Their cooperation is us. Each of us is an organisation of about a million billion cells. These cells are specialised into many different types that team up to form organs such as the heart, stomach, and bones. Like the goods and services produced in human society, the key functions of the human body are all the product of the coordinated activities of thousand and thousands of differently-specialised and interdependent cells. If this cooperation breaks down, so to do our bodies.
Cancer is one example of what happens when cells go their own way at the expense of the body.
And the cells themselves are cooperative organisations. Without extensive cooperation between the molecular processes and organelles that make up cells, we would not exist. Each of our million billion cells is made up of thousands of incredibly small and intricate parts that cooperate together to produce the functions of the cell. At the molecular level, a human cell may contain up to 100,000 different proteins. Often these enzymes cooperate to form teams in which each member regulates a particular step in a sequence of reactions.