Humans are extremely special species among the creatures on Earth. We are the only species that has developed high intelligence, knows how to dress, cook, invent smartphones, self-driving cars, …
But what if humans suddenly went extinct? What other animals might have evolved to have the intelligence and skills to create complex, vast societies like ours?
For one thing, if we suddenly go extinct, the environmental damage we cause won’t go away immediately. Climate change will continue to drive many species towards heat tolerance to survive. Cold-tolerant species will also continue to struggle, meaning polar bears and penguins are unlikely to thrive for millennia after humans disappear.
A feature that helps people to be able to build and create flexibly is our skillful hands. To fulfill the same ecological role as humans – that is, building cities and improving the environment – another species would need to develop the same capacity to manipulate objects.
Other primates, such as chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), formerly known as bonobos, which are our closest living relatives, had opposable thumbs that they use to make tools in the wild. It is possible that if humans go extinct, these species will replace us, a “Planet of the Apes” future.
There is precedent for that kind of substitution, with our species outliving intelligent Neanderthals during the last ice age 40,000 years ago, according to a 2021 study published in the journal Nature. Even so, it would probably take hundreds of thousands or even millions of evolutionary years for other apes to develop the ability to create and use sophisticated tools like humans. The common ancestor of modern humans and chimpanzees lived about 7 million years ago.
But any catastrophe powerful enough to wipe out humans has the potential to wipe out chimpanzees and their relatives, leading us to find another tool-wielding candidate to fill the void. human: bird.
When the ornithopod went extinct 66 million years ago, mammals rose to fill the void. If humans die, it is possible that birds, the only surviving dinosaurs, will take our place as the most intelligent and skillful land animals.
Some birds, such as crows, have intelligence comparable to chimpanzees, according to research published in 2020 in the journal Science. And some birds are able to use their ingenious feet and beaks to shape a hook from a rope, according to a famous 2002 study published in the journal Science.
Meanwhile, trained African gray parrots (Psittacus erithacus) can learn up to 100 words and do simple math operations, even understanding arithmetic concepts like “zero”.
Birds can congregate in large flocks, and some species, such as the weaver bird (Philetairus socialus), even build communal nesting sites. According to research published in the journal Frontiers in Ecology and Evolution, some weavers’ nests remain in use for decades.
But there is another group of animals that are extremely adept at manipulating things with their limbs – all eight.
The octopus is perhaps one of the most intelligent animals on Earth. They can learn to distinguish between real and virtual objects, according to a 2020 study published in The Biological Bulletin. They can even change their own habitat by removing algae from their nests and fenced off with seashells. They are also community-dwelling species.
However, the octopus will find it difficult to adapt to life on land. Vertebrates have iron in their blood cells, which binds oxygen very efficiently. In contrast, octopuses and their relatives have copper-containing blood cells. These molecules still bind to oxygen, but not as efficiently, and as a result the octopus is confined to oxygen-saturated water instead of thin air.
Therefore, the octopus and its relatives are unlikely to move to land and become the most intelligent land animal. The researchers suggest that social insects, such as ants and termites, are more likely.
Insects are well adapted to different types of environments. They have been around for about 480 million years, according to the Natural History Museum in London. In that time, they’ve grown to fill almost every conceivable nook, from flying, to burrowing, to swimming, and even building elaborate city-like towers.
The social behavior of ant and termite colonies is perhaps more similar to human civilization than to any other species on Earth. According to a study published in the journal Proceedings of the Royal Society B in 2017, ants can grow fungi in nests, and termites can communicate long distances inside the nest using vibrations. If humans go extinct, it’s possible that these insect swarms will take over the world – assuming they survive climate change.
Of course, all of this is just hypothetical; we can barely really predict how evolution will unfold on a geologic chronological scale. It is possible that another species replaces humans, but it takes millions of years of good selection. However, some scientists are less optimistic, arguing that “nature won’t make that mistake a second time”.