In sports, each person or team is trying to beat each other.  Winning usually means you scored more points than the other players or you finished first.  There are also some games where winning is based on luck.  However, you need more than luck to win in most sports and games.  People need a skill to play them well.  A person who has these skills can practice and become better at the game.  They can beat other people.  When people play against each other to win, it is called competition.



If we need food we can grow it or go to the store.  Most living things do not have stores and cannot grow their own food.  They must make, find, or kill their food to survive.  Sometimes organisms can eat what they need and there may be food left over.  Most of the time there is not enough food for everything to survive, though.  Some will be able to get enough food to live and some will not.  It's a competition, but not in the same way as people compete at games.  Organisms need to compete to stay alive, and it will not be easy for all of them.



New ideas in science often come from other ideas.  People almost never think of something new without the help of ideas that other people thought of before them.  Let's think about soccer shoes.  People didn't always wear shoes.  Maybe someone had to think about tying leaves or sticks to their feet.  The next person may have thought about making shoes out of animal skin or fur.  Then someone else started wearing shoes that would be better for playing sports, and not just for walking.  Someone else decided to make shoes that have treads on the bottom of the shoes so they wouldn't slip on the field.  Someone else put metal spikes on the bottom.  Others saw that the metal could hurt floors, soccer fields, and other people.  They invented shoes with plastic spikes to make them safer.  Each idea starts with another and tries to make it better.


There was one scientist who had an interesting idea about people.  He said that people compete with each other for food, water, and space.  He noticed that the number of people in a city usually grows.  New people move there and people who already live there have children.  He said that the more people there were, the harder it would be for each of them to stay alive.  Each person had to fight to survive.  This man's name was Thomas Malthus.  He wrote a book about his ideas called An Essay on the Principle of Populations.  He believed that people compete to stay alive and to have food, water, and shelter.  His idea later helped a lot of people with their own ideas about how animals and other organisms compete too.


Animals need to fight to stay alive, too.  Since they cannot buy water or grow food, they need to find it.  Most of them cannot build a home, so they also need to find a safe place to live.  These things make it easier for some animals to live in certain places.  For example, a cockroach can live in a city.



Cockroaches are very small and can fit in tiny cracks, under doors, or in holes in buildings.  They are also afraid of light.  Once someone turns on a light and would be able to see them, they are already running away to hide.  The cockroach also eats food that is old and rotting.  There are plenty of places in a city where a cockroach could select, or choose, what to eat.  A cockroach is also one of the fastest insects in the world for its size.  There are plenty of hiding places in a city, plenty of things to eat, and there is plenty of water to drink.  Organisms can select, or choose, their environment, but in some ways their environment can also select them.



On the other hand, think about an elephant living in the city.  Elephants spend about 16 hours a day eating plants.  There would not be enough plants for them to eat in a city.  There also would not be many places for an elephant to hide.  They usually live in the forest and, of course, there are no big forests in a city.  A cockroach is suited to live in the city.  To be suited for an environment means that it works for you to live there.  It "fits like a suit."   An elephant is not suited to live in the city, though.  It would not have enough food, and there is little shelter.  Animals can best survive in a place where they can easily find the things they need.  In other words, animals can survive the best in an environment that they are best suited for.