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We are on the cusp of a voice AI boom, with tech companies such as Apple and OpenAI rolling out the next generation of artificial-intelligence-powered assistants. But the default voices for these assistants are often white AmericanBritish, if youre luckyand most definitely speak English. They represent only a tiny proportion of the many dialects and accents in the English language, which spans many regions and cultures. And if youre one of the billions of people who dont speak English, bad luck: These tools dont sound nearly as good in other languages. This is because the data that has gone into training these models is limited. In AI research, most data used to train models is extracted from the English-language internet, which reflects Anglo-American culture. But there is a massive grassroots effort underway to change this status quo and bring more transparency and diversity to what AI sounds like: Mozillas Common Voice initiative. The data set Common Voice has created over the past seven years is one of the most useful resources for people wanting to build voice AI. It has seen a massive spike in downloads, partly thanks to the current AI boom; it recently hit the 5 million mark, up from 38,500 in 2020. Creating this data set has not been easy, mainly because the data collection relies on an army of volunteers. Their numbers have also jumped, from just under 500,000 in 2020 to over 900,000 in 2024. But by giving its data away, some members of this community argue, Mozilla is encouraging volunteers to effectively do free labor for Big Tech. Since 2017, volunteers for the Common Voice project have collected a total of 31,000 hours of voice data in around 180 languages as diverse as Russian, Catalan, and Marathi. If youve used a service that uses audio AI, its likely been trained at least partly on Common Voice. Mozillas cause is a noble one. As AI is integrated increasingly into our lives and the ways we communicate, it becomes more important that the tools we interact with sound like us. The technology could break down communication barriers and help convey information in a compelling way to, for example, people who cant read. But instead, an intense focus on English risks entrenching a new colonial world order and wiping out languages entirely. It would be such an own goal if, rather than finally creating truly multimodal, multilingual, high-performance translation models and making a more multilingual world, we actually ended up forcing everybody to operate in, like, English or French, says EM Lewis-Jong, a director for Common Voice. Common Voice is open source, which means anyone can see what has gone into the data set, and users can do whatever they want with it for free. This kind of transparency is unusual in AI data governance. Most large audio data sets simply arent publicly available, and many consist of data that has been scraped from sites like YouTube, according to research conducted by a team from the University of Washington, and Carnegie Mellon andNorthwestern universities. The vast majority of language data is collected by volunteers such as Blent zden, a researcher from Turkey. Since 2020, he has been not only donating his voice but also raising awareness around the project to get more people to donate. He recently spent two full-time months correcting data and checking for typos in Turkish. For him, improving AI models is not the only motivation to do this work. Im doing it to preserve cultures, especially low-resource [languages], zden says. He tells me he has recently started collecting samples of Turkeys smaller languages, such as Circassian and Zaza. However, as I dug into the data set, I noticed that the coverage of languages and accents is very uneven. There are only 22 hours of Finnish voices from 231 people. In comparison, the data set contains 3,554 hours of English from 94,665 speakers. Some languages, such as Korean and Punjabi, are even less well represented. Even though they have tens of millions of speakers, they account for only a couple of hours of recorded data. This imbalance has emerged because data collection efforts are started from the bottom up by language communities themselves, says Lewis-Jong. Were trying to give communities what they need to create their own AI training data sets. We have a particular focus on doing this for language communities where there isnt any data, or where maybe larger tech organizations might not be that interested in creating those data sets, Lewis-Jong says. They hope that with the help of volunteers and various bits of grant funding, the Common Voice data set will have close to 200 languages by the end of the year. Common Voices permissive license means that many companies rely on itfor example, the Swedish startup Mabel AI, which builds translation tools for health-care providers. One of the first languages the company used was Ukrainian; it built a translation tool to help Ukrainian refugees interact with Swedish social services, says Karolina Sjberg, Mabel AIs founder and CEO. The team has since expanded to other languages, such as Arabic and Russian. The problem with a lot of other audio data is that it consists of people reading from books or texts. The result is very different from how people really speak, especially when they are distressed or in pain, Sjberg says. Because anyone can submit sentences to Common Voice for others to read aloud, Mozillas data set also includes sentences that are more colloquial and feel more natural, she says. Not that it is perfectly representative. The Mabel AI team soon found out that most voice data in the languages it needed was donated by younger men, which is fairly typical for the data set. The refugees that we intended to use the app with were really anything but younger men, Sjberg says. So that meant that the voice data that we needed did not quite match the voice data that we had. The team started collecting its own voice data from Ukrainian women, as well as from elderly people. Unlike other data sets, Common Voice asks participants to share their gender and details about their accent. Making sure different genders are represented is important to fight bias in AI models, says Rebecca Ryakitimbo, a Common Voice fellow who created the project's gender action plan. More diversity leads not only to better representation but also to better models. Systems that are trained on narrow and homogenous data tend to spew stereotyped and harmful results. We dont want a case where we have a chatbot that is named after a woman but does not give the same response to a woman as it would a man, she says. Ryakitimbo has collected voice data in Kiswahili in Tanzania, Kenya, and the Democratic Republic of Congo. She tells me she wanted to collect voices from a socioeconomically diverse set of Kiswahili speakers and has reached out to women young and old living in rural areas, who might not always be literate or even have access to devices. This kind of data collection is challenging. The importance of collecting AI voice data can feel abstract to many people, especially if they arent familiar with the technologies. Ryakitimbo and volunteers would approach women in settings where they felt safe to begin with, such as presentations on menstrual hygiene, and explain how the technology could, for example, help disseminate information about menstruation. For women who did not know how to read, the team read out sentences that they would repeat for the recording. The Common Voice project is bolstered by the belief that languages form a really important part of identity. We think its not just about language, but about transmitting culture and heritage and treasuring peoples particular cultural context, says Lewis-Jong. There are all kinds of idioms and cultural catchphrases that just dont translate, they add. Common Voice is the only audio data set where English doesnt dominate, says Willie Agnew, a researcher at Carnegie Mellon University who has studied audio data sets. Im very impressed with how well they've done that and how well they've made this data set that is actually pretty diverse, Agnew says. It feels like theyre way far ahead of almost all the other projects we looked at. I spent some time verifying the recordings of other Finnish speakers on the Common Voice platform. As their voices echoed in my study, I felt surprisingly touched. We had all gathered around the same cause: making AI data more inclusive, and making sure our culture and language was properly represented in the next generation of AI tools. But I had some big questions about what would happen to my voice if I donated it. Once it was in the data set, I would have no control about how it might be used afterwards. The tech sector isnt exactly known for giving people proper credit, and the data is available for anyones use. As much as we want it to benefit the local communities, theres a possibility that also Big Tech could make use of the same data and build something that then comes out as the commercial product, says Ryakitimbo. Though Mozilla does not share who has downloaded Common Voice, Lewis-Jong tells me Meta and Nvidia have said that they have used it. Open access to this hard-won and rare language data is not something all minority groups want, says Harry H. Jiang, a researcher at Carnegie Mellon University, who was part of the team doing audit research. For example, Indigenous groups have raised concerns. Extractivism is something that Mozilla has been thinking about a lot over the past 18 months, says Lewis-Jong. Later this year the project will work with communities to pilot alternative licenses including Nwulite Obodo Open Data License, which was created by researchers at the University of Pretoria for sharing African data sets more equitably. For example, people who want to download the data might be asked to write a request with details on how they plan to use it, and they might be allowed to license it only for certain products or for a limited time. Users might also be asked to contribute to community projects that support poverty reduction, says Lewis-Jong. Lewis-Jong says the pilot is a learning exercise to explore whether people will want data with alternative licenses, and whether they are sustainable for communities managing them. The hope is that it could lead to something resembling open source 2.0. In the end, I decided to donate my voice. I received a list of phrases to say, sat in front of my computer, and hit Record. One day, I hope, my effort will help a company or researcher build voice AI that sounds less generic, and more like me. This story has been updated.

But 155 sites added in updated 2024 list, including a 15th century school house which survived an arson attack by suffragettesSaltdean Lido has been removed from the Heritage At Risk Register following a restoration by Conran & PartnersHistoric England has removed Saltdean Lido from its Heritage At Risk Register following a restoration programme but named an additional 155 sites in need of attention.The heritage advisor has published its annual roundup of historic sites deemed to be at risk due to neglect, structural deterioration or the risk of redevelopment.Richard Jones streamline moderne lido in east Sussex, completed in 1938, is among 124 sites removed from the list due to being considered no longer at risk.Added to the register in 2011, the grade II*-listed building has been restored by Conran & Partners, working for a local community action group, with the project supported by the National Lottery Heritage Fund and Historic England.It is now home to a caf, restaurant, gym, public library, and multiple work and exercise spaces, and hosts a wide variety of events in its art deco ballroom.The painted hall at Sherborne HouseOther buildings removed from the list include the grade I-listed Sherborne House in Dorset, which has been transformed into an arts venue by local architect Spase.Built around 1720 for Henry Seymour Portman, it features a grand hall with murals by James Thornhill, the Dorset-born artist whose other works include the Painted Hall at the Royal Hospital in Greenwich and the inside of the dome of St Pauls Cathedral.The Sherborne House Trust acquired the building in 2018 and plans for its transformation into an arts venue were approved in 2021.The grade II-listed Abney Park chapel and graveyard in Stoke Newington, London, has also been crossed off the list following a 5m restoration funded by the National Lottery Heritage Fund, the National Lottery Community Fund, Hackney Council and Historic England.The grade II-listed Abney Park chapel and graveyard has been removed from the listThe early 19th century site had been on the list since its creation in 1998, with Historic England describing its removal as a major achievement.The graveyard boasts a new cafe, community room and workshop spaces, while the chapel now hosts events and has held its first ever wedding.A total of 4,891 sites are on this years register, 20 more than last year. They include 1,442 buildings and structures, 969 places of worship, 103 parks and gardens, three battlefields and four shipwrecks.Recently added sites include a rare Victorian windmill which, while still in working order and producing flour, has been found to be in need of urgent repairs due to water seepage and rotting timbers.Volunteers from the Waltham Windmill Preservation Society are repairing the Victorian windmill, which is still in operationThe mill is run by dedicated volunteers from the Waltham Windmill Preservation Society who regularly hold fundraising events to help pay for ongoing maintenance. Repair work is already underway, helped by a 63,000 grant from Historic England.The early 15th century Kings Norton Old Grammar School in Birmingham has been added to the list despite winning a restoration award just 20 years ago.Kings Norton Old Grammar School survived an attack by two suffragettes in 1913Believed to have been originally built as a priests house, it was remodelled in the 17th century before surviving an intended arson attack by two suffragettes in 1913.The campaigners had left a note on a blackboard explaining that they had been so charmed by the building that they had decided to refrain from their design of destruction.However, the building is now deteriorating as external panels are detaching from the frame, allowing in damp and rainwater.The grade I-listed Tamworth Castle is also in need of further repairs after initial restoration work was completed last year.> Also read:Save Britains Heritage adds 86 new entries to Buildings at Risk registerOne of the best preserved motte and bailey castles in the UK, it has a history going back well over a thousand years, the site having been occupied by a palace for the Kings of Mercia before the 9th century Viking invasions.It was rebuilt as a castle after the 1066 Norman Conquest, captured by Parliamentarians during the English Civil War and has been a museum since 1899.Historic England said the site had seen its fair share of battles and needs some attention before it is fighting fit once more.Tamworth Castle is in need of a further round of repairs following an initial restoration completed last year

Councillors said schemes tenuous community benefits did not justify proposed two-storey roof extensionCGI of Makes proposals for the 48 Chiswell Street siteMake Architects is facing another delay on a major project following Islington councils vote to defer a decision on a redevelopment scheme near the Barbican.Councillors voted to kick the 48 Chiswell Scheme into the long grass due to an egregious failure to meet a range of planning policies including Islingtons tall building policy.Representatives from Make were told to go back to the drawing board and remove the top storey of the scheme, which proposed a two-storey roof extension on top of an existing building which is already considered to be at the height limit for the area.Make is also currently waiting for a High Court decision on the 500m redevelopment of ITV Studios, which has been beset by a series of planning wrangles since it was first put on ice by the secretary of state more than two years ago.The existing building is already at the maximum height for the area under Islingtons tall buildings policyThe 48 Chiswell Street scheme, designed for Berkeley Estate Asset Management, is proposing the partial demolition and refurbishment of a 1980s office on the fringe of the City of London.It had been recommended for approval ahead of yesterdays planning committee meeting, with Islingtons planning officers arguing a breach of the areas policy on tall buildings was outweighed by the schemes high quality architecture and a range of community benefits, including affordable workspace.But while committee chair Martin Klute said the scheme was exciting and welcomed the retention of the existing buildings structural frame, he described its claimed community benefits as tenuous.Of particular concern as a purported mitigating factor for the height policy breach was the proposed affordable workspace, which was not considered to be particularly lettable because it was located in the sites basement, Klute said.The additional benefits that this [proposal] grants.seem very vague and ill thought through, he said.The committee is used to having projects of that sort linked to the building closely described, valued and knitted into the purpose and function of the building. This all seems very tenuous.The height of the proposals had been consistently criticised by Islingtons design review panel and by the Greater London Authority throughout the pre-application process in comments described by Klute as very pointed and clear.The proposals, on the rear left of the CGI, are on the fringe of the City of LondonHe said: Building heights are always being significantly challenged by developers trying to gain extra height, and in other cases where we have allowed extra height, this has always been coupled with a balance of exceptionality.Councillor Paul Convery added: When a building proposal is significantly non compliant we want to see something that significantly knocks our socks off, that really is exceptional, that really does tilt that balance of harm by a very significant package of benefits, and to be honest I dont think that is whats available here.Councillor Toby North called for the scheme to be reduced in height, adding I cant see any justification for the egregious failure to meet a number of policies.> Also read:Sluggish economy and rising tax bill send Makes numbers into reverseThe submitted scheme would have seen a comprehensive overhaul of the existing 1987 building, including the demolition of its prominent pentagonal entrance tower, replacement of external facades and adjustments to internal layouts.The project team includes cost consultant Turner & Townsend Alinea, project manager Blackburn, structural engineer Elliott Wood, planning consultant Gerald Eve and landscape architect Townshends.Make and Berkeley Estate Asset Management have been contacted for comment.The sites pentagonal entrance tower would be demolished under the proposals

Our Experts Written by James Bricknell Our expert, award-winning staff selects the products we cover and rigorously researches and tests our top picks. If you buy through our links, we may get a commission. Reviews ethics statement Why You Can Trust CNET 16171819202122232425+ Years of Experience 14151617181920212223 Hands-on Product Reviewers 6,0007,0008,0009,00010,00011,00012,00013,00014,00015,000 Sq. Feet of Lab Space How we test CNETs expert staff reviews and rates dozens of new products and services each month, building on more than a quarter century of expertise. What to consider Posture Avoid back, arm and wrist pain with good posture. Sit back in your seat and support your feet the best you can. Chair posture A chair with lumbar support will help keep your lower back from getting sore. If it doesnt have support, roll up a towel and put it behind your back. Wheel Quality It may not feel important, but an office chair with wheels that roll well will make your life easier. Look for strong wheels or invest in an upgrade. Table of Contents Our Picks $466 at Branch Furniture Best overall office chair The Verve chair by Branch View details $466 at Branch Furniture View details $240 at Amazon Best low-price mesh back office chair Sihoo Doro C300 View details $240 at Amazon View details $733 at Oak Hollow Best mesh office chair Oak Hollow Aloria Series View details $733 at Oak Hollow View details $77 at Amazon Best value office chair Amazon Basics leather-padded swivel chair View details $77 at Amazon View details $249 at OdinLake Best office chair with full control OdinLake Upgrade 518 View details $249 at OdinLake View details $200 at Eureka Best budget executive office chair Eureka Galene executive chair View details 5% exclusive CNET offer applied at checkout $200 at Eureka View details $1,897 at Anthros The most comfortable office chair I've ever used The Anthros chair View details $1,897 at Anthros View details $450 at Amazon Best mid-priced office chair Hon Ignition 2.0 View details $450 at Amazon View details $300 at Flexispot Best office chair with a headrest Flexispot C7 View details $300 at Flexispot View details $857 at Steelcase Best build-your-own office chair Steelcase Karman View details $857 at Steelcase View details $210 at Amazon Best office chair for bigger gamers EasySMX Big and Tall gaming chair (Update: Out of Stock) View details $210 at Amazon View details $1,300 at Amazon Most comfortable high-end office chair Herman Miller Mirra 2 View details $1,300 at Amazon View details $200 at Amazon Best office chair for posture Nypot Premium ergonomic kneeling chair View details $200 at Amazon View details $290 at Ikea Most durable office chair Ikea Markus chair View details $290 at Ikea View details $1,165 at Amazon Best standing desk office chair HAG Capisco adjustable standing desk chair View details $1,165 at Amazon View details Table of Contents A great office chair can cost $1,000 or more, but not every ergonomic chair will work for every person. If you're looking for adjustable lumbar support, a foam seat cushion or head support, our CNET experts have found the best office chairs to meet all those needs and more. Read more: Best Gifts for Gamers for the Holidays 2024Despite the many chairs on the market, not all of them will support your body properly -- which is absolutely necessary if you sit in a chair for long periods. Getting the right gaming and office chair means having proper lumbar support, seat depth and comfort to avoid back and neck pain. Are you a fan of gaming chairs? Do you want something fancier, like an ergonomic office chair from Herman Miller? Or maybe youre looking for a budget chair? We've tested a huge range of chairs, from $50 to $3,000; and these are the best office chairs.What is the best office chair of 2024? Verve Chair by Branch is the overall best office chair. BranchIf you spend time working, gaming or doing anything that involves sitting for a long time, you need a high-quality, supportive chair. Our top pick, the Branch Verve, is a great midrange option that's comfortable, durable and looks great.Getting the right support while you're sitting can help with your posture as well as the muscle soreness that can stem from a bad chair. During the pandemic, many of us at CNET had to turn parts of our homes into offices, which gave us a chance to test a lot of office chairs. Today, remote and hybrid work is sticking around, making a good chair imperative. We've been testing office chairs at CNET for over nine years, and I've been sitting on them for decades. That means we can help you make an informed decision about where to rest your rump.Note: Prices vary on third-party sites, so prices quoted here may change. We'll regularly update this list of the best office chairs to reflect the most accurate prices. Best office chairs of 2024Filter by Showing 17 of 17 Results

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November 15, 20247 min readThe Tooth Is Stranger Than FictionAnglerfish have invisible fangs, narwhal tusks are extra-long canines, and more facts from the weird and wonderful study of teeth will astound youBy Zane WolfIn this bridled parrotfish (Scarus frenatus) beak, layers and layers of teeth can be seen compressing into an incredibly stiff conglomerate structure. Nature Picture Library/Alamy Stock PhotoDo you think teeth are boring or gross? From the iron-laden teeth of Komodo dragons to the horns on unicorns of the sea, the animal kingdom is filled with marvelous dental adaptations that will have you thinking again.Sharks are covered in toothlike scales called denticlesColored micrograph of shark skin showing the complex three-dimensional structures of its denticles.Gregory S. Paulson/Getty ImagesOn supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.Cartilaginous fishes such as sharks, rays, skates and chimaeras grow three-dimensional scales on the surface of their skin. Each toothlike scale has a pulp cavity containing blood vessels and nerves and is covered in a mineralized, enamel-like tissue called enameloid. These scalesvery unlike bony fishes flat dinner-plate-like scalesare called denticles and have widely different shapes and features, not just across species but also in an individual fish. Denticles found on a sharks nose might be flat and round, resembling the patched surface of a soccer ball. But elsewhere on the body the denticles might look like overlapping cupped hands with ridges and points.These denticles can serve a variety of functions, such as decreasing drag while swimming and perhaps even increasing thrust directly, explains Purdue University biomechanist Dylan Wainwright. We think theyre also functioning in some way as protection for sharks, Wainwright continues. They may protect from both big things like bites from other sharks [and] from small things like ectoparasites. (Some fish have been observed rubbing against sharks rough skin to scrape off their own parasitic riders.)We still dont know where teeth come fromTwo competing theories about the evolutionary origins of teeth have been battling back and forth for decades, vacillating with the latest supporting discoveries in developmental biology or the fossil record. The outside-in hypothesis suggests that toothlike dermal scales with pulplike centers covered in hardened mineralsimilar to denticles found todaygradually migrated across the bodys exterior surface over successive generations of fish before moving inward to take up residence in our ancestors jawbones. The inside-out hypothesis suggests that teeth originated internally before migrating forward in the oral cavity to become oral teeth.An investigation of a fossilized sawtooth sharks rostral denticles (the teeth on the fishs sawlike bill) showed complex internal structures incredibly similar to those found in shark teeth. This discovery suggests that the developmental gap between dermal scales and teeth is smaller than originally thought, edging the outside-in hypothesis ahead of inside-out once more. Given the inherently spotty nature of the fossil record, however, it is entirely possible that we will never know exactly where our oral teeth come from.Some fish species have not one, not two, but three varieties of teethMost fish have two sets of teeththe oral teeth located near the front of their mouth for grabbing and chomping and the pharyngeal teeth located in their throat for the slicing and dicing. But some fish, comprising a group known as osteoglossomorphs, have also developed a third set of teethbony plates formed by the roof of their mouth and their tongue (osteo means bony; glossi means tongue) that help crush and grind their food. It seems like fish just put teeth wherever they want, says Kory Evans, a fish biologist at Rice University, and fishes can continue making teeth throughout their entire life, which is really impressive.The most numerous vertebrate fossils on the planet are microfossil fish teethAs fish routinely replace their teeth, the shed teeth will fall to the bottom of the water column and become enshrined in the sediment. Unlike more porous bones, these hardened teeth are less susceptible to erosion and degradation. Given that fish have existed for 530 million years or so, it should come as no surprise that sediment from around the globe is chock-full of fish tooth fossils. But good luck spotting them in the wild. Theyre smaller than the human hair, but these little, teeny, tiny fish teeth can tell mighty stories, says Elizabeth Sibert, an oceanographer and paleobiologist at Woods Hole Oceanographic Institution.Resembling microscopic ice cream cones, these micro teeth can vary in thickness, length, curvature, presence or absence of barbs, and so on. From the relative abundances of these teeth over time and the geographic distribution of differently shaped ones, Sibert and her collaborators can make inferences about animal diversity, animal abundance and food webs from oceans long past. And just how many of these microfossil teeth might be out there? Certainly billions, Sibert guesstimates, and I think trillions might not be that far off.Parrotfish beaks, built from compressed teeth, have the stiffest biomineral ever foundHeavybeak parrotfish (Chlorurus gibbus) featuring an impressive beak.Ute Niemann/Alamy Stock PhotoMost parrotfish species munch through coral in search of polyps and algae (contributing to white sandy beaches), but biting through coral is no easy feat. Parrotfish beaks are composed of the stiffest biological mineral ever discovered, supplanting limpet (snail) teeth, the previous record holder.Parrotfish beaks form by compressing up to 1,000 teeth arranged in as many as 15 rows into one hard, conglomerate structure covered by a layer of enameloid. Crystals in the enameloid are woven together much like fabric but on the scale of two to five microns (smaller than a red blood cell). This woven structure affords one square inch of a parrotfishs beak the ability to withstand a force equivalent to the weight of 88 elephants.Deep-sea fishes transparent teeth may provide camouflageJagged, transparent fangs can be seen in the mouth of this deep sea Anglerfish (Melanocoetus sp.) female.Nature Picture Library/Alamy Stock PhotoDeep-sea fish will never win beauty pageants, but surviving under hundreds of meters, if not several kilometers, of water is not easyand these fishes are brimming with incredibly bizarre adaptations that should definitely win them some awards. The long, spindly, transparent teeth of anglerfish, dragonfish, and the like are fascinating in more ways than one. First, while the long fangs may look sharp, these teeth are actually not designed to puncture but to trap! Many deep-sea fish species have depressible teeth that bend only inward and function like a one-way valve. Food can come in, but it cant go out. Additionally, research suggests that a dragonfishs smile doesnt exactly light up a room. Any ambient light (like that generated from luminescing prey) passes through the tooth structure instead of bouncing off a dense surface and reflecting outward, like it would from our own pearly whites. This lets the deep-sea nightmares sneak closer to prey without their exposed teeth giving away the game.Snake fangs evolved multiple times yet still all look identicalWhile most reptiles lack fangs and venom, many different snake species have evolved mechanisms to deliver venom through their teeth. Snakes display two main types of venom-delivering fangs: grooved fangs, in which venom runs down a backside channel, and tubular fangs, in which venom flows through an enclosed delivery duct within the fang itself. Tubular fangs have evolved in three separate snake families (vipers, cobras and burrowing asps). In a class of animals where fangs are not all that common, how is it that fangs evolved not just once but multiple times across disparate snake families and converged on roughly the same structures each time?The answer appears to have a root cause. Many reptilian teeth have a pattern of zigzagging indentations called plicidentine around their base, where they attach to the jaw. Scientists hypothesize that one of the zags eventually developed into a long channel running the length of the fang, which could then be fully encapsulated within the fang as a canal. The presence of plicidentine forms an evolutionary shortcut to venom delivery that made repeated evolution of that adaptation more likely.Nature evolved metal teeth long before humans invented the sawFor a few lucky critters, jaws of steel is not too far off from the truth. Some animals have evolved chompers that contain iron to reinforce and protect their teeth from wear and tear. Beavers are a prime mammalian example; their incisor enamel is enriched with iron and capable of withstanding the repetitive gnawing and chomping of fibrous plant tissue. Researchers recently learned that Komodo dragon teeth also contain iron strategically located along their serrated edges. This is particularly surprising given that Komodo dragons, like most reptiles, replace their teeth frequently. The metabolic cost of investing in and growing thousands of iron-laden teeth over their lifetime must be worth it.Narwhal tusks are overgrown canine teethNarwhal (Monodon monoceros) crossing tusks above the water's surface off of Baffin Island, Nanavut, Canada.Nature Picture Library/Alamy Stock PhotoThe defining characteristic of the narwhal, or unicorn of the sea, is a long, spiraling tusk erupting from the animals forehead. But its not a hornits a tooth. Narwhals have two large teeth embedded horizontally in their skull, and one of them (usually the left tooth, though sometimes the right or rarely both) erupts from the skull to continue its growth into what we think of as a horn. And even more strangely, these tusks always spiral in the counterclockwise direction, even in the odd instances where a narwhal has two horns. This might be the mechanism by which the tusks of narwhals grow straight, compared with the curved tusks of elephants and boars and the impressively large, curving canines of walruses and hippos. Additionally, the tusks are not covered in enamel, as most teeth are, but in cementum, a more flexible mineral coating. Given that most narwhal tusks are grown by males, it is no surprise that they have been shown to play a role in sexual selection.Plaque-causing bacteria and fungi can walk across the surface of our teethWe have known for a while that bacteria residing on human teeth can cause surface damage leading to plaque buildup and tooth decay. But scientists made a few startling discoveries more recently that might provide the motivation to brush and floss just a bit more regularly. Not only did they discover fungi in the saliva samples of children with severe tooth decay, but they also saw the bacteria and fungi interacting under a microscope! These conglomerations are capable of spreading or walking across the surface of teeth and combining with other Frankensteinian bacteria-fungi colonies to grow larger and larger.