Johnny Thompson, a philosopher, studies the concept of a possible "Plan B" for evolution in case of humanity's extinction.
This modest flightless bird inhabits Aldabra Atoll. Externally, it does not stand out: its brown feathers and size are similar to that of a chicken.
About 136,000 years ago, white-throated rails from Madagascar arrived at this atoll, where they found ideal living conditions: the absence of predators and threats from humans. As a result, they evolved into flightless forms. Why expend energy on flying if it is unnecessary?
However, a catastrophe soon occurred — the island was submerged. The birds, unable to fly or swim, went extinct. But later, when the water level dropped, their ancestors from Madagascar returned to the atoll. This cycle repeated: the rails lost their ability to fly again and remained on the island. Fossil studies confirmed that these were the same birds, only with slightly changed traits.
This phenomenon is called "iterative evolution."
Philosopher Toby Ord, author of the book "The Precipice: Existential Risk and the Future of Humanity," also explores the likelihood of humanity's extinction. He questions whether humans or other primates could evolve again in the event of a catastrophe.
Stories of Iterations
There are other examples of iterative evolution beyond Aldabra. For instance, different species of sea turtles independently developed adaptations to seagrass in different eras. Climate changes led to the extinction of turtles in certain regions, but when suitable conditions returned, similar adaptations emerged: long limbs and powerful jaws. Each time the sea created favorable conditions, evolution reshaped the turtles.
Evolution selects the most suitable genes for a specific environment. Therefore, over billions of years, the same traits can reappear repeatedly. Temporal climate fluctuations — from cold to warm — contribute to changes in species occupying different ecological niches. Thus, the existing species are best suited to the current environment.
These are not exact copies but variations of the same. Familiar shapes created by different evolutionary paths.
Despite the vast size of populations, examples of complete species recreation are not yet known. Cuvier's rail from Aldabra and the white-throated rail from Madagascar are essentially the same species, with one important difference: the loss of the ability to fly. Climate and ecological changes can destroy species, and when they return, their genetic makeup changes. To recreate an extinct species, it is necessary to restore not only the traits but the entire genetic code — a unique combination. The genome of each species contains billions of base pairs, and even minor mutations can lead to new biological features.
Considering the millions of mutations occurring over countless generations, the probability that nature will create the same design is virtually zero.
Humans, but Not the Same
Thus, for Homo sapiens, the prospects do not look too bright. If humanity were to suddenly go extinct, the likelihood that its genome would evolve in the same way as before is extremely low. The question is whether human traits could re-emerge after billions of years.
Paleontologist Simon Conway Morris argues that there are common patterns of convergent evolution in the history of life. Similar adaptations, such as eyes, wings, and streamlined body shapes, develop independently in different lineages. He believes that evolution often follows similar paths because physical and biological constraints guide it toward optimal solutions. In his view, the emergence of intelligent life is not a coincidence but a consequence of evolutionary processes.
As an example, he cites intelligence in various animals. Crows using tools, dolphins solving problems, and octopuses escaping enclosures demonstrate cognitive abilities that have appeared repeatedly and in various forms. For Conway Morris, human intelligence is a convergent trait that could manifest again under suitable conditions. Evolution, he says, is not random; it is governed by deep structural patterns that lead to recurring outcomes, even complex ones like intelligence.
Therefore, there is hope for the restoration of intelligence and reasoning similar to that of humans. Ord adds: "It is important to have the possibility of revival — the possibility that something can reappear after extinction. But the odds of that are much lower than we imagine."
How Unique Are We
A small comfort is that it is unlikely that human actions alone — with nuclear weapons, artificial intelligence, or viruses — could destroy all life on Earth. This is a positive note. As Ord points out: "If all life on Earth were to disappear, it would be a catastrophe… All future beings that could ever exist would be lost… It took about four and a half billion years to reach this point, and Earth has only about 500 million years left to develop complex life before it becomes too hot."
Nevertheless, it can be confidently stated that within those 500 million years, intelligence will arise, even if Homo sapiens disappears instantly.
Reflecting on the possible extinction of humanity, we realize how unique we are and how fortunate we are to live at this moment. The fact that I was able to write this article and you are able to read it is a stroke of luck comparable to winning the lottery. As paleontologist Stephen Jay Gould said, if you "rewound the film of life differently," the outcome would be entirely different. There would be no humans, no Mozart, and perhaps only mollusks would remain.
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