Heat
Unlike most living species, humans can adapt through their behavior to climate change, instead of simply migrating or seeing the appearance of beneficial mutations for survival. But these genetic mutations also exist in humans.
Climate change could increase the amount of ultraviolet (UV) radiation reaching us, says Christopher Wills, a biologist emeritus at the University of California, San Diego who published in 1999 Children of Prometheus, where he argues that human genetic evolution is accelerating. “It could promote UV-resistant skin pigments, so darker skin. Frost resistant little noses might also become less common because they will be less needed. »
Also “resistance to malaria and Lassa fever, which are more common in areas where these diseases have been common for a long time,” notes Scott Solomon, a biologist at Rice University in Houston, who published in 2016 the book Future Humans – Inside the Science of our Continuing Evolution.
Several centuries
PHOTO MARK SCHIEFELBEIN, ASSOCIATED PRESS ARCHIVES
The adaptation of Tibetans to life at high altitude several millennia ago is considered a “recent” development.
But when we say “recent” and “next” evolution, we are still talking in terms of centuries. Mr. Wills considers, for example, “recent” the adaptation of Tibetans several millennia ago to life at high altitude, or the pale complexion which increases the ability to absorb UV rays, necessary for the creation of vitamin D. In these two cases, these are genes from missing cousins ofHomo sapiens, Neanderthal and Denisovan. “I would say that kind of genetic adaptation can happen over a few dozen generations,” says Wills. In other words, over several centuries.
And rapid genetic mutations have their share of problems. “The fastest mutations, which affect a single gene, often come at a cost,” says Wills. For example, resistance to malaria increases the prevalence of sickle cell anemia [une maladie chronique héréditaire qui touche 10 fois plus les Noirs que la moyenne de la population aux États-Unis]. Gene combinations conferring an evolutionary advantage take longer to emerge, but they have fewer disadvantages, this is a more optimized adaptation. »
Culture
Research on the effects of climate on human evolution focuses on behavior. Scott Solomon thus believes that the greatest impact of global warming on human evolution will come from migration.
PHOTO FROM RICE UNIVERSITY WEBSITE
Scott Solomon, biologist at Rice University
Since the Second World War, humans have experienced unprecedented migrations, due to modern means of transport. It will accelerate with climate change. These migrations will create an unprecedented mixing of genes, from which will emerge several mutations that are difficult to predict.
Scott Solomon, biologist at Rice University
At the University of Montreal, Julien Riel-Salvatore is working on the passage of Neanderthal man to Homo sapiens. ” Afterwards sapiens went from a hunter-gatherer lifestyle to sedentarization, with agriculture, says the anthropologist. This is ‘recent’ human evolution. For 50,000 years, there has clearly been an adaptation of humanity to the climate. And these adaptations are cultural. There was a cultural baggage transmitted from one generation to another. »
“Lung capacity at high altitude, a reduced propensity to shiver, clear skin that allows more vitamin D to be metabolized are adaptations of degree rather than substance,” says Riel-Salvatore. These are small improvements, not big changes. Lately I’ve seen some news that links curly hair to hot climates, because it helps release heat. »
Sleep
Among the behaviors that climate change could affect are sleep and exercise.
By studying an international database of sleep measurement by a bracelet (worn permanently and therefore giving an objective indication of sleep), Danish researchers have for example calculated that we sleep 10 minutes less if the outside temperature is 20 ℃ rather than 10 ℃, and 14 minutes less if it reaches 30 ℃. “Yes, there is air conditioning, but in temperate climates its use is not always optimal,” says Kelton Minor, an epidemiologist at the University of Copenhagen, lead author of the study published last year in the review One Earth.
Charles Morin, a sleep psychologist at Laval University, believes that 14 minutes represents a “significant” difference. “Yes, you can adapt to the heat with air conditioning, but in poor countries, it’s not always possible,” says Morin.
Exercise
PHOTO PHILIPPE BOIVIN, LA PRESSE ARCHIVES
Extreme heat is a barrier to physical activity.
Global warming could also reduce the practice of physical activity, which is so beneficial to health.
“We exercise less when it’s very hot, it’s proven,” says Paquito Bernard, researcher in physical activity at the University of Quebec in Montreal (UQAM). Physical activity increases from 0 to 28℃. Then there is a plateau, then it descends rapidly. »
Milder winters don’t make up for less physical activity in the summer, and more people don’t hit the gym when it’s too hot, he said. “Australian studies of older people have shown that when it’s hot, people don’t exercise more indoors even though they exercise less outdoors. »
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- 0.08°C
- Increase in average global temperature in each decade, between 1880 and 2020
Source: NOAA
- 0.18°C
- Increase in average global temperature in each decade, between 1980 and 2020
Source: NOAA