Margaret Schoeninger: Nutrition and Paleodiet

(electronic beeping) (light music) – [Narrator] We are the paradoxical ape. Bipedal, naked, large-brained, long the master of fire,
tools, and language, but still trying to understand ourselves. Aware that death is inevitable, yet filled with optimism. We grow up slowly. We hand down knowledge. We empathize and deceive. We shape the future from
our shared understanding of the past. Carta brings together experts
from diverse disciplines to exchange insights on who we are and how we got here, an exploration made
possible by the generosity of humans like you. (light music) – So, I was given the title
of Nutrition and Paleo Diet, and like Jim, I have battled
with what, how to handle this. And you’re gonna just get what I did. I made a decision and I’ve done it. So, let’s start with the
reasons for focusing on diet. This is where I start my class on the evolution of human diet. Why do we bother to study diet? And I’ve just given you a series of them. Subsistence strategies
result from various pressures including intra-species
competition for mates and food. In other words, so you can
begin to learn something about behavior based on what
the subsistence strategy is. Inter-species competition
for food and space. Predator avoidance, and
all of those things that are never considered when
we try to reconstruct the behavior of some fossil species. And I’m not going to
attempt to do that today, although I do think about
these things in my mind. But what I am gonna try
to do today is to raise a couple of questions that
we might want to think about when we talk about
nutrition and paleo diet. So, although Jim says
that this is something that we shouldn’t just focus on, I am going to be talking
about differential survival and fertility, diet and fitness. Not so much because I
think they’re the only way to look at something, but because food is the incredible thing
that you have to survive in order to reach sexual maturity. And after that, you have
to have enough food, especially the female, to
feed herself and whatever fetus she’s bearing, or, if it’s a mammal, then nursing that child afterwards. So food is incredibly necessary, both for individual survival and for survival of the species. The other thing is that,
having been at UCSD and looking to see what kind of work Shirley Strum’s been doing for 30 years, I can tell you, it’s
absolutely incredible. So let me focus on a
couple of things here. Food and reproduction, getting
it right makes a difference. So differential fertility. What you have here is rainfall
in the preceding months. So between 150 and 550. This is what’s important
for what I’m talking about. Age at the onset of sexual swelling, so that’s the age at
which the female can be, or male or female, can
begin to bear young. And what we’re looking at is a difference of almost two years between
a low rainfall period and a high rainfall period. It’s not the water, per se,
it’s a matter of the bio-mass that’s produced because of the rainfall. Adding onto this is a
follow-up study that she did in which she’s looking
at an introduced Opuntia. That’s the Optuntia from outside our area where you get those beautiful fruits and you sell them at markets here. And these baboons of
Shirley’s have learned how to roll the fruit in the soil, take the spines off of it, and eat it. Now, this is the rainfall,
but as rainfall increases, you increase the Opuntia production. The thing actually produces
bright fruits year round. It’s low in acid, 65% is simple sugar. Well, you add weight, you
decrease birth spacing, which is exactly what
happened with these animals, increase rain, increase output, increase, tor decrease the period of
time at which you actually come to sexual maturity, and
decrease birth spacing, and you’ve got a larger
population than the guys next door who don’t have
any of these things. So it really does make a difference in terms of reproduction,
just in terms of the data that my own colleague was producing. Now, differential survival. This is what we’re hearing
about all the time, and I think I’ve heard
it from several people talking about paleo diet. This actually started with a
graduate student at Harvard. And I just checked with Jim, and in fact, he was a graduate student at
the time that Jim was there, and this is Mel Konner,
who then went to Emory. And combined with his other
colleague, Boyd Eaton, they put together a
summary of what they found of people in the ethnographic
record of what they ate. And this they called
Paleolithic Nutrition. They called it that, and it was the title of the article that was published in the New England Journal
of Medicine in 1985. But you go and reread that,
which all my students had to do, you go back and look at that
article and they’re really talking about things like
sodium-potassium ratio. They’re looking at whether you’ve eaten saturated fats or not. And what we’ve managed
to do now, of course, is go on to the Paleo Diet. The Paleo Challenge. The Seven Day Paleo For Beginners. So, you’ve got all of these things. Now the thing about the
Paleo Diet by Loren Cordain, who was one of S. Boyd Eaton’s students, it’s getting a little inbred here. Loren Cordain pointed out
that these are the things we were designed to eat. Designed to eat. And that these were
the things that we were really selected to eat. And so, that’s where it’s
gone with this Paleo Diet, almost beyond what,
definitely beyond what Boyd and Eaton did originally. You’ve got Love Paleo, Health and Weight, I even saw Diet for Children, the Paleo Diet for Children. So I didn’t put that up here. Now, in terms of what
we were designed to eat, I think there might be another way of looking at that. And that is, what is around? So when we’re looking at a tropical band, what is available? So, in a typical West
African forest, on average, this is by Hladik and Chivers, who did some amazing work back in the 90s. I also have to have my students go back and look at papers that
are not necessarily online. So, if you look at that,
what you see is that the vast majority of available food is leaves. So you’ve got 12,000 kilograms of leaves compared to 23 kilograms of invertebrates, and 500 kilograms of fruits. But if you look at primates, and I’ll go into a little
bit of why in a little bit, but when you look at
primates, what are the foods that primates go for? Fruit, because it’s high in energy. Insects, because they’re high in protein. And leaves, because they’re
also high in protein. But if you look across
all living primates, there are definite patterns, and that is a relationship
between food and body size. So if you look at the insect eaters, they’re all small, very small. This is something you hold in your hand. Microsebus is one of the tiniest primates and that’s almost fully insectivorous. The large animals can survive on leaves. So mountain gorilla is about the only one that survives totally on leaves. But most of them combine them with fruit in order to get the energy, because you can’t get
enough from these others. So you’ve got Frugivore/Insectivore, which are sort of on the smallish side. You have Frugivore/Folivores, which are on the larger side. Humans? We fall into the Frugivore/Folivore, but not many of us are Folivores. If you look at it another way, this was John Fleagle’s description. What he did is he showed
Insectivores and Folivores. There’s some fairly pure Folivores, we won’t talk about those. Those are Colobinae monkeys. Frugivores, total Frugivores, but most of them are gonna be mixed, fruit and insects or fruit and leaves. Where are humans? This is where we are. We’re almost up by the gorilla, which can eat just leaves, and we don’t. So, do you think I’m
gonna give you an answer? No. The question is why. Why are we so different? So, where we have to go is
back into the fossil record, as Bill said, and I’m really,
I’m not a paleontologist, but we definitely need more information from the fossil record. And I’m gonna give you
a couple of examples. One is an archaic primate
called Carpolestes. The next one is Aegyptopithecus, and it is at the base
of the division between monkeys and apes, so you’ve
got the combination there. You’ve got Proconsul, which
is at the base of the apes, it’s gonna be. Then you have Ardipithecus. And depending on where
you put that position, there is a very different interpretation. And mine will be different
from Bill’s because I put the time period in a
different place than he did. So let’s move on. Carpolestidaes, this is
a mouse-sized primate, lived 58 million years ago, and it was an almost-complete skeleton. It’s been reconstructed and
now reconstructed arborial, as someone else was pointing out. These are all arborial. We are also arborial primates. But the thing that’s so
incredible about this primate is its hands, because what that is doing is it has hands on both the
fore-feet and the hind-feet, as was pointed out. And what that thing
can do is grab and pull something toward it. So it doesn’t have to jump in the trees, which was the other idea,
they jumped after insects, it actually can pull toward it. It does not have complete
three-dimensional vision, but it’s enough of an overlap
that when it pulls toward it, it knows exactly where
that thing is in space. So, that’s a baseline
primate, is to be able to pull something toward you and feed on it, which is usually the
fruit, which is the energy. Let’s jump to 30 million years ago. And believe me, I did
select these on purpose, ’cause to me, these are
really critical divisions, what happens here. They are prior to the division between the apes and the old world monkeys. But the thing that’s of
most interest is that it does not look like an early monkey. It has a body like a monkey. It moves around in the trees. It’s arborial, it grabs. But it has a head like an ape. So this is not like anything alive today. This is something completely different. And if we’re gonna look
at the evolution of diet, we have to think about these animals, not just the ones that are alive today. Today, this is what the area looks like. Back then, this is what it looked like. It was a forest. They had crocodiles there, snakes, various things like that. Thank you. So, here we go. We got Aegyptopithecus in the trees as a fairly large primate. If we move another millions of years to Proconsul baseline ape, again, it is a monkey-like body and it’s got an ape-like head. So the teeth look like apes, the head looks like an ape, the body is moving
around just like a monkey without a tail. And what we know from
the biochemistry of it, what we know from the microwear of it, everything, we know it’s tree living, and it’s fleshy fruits and leaves. Now, depending on where you put that line, Ardipithecus is at the base
of chimpanzees and humans, or, where Bill put it, was up where humans and not with chimpanzees. That gives you the
interpretation that the last common ancestor was a knuckle-walker. Keep in mind that the two
knuckle-walkers in Africa do not do it the same way. So gorillas do not knuckle-walk
the same way chimpanzees do. And the way in which Tim
White interpreted this is that the last common
ancestor could just as easily been a biped
as a knuckle-walker. If you think about it that way, that gives you a slightly different way of thinking about diets. So, whether or not that’s what turns out to be correct, we ought to at least think about that as an option. Pan was a knuckle-walker. Ardipithecus was a
facultative upright walker. Highly accomplished climber, Pan, it was competent, Ardipithecus. Enlarged incisors for eating fruit? Yes, fruit-eating, that’s
what all primates do. And the Ardipithecus, woodland to forest, omnivore, and fruit eater. If we just go through these, we get very fleshy fruits, nut-like oil-seeds in the early ones. And this comes from bone chemistry. It also comes from morphology. If you look at the very
robust Australopithecine, what you find is that they’re probably adding-in things like these sedges, which no self-respecting
primate eats like that. In fact, I’m ready to take
them out of the primate order, based on diet. If you then look at these others, the Australopithecines, the later ones, you’re looking at things
with some grass in it, but mostly, again,
fleshy fruits and leaves. You move into the more recent
ones and what you’re getting are berries, grasses, roots, nuts, a whole mixture of things. And if we look at the very early Homo, what we’re finding is a modern body size. We think they’re eating meat. And what I want to leave
you with here is, why? We still don’t know why. It’s not because meat’s
that easily digested. Yes, it’s good for us. There’s not much fat on it in a desert. So, going forward? Before we can answer anything? I’ll just go through
these extremely quickly. More fossils. I would put it at the late Miocene, the mid-to-late Miocene. We definitely need to know that. Between 4.4 and now we don’t
have that many fossils. We need to have more
studies on gut microbiota and how it varies across primates. How, and this is one of
the things that Alyssa will be talking a little bit later, but she and a colleague,
Schnorr, actually did, have been starting to
look at this in the Hadza. Genetic, physiological, and
morphological adaptations of primates to different, at different subsistence strategies. And finally, I’ll give a
shout-out for Richard Wrangham. We need to know more
about when controlled use of fire occurred, and when
cooking began to occur. Because we are the only animal that cooks. Thank you. (audience clapping) (bright music)

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Reader Comments

  1. positivedennis

    She did not actually say anything. But she hinted at fire being the crucial difference. If so that implies a lot of meat.

  2. Bev1946

    Our jaws were large when we consumed only raw food. When we began to cook food, our jaws became smaller and our brains grew.

  3. Karlstens

    Fire brings both cooking and warmth. So the humans who could start a fire and keep warm would have also pulled all the babes and had the sexy times. Not smart enough to spark your own fire, or in with the clique who can? Uh oh…

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