Since it appeared on the world stage the virus that causes COVID-19 has infected hundreds of millions of people, killed millions and disrupted society in ways that will ramify for decades. COVID-19 is a story of politics, culture, and medicine, but underneath it all it is also an extraordinary story of evolution. Charles Darwin imagined that evolution by natural selection proceeded too slowly to be observed in action. It was, he thought, a process that required decades, centuries or, more often, millennia.
COVID-19 is a reminder that evolution can occur in weeks, days or even just hours. It occurs on the body of each person that is infected. On our bodies, strains of the virus that causes COVID-19 have evolved relative to human immune systems, vaccines and even the need to travel from one individual to another. In this regard, the Omicron variant is as powerful a testament to the force of natural selection as are blue whales, ants that farm fungi or finches in the Galapagos Islands.
Were he alive today, Charles Darwin would have been, first and foremost, terrified of contracting COVID-19. He was constantly worried about his health (and, of course, at the age of 212, he would have had reason to worry). But he would also marvel at the speed of the virus’s evolution. Over the last decade, biologists have discovered evolution occurring all around us.
Read more on evolution:
- Mother Nature’s Ingenuity: 9 exquisite eggs that demonstrate how incredible evolution can be
- Instant Genius Podcast: The origin and evolution of mammals, with Dr Elsa Panciroli
The rate of evolution of new lineages and forms may actually be sped up on our bodies, in our homes, around our cities and throughout our farms. In my new book, The Natural History of the Future, I consider the rules of this acceleration. Here are some of my favourite examples of the evolution being observed right now, examples in which the story will be different a decade from now precisely because these species are continuing to evolve.
Species that evolve with the heat of cities
We make cities hot. Pavements and buildings store heat and reradiate it back up from beneath our feet. In some cities, the blocks with the most cement and the least green life are already as hot as the surrounding countryside is predicted to get in 2100. Some species are evolving to cope with this heat. In the hottest parts of Cleveland, Ohio, urban ants living inside tiny acorns have evolved the ability to tolerate more extreme heat than their country cousins can.
Natural selection is favouring heavier tree seeds
In Montpellier, France, the future is unfolding along busy streets. Even in the most urban parts of Montpellier, one finds the fuzzy yellow flowers of the hawksbeard plant (Crepis sancta). In natural habitats, hawksbeard tends to produce lighter seeds that are able to catch the wind and travel to new patches. But in Montpellier, hawksbeard often live in tree pits. In those tree pits, the next patch of habitat is likely to be far away. To cope, urban hawksbeard plants with heavier seeds that do not fly are being favoured by natural selection; their chubbier seeds are more likely to land in the same tree pit again and survive.
New York rats need a new meeting space
In Manhattan, rats in Uptown and rats living Downtown have stopped meeting up in midtown (perhaps because the number of overnight residents and hence food is slightly less in a band of midtown). Without meeting, the rats aren’t mating and sharing their genes. And so they are diverging, embarking on their own independent evolutionary trajectories.
The pigeon population is separating
Pigeon populations too are going their separate ways. The pigeons of Boston, for example, are diverging from those of New York City. Eventually, where cities stay separated, each city may have its own unique pigeon. Nor is it just the pigeons. The lice on pigeons are evolving. Pigeons have two kinds of lice. One kind rides from pigeon to pigeon on tiny flies (really); they are likely to evolve more slowly because their peregrinations keep their genes moving from here to there and there to here. The other kind of pigeon louse passes from mother pigeon to baby pigeon.
Foxes with the faces of dogs
Foxes in cities, for reasons that aren’t totally clear, are evolving faces that look more like those of dogs. Keep an eye out for their shorter snouts and weaker jaws. And stay tuned for more studies of just why this shift is occurring.
Lizards with longer ‘grabbier’ toe pads
In Puerto Rico, urban Anolis lizards have evolved longer limbs and “grabbier” toe pads that together allow them to better cling to buildings and other human-made structures.
An evolving taste for starch
For most mammals, starch has no taste and therefore there is no reward for searching it out. Humans however have evolved extra copies of amylase genes. These genes produce the enzyme amylase in human mouths which begins to break down starch into simple sugars; those sugars are then sweet. Clearly, humans in agricultural societies that ate more starch were more likely to survive. We now know that many of those mammals that depend on human garbage and hand outs have also undergone the same evolutionary transition.
Cockroaches adapt to avoid bait
Cockroach baits felt like a revolution. Rather than spraying pesticides around a house, the baits allowed cockroaches to be beckoned to the pesticide. The baits contained glucose which attracted cockroaches until the widespread use of baits inadvertently triggered evolutionary changes in German cockroach brains. Some German cockroach populations have evolved so as to perceive the taste of glucose as bitter and avoiding baits.
Your refrigerator is alive
In your refrigerator, bacteria are alive and actively metabolising in all of your stored food, but especially in fermented foods such as yoghurts and cheeses. Even within an individual block of cheese or container of yoghurt, bacteria can undergo great evolutionary change over even just a few days. But the greater evolutionary changes occur in the viruses that attack the bacteria that produce cheeses and yoghurts.
The bacteria inside of you is always evolving
Even closer to home, in your gut, bacteriophages are evolving relative to changes in the bacteria on which you depend for survival. Each bacteria species in your gut appears to have one, if not more, specialised kinds of bacteriophages that attack it. These bacteriophages evolve so quickly that if two twin babies were inoculated with the same bacteria and bacteriophage species at birth, the bacteriophages in one baby would be recognisable as separate species from those in the other.
The truth is that many of these changes are not only observable in real time, they are also predictable. Evolutionary biologists are watching their predictions, developed while studying the past rise up all around them in their daily lives. They see tests of their predictions in gutters, on sidewalks, and even in their refrigerator. And they’ve only just begun to look.
Consider the reality that as you inhale, that you are breathing in hundreds (and often thousands) of species. Most of those species are as of yet unstudied. They are all evolving. Some fast and some slow. Inhale. Exhale. It is there, the relentless ongoings and goings on of natural selection, the never-ending story of evolution, a story that began billions of years ago and continues everywhere there is life.
A Natural History Of The Future by Robb Dunn is out now (£14.99, Hachette)
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