Is our existence a miracle? Humans rule the world. But new research shows that our ancestors narrowly avoided extinction. Some think that we should marvel at just how lucky we are to exist.
Early humans nearly wiped out, say scientists
Survivors: Today, there are 8.1 billion people worldwide, from a low of just over 1,000. Glossary
Population - All of the people that live in a place.
Big Bang - The moment the universe came into being. It is thought that this took place in a kind of explosion from a dimensionless singularity.
Cell - Cells are the basic building blocks of all living things. A cell is also a room with bars that prisoners are kept in.
Organisms - An organism is an individual animal, plant, or single-celled life form.
Ancestors - The people related to us who lived a long time ago.
Miracle - Something amazing or wonderful. It is a very unusual event.