[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
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
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