Chimpanzee teeth skull9/16/2023 ![]() ![]() We are highly intelligent, extremely social, remarkably resourceful, able learners, skilled teachers, and as a result, a remarkable evolutionary success story. Supported in part by The Leakey Foundaiton, Scientists at the University of Arizona and Arizona State University published a study in Science Advances this week that they think has finally cracked the case. Paleoanthropologists have wondered for a long time how and why humans evolved molars that emerge at these specific ages and why those ages are so delayed compared to living apes. These teeth come in at a much later age than they do in our closest living relative, the chimpanzee, who get those same adult molars at around three, six, and 12 years old. These are the ages that most people get their three adult molars or large chewing teeth towards the back of the mouth. ![]() Many omnivores also have well-developed incisors to break through wood or hard seeds.Six, 12, and 18. Their molars typically have high crowns and sharp edges for shearing meat, and wide surfaces for crushing bone and plant material. Omnivores tend to have canine teeth that are chisel-shaped with a narrow tip, useful for capturing and biting food. There is often a gap between the front and back teeth, called a diastema, which provides space for the plant tissue to be repositioned as they chew. In rodents, these teeth continually grow to keep sharp. Many have well-developed incisors that serve as chisels to break through wood or hard seeds. Plant/vegetation eaters, or herbivores, tend to have broad, tall, flat molars that help them grind tough plant tissue. ![]() Their molars are serrated and narrow for shredding meat into smaller pieces before swallowing. Their incisors, used mostly for grooming, are relatively small. Meat eaters, or carnivores, have long, sharp-tipped canine teeth for catching and tearing into prey. Does the animal eat meat, plants, or both? Graphic by Jennifer Renteria, Smithsonian. ![]() The combination of canines and wide molars indicates raccoons are omnivores. This gives them better peripheral vision, so they can detect a predator sneaking up on them. Prey tend to have their eye orbits situated farther on the side of their heads. Binocular vision aids in depth perception, which helps predators determine how far they need to pounce or jump in order to catch their prey. Predators tend to have eye orbits that face forward, which gives them better binocular vision. Cats (family Felidae) may be diurnal, nocturnal, or crepuscular, depending on the activity cycles of the prey they rely on. Some animals, such as deer, skunks, and possums, are most active at dawn and dusk ( crepuscular), and tend to have intermediate-sized eye orbits. This applies to humans, most other primates, and large mammals such as hippos, elephants, and giraffes, among others. In contrast, animals that are most active during the day ( diurnal) have smaller eye orbits. The enlarged area corresponds with larger eyes with pupils that can open very wide, allowing more light to enter. Nocturnal animals that are active at night, such as coyotes, bats, and some monkeys, tend to have large eye orbits in relation to the rest of their skull. Is the animal nocturnal? Is the animal predator or prey? Humboldt’s Night Monkey (Aotus trivirgatus) is nocturnal and has large eyes. ![]()
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