Evolution is how living things change over time. Imagine that animals and plants can pass on their traits, like the color of their skin or the way they catch food. Over many years, those traits might change. The ones that help the animal or plant survive and have babies become more popular. A long time ago, two men, Charles Darwin and Alfred Russel Wallace, thought about why animals and plants are so good at living in their homes, like the forest or the ocean. They wrote that the best traits for living in a place will be the ones that the animals or plants pass to their babies. Later on, scientists learned that information about traits is kept in something called DNA, which is like a recipe for making a living thing. This DNA can change a little each time it is passed to babies, and that's how living things evolve. All living things on Earth, from the smallest bugs to you and me, started from the same very old family that lived billions of years ago. We have even found very old rocks that show us this family story.

Primates are a big group of animals with many kinds. They can be split into two groups. One group has animals like lemurs. The other group has animals like monkeys and apes. These animals started living a long time ago and live in trees in hot places. They have big brains, can see well, see colors, move their shoulders a lot, and can use their hands in clever ways. They can be very small like a tiny lemur or very big like a gorilla. There are a lot of different kinds of these animals. We even find new ones sometimes. These animals have bigger brains than other animals and they can see better but do not smell as well. Monkeys and apes are very good at this. Many can use their thumbs to hold things and some, like humans and monkeys, live on the ground. But they can all climb trees. They jump from tree to tree or swing on branches. Some walk on two legs and some use their hands a bit when they walk on all fours. Primates like to be with others. They can live in pairs, families, or groups with one male or many males and females. They have different ways of living together. Young females often move to new groups.

Some animals that give milk and have fur can make venom. They use venom to catch food, protect themselves, or fight with others. Only a few types of these animals can make venom. They belong to special groups of animals. Most animals with fur don’t need venom because they can catch food with their teeth or claws. A long time ago, many of these animals may have had venom. Today, snakes and some fish have a lot of venom. Some birds can make you sick if you touch or eat them, but they don’t have venom. A few water animals with soft bodies can also make venom. To be called a venomous animal, some people say it must have a special part of the body to make venom, a way to put the venom outside, and something sharp to put the venom into another animal.