The modern world is radically at odds with the way human senses have evolved, helping to make us short-sighted, obese and depressed, scientists have warned.
Spending large amounts of time indoors under artificial light and staring at computer screens has helped produce a “myopia epidemic” with as many as 90 per cent of people in some parts of the world needing glasses.
Industrial food production has also turned primates’ taste for sugar — which evolved to persuade us to gorge on healthy fruit when it was ripe — into one of the main causes of the soaring rates of obesity in the Western world.
And our sense of smell is under attack from air pollution, producing an array of different effects, including depression and anxiety.
Three experts in each of the senses spoke about their work at the annual meeting of the American Association for the Advancement of Science in Boston.
Professor Amanda Melin, of Calgary University, told a press briefing that the indoor lifestyle of many people in cities and the use of computers posed problems for our eyes.
“We’re inside, we’re in fake lighting, we’re not spending as much time outside in the context in which our vision system evolved,” she said.
“And our lighting, as well as other things like near work tasks, might be drastically affecting our acuity.
“What we need to do is we need to get outside more in order for our eyeball to grow properly and for us to have the right proportions so that the images are really clearly in focus on the retina.
“I’m a myope and when I take off my glasses you all become extremely blurry.
“And so we need to think about perhaps putting policies in place to get kids and young adults outdoors more.”
Paul Breslin, professor of nutritional sciences at Rutgers University, said one reason for the obesity crisis was our taste for sugary food that stems from “the ape that’s in us”.
“The love of sugar in humans, I think, can be tied to the fact we are an ape and shared a common ancestor millions of years ago with the other apes on the planet … all of which live in forests and are primarily eating fruit, which is both sweet and sour,” he said.
“In the forests around the equator, there are no seasons. The fruits just come and go as the trees come into fruit … animals will go up into the trees and gorge on the sugary foods until there are no more to eat and will actually become chubby in the process.”
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They then return to the ground and eat food like insects and leaves that are not as sweet.
But, in the modern world, sugary treats are available all year round.
“We climb up into this tree that our society has created and we gorge on the fruit but the tree never comes out of fruit and we never come down out of the tree, so we gorge and gorge and gorge on sugary foods and get chubbier and chubbier,” Professor Breslin said.
“That ape that’s in us drives us up into the tree to love these sugary and sour foods. We have to keep in mind that we need to force ourselves down out of that periodically.”
And Professor Kara Hoover, of Alaska University, said humans’ noses appeared to be “in a state of mismatch” with the modern world.
“Our sense of smell evolved in very odour-rich landscapes in which we were interacting regularly with the environment,” she said.
“Now today we’re not interacting with the environment and we’re in very polluted places.
“Pollution tends to disrupt the sense of smell and that puts you at greater risk of things like mental health disorders, such as depression and anxiety, and it also puts you at greater risk for physical health [problems], such as obesity, and greater risk for social health, not being able to pick up on social cues from other human beings.”
Having a poor sense of smell is thought to contribute to over-eating because people get less enjoyment from their food. Smell can also be used to detect fear or anxiety in others.
Professor Hoover said cutting pollution from fossil fuels and other sources could help.
“The greener the city the better the environment would be for our sense of smell,” she said.
“And also the greener the city the more we might be encouraged to go our and play in parks, getting exposed to sunlight and getting away from the computer more regularly.
“I think it’s continuing the theme that we’re talking about quite a lot in modern society today, having a better, healthier atmosphere.”
Professor Melin said being able to go outside was also good for our eyesight but that “if we are recommending going outside” there was a need to make sure “it’s not a polluted environment”.