The report is due tomorrow
The report is due tomorrow. more like ours today
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Have you ever been in a museum staring down a mounted T-Rex and feeling incredibly grateful that it’s not around anymore because each of those teeth are the size of a banana? (I’m asking for a friend.) Fossilized teeth have way more value than just inspiring awe and sometimes terror in museum visitors—they can tell paleontologists a lot more about the evolutionary past, from a creature’s diet to when humans started to develop tools.
So here’s what makes teeth a paleontologist’s best friend: teeth are hard, compact, and already have a layer of mineralized tissue called enamel on the outside. This makes them an almost perfect specimen for preservation in the fossil record. In fact, tooth enamel is one of the hardest biological substances around, and enamel isn’t just protecting a tooth during an animal’s life—it’s preserving its history for millions of years.
Part of that history lies in the shape and size of all the little nooks and crannies that make up a tooth’s shape. There are big differences between teeth, like how square, smooth molars help some animals munch all day on grass while sharp fangs help others bring down prey. But there are also more subtle similarities and differences in tooth anatomy between closely related species. These anatomical features are passed down or evolved through generations, meaning paleontologists can map tooth surfaces like a landscape to start building family trees.
In some cases, teeth might be the only fossils researchers have to work with in figuring out who’s related to whom, since teeth keep so well. And if they look even closer, scientists can see more signs of how an ancient creature lived—because if you think about it, teeth are the only parts of our skeleton that interact directly with the environment. Every time an animal munches on, say, a leaf, tiny bits of silica from the plant cells are dragged across the tooth surface, leaving a trail of microscopic scratches behind. Or if it’s gnawing on a nut, the hard chunks pound microscopic pits into the tooth. Paleontologists call this a “food print” and it tells them what an animal ate, at least in the weeks leading up to its death.
But teeth can tell paleontologists more than just what was going on in the mouths of ancient animals—they can give us clues about other parts of their bodies, as well. Take ancient humans for example. Like the rings of a tree, scientists can count the growth lines in their enamel to get a sense of a person’s age or health. See, as teeth mature and develop, new layers of enamel are laid down through a process called amelogenesis. As that process speeds up or slows down, it leaves bands in the enamel, and because this happens in a 24-hour cycle, those growth lines can show how old a prehistoric human was when they died—kinda like tree rings, but for days instead of years. Since your teeth stop growing eventually, it tells us the most about an individual’s juvenile years. Defects in that growth can also show that a person was sick, stressed, or malnourished during a particular time in their lives, since those things will affect how well teeth can lay down new enamel layers.
In 2022, scientists used teeth from primates in the fossil record to model how early humans grew during pregnancy. The big brains of anatomically modern humans take some time to grow, and the researchers showed that the proportions of a species’ teeth are related to both its brain size and how long it takes to develop in the womb. So by studying the proportions of teeth from different primate species, researchers could predict when early human brains started to evolve to be more like ours today.