We’ve got some good news and some bad news.
The bad news first? Okay. Well, humans will go extinct. And there’s a popular but controversial mathematical theory that suggests we’re closer to the end than we are the beginning.
The ‘good’ news, however, is that it reckons we’ve still got roughly another 17,100 years left. Phew.
The estimate comes from the so-called ‘Doomsday Argument’, a statistical idea first proposed by astrophysicist Brandon Carter back in in 1983.
It doesn’t attempt to predict exactly what event will or could wipe humanity out, only when the maths suggests our species might reach its end.
What is the Doomsday Argument?
The theory is based on something called ‘The Copernican Principle’, which argues that humans don’t occupy a uniquely special position in the universe or in history.
Basically, it says we shouldn’t assume we’re living at an unusually early or unusually late stage of human existence.
The argument uses a person’s position in the overall sequence of humans who have ever lived as a statistical clue about how many people may come after them.
Researchers begin with an estimate that around 117 billion people have lived throughout human history.
They then assume there is a 95% chance we are not among the first 5% of all humans who will ever exist.
From there, the calculation then suggests that the total number of humans who will ever be born is unlikely to be in excess of around 2.34 trillion.
This figure is reached by multiplying the current number of humans who have lived by 20, based on the idea that our position in history is not unusually early.
At today’s birth rates, that total would be reached roughly 17,100 years from now. The year would be 19,126.
However, the calculation is not a prediction that humanity will definitely disappear at that point, or even that extinction is likely to happen because of a specific threat.
Instead, the theory argues there is a 95% probability that humanity would become extinct before reaching that total population figure.
It’s essentially a warning about the limits of assuming that our species will continue indefinitely.
The maths doesn’t attempt to explain what might wipe us out. Potential risks that are often discussed by scientists include things such as nuclear war, climate change, pandemics, asteroid impacts, artificial intelligence and other general global catastrophes.
Some researchers point out that future threats may come from technologies or events that don’t even exist or can be known about at the moment, making them impossible to predict currently.
The Doomsday Argument has remained controversial since it was introduced.
Why do many experts argue against the theory?
Plenty of scientists, mathematicians and experts reject it because they believe the assumptions behind the calculation are all a bit too uncertain.
Critics argue that humanity’s future population isn’t random and could be heavily influenced by factors such as falling birth rates, medical advances, economic changes and technological development.
Another criticism is that the argument doesn’t really account for the possibility of humans expanding beyond Earth.
If future generations establish permanent settlements on other planets (something which seems more possible by the day), then humanity’s long-term survival could look very different from the scenario imagined by the theory. So it’s got its limits.
Even researchers who support the idea generally describe it as a statistical argument rather than an actual, firm forecast.
They argue it should be viewed as a mathematical exercise that encourages discussion about humanity’s future, rather than a countdown clock ticking towards extinction. Which is fairly disappointing in terms of being able to schedule the apocalypse.
The study is not alone in examining the possible future of the human population.
A more recent study attempting to use probability to predict what lies ahead for us, published in August 2025, only gives us a little more than 300 years before we all say bye bye.
It states: ‘Given the decline in fertility between 2019 and 2024 and employing a probabilistic forecasting method, by 2139 the world population will be between 1.55 billion and 1.81 billion… by 2339 there will be no humans.’
Whether the Doomsday Argument proves useful as a way of thinking about humanity’s future remains debated. For now, it is best viewed as an intriguing piece of probability theory rather than a warning that civilisation has a set expiry date.
Thankfully, you don’t need to start rearranging your diary just yet.