 3D scans of fossils have yielded evidence that the external bumps contained dentine, which likely helped fish sense their surroundings. Scientists reported the findings Wednesday in the journal Nature. 'Covered in these sensitive tissues, maybe when it bumped against something it could sense that pressure, or maybe it could sense when the water got too cold and it needed to swim elsewhere,' said lead study author Dr. Yara Haridy, postdoctoral researcher in the department of organismal biology and anatomy at the University of Chicago, in an email. During its analysis, the team also uncovered similarities between the odontodes and features called sensilla, which exist as sensory organs in the shells of modern animals such as crabs and shrimp, and can be found in fossilized invertebrate arthropods. The development of odontodes in fish, which are vertebrates, and sensilla in arthropods, which are invertebrates, is a prime example of evolutionary convergence — when similar features evolve independently in different animal groups, Haridy said. 'These jawless fish and Aglaspidid arthropods (extinct marine arthropods) have an extremely distant shared common ancestor that likely had no hard parts at all,' Haridy said. 'We know that vertebrates and arthropods evolved hard parts independently and amazingly they evolved similar sensory mechanisms integrated into their hard skeleton independently.' While arthropods have retained their sensilla, odontodes appear to be the direct precursors to teeth in animals. As the researchers compared sensilla and odontodes, they also arrived at another finding: One species, once considered to be an ancient fish, was actually an arthropod. Haridy's original aim was to solve the mystery of the oldest vertebrate animal that exists in the fossil record. She approached museums across the country and asked whether she could scan any fossil specimens they had from the Cambrian Period, 540 million years to 485 million years ago. Then, she settled in for an all-nighter at the Argonne National Laboratory, where she used their Advanced Photon Source to capture high-resolution computer tomography, or CT, scans. 'It was a night at the particle accelerator; that was fun,' Haridy said. At first glance, a fossil of a creature called Anatolepis looked like a vertebrate fish – and indeed, previous research from 1996 had identified it as one. Haridy and her colleagues noticed that there was a series of pores filled with a material that appeared to be dentine. 'We were high fiving each other, like 'oh my god, we finally did it,'' Haridy said. 'That would have been the very first tooth-like structure in vertebrate tissues from the Cambrian. So, we were pretty excited when we saw the telltale signs of what looked like dentine.' To confirm their discovery, the team compared the scans with those of other ancient fossils, as well as modern crabs, snails, beetles, sharks, barnacles and even miniature suckermouth catfish that Haridy had raised herself. Those comparisons showed that Anatolepis more closely resembled arthropod fossils, including one from the Milwaukee Public Museum. And what the team thought were tubules lined with dentine were actually more similar to sensilla. But they did find dentine-containing odontodes in ancient fish like Eriptychius and Astraspis during the scans. The confusion over Anatolepis' true nature had stemmed from the fragmentary nature of the fossils. The most complete pieces are only about 3 millimeters (0.1 inches) in size, Haridy said, which proved to be a challenge for comparative research reliant on external imaging. But the new scans she conducted enabled a 3D look at the fossils, revealing their internal anatomy. 'This shows us that 'teeth' can also be sensory even when they're not in the mouth,' Haridy said. 'So, there's sensitive armor in these fish. There's sensitive armor in these arthropods. This explains the confusion with these early Cambrian animals. People thought that this was the earliest vertebrate, but it actually was an arthropod.' The cutting edge modern imaging used in the study is resolving the debate over Anatolepis, said Dr. Richard Dearden, a postdoctoral research fellow at the Naturalis Biodiversity Center in Leiden, the Netherlands. Dearden was not involved in the new research. '(The study authors) use cutting edge modern imaging approaches to try and settle this question, assembling an impressive swathe of comparative data to convincingly establish that Anatolepis is indeed not a vertebrate,' Dearden said in an email. Armored jawless fish like Astraspis and Eriptychius and ancient arthropods like Anatolepis coexisted in the muddy shallow seas of the Ordovician period, which occurred between 485.4 million and 443.8 million years ago. Other contemporaries of these animals included large cephalopods such as giant squid, as well as huge sea scorpions. Features like odontodes and sensilla would help fish and arthropods distinguish predators from prey. 'When you think about an early animal like this, swimming around with armor on it, it needs to sense the world. This was a pretty intense predatory environment and being able to sense the properties of the water around them would have been very important,' said senior study author Dr. Neil Shubin, the Robert R. Bensley Distinguished Service Professor of Organismal Biology and Anatomy at the University of Chicago, in a statement. 'So, here we see that invertebrates with armor like horseshoe crabs need to sense the world too, and it just so happens they hit on the same solution.' Several modern fishes have odontodes, while sharks, skates and some catfishes are covered in small toothlets called denticles, which cause their skin to feel like sandpaper, Haridy said. Haridy studied the tissues of the catfish she raised and realized their denticles were connected to nerves much in the same way that teeth are in animals. When comparing teeth, odontodes and sensilla, they were all incredibly similar, she said. 'We think that the earliest vertebrates, these big, armored fish, had very similar structures, at least morphologically. They look the same in ancient and modern arthropods, because they're all making this mineralized layer that caps their soft tissue and helps them sense the environment,' Haridy said. It's likely that the genes necessary to form odontodes also produced sensitive teeth in animals — including humans — later, according to the study authors. The findings support the idea that sensory structures appeared first on exoskeletons, which then provided the genetic information that could then be used to create teeth as they became a necessary part of life, the study authors noted. 'Over time, fish evolved jaws, and it became advantageous to have pointy structures around and in the mouth,' Haridy said. 'Little by little some fish with jaws had pointy odontodes at the edge of the mouth and then eventually some were directly in the mouth and then lost across the body. The relationship between odontodes and teeth is continuously being clarified by new fossils and modern genetics.' The new research refines the timeline for the first appearance of hard tissues and the earliest ancestors of jawed fishes by removing Anatolepis from the fish tree of life, said Dr. Lauren Sallan, assistant professor and head of the macroevolution unit at the Okinawa Institute of Science and Technology in Japan. Sallan, who was not involved in the new study, said it also raises an intriguing new hypothesis that the scalelike precursors of teeth evolved to detect prey, friends or predators in the water. 'This is a real challenge to seemingly obvious assumptions that hard tissues like dentine and structures like scales and teeth evolved (primarily) for protection on the body or feeding in the throat,' Sallan said. 'Instead, they may have been 'exapted' (subsequently modified) for these uses, much like how limbs evolved before they were used to walk on land. It's also interesting to see the degree of convergence between early armored arthropods and fishes, and raises questions about how much ecological overlap occurred between these two groups.' Haridy wants to continue the search for fossils that could lead to the oldest vertebrate, given that researchers expect there are earlier vertebrates than Astraspis and Eriptychius. And even though they didn't discover it through this research, they made worthwhile findings, Shubin said in an email. 'We were disappointed that (Anatolepis) wasn't a vertebrate but we were amazed by the new ideas that arose,' Shubin said. 'And that took us in an entirely new direction. That's science.'
