Strange evolution: The weird future of life on Earth.

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From walking trees to floating toads, the far future of nature on our planet could be like nothing we’ve seen before.


▼ In the early 1980s, the author Dougal Dixon published a cult book called After Man: A Zoology of the Future, which imagined what life would look like millions of years from now. Dixon envisaged shrews that use their tails as parachutes, flying monkeys (or “flunkeys”), super-long coiled snakes that strike out to snatch birds mid-flight, nightgliders that impale their prey with long spikes on their chests, and flower-faced birds and bats that fool pollinating insects into landing in their hungry mouths.  
Shrews that use their tails as parachutes, flying monkeys (or “flunkeys)… and flower-faced birds and bats
Decades later, Dixon says his book was not an attempt to predict the future, rather it was an exploration of all the possibilities of the natural world. “Popular-level books on evolution, even though it’s not intentional, seem to suggest evolution is something that happened in the past,” he says. “That’s not the case at all. Evolution is taking place today, it will continue to take place well into the future, long after we are gone.”
While Dixon’s book was a work of fiction, most biologists agree that millions of years from now Earth will be a very different place. “I think it’s gonna look and feel like an alien planet,” says Athena Aktipis, an evolutionary biologist at Arizona State University.
Whatever evolves will feel foreign and unlikely to us today – just as our current world, dominated by mammals, would have seemed improbable from the perspective of the dinosaur era. So, what might life look like in the future? What creatures could develop in, say, 100 million years, given what we know about life on Earth and the principles of evolution?
Let’s start by zooming back millions of years to a much earlier era of life on our planet. In the Cambrian explosion, some 540 million years ago, the Earth became populated by a whole host of “weirdo” and “cartoonish” creatures, according to Jonathan Losos, an evolutionary biologist at Washington University in St Louis.
“The Burgess Shale [in Canada] was inhabited by a veritable bestiary of the bizarre,” he writes in his book called Improbable Destinies: Fate, Chance, and the Future of Evolution. One animal, Hallucigenia, with its thin, tube-like body covered in rows of enormous spines, and stick-like clawed appendages was “similar to something out of a Futurama episode”.
So, it is not impossible for similarly weird and unusual creatures to evolve in future. “Just about anything plausible you can imagine has evolved somewhere at some point in some species,” Losos argues. “Given enough time, even the improbable will occur eventually.”
According to Losos, the world of biological possibilities is vast, and we may not have seen everything yet. “I, for one, am not at all convinced that life on Earth has uncovered every conceivable way of existing on a planet like our own, or even most of the ways,” he writes.
Still, it’s difficult to predict which of those possibilities we may end up with. Losos’ book analyses the arguments for and against the predictability of evolution: the question of whether history would repeat if we were to “replay the tape of life”. The evidence is split, and we simply don’t know to what extent evolution is predictable and repeatable over long time periods. Add to that an element of chance – a huge volcanic eruption or an asteroid hitting the Earth, and firm predictions become near impossible.
Yet, wecanmake educated guesses.
First, however, we must address the impact of a major evolutionary force that is already transforming life worldwide:Homo sapiens.
We may well see the evolution of a bird beak specialised for feeding out of tin cans
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 deal with the altered, and probably polluted, environments that we create. “We may well see the evolution of a bird beak specialised for feeding out of tin cans, or rats developing oily fur to slough off toxic wastewater,” writes Peter Ward, a paleontologist at the University of Washington, Seattle, in his 2001 book Future Evolution.
Ward foresees opportunities for new types of species that possess “weedy” qualities – hardy, adaptable creatures that don’t mind living around humans and are able to make use of their world, such as house cats, rats, raccoons, coyotes, crows, pigeons, starlings, sparrows, flies, fleas, ticks, and intestinal parasites.
On a hotter, dryer Earth warmed by humans, a lack of fresh water may also prompt novel adaptations. “I would imagine animals that would evolve weird specialisations to capture moisture from the air,” says Patricia Brennan, an evolutionary biologist at Mount Holyoke College in Massachusetts. “Larger animals might evolve things like extended sails or skin flaps that they could extend out in the early morning to try to capture moisture. The frilly collars of some lizards, for example, could become very large and exaggerated to gather water in this way.”
In a hotter world, Brennan also envisages the rise of naked mammals and birds: “Mammals may lose fur in some patches and collect water in skin pockets. In a warming planet, endothermic animals [those that generate their own heat] may have a hard time, so birds in warmer climates may lose contour feathers to prevent overheating, and mammals may lose most fur.”
Future humans may also decide to directly manipulate life – in fact, it’s happening already. As the researcher Lauren Holt wrote for BBC Future’s Deep Civilisation series earlier this year, one trajectory for life on Earth could be a “post-natural” one. In this scenario, genetic engineering, biotechnology and the influence of human culture could redirect evolution down radically different paths, from mosquitoes that contain gene drives to mechanical pollinator drones. The evolution of life would be entwined with humanity’s own desires and needs.
However, there are alternative paths for future evolution: for example, our more enlightened descendants may decide to rewild nature and let natural evolution pursue its course, or humans could become extinct (which was the scenario of After Man).
Extinction in particular can lead to sweeping evolutionary innovation. In essence, a mass extinction resets the evolutionary clock, argues Ward. After previous mass extinctions, he says, Earth’s plants and animals changed radically.
The Permian extinction, around 252 million years ago, eliminated over 95% of marine and 70% of land species, including fin-backed reptiles and massive mammal-like reptiles that ruled the Earth at the time. It made space for dinosaurs to evolve and take over as the dominant land animals, an outcome perhaps as unlikely and unexpected as the take-over by mammals when they replaced dinosaurs after the Cretaceous-Tertiary mass extinction.
“There was not only a turnover, but also what we might call a ‘changeover’,” Ward writes. “Mass extinctions did more than just change the number of species on Earth. They also changed the makeup of the Earth.”
Following an extinction, some biologists think it’s possible that whole new lifeforms with new capabilities will evolve; so different that we can’t even imagine what they might be like. For the first billion years or so of life on Earth, for example, oxygen-breathing animals would have been inconceivable, because oxygen was in short supply and cells hadn’t evolved to use it for energy. That changed forever with the Great Oxidation Event, around 2.4 billion years ago, when the arrival of photosynthesising bacteria led to the Earth’s first mass extinction.
“The microbes caused the whole planet to have oxygen and that created a huge shift,” says Leonora Bittelston, an evolutionary biologist at the Massachusetts Institute of Technology. “There have been a lot of innovations that could have been hard to predict before they happened – but once they start happening, they do change our planet.”
So, if humans die off, how wild and sophisticated could things get 100 million years from now? Could we see trees starting to walk, or feasting on animals after killing them with toxic fumes or poisonous darts? Could sea life change, with spiders taking to the water, using their webs to net sardines, while fish learn to fly so they can feed on insects and birds? Could deep-sea animals project bright holograms of themselves to fool predators, attract prey or impress potential mates? Perhaps killer whales and catfish will regain their ancestors’ past ability to run on land so that they can hunt more effectively onshore?
If humans die off, how wild and sophisticated could things get? (▪ ▪ ▪)

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