These mismatch diseases, as evolutionary biologists refer to them, can offer some clues as to how our "Stone Age bodies" are responding to our modern environment.
“The mismatch disease is a key concept in the field of evolutionary medicine,” Lieberman told FoodNavigator-USA. “One of the hallmarks is that many of these diseases that are common today used to be rare. Look at hunter-gatherer, substance farming and small-scale societies. You didn’t see a whole lot of heart disease or type 2 diabetes. People did get it, but anybody who looks at a graph of new incidences of type 2 diabetes will see a pretty steep slope. And the reason is that our bodies are poorly adapted for these modern, novel conditions.”
In a new book he authored titled The Story of the Human Body: Evolution, Health and Disease, Lieberman traces mismatch diseases like diabetes back to their roots and calls into question our culture’s overwhelming focus on treatment of symptoms instead of prevention.
‘We’re adapted to put on fat, not to lose it’
Most diseases originate from a combination of genes and environmental responses. As human genes haven’t changed much over the last few millennia, what has changed significantly—particularly since the advent of farming and more recently, the shift to a post-industrial lifestyle—is our environment, which brought with it increased access to processed food, including large amounts of sugar and simple carbohydrates, along with a much more sedentary lifestyle, Lieberman said.
“These shifts are happening in bodies that have evolved over millions of years,” he said. “We’re adapted to put on fat, not to lose it; we’re adapted to be physically active, not inactive.”
Because our bodies aren’t used to metabolizing such large amounts of sugar, the result is that we get sick. The cultural response is (understandably) to treat the symptoms, Lieberman said.
Cultural obligation to alleviate suffering
That’s where the second major theme of the book, dysevolution, comes in, whereby we treat the symptoms of physiological problems instead of focusing on prevention.
“There are lots of diseases we get that are mismatched and we have a cultural response to alleviate suffering. Someone with diabetes, we give insulin. There are also various pharmaceuticals that can act at different points in the pathway, but they don’t cure you of diabetes. You can cure some people of type 2 diabetes through vigorous exercise and serious dieting, which can enable their insulin receptors to become re-sensitized. Diet and exercise are the best forms of prevention.”
Most doctors know it is difficult for many to lose weight and often medication is the only viable option for elderly patients or those who have a hard time becoming active. But, Lieberman noted, “one of questions we have to ask ourselves is, to what extent are we allowing the disease to persist because we are getting more effective at treating it?”
Have to treat our bodies
There are currently 50 million people suffering from type 2 diabetes in India, and that number is projected to double by the end of the century. With such staggering figures looming as lifestyles continue to change at a much faster clip than the human body, Lieberman said it's important to start treating our bodies now instead of waiting to treat the symptoms of so many people later.
“There is no super drug out there to prevent people from suffering,” Lieberman said. “It also costs a lot to treat type 2 diabetes. We can’t afford it, so how is India going to afford it? Or China for that matter? We can’t wait for scientists to figure out how to regrow our pancreases. Let’s not kid ourselves. We need to treat our bodies.”