BBC – Future – Strange evolution: The strange future of life on Earth

In the early 1980s, author Dougal Dixon published a cult book called After the Man: A Zoology of the Future, which imagined what life would look like in millions of years . Dixon has imagined shrews using their tail as a parachute, flying monkeys (or "flunkeys"), very long coiled snakes that catch flounces flying, gladiators that impale their prey with long spikes on their chests. and flowers the birds and bats that deceive the pollinating insects so that they land in their hungry mouth.

Shrews that use their tail as parachutes, flying monkeys … or bats

Decades later, Dixon said that his book was not an attempt to predict the future, but rather an exploration of all the possibilities of the natural world. "Books on popular level evolution, even if it's not intentional, seem to suggest that evolution is something that has happened in the past," he says. . "This is not the case at all, the evolution is happening today, it will continue long after we leave."

Although Dixon's book is a work of fiction, most biologists agree that millions of years from now, Earth will be a very different place. "I think it will look like an alien planet," says Athena Aktipis, an evolution biologist at Arizona State University.

What will evolve will seem alien and unlikely today – just like our current world, dominated by mammals, would have seemed unlikely from the point of view of the dinosaur era. So what could life look like in the future? What creatures could grow in, say, 100 million years, considering what we know about life on Earth and principles of evolution?

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Let's start by going back millions of years into a much older era of life on our planet. In the Cambrian explosion, about 540 million years ago, the Earth was populated by a whole series of "weird" creatures and "caricaturists", according to Jonathan Losos, biologist of the evolution at the Washington University of St. Louis.

"Burgess Shale [in Canada] was inhabited by a real bestiary of the weird, "he writes in his book Improbable Destinies: Destiny, Chance and the Future of Evolution. An animal, Hallucigenia, with its thin, tubular body covered with huge spines and its stick-shaped appendages, resembled "an episode of Futurama".

It is therefore not impossible for such strange and unusual creatures to evolve in the future. "Pretty much anything you can imagine has evolved somewhere in some species," says Losos. "Over time, even the improbable will eventually happen."

According to Losos, the world of biological possibilities is vast and we may not have seen everything yet. "For my part, I am not at all convinced that life on Earth has uncovered every conceivable means of existence on a planet like ours, or even most of the ways," he writes.

However, it is difficult to predict which of these possibilities we will find ourselves. Losos's book analyzes the arguments for and against the predictability of evolution: the question of whether history would repeat itself if we were to "replay the tape of life". The evidence is shared and we just do not know how predictable and repeatable the evolution is over long periods of time. Add to that an element of chance – a huge volcanic eruption or an asteroid striking the Earth, and firm predictions become almost impossible.

Yet we can make informed assumptions.

However, we must first deal with the impact of a major evolutionary force that is already transforming life around the world: Homo sapiens.

We can see the evolution of a bird's beak specialized in canned food.

If humans thrive for millions of years, they will have a marked effect on future evolution and natural selection will produce new varieties of life to cope with the modified and possibly polluted environments we create. "We can see the evolution of a bird's beak specializing in canned food, or rats developing oily furs to eliminate toxic wastewater," writes Peter Ward , paleontologist at the University of Washington in Seattle, in his 2001 book Future Evolution.

Ward provides opportunities for new types of species with "harmful" qualities – robust and adaptable creatures that are not afraid to live with humans and are able to use their world, such as domestic cats, rats , raccoons, coyotes, crows, etc. pigeons, starlings, sparrows, flies, fleas, ticks and intestinal parasites.

On a warmer and drier land, warmed by humans, the lack of fresh water can also lead to new adaptations. "I would imagine animals that could develop strange specializations to capture the air humidity," says Patricia Brennan, an evolution biologist at Mount Holyoke College, in the United States. Massachusetts. "Larger animals can evolve things like elongated veils or shreds of skin that they could spread early in the morning to try to capture the moisture. The ruffled collars of some lizards, for example, could become very large and exaggerated to collect water in this way. "

In a warmer world, Brennan is also considering the rise of mammals and naked birds: "Mammals can lose hair in certain areas and collect water in the skin pockets. On a warming planet, endothermic animals [those that generate their own heat] In warmer climates, birds may lose their feathers to avoid overheating and mammals may lose most of their fur. "

Future humans may also decide to directly manipulate life – in fact, this is already happening. As researcher Lauren Holt wrote for BBC Future's Deep Civilization series earlier this year, a life trajectory on Earth could be a "post-natural" trajectory. In this scenario, genetic engineering, biotechnology and the influence of human culture could redirect evolution on radically different pathways, from gene-carrying mosquitoes to mechanical pollinator drones. The evolution of life would be related to the desires and needs of humanity.

However, there are alternative pathways for future evolution: for example, our more enlightened descendants may decide to restore nature and let natural evolution take its course, or humans could extinguish it. (Such was the scenario of After Man).

Extinction in particular can lead to radical evolutionary innovation. In essence, a mass extinction resets the evolutionary clock, Ward says. After previous mass extinctions, he says, the plants and animals on Earth have changed dramatically.

The extinction of the Permian, about 252 million years ago, eliminated more than 95% of marine species and 70% of terrestrial species, including fin reptiles and huge mammalian reptiles who reigned on Earth at the time. This left room for dinosaurs to evolve and become the dominant terrestrial animals, perhaps as unlikely and unexpected outcome as mammalian management when they replaced the dinosaurs after extinction. massive Cretaceous and Tertiary.

"There was not only a turnover, but what we might call a" change, "writes Ward." The massive extinctions did more than just change the number of species on Earth. Earth. "

After extinction, some biologists believe that new life forms with new capabilities may evolve. so different that we can not even imagine what they might look like. During the first billion years of life on Earth, for example, oxygen-breathing animals would have been inconceivable because oxygen was scarce and cells had not evolved to benefit from it. That changed forever with the Great Oxidation Event, about 2.4 billion years ago, when the arrival of the photosynthetic bacteria led to the first mass extinction of the Earth.

"The microbes have caused oxygen to the entire planet, which has caused a huge change," says Leonora Bittelston, an evolution biologist at the Massachusetts Institute of Technology. "There were a lot of innovations that could have been hard to predict before they happened – but once they start happening, they change our planet."

So, if humans die, how could things become wild and sophisticated in 100 million years? Can we see trees walking or feasting on animals after killing them with poisonous fumes or toxic darts? Could marine life change, with spiders taking to sea, using their webs to spin sardines, while fishes learn to fly to be able to feed on insects and birds? Could deep-sea animals project themselves into bright holograms to fool predators, attract prey or impress potential mates? Maybe killer whales and catfish will regain the past ability of their ancestors to run on land so they can hunt more effectively on land?

If humans die, how can things become wild and sophisticated?

Could we also see organisms settling in previously under-explored habitats: for example, giant and light poisonous mushrooms floating in the air like an aerial jellyfish, entangling and consuming everything they are bumping into? Or could insects and spiders build silk nests in the clouds and feed on photosynthetic organisms in the sky? And if plants or microbes developed something like solar panels to track and focus sunlight, could oases of green life blossom on icy glaciers?

None of these fantastic creatures seems impossible, Aktipis says. Many of them are based on what already exists in nature: there are marine spiders and slippery, there is a microbial life in the clouds and deep sea fish hang in front of them bioluminescent balls to attract their prey. Some populations of killer whales and catfishes can fish for animals on the shoreline, and small independent oases of life thrive on the ice, in which there are residues of cryoconite, a black dust of soot, rocks and microbes.

Jo Wolfe, an evolutionary biologist at Harvard University, notes that some trees are able to "walk" very slowly when moving to water sources, and think that trees may be able to evolve to hunt using toxic gases or even pointed branches. After all, we already have carnivorous plants like the Venus fly trap. She also reports the existence of fish-eating spiders and claims that microbes living in the clouds could possibly come from the multitude of microorganisms known as Prochlorococcus who live in the highest layers of the ocean.

In nature, it is often enough that unusual adaptations develop to create extreme environments. The Earth already has a lot, and that will not change. For example, think about how male monkfish reacted to the serious shortage of potential partners in the depths of the ocean. When he meets a woman, he actually melts into his body. "It's so unlikely that he's meeting another woman again that he's just giving up to become a sperm accessory for her," says Kristin Hook, behavioral ecologist at College Park, University. from Maryland. "So, we could see animals do more of that stuff, and over time, I imagine that breeding favoring animals that can self-pollinate themselves when finding a partner is almost impossible. "

From what we know of nature, we should not assume that future creatures will remain confined to their current habitats. Lynn Caporale, biochemist and author, points out that some "flying" fish can already catch insects (and even birds) and that some fish can walk on land or even climb trees. Even squids occasionally fly over the surface of the ocean, using jets of water for their propulsion and fins that duplicate them.

Imagine a toad becoming a zeppelinoid, a new type of floating animal that conquers the lower atmosphere

This potential for habitat change offers fantastic opportunities. Let's take a toad whose esophagus swells like a big gas bag used to call. In his book, Ward thinks of a fun way to turn it into "zeppelinoid", a new type of floating animal that will conquer the lower atmosphere. The toad could evolve to turn hydrogen into water and store it in its throat, thus helping it to float and float in the air. His legs – which are no longer necessary for walking – could become pendent tentacles used for feeding and evolve to become larger in order to avoid being eaten – perhaps even larger than a blue whale. The giant zeppelinoids would float in the air like jellyfish, dragging their tentacles to catch prey such as deer and grazing on the treetops. They would fill the skies and their changing shadows would dominate the landscape – the age of the flying toad.

The zeppelinoids, says Ward, are "a fairy tale – but there is a glimmer of reality in this fable." Once upon a time, it was the first flying organism and the first lifeguard, and we know that more and more species have evolved, because innovation has allowed them to take hold of it. a habitat they had never had access to before.

Since our understanding of evolution and genetics is incomplete and many will likely depend on fortuitous events, no one can know for sure what future life will look like. Choosing the evolutionary winners of the future is tantamount to trying to pick winners or predicting the time that he will make, Ward writes. We have some data to make informed assumptions, but also a great deal of uncertainty. "One can only guess at the colors, habits and forms of newly developed wildlife."

Losos agrees. "At the end of the day, the possibilities are so vast and uncertain that it is really pointless to try to speculate on what life might look like – there are far too many degrees of freedom. Life could go in so many different ways.

But if the strangeness of today's life is a guide, we should not neglect the possibility that future evolution can take truly breathtaking paths. And much of today's natural creativity and diversity remains unexplored.

Indeed, Dixon notes that many of the original "purely speculative" creations he describes in his 1981 book After Man were later discovered: for example, bats and snakes that can take them into the air. As he reflected in the 2018 edition of the book: "Many times, I have encountered new developments and ecological or evolutionary reflections:" If I had put that in After Man, everyone would have laughed. "

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Mico Tatalovic is a freelance journalist and tweets @MTatalovic

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