The Ancestral Human Diet | Peter Ungar | TEDxDicksonStreet

[Music] so was the ancestral human diet my name is peter unger I'm a paleoanthropologist at the University of Arkansas I study human evolution and more specifically I reconstruct the diets of our ancient ancestors people often ask me what the ancestral or natural human diet is or was and this is an issue that's been debated for literally thousands of years often framed as a question of the morality of eating meat the lion has no choice but we do take for example Pythagoras not only the patron saint of high school triangle formulas but also of ethical vegetarianism and he once wrote oh how wrong it is for flesh to be made from flesh and the argument hasn't really changed much for the last 2,500 years only today we also have Sarah Palin who wrote in going rogue in American life if God had not intended us to eat animals why did he make them out of meat she actually has a point whether or not you agree with it when we look at fossil sites like Olduvai Gorge in Tanzania we see bones eroding out of the ground covered in the tell-tale scars of butchery cut marks all over them there's very little doubt that our ancestors ate meat millions of years ago but we also have sites like Oh hollow - on the Sea of Galilee in Israel we have the wild ancestors of wheat and barley and rye people were eating these ten thousand years before the origins of Agriculture during the the the peak of the last great Ice Age there's nothing unnatural about gluten either and fact when we look at Neanderthal teeth we find buried deep within the Tartar on that teeth on those teeth the little granules of starch of barley so all this despite the pervasive call today to cut carbs and this brings us directly into the heart of the matter the Paleolithic diets of today people who advocate for these diets argue that we should be eating more like our ancestors ate just as you you wouldn't put regular fuel in a in a car built for diesel you shouldn't be eating foods that we're not evolved to eat so whether you're stuffing your face or filling your tank the wrong fuel can wreak havoc on the system and according to these diet gurus many of the chronic degenerative diseases we face today not just obesity but heart disease type 2 diabetes several forms of cancer can all be linked to a mismatch between what we eat and what our ancestors evolved to eat what do these Paleolithic diet gurus tell us to eat well we should be getting our protein from grass-fed cows and fish we should be getting our carbohydrates from non starchy vegetables and fruits but we should need is breads and legumes dairy potatoes any kind of highly processed or refined foods those are out now I'm not a dietitian and I cannot speak with authority about the nutritional costs and benefits of either of these diet types but I can speak to the Paleolithic underpinnings of at least one of these diets the human fossil record dates back about seven million years we've got thousands of fossils today representing this time period we can divide these fossils into roughly four groups the first group I would call RT Pittacus and friends these hominins as they're called live between about seven and four and a half million years they lived largely in the trees of what is today Africa hadn't yet come down to the ground then around four to two million years ago we get the next group one that we can call Australopithecus now Australopithecus had come down from the trees somewhat which makes sense in light of the fact that savannas are beginning to spread across the African continent particularly the eastern and southern parts then about two and a half million years ago there's a fork in the evolutionary road in one direction we get a group called Paranthropus are near cousins these hominins were extremely specialized big heavy skulls thick jaws powerful chewing muscles suited to life in the open savanna and in the other direction we get our own ancestors the biological genus Homo where we've got wimpier skulls smaller teeth but a growing brain over time so how do we reconstruct the diets of these hominins well I look at their teeth teeth are the most commonly preserved fossils they're the hardest they are the most durable and they're the only durable parts of the digestive system that preserve and actually come into contact with food during life so if we can learn something about the diets of our ancestors by looking at their teeth we can say something about food preferences in the past how do we do this well we look at the sizes shapes and structures of teeth of living primates and try to relate those to their diets so we can go back to the fossils look at their teeth and infer diet on this image for example we have three monkey species at the bottom we have a languor in the middle and macaque and in the top we have a mangabey monkey the languor eats leaves the macaque soft fruits and the manga be at least on occasion hard foods like nuts and bark and we can see these differences reflected in the shapes of their teeth for example the Langer has long sharp sheering blades for slicing or shearing through tough leaf material the mangabey has blunt flat thickly enameled teeth for crushing hard foods and then the CAC is somewhere in the middle now this can teach us something about what our ancestors were capable of eating but not necessarily what they ate on a daily basis for example the mangabey at the top only eats hard foods a couple of months out of the year typically when their preferred foods soft fleshy fruits are just not available nevertheless they have to be able to eat these kinds of foods to survive the lean times so they have to have teeth capable of this but how do we reconstruct the diets of our ancestors on a daily basis what they eat regularly well we use what I call food prints which are like footprints in the sand traces of the actual activities of one's living organisms and the food print that I look to is one called dental Micra where the microscopic scratches and pits that form on a tooth as the result of its use so if you look at the top image you see a microscopic wear surface of a capuchin monkey which eats hard foods like nuts and seeds it's covered in pits or craters on the bottom we see the microscopic wear of a howling monkey that eats leaves its teeth are lined with long parallel scratches turns out that the the the the teeth of the capuchin monkey are pitted because they crushed those hard foods whereas the teeth of the howler monkey are scratched because as their teeth slide together in shearing the abrasives and the leaves get dragged along the surface of the tooth causing those long parallel scratches now engineers call the top surface complex and the bottom surface simple because all the features on that bottom surface are roughly the same size and shape and orientation ok well now let's go take a look at our actual ancestors we start with something like Ardipithecus that lived again seven to about four and a half million years ago its teeth are fairly conservative the enamel is reasonably thin it's got moderate length crests the teeth are fairly small it's pretty much what you'd expect of a soft fruit eater but then when we get to Australopithecus and particularly homo the teeth are getting larger the enamel is getting thicker their surfaces are getting flatter we're seeing more and more specialization but when we get to homo the teeth get smaller the enamel gets thinner the crests get shorter it's almost a reversal of trends so when we look at this along a timeline we start with something that looks essentially like a soft fruit eater in a closed forest and then over time from early Australopithecus too late Australopithecus and Inter / anthropocentrism tough and abrasive but then this fork in the road about two and a half million years ago with our own ancestors the teeth get thinner smaller the brains get larger we start to see meat entering in the record at least judging from the cut marks on the bones found alongside these ancestors what did the food prints teach us well in this slide what we have is we have three different types of hominins we have the Australopithecus group in red our own ancestors Homo in blue and the / anthropocentric employer indicate softer foods higher values foods and what we see immediately is that Australopithecus had a fairly narrow range of foods at least judging from this evidence mostly soft but when we get to homo the early homo the first one on the left and then particularly later homo the breadth of diet seems to be getting greater and greater Paranthropus is also interesting the first species there has a fairly narrow range of diets much like Australopithecus but the second species has a much broader range of diets pretty much what you'd expect of a manga be that sometimes needs hard foods but sometimes eats softer foods so when we break this apart and we start with a diet of our own ancestors we see a progressive broadening over time from early to late Australopithecus and then early to later homo and when we look at per anthropocentric species with the same shape teeth the same shaped skulls but very different diets one very narrow the other very broad and what this tells me is that tooth shape alone is not enough to predict diet there's more to diet than the shapes of your teeth and this introduces the concept that I call the biospheric buffet I think of the biosphere that part of our planet which harbors life is a giant buffet of sorts animals belly up to the sneeze guard with their plates in their hands and they pick and choose from whatever foods are available to them in a given time in a given place yes teeth are important they're the utensils that you have to eat with but they're not enough to tell us at least their shapes what animals eat availability is key this explains why a chimpanzee in the forest eats forest foods why a baboon or in this case a gelada monkey eats its eats Savannah resources yes their teeth are important but they're not enough and this is especially relevant when thinking about human evolution because climatologist teach us that environment varied over time dramatically it swings back and forth from cool and dry to warm and wet during the course of human evolution and with those swings and climate come changing availabilities of different kinds of foods there is a trend over time cooler and drier through human evolution which explains the spread of savannas across eastern and southern Africa but it's there's more than that there's also an increase in the amplitude of the swings in the intensity of the swings and many people including may have argued that it is that sort of change ability in the environment that variation that there's the variability in the environment that has made us human it's selected for our flexibility our versatility so let's go back to the original question what was the ancestral human diet well in light of what we've learned the question itself really doesn't make a lot of sense our lineage was a work in progress right our diets varied over time and space with shifting availabilities of different kinds of foods and in fact this is what allowed our ancestors to find something to eat no matter where they roamed whether it's up in the High Arctic where nearly all of their food was marine mammals and fish or down by the equator where they could take 70% of their calories from sugary melons and starchy roots in an effect our evolution has prepared us for a versatility that's allowed us to take over the world so in the end when I think about the evolution of human diet when I think about the Paleolithic diets I don't think about planning our menu for today I think about the verse the flexibility that our evolution has prepared us for we can eat the good we can eat the bad and we can eat the ugly this versatility is to me what defines us as humans and is the key to our evolutionary success thank you [Applause] [Music] [Applause] you you

Channel: TEDx Talks

Views: 60,144

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Keywords: TEDxTalks, English, Science (hard), Ancient world, Anthropology, Biosphere, Evolution, Food, Human origins, Paleontology, Primates

Id: Tg9cBJNiHYg

Length: 16min 6sec (966 seconds)

Published: Wed Jan 31 2018