The secret history of teeth revealed: How they originated inside a 465-million-year-old fish's body
Our knowledge about the origins of teeth pertains to that of the entire body, a natural occurrence made up of tissues. But did you know that human teeth evolved from the "body armour" of an extinct fish that lived 465 million years ago?
From vertebrates to teeth
In a
published in the journal Nature on Wednesday, researchers showed how sensory tissue discovered on the exoskeletons of ancient fish is linked to the same "genetic toolkit" that produces human teeth.
Tired of too many ads? go ad free now
"This shows us that 'teeth' can also be sensory even when they're not in the mouth," said Yara Haridy, co-author of the study and palaeontologist and evolutionary biologist at the University of Chicago.
Initially, researchers set out to identify the earliest vertebrate in the fossil record seeking specimens from the Cambrian and Ordovician periods. An obvious sign of a vertebrate species is the presence of internal tubules for dentine, a calcified tissue that is found under the enamel in the human teeth, but also in the external bumps or odontodes in ancient fish armour.
While making the use of high-resolution CT scans to analyse the jawless "first fish" species Anatolepis heintzi, the researchers discovered pores filled with dentine. They also compared the fossil to a coterie of ancient fossils and modern marine life.
The shocking discovery
Upon closer investigations, researchers realised that the supposed dentine-lined pores were like the sensilla, the sensory organs on the shells of crabs, thus making A.
Heintz, an ancient invertebrate arthropod and not a vertebrate fish.
Vertebrates and invertebrates, both have sensory armours connected to nerves that help them sense their environment. To substantiate the discovery that the fish was an arthropod, the team scanned fossils and modern specimens from snails and barnacles to sharks and catfish. It was revealed that the suckermouth catfish raised in Hardy's own lab had small tooth-like scales on their skin, called denticles, that were connected to nerves.
Tired of too many ads? go ad free now
This discovery also led to the realisation that ancient vertebrates had the same mineralized tissue that evolved into dentine and then our sensitive teeth. These tissues helped them sense their environment like cold waters or pressure from nearby objects, just like our teeth.
Thus, this study also supports a key theory in evolutionary biology called the "outside-in" hypothesis where sensory structures evolved on exoskeletons at least 460 million years ago and were used by animals to make 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 armour of early vertebrates," wrote the researchers in the study.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Time of India
a day ago
- Time of India
Homo Sapiens Adaptability: Early humans survived in a range of extreme environments before global migration, study says
WASHINGTON: Humans are the only animal that lives in virtually every possible environment, from rainforests to deserts to tundra. This adaptability is a skill that long predates the modern age. Tired of too many ads? go ad free now According to a new study published Wednesday in Nature, ancient Homo sapiens developed the flexibility to survive by finding food and other resources in a wide variety of difficult habitats before they dispersed from Africa about 50,000 years ago. "Our superpower is that we are ecosystem generalists," said Eleanor Scerri, an evolutionary archaeologist at the Max Planck Institute of Geoanthropology in Jena, Germany. Our species first evolved in Africa around 300,000 years ago. While prior fossil finds show some groups made early forays outside the continent, lasting human settlements in other parts of the world didn't happen until a series of migrations around 50,000 years ago. "What was different about the circumstances of the migrations that succeeded - why were humans ready this time?" said study co-author Emily Hallett, an archaeologist at Loyola University Chicago. Earlier theories held that Stone Age humans might have made a single important technological advance or developed a new way of sharing information, but researchers haven't found evidence to back that up. This study took a different approach by looking at the trait of flexibility itself. The scientists assembled a database of archaeological sites showing human presence across Africa from 120,000 to 14,000 years ago. Tired of too many ads? go ad free now For each site, researchers modelled what the local climate would have been like during the time periods that ancient humans lived there. "There was a really sharp change in the range of habitats that humans were using starting around 70,000 years ago," Hallet said. "We saw a really clear signal that humans were living in more challenging and more extreme environments ." While humans had long survived in savannas and forests, they shifted into everything from dense rainforests to arid deserts in the period leading up to 50,000 years ago, developing what Hallet called an " ecological flexibility that let them succeed." While this leap in abilities is impressive, it's important not to assume that only Homo sapiens did it, said University of Bordeaux archaeologist William Banks, who was not involved in the research. Other groups of early human ancestors also left Africa and established long-term settlements elsewhere, including those that evolved into Europe's Neanderthals, he said. The new research helps explain why humans were ready to expand across the world way back when, he said, but it doesn't answer the lasting question of why only our species remains today.
India Today
a day ago
- India Today
Humans adapted to diverse habitats before trekking out of Africa
Small bands of Homo sapiens made a few failed forays leaving our home continent before the species finally managed to launch a major dispersal out of Africa roughly 50,000 years ago, going first into Europe and Asia and eventually the rest of the why was this migration successful after the prior ones were not? New research is offering insight. It documents how human hunter-gatherers in Africa began about 70,000 years ago to embrace a greater diversity of habitats such as thick forests and arid deserts, acquiring an adaptability useful for tackling the wide range of conditions awaiting beyond the the dispersal 50,000 years ago was successful is a big question in human origins research. Our results suggest that one part of the reason is that humans had developed the ecological flexibility to survive in challenging habitats," said Loyola University Chicago archeologist Emily Hallett, co-leader of the study published in the journal Nature. Looking at an array of archeological sites in Africa, the study detailed how human populations expanded their range into the forests of Central and West Africa and the deserts of North Africa in the roughly 20,000 years preceding this examples of archeological sites dating to this time that illustrate the expansion of human niches to harsh deserts include locales in Libya and Namibia, and examples of expansion to forested habitats include locales in Malawi and South sapiens arose roughly 300,000 years ago, inhabiting grasslands, savannahs and various other African ecosystems."Starting from about 70,000 years ago, we see that they suddenly start to intensify this exploitation of diverse habitats and also expand into new types of habitat in a way we don't see before. They exploit more types of woodland, more types of closed canopy forests, more types of deserts, highlands and grasslands," said archeologist and study co-leader Eleanor Scerri of the Max Planck Institute of Geoanthropology in Germany."An Ice Age was coming, which means drier conditions in parts of Africa. It seems possible that humans responded to this squeeze by learning how to adapt to new niches," Scerri increased ecological flexibility of the species appears to have reflected cultural and social advances such as passing knowledge from one generation to the next and engaging in cooperative behavior, the researchers said."This must have entailed profound changes in their interaction with the natural environment, as it allowed them to occupy not only new environments in Africa, but entirely new conditions in Eurasia as well," said evolutionary biologist and study co-leader Michela Leonardi of the Natural History Museum in London."Another way to phrase this is that the ability to live in a variety of environments in Africa is not directly the adaptation that allowed a successful out of Africa, but rather a sign that humans by that point were the ultimate generalist, able to tackle environments that went from deep forest to dry deserts," said University of Cambridge evolutionary ecologist and study co-leader Andrea flexibility is the key trait that allowed them, later on, to conquer novel challenges, all the way to the coldest tundras in Siberia."Trekking out of Africa, Homo sapiens encountered not only new environments and unfamiliar animals and plants, but also other human species, including the Neanderthals and Denisovans. The ecological flexibility learned in Africa may have provided an edge when Homo sapiens encountered these other humans, both of whom disappeared relatively soon thereafter, the researchers evidence indicates that today's people outside of Africa can trace their ancestry to the population of humans, numbering perhaps only in the thousands, who engaged in that pioneering migration out of Africa approximately 50,000 years ago."I think that adaptability and innovation are hallmarks of our species, and that they allowed us to succeed in every environment we encountered," Hallett said. "At the same time, we are almost too good at adapting to different places, to the detriment of most other species on Earth."Trending Reel
India Today
a day ago
- India Today
Scientists discover 540-million-year-old secret that fuels life on Earth
A new study by Nasa scientists has revealed a deep, previously unrecognised connection between the ebb and flow of Earth's magnetic field and the rise and fall of atmospheric oxygen over the past 540 million years — a discovery that could reshape our understanding of what makes Earth magnetic field, generated by the swirling motion of molten iron in its core, acts as a vast shield, protecting the atmosphere from being stripped away by the relentless solar scientists have long speculated that this field is crucial for preserving the planet's life-sustaining gases, direct evidence linking magnetic field strength to oxygen levels has been elusive until now. By meticulously analysing two independent datasets — one recording ancient magnetic field strength in rocks and minerals, and the other tracking atmospheric oxygen through geochemical proxies — researchers found that the two have fluctuated in near lockstep since the Cambrian explosion, a period when complex life first flourished on in magnetic field intensity coincided with spikes in oxygen, while troughs in one matched dips in the other, with the strongest correlation occurring with virtually no time lag.'This is the first discovery we've ever had to establish the link between the geomagnetic field and the oxygen level,' said study coauthor Weijia Kuang, a geophysicist at NASA's Goddard Space Flight Center. The findings suggest that processes deep within Earth—such as the movement of continents or changes in the core—may simultaneously influence both the magnetic field and the chemical makeup of the only does this research offer new clues about how Earth has maintained the delicate balance needed for life, but it may also help scientists identify the conditions necessary for habitability on other the exact mechanisms behind this connection remain unclear, and researchers caution that more work is needed to unravel the complex interplay between Earth's interior dynamics and its surface scientists probe deeper into Earth's past, this discovery opens a fresh perspective on the forces that have shaped—and continue to sustain—life on our planet.
