'We're changing the very course of evolution on this planet,' says renowned Canadian biologist

As humans alter the natural environment at an unprecedented rate, we're also changing the speed and direction at which other species evolve.

"We're changing the very course of evolution on this planet," said Sarah Otto, a renowned theoretical biologist at the University of British Columbia. 

She is Canada Research Chair in theoretical and experimental evolution, and she was named a MacArthur "Genius" Fellow in 2011. 

"Today we're really changing the force of selection across the world, leading less and less to natural selection and more and more to anthropogenic selection, selecting for species that can survive us," she told The Sunday Edition's host Michael Enright. 

Underground mosquitoes and car-dodging swallows

In responses to human-altered landscapes, cliff swallows that live by highways have evolved to have shorter wingspans to make it easier for them to dodge cars. Mosquitoes in France have evolved to live underground, so they can bite humans in subway tunnels. 

"Normally, mosquitoes wouldn't go into subway systems and live underground, but now they have a great food source of humans. Not only have they adapted to a subterranean lifestyle, but they've also changed what food preferences they have — going for humans more than birds, which is what they used to bite more often," Otto said. 

The species that can't keep up have seen their numbers dwindle or even vanish into extinction. The pressures are especially acute for species with longer reproductive cycles. 

"What we're seeing here in B.C. is an increasing mismatch between where trees are growing and where they are optimally adapted. So as the climate warms, there is an estimated one kilometre per year additional mismatch between where they would best grow and what their current environment is," she said. 

"The trees can't up and walk. So I think that the long-lived species are going to have a harder time keeping up with these increasing human-derived selection pressures."

Diseases and evolution

Microbes, though — such as bacteria and viruses — are the speed demons of natural selection, which helps explain why they so often seem a step or two ahead of our attempts to control or eradicate them.

And the increased proximity between humans and animals has also increased the rate at which new diseases like COVID-19 jump between species.

"[For a disease], jumping to a new host species is tricky because it has to be able to not only infect that individual human, but it has to evolve to be able to transmit from human to human. But now as we're both trading in wildlife and the number of humans is approaching eight billion people, there's just so many opportunities for those jumps," Otto said. 

Scientists are racing to figure out how COVID-19 is evolving. 

"One of the good pieces of news about COVID is that, as far as we can tell, its mutation rate is about one third that of the flu. There have been people worried that a vaccine may only be good for a little while, but the flu vaccine lasts a year … the lower mutation rate relative to the flu should be a good sign for vaccine development," she said. 

Still, a vaccine for COVID-19 would have to be updated to keep up with evolution. 

"You can't stop evolution, and it will evolve to whatever vaccines we do have. But right now, we don't have any evidence yet that it has evolved to transmit more or be more virulent in humans," Otto said. 

"I've been modelling it with colleagues across the world. Our sense is that the strongest selection pressures right now on COVID are probably to be a little less virulent, and so prolong that pre-symptomatic period where people are feeling just fine, because in that period, they are also transmitting the virus. I don't have a crystal ball and I can't tell you exactly the directions in which COVID might evolve, but that is at least one strong selection pressure."

'It should make us all take pause'

Evolution appears to be a slow process — major changes in species often take hundreds or thousands of years to take shape.

But Otto said we need to be aware that evolution can happen much faster than that, and that it's happening all around us. 

"In the lab we use yeast. Yeast replicates every 90 minutes. Over the course of a day, in a week, we see evolutionary change that we can track," she said. 

"It's not evolution like you might have been taught — something that you look into fossil records to track. Now we can track this over the course of days."

She said when species go extinct due to human pressures, or evolve to survive the world we've made, we lose natural "treasures."

"Evolution is one of the most wondrous aspects of this planet. It's led to incredible diversity of life," she said. 

"So to be watching, as the species blink out, and the rest have to adapt to us, it really makes me take pause. I think it should make us all take pause."

Click 'listen' above to hear the full interview.