It is 2023, and humans rule the Earth. There are 8.1 billion of us, spread across 900,000 km² of land. Our biomassThe total weight of a set of organisms (although the word is also used to describe a kind of energy production in which plant and animal remains are used as fuel). is bigger than that of all wild animals combined. We build cities, farm the land and mine mineral resources. We can even zip around the world by air.

Wild animals may attack a person here and there. BacteriaA large group of single-cell microorganisms. Some cause disease in animals and humans. may make us sick. Natural disasters may disperse people. But we remain the undisputed masters of the planet. The BBC's Jon Farrar writes: "We stand astride the world as a god."

Yet things could have happened very differently. A new study has found that we almost became extinct.

Researchers discovered that about 900,000 years ago, the number of our ancestors decreased by 98.7%.¹ Only about 1,280 humans remained on Earth. The populationAll of the people that live in a place. remained tiny for the next 117,000 years before springing back up.

We now take our world for granted. But our very existence is the result of an infinitesimally unlikely sequence of events.

Roughly 13.8 billion years ago, the universe came into existence with the Big BangThe moment the universe came into being. It is thought that this took place in a kind of explosion from a dimensionless singularity.. This set the basic laws of nature, such as the speed of light, strength of gravity and the elements that make up the world. If these were just a little different, the universe would not be able to support life.

Then, 4.6 billion years ago, a dying star exploded and created the Sun, providing light and heat. Later, 4.5 billion years ago, a young planet hit the Earth and almost destroyed it. The resulting briers became the Moon. And 4 billion years ago, water arrived via icy comets.

This was required for life to begin. When it did, it was with simple single cell organisms. But it took a billion more years for the two to combine and create the first complex life form. One of these new forms then separated oxygen from carbon dioxide, creating the template for modern animal life.

Organisms grew steadily more advanced. Sixty-five million years ago, the Earth was ruled by dinosaurs. By chance most of them were wiped out by an asteroidA small body in space, made of metal and rock material. Asteroids usually orbit the sun, but if knocked off course they can be drawn into Earth's gravity and fall towards it. . But our mammal ancestors managed to survive. They gradually evolved into what we came today.

It is an extraordinary chain of luck. As astronomer Carl Sagan once said: "Extinction is the rule. Survival is the exception." We have won the cosmic lottery time and time again.

This suggests that the fact of our existence is nothing short of a miracleSomething amazing or wonderful. It is a very unusual event.. Another new paper from the University of Oxford even claims that there is a "vanishingly small" chance of intelligent life existing anywhere else. We might be a true one-off.

Yet others think we should not get ahead of ourselves. There is still much that we do not know. The universe extends far beyond our knowledge. Other lifeforms like us may have evolved elsewhere.

Some believe that our universe is just one part of an even vaster multiverseThe idea that there may be many universes, and ours is just one of them. . As astronomer Martin Rees asks: "Could it be that our observable domain is a tiny part of a far larger and possibly diverse ensemble?" In such a humongous cosmosThe universe, especially when it is understood as an ordered system. with infinite possibilities, no one stream of events seems so remarkable. 

Yes: We exist because of a long series of chance reactions and collisions, universe-creating explosions and microscopic bacteria: a story so miraculous that it makes science fiction dull by comparison. 

No: A miracle is something that defies natural laws. Humanity is exceptional. But our existence can be explained scientifically as a series of processes. The miracle is not us but the Big Bang itself.

Or... Calling human life a miracle suggests that it is a good thing. But it is actually anything but. We have gobbled up resources, warmed the atmosphere and polluted the oceans. Our existence is a curse.

Biomass - The total weight of a set of organisms (although the word is also used to describe a kind of energy production in which plant and animal remains are used as fuel).

Bacteria - A large group of single-cell microorganisms. Some cause disease in animals and humans.

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.

Asteroid - A small body in space, made of metal and rock material. Asteroids usually orbit the sun, but if knocked off course they can be drawn into Earth's gravity and fall towards it.

Miracle - Something amazing or wonderful. It is a very unusual event.

Multiverse - The idea that there may be many universes, and ours is just one of them.

Cosmos - The universe, especially when it is understood as an ordered system.