From paleo diets to digital detoxes, our search for a ‘natural’ life doesn’t stack with evolution – Health
The modern caveman movement, paleo diets, digital detoxes and off-grid living all seek to get back to a natural way of life, one that humans evolved to adapt to.
But have humans ever truly lived in harmony with their environment?
No, says Marlene Zuk, an evolutionary biologist from University of Minnesota. But that’s OK — in fact, it’s the whole point of evolution.
The notion that humans are not evolved to suit our modern world is flawed, said Professor Zuk, who spoke last night on what she terms “paleofantasy” at a public lecture at the University of Sydney.
“Lots of people have this sense of ‘what’s gone wrong in modern life?’ We’ve got an obesity epidemic, we’ve got the environment that seems to be being destroyed, things seem to be out of control,” she said.
“There’s this natural inclination to think, wasn’t there a time when everything was better?”
But different people have different ideas of when this time was.
Should we be trying to emulate the diets and activity levels of cavemen? Would we be healthier and happier if we lived like early agricultural people? Or is it modern technology we should be avoiding, by harking back to a mid-20th century lifestyle?
“How you react to thinking about whether humans were once in harmony depends on what you think harmony is, and when it actually happened,” she said.
Evolution didn’t just happen a long time ago
Professor Zuk argues it’s not modern life that’s killing us — rather, the world has always been a dangerous place, and we’re constantly evolving to adapt to it.
“[People often think] evolution’s this very slow and almost static process where a lot of things happened a really long time ago. Fishes came on land, and then there were dinosaurs, and then there were mammals, and then eventually there were people and, phew, now we’re all done with that and anyway, it all happened a long time ago,” she said.
“But that’s not how evolution works at all — it’s continuous and it’s happening all the time.”
An example from not so long ago in human history is lactase persistence — our ability to digest milk after weaning.
Thousand of years ago we couldn’t drink milk after we were babies, but then we started keeping livestock. Before long, some human populations adapted to be able to digest this food source into adulthood.
“We were in harmony with our environment back when we couldn’t drink milk and but now the environment’s changed, our genes have changed and we’re in harmony with our environment now too,” Professor Zuk said.
But yes — there are often some trade-offs when it comes to evolution, Professor Zuk conceded.
Evolutionary biologists call this a “mismatch” between a modern environment and an environment we’re more accustomed to historically.
An example of this is the reason humans are prone to choking on their food.
Our ancestors, as well as modern apes like chimpanzees, didn’t have a space between the horizontal tube that leads into the jaw and the vertical tube that leads to your throat, the way modern humans do.
But the space, which makes it possible for us to choke on food, also allows us to do something else: speak.
“Talking is really advantageous for people and so selection ended up producing people who could talk, even if we ended up losing folks who choked along the way,” Professor Zuk explained.
“And that’s how evolution works.
So does that mean we have nothing to learn from the human lifestyles of days gone by? Of course not.
“No-one’s going to argue that eating a tonne of sugar and sitting on a sofa watching television all day is healthy,” Professor Zuk said.
“That’s indisputable, and it’s also indisputable that our ancestors didn’t do those things and, in some ways at least, they were healthier. So in that sense, sure, I get what people are trying to do.
“But there’s a big difference between saying ‘our bodies work better when we don’t eat so much sugar and when we move around more’ and saying ‘we should replicate a particular period in the past and that’s when humans were at a peak’.
“One of the things you realise if you study evolution is that there isn’t anything we were ‘meant’ to do.”