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 evolved eating during the Stone Age
during the last 2 million years and what we’re stuffing our face
with today, advocating for a return towards a hunter-gatherer type diet of lean meat,
fruits, vegetables, and nuts. Though it may be reasonable to assume
our nutritional requirements were established
in the prehistoric past, the question of which
prehistoric past remains. Why just the last 2 million? We’ve been evolving for 25 million years
since our common great ape ancestor during which our nutrient requirements
and digestive physiology were set down, and therefore probably little affected
by our hunter-gatherer days at the tail end. So what were we eating
for the first 90% of our evolution? What the rest of the great apes
ended up eating: 95 plus percent 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, trans fats
and massive amounts of fiber, which pulls cholesterol
from the body. Now this could be a problem
since our body needs a certain amount of cholesterol,
so our bodies didn’t just evolve to make cholesterol,
but to preserve it, recycle it; our bodies evolved
to hold on to cholesterol. And so if you think of the human body
as a cholesterol conserving machine and plop it into the modern world of
bacon/eggs/cheese/chicken/pork/pastry, well then no wonder artery-clogging
heart disease is our #1 cause of death. What used to be so adaptive
for 90% of our evolution, holding on to cholesterol at all costs
since we aren’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. You can feed a dog 500 eggs worth
of cholesterol and a stick of butter and they just wag their tail; their bodies evolved from wolves is used to eating
and getting rid of excess cholesterol whereas 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% of our evolution, why didn’t we better adapt to meat-eating
in the last 10%, 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
that got heart attacks die off and get replaced by those
that could live to a ripe old age with clean arteries
regardless what they ate? Because most
didn’t survive into old age, they didn’t live long enough
to get heart attacks. When the average
life expectancy is 25, then the genes that get passed along
are those that can just live to reproductive age
by any means necessary, and that means
not dying of starvation so the higher the calorie foods,
the better. So eating lots of bone marrow
and brains, human and otherwise, would have a selective advantage, as would discovering a time machine stash
of Twinkies for that matter. If we just 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 on down the list. In a sense, these populations
in rural China and Africa were eating the type of diet we’ve been eating for 90%
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, they 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. Perhaps, because that’s what we ate throughout the vast majority
of our evolution.