There are so many different kinds of animal, all with vastly different features that seem perfectly adapted to their environment. To someone a couple of hundred years ago, this fact must have looked inexplicable, and this explains why it was often theological stories that were told to account for such varied phenomena. However, since Darwin's Origin of Species, humanity has been able to explain all of the features of all the different animals in a simple, elegant narrative.
Take all the different teeth of animals for example. Each one seems perfectly suited to biting, and chewing, the specific food that they each require. The teeth found in a carnivore include a highly evolved fourth upper premolar, and first lower molar teeth, which are perfect for tearing flesh. These four teeth have extremely sharp edges that slide past each other snugly when the mouth shuts. The restricted movement of the jaw helps these teeth hang on to the prey.
Herbivores, however, have no need for such violent teeth, and so have less pronounced, or sometimes no canines at all. Their incisors are highly evolved, perfect for cutting grass; and they also have lots of flat premolars and molars for grinding their food up. So we know that each kind of animal has teeth that are particularly beneficial to their environment. But how does this come about?
Across many generations, there occur in nature small changes, or mutations, some of which will change the shape of animal's teeth; but these changes do not have goals, and are random. So how do they seem to tend towards advantageous changes? That is where the concept of natural selection can help us.
When an animal is subject to an advantageous mutation, such as more effective flesh-ripping teeth in a carnivore, the chance that animal has of surviving is vastly increased. This animal, therefore, is much more likely to find a mate and breed, thus passing on the relevant gene. It is the harsh, changing, and highly selective environment that explains why beneficial mutations shine through.
Take all the different teeth of animals for example. Each one seems perfectly suited to biting, and chewing, the specific food that they each require. The teeth found in a carnivore include a highly evolved fourth upper premolar, and first lower molar teeth, which are perfect for tearing flesh. These four teeth have extremely sharp edges that slide past each other snugly when the mouth shuts. The restricted movement of the jaw helps these teeth hang on to the prey.
Herbivores, however, have no need for such violent teeth, and so have less pronounced, or sometimes no canines at all. Their incisors are highly evolved, perfect for cutting grass; and they also have lots of flat premolars and molars for grinding their food up. So we know that each kind of animal has teeth that are particularly beneficial to their environment. But how does this come about?
Across many generations, there occur in nature small changes, or mutations, some of which will change the shape of animal's teeth; but these changes do not have goals, and are random. So how do they seem to tend towards advantageous changes? That is where the concept of natural selection can help us.
When an animal is subject to an advantageous mutation, such as more effective flesh-ripping teeth in a carnivore, the chance that animal has of surviving is vastly increased. This animal, therefore, is much more likely to find a mate and breed, thus passing on the relevant gene. It is the harsh, changing, and highly selective environment that explains why beneficial mutations shine through.
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