Our epidemics of dietary disease have prompted a great deal of research into what humans are meant to eat for optimal health. In 1985, an influential article was published proposing that our chronic diseases stem from a disconnect between what our bodies ate while evolving during the Stone Age (about 2 million years ago) and what we’re stuffing our face with today. The proposal advocated for a return towards a hunter-gatherer type diet of lean meat, fruits, vegetables and nuts.
It’s reasonable to assume our nutritional requirements were established in the prehistoric past. However, the question of which prehistoric past we should emulate remains. Why just the last 2 million? We’ve been evolving for about 20 million years since our common great ape ancestor, during which our nutrient requirements and digestive physiology were set down. Therefore our hunter-gatherer days at the tail end probably had little effect. What were we eating for the first 90 percent of our evolution? What the rest of the great apes ended up eating—95 percent or more plants.
This may explain why we’re so susceptible to heart disease. For most of human evolution, cholesterol may have been virtually absent from the diet. No bacon, butter or trans fats; and massive amounts of fiber, which pulls cholesterol from the body. This could have been a problem since our body needs a certain amount of cholesterol, but our bodies evolve not only to make cholesterol, but also to preserve it and recycle it.
If we think of the human body as a cholesterol-conserving machine, then plop it into the modern world of bacon, eggs, cheese, chicken, pork and pastry; it’s no wonder artery-clogging heart disease is our #1 cause of death. What used to be adaptive for 90 percent of our evolution—holding on to cholesterol at all costs since we weren’t getting much in our diet—is today maladaptive, a liability leading to the clogging of our arteries. Our bodies just can’t handle it.
As the editor-in-chief of the American Journal of Cardiology noted 25 years ago, no matter how much fat and cholesterol carnivores eat, they do not develop atherosclerosis. We can feed a dog 500 eggs worth of cholesterol and they just wag their tail; a dog’s body is used to eating and getting rid of excess cholesterol. Conversely, within months a fraction of that cholesterol can start clogging the arteries of animals adapted to eating a more plant-based diet.
Even if our bodies were designed by natural selection to eat mostly fruit, greens and seeds for 90 percent of our evolution, why didn’t we better adapt to meat-eating in the last 10 percent, during the Paleolithic? We’ve had nearly 2 million years to get used to all that extra saturated fat and cholesterol. If a lifetime of eating like that clogs up nearly everyone’s arteries, why didn’t the genes of those who got heart attacks die off and get replaced by those that could live to a ripe old age with clean arteries regardless of what they ate?
Because most didn’t survive into old age. Most prehistoric peoples didn’t live long enough to get heart attacks. When the average life expectancy is 25 years old, then the genes that get passed along are those that can live to reproductive age by any means necessary and that means not dying of starvation. The more calories in food, the better. Eating lots of bone marrow and brains, human or otherwise, would have a selective advantage (as would discovering a time machine stash of Twinkies for that matter!). If we only have to live long enough to get our kids to puberty to pass along our genes, then we don’t have to evolve any protections against the ravages of chronic disease.
To find a population nearly free of chronic disease in old age, we don’t have to go back a million years. In the 20th century, networks of missionary hospitals in rural Africa found coronary artery disease virtually absent and not just heart disease, but high blood pressure, stroke, diabetes, common cancers and more. In a sense, these populations in rural China and Africa were eating the type of diet we’ve been eating for 90 percent of the last 20 million years, a diet almost exclusively of plant foods.
How do we know it was their diet and not something else? In the 25 year update to their original paleo paper, the authors tried to clarify that they did not then and do not now propose that people adopt a particular diet just based on what our ancient ancestors ate. Dietary recommendations must be put to the test. That’s why the pioneering research from Pritikin, Ornish and Esselstyn is so important, showing that plant-based diets can not only stop heart disease but have been proven to reverse it in the majority of patients. Indeed, it’s the only diet that ever has.
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Here are three new films to watch this Earth Week that will transport you from pole to pole and introduce you to the scientists and activists working to save our shared home.
1. The Year Earth Changed
Where to Watch: Apple TV+
When to Watch: From April 16
The coronavirus pandemic has brought home the stakes of humanity's impact on the environment. But the lockdowns also proved how quickly nature can recover when humans give it the space. Birds sang in empty cities, whales surfaced in Glacier Bay and capybara roamed the South American suburbs.
The Year Earth Changed captures this unique year with footage from more than 30 lockdowned cities between May 2020 to January 2021. Narrated by renowned wildlife broadcaster David Attenborough, the film explores what positive lessons we can take from the experience of a quieter, less trafficked world.
"What the film shows is that the natural world can bounce back remarkably quickly when we take a step back and reduce our impact as we did during lockdown," executive producer Alice Keens-Soper of BBC Studios Natural History Unit told EcoWatch. "If we are willing to make even small changes to our habits, the natural world can flourish. We need to learn how to co-exist with nature and understand that we are not separate from it- for example if we closed some of our beaches at for a few weeks during the turtle breeding we see that it can make a huge difference to their success. There are many ways that we can adapt our behavior to allow the natural world to thrive as it did in lockdown."
2. After Antarctica
Where to Watch: San Francisco International Film Festival
When to Watch: 12 a.m. PST April 9 to 11:59 p.m. April 18
In 1989, Will Steger led an international team of six scientists and explorers to be the first humans to cross Antarctica by dogsled. Steger and his team weren't just in it for the adventure. They also wanted to draw attention to the ways in which the climate crisis was already transforming the icy continent and to rally support for the renewal of the Antarctic Treaty, which would keep the continent safe from extractive industries.
In After Antarctica, award-winning filmmaker Tasha Van Zandt follows Steger 30 years later as he travels the Arctic this time, reflecting on his original journey and once again bringing awareness to changes in a polar landscape. The film intersperses this contemporary journey with footage from the original expedition, some of which has never been seen before.
"Will's life journey as an explorer and climate activist has led him not only to see more of the polar world than anyone else alive today, but to being an eyewitness to the changes occurring across both poles," Van Zandt told EcoWatch. "But now, these changes are happening in all of our own backyards and we have all become eyewitnesses. Through my journey with Will, I have learned that although we cannot always control change, we can change our response. I feel strongly that this is a message that resonates when we look at the current state of the world, as we each have power and control over how we choose to respond to hardships, and we all have the power to unite with others through collective action around a common goal."
After Antarctica is available to stream once you purchase a ticket to the San Francisco International Film Festival. If you miss it this weekend, it will screen again at the Minneapolis St. Paul International Film Festival from May 13 to May 23.
Tasha Van Zandt
3. The Race to Save the World
Where to Watch: Virtual Cinema
When to Watch: From Earth Day, April 22
While many films about the climate crisis seek to raise awareness about the extent of the problem, The Race to Save the World focuses on the people who are trying to stop it. The film tells the story of climate activists ranging from 15-year-old Aji to 72-year-old Miriam who are working to create a sustainable future. It follows them from the streets to the courtroom to their homes, and explores the impact of their advocacy on their personal lives and relationships.
Emmy award-winning documentary filmmaker Joe Gantz told EcoWatch that he wanted to make a film about climate change, but did not want to depress viewers with overwhelming statistics. Instead, he chose to inspire them by sharing the stories of people trying to make a difference.
"Unless millions of people take to the streets and make their voices heard for a livable future, the politicians are not going to get on board to help make the changes needed for a sustainable future," Gantz told Ecowatch. "I think that The Race To Save The World will energize and inspire people to take action so that future generations, as well as the plants, animals and ecosystems, can survive and thrive on this planet."
Check back with EcoWatch on the morning of Earth Day for a special preview of this inspiring film!