It has been estimated that 99.9% of all species that ever existed on Earth are extinct. In roughly 5 billion years, the Sun will start turning into a red giant star and expand out to the Earth orbit. Our planet might survive, but the most recent simulations suggest that the dying Sun will eventually swallow Earth.
Humans are very likely to disappear from this planet long before then. According to estimates, conditions to support life on Earth will last for between 1.5 and 2 billion years.
So how much time is left for humans?
What about using math to forecast the future of the human species. The over-simplistic mathematical argument for the prediction of the demise of our species already exists. The so-called doomsday calculation, also known as the Doomsday argument, is a group of probabilistic arguments about the likely survival of humankind.
An early version of the Doomsday argument was introduced by the astrophysicist Brandon Carter (the Carter catastrophe), though he did not publish on Doomsday per se. In the early 1980s, Carter came up with the idea that the human race is halfway to its extinction. The risk that our species will soon die out has been largely underestimated. We can try to compensate for this by taking greater care but according to Carter, Doom Soon is a more likely scenario than Doom Delayed.
Carter also coined the term anthropic principle as a contrast to the Copernican principle that states the Earth is not in a specially favoured position in the universe and we, as intelligent observers do not occupy a special place.
The anthropic principle or argument of fine-tuning expresses an intriguing thought that the physical characteristics of the universe are not only perfectly tuned for life, but the universe is the way it is precisely to enable carbon-based life. If the fundamental properties of the universe were any different, we would not be here, thus no conscious and sapient life to observe it.
Since Carter, the Doomsday argument was developed and popularized by Leslie, Nielsen, Gott (among others). In 1993, the Princeton University astrophysicist John Gott published a hypothesis about the total longevity of our species. It is a version of the Doomsday argument he called the ‘delta t’ argument, based on applying the Copernican principle to time.
Below is Gott’s formula for predicting how long our species is going to last. As stated by Gott, the equation is applicable for making a wide range of predictions about almost everything.
1/39 x t past < t future < 39 x t past
The prediction about how long the human race will last is based on how long it has been in existence so far (t past). Our species was thought to be roughly 200,000 years old. The latest finds in Morocco confirmed that Homo sapiens entered the scene between 350,000 and 300,000 years ago in Africa.
Taking the value of 200,000 for t past, Gott predicted with the 95% probability that the future longevity of our species is at least 5100 years but less than 7.8 million.
1/39 x 200,000 < t future < 39 x 200,000
5,120 < t future < 7,800,000
Needless to say, there were many refutations of the argument, rolling eyes, and heated discussions in the scientific community. The author’s replies to numerous objections to the argument would easily fill a book. Over the years, the Doomsday argument has gained many proponents as well. Though being extremely controversial still arouses a lot of interest.
Considering the doomsday math flawed or believing it is just a good philosophical puzzle, Gott’s numbers are pretty in line with those for other extinct species of hominins and mammals. The actual evidence shows that the average survival time for mammalian species has been 2.33 million years. Homo erectus lasted about 2 million years, while Neanderthals lasted 300,000 years. One of the biggest dinosaurs that ever lived, Tyrannosaurus rex lasted 2.5 million years.
Predicting the future of complex systems is, to say the least, a difficult challenge because there are far too many variables to be predicted. Accurate scientific predictions about the evolution of Homo sapiens are impossible because of the various directions that human evolution might take.
Will Homo nouveau replace Homo sapiens as predicted by physician Don Simborg? Could technology or a global catastrophe induce this new species? Will Homo sapiens create Homo nouveau, and two Homo species coexist with one another?
We do not know the answers. As humans, we will continue to evolve and adapt, but the prospects of humanity are uncertain.
Who knows what our species and those that evolve from us will become and do here on Earth, and later if humans migrate to other planets, outside our solar system?
But what are the chances of spreading across the universe?
The physicist Enrico Fermi posed a famous question: “If aliens exist, where are they all?” It is known as the Fermi paradox. One of the possible answers to that question is that intelligent life is self-destructed and destroys itself before it can spread.
The chances for asteroid impacts, super-volcanoes, natural disasters, pandemics, and the like to wipe out all humans are extremely small.
We are the most dangerous threat to ourselves.
The odds of surviving another 5,120 years despite many global threats induced by human activities seem pretty good from the current perspective!
The fact that our species is capable of a long future does not mean this is probable. It may be something that has to be earned by being smarter, wiser, kinder, more careful — and luckier — than we’ve ever had to be before.
As the Copernican principle states, we are not significant species in the universe, who lives in a special place, at a special time. Even so, what an amazing species we are and what an incredible journey Homo sapiens had hitherto!
Let us hope we are smart and wise enough to protect ourselves from us.
Author’s Note: This article is an excerpt from my Medium story, What Does the Future Hold for You, Homo sapiens?