The big bodies and canines of males help them fight each other to compete for females. These males also have much bigger canines than females. In many monkeys and apes, males are much bigger than females. Currently, there are two possible explanations. Scientists are still trying to figure out why human canines are so small. In humans, the upper canines do not even reach the pink tissue (gums) of the lower jaw. For example, in gorillas, the upper canines extend past the lower teeth. During human evolution, the canine has become much smaller. Paleoanthropologists (scientists that study hominin fossils) have made several important discoveries about how our canines have changed through time. So, what makes a hominin a hominin? There are two important traits that all hominins share: 1) the size and shape of the canine tooth and 2) our dependence on bipedality, or walking on two legs. Humans, Neanderthals, and Lucy are all hominins. She is not as closely related to us as many other species that have lived, but Lucy was also a hominin. Lucy’s formal name in science is Australopithecus afarensis. If we go back to 3.2 million years ago, we could have met a very famous distant ancestor, Lucy. The formal scientific name for Neanderthals is Homo neanderthalensis. If we traveled back about 40,000 years ago, we could have met one of the Neanderthals, a fellow member of the genus Homo. Our hominin family is at least seven million years old and includes other hominins who are now extinct. All humans ( Homo sapiens), including our distant human ancestors, are called hominins. The size and shape of our canine teeth is one trait that we share with the group called hominins. However, humans have smaller canines than many of these animals. In real life, many animals use their canine teeth to fight off predators and mating rivals. You may know it from stories and movies about vampires, as they typically are supposed to have large, pointy canines. The canine is your third tooth when you start counting from one of your front teeth. If we compare humans to our closest living cousins-chimpanzees-we can see that we share a number of traits with them as well. One of these traits is our teeth. By studying these traits, we can figure out what traits we have inherited from our distant ancestors. When we look at a human fossil, we can see many traits. The human fossil record is like our family photo album. We look like our parents and grandparents because we have inherited traits (like the shape of our nose or the color of our eyes) from them. You see a woman in a Victorian style dress, and you think she looks like your sister. You flip another page and go further back in time. Your father looks a lot like the man in the black and white photograph. You see a young man dressed in a uniform from the 1940s. Sitting on the sofa, you flip through a family photo album.
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