MARIANNE HUNT: Welcome back
to campus for those of you who I haven't seen yet, but
my name is Marianne Hunt. I work in the Alumni
Relations department in the lifelong learning area. And in our department, we work
to bring you educational content programming like this-- faculty lectures at reunion and at
homecoming and other home football games. We also go around the country with
our Dartmouth On Location program, and we even go abroad with
our alumni travel program. Which I'm very pleased to say
that both of our gentlemen who are speaking this afternoon are
willing to participate in as well. So if you want to learn any more about
those programs, please see our website alumni.dartmouth.edu. And I would like to take a
moment to just remind you, because there was a little bit of noise
when that announcement is going on, to turn your cell phones down please. And it is an extreme honor for me today
to introduce you to Professor Nate Dominy and Jerry DeSilva. I've had the pleasure of working
with them on many of our programs and as I said happy to be working
with them on more coming up. And you'll have to
forgive me now because I'm going to read their credentials. So I don't want to sell
them short, but they're so qualified that it's going to
require a little bit of reading. So Jerry DeSilva is an assistant
professor of anthropology. He attended Cornell University
for his undergraduate and received his PhD from
the University of Michigan. He is a paleoanthropologist specializing
in the locomotion of the first apes and early human ancestors. His particular anatomical
expertise, the human foot and ankle, has contributed to our understanding
of the origins and evolution of upright walking in the human lineage. He has studied wild chimpanzees in
Western Uganda and early human fossils in museums throughout
eastern and South Africa. Professor Nate Dominy
is an anthropologist and evolutionary biologist. He studies the behavior, ecology,
and functional morphology of human and non-human primates. He has worked in Africa since 1999,
receiving grants or fellowships from the National Institute of Health,
National Science Foundation, National Geographic Society, Packard Foundation,
Mellon Foundation, and Smithsonian Tropical Research Institute. He's an elected fellow of the
American Association for Advancement of Science, the Explorers Club,
and the Royal Geographic Society. So you can see why I
needed to read that now. His research philosophy is to
integrate tropical field work with mechanical molecular and
isotopic analysis in order to better understand how and
why adaptive shifts occurred during the primate evolution. And today they're going to tell
us about their exciting research and what they're doing
with our undergraduates. So please help me
welcome Nate and Jerry. [APPLAUSE] NATE DOMINY: OK, thank
you very much, Marianne, for that very kind introduction. I am delighted to be here to
welcome you back to Dartmouth and to introduce myself
and Jerry DeSilva and talk to you a little bit
about our own research interests and how we've chosen to
integrate our research with our educational interests. So I will begin by introducing
ourselves a little bit. Now I'm going to turn over
the stage to Professor DeSilva to talk about his own research. And I'll talk about my research. And then jointly we'll
talk about a recent course that occurred on Dartmouth and in South
Africa during the last fall quarter. So here we are at a fossiliferous
site in South Africa, and professor Silva arrived
in Dartmouth in 2015. I arrived in 2010. And we realized that this
was an exciting opportunity to integrate our research
and our teaching interests because we have shared
interests in South Africa. Jerry studies early human
ancestors, fossil hominins, we say, and how they moved
about their landscape. I'm interested in feeding. I think food is pretty important. After all, you have to eat to survive. And I think most of the
milestones of human evolution can be interpreted some way through
the lens of foraging behavior-- the way that humans detect
food on the landscape, the way they engage their anatomy to
acquire that food resource, and the way they engage their digestive
system to assimilate resources from that particular food item. I think all of those
stages are important, and South Africa is a wonderful place
to study those kinds of interactions. And so together we
realized that his interest in the fossil record, the deep
time history of South Africa, my interest in contemporary foragers,
humans and non-human primates and how they interact
with that landscape, that this was a really perfect
storm of opportunity and interests to create a really exciting course. And so this slide is meant to transition
to our particular research interests. Here is an example of a fossil
hominin that's relatively complete. We'll learn more about it. We actually have a cast
in front for you to see. And the way this thing
walked we think is important for examining
its paleobiology, the way it interacted
with this landscape. And here I am focused on contemporary
humans, modern humans that are also foraging on this landscape. And the way they saw this
ecological problem may help us understand how early human ancestors
solved similar ecological problems. So with that, I will turn
it over to you, Jerry. JERRY DESILVA: Great. Thanks, Nate. And welcome back, everyone. It's really a pleasure to be here
to talk to you about my own research and to tell you a little bit
about what Nate introduced; our role in this class, Anthropology
70 Experiencing Human Origins, and how our research integrated
beautifully with one another and with this opportunity to teach
15 students in the fall term of 2016. It was really an
extraordinary experience. Now as Nate mentioned,
as Marianne introduced, I'm interested in the origins
and evolution of humans. We know by studying the genetics
of humans and our closest ape relatives that humans and chimpanzees
are first cousins of one another and that they share a
common ancestor that lived about seven million years ago,
presumably on the African continent. What we don't know in as much
detail is the path and the process by which humans became human. And that's where we rely
on the fossil record. But the fossil record, even though
we have thousands of fossils-- we're talking about millions of years. And so we only have a couple of
fossils representing each few thousands of years of existence. So every time we find
new fossils, it really does help us complete the
picture that much more. And oftentimes it forces us
to ask questions we never even thought to ask in the first place. So discovering new
fossils is really, really, really important in understanding
why humans are the way they are. Now the particular group of early
human ancestors that I'm interested in are a group called Australopithecus. Many of you probably know about
Lucy, the famous Lucy skeleton, discovered in Ethiopia in
the 1970s by Don Johannson. She's an Australopithecus. But we find lots of different
kinds of Australopithecus throughout eastern and South Africa. And in fact, the very first
Australopithecus fossil ever discovered was found in South Africa in 1924 by an
anatomist by the name of Raymond Dart. This is known as the Taung child. Raymond Dart was interested
in these fossils that were being discovered from limestone caves. They were being blown out of
limestone caves by the miners. And he was interested in the baboon
fossils that were being found. Well, one day, and as
the story goes-- who knows how true this
is-- but the story is, he was in a tuxedo preparing
for his best friend's wedding, and a box arrived at his door. And he opened up the box and this
little face was staring at him. And he went to the wedding,
and he came back quickly and pulled out his
wife's knitting needles and slowly etched away rock and freed up
this absolutely beautiful little skull of a child, what we know now as
roughly three-year-old individual. But it was no monkey, or it wasn't even
the anatomy that we see in modern apes. In fact, what he noticed
were the small canine teeth, which is more similar to what
you find in humans today. And he noticed that, although the
brain, the preserved fossilized endocast of the brain, was small
like an apes' would be, it was structured more like a human's. And the hole at the
bottom of the skull, which suggests that this thing could walk
around on two legs, like we do. And that's my particular
area of interest-- is the origins and evolution
of upright walking. Now since that time in the
1920s, it's been almost 90 years. And researchers have found many,
many, many fossils in South Africa. In fact, the region right
outside of Johannesburg where we went with our students is
known as the Cradle of Humankind. Now that doesn't mean that's the only
place where humans we're evolving. But it's littered with cave sites
where we find a really nice record of human evolution. Now after Raymond Dart
worked on the Taung child, fossils were found at a
site called Sturk-Fontaine, which we'll talk about later. Fossils were found all
through this valley. And there's a colleague
and a friend of mine by the name of Lee Berger who worked
at the site of Gladysvale, which is shown up there in the upper left. And he worked there for about 20 years. And at Gladysvale, he
found about 20,000 fossils. It sounds amazing, right? 20,000 fossils. What he found were
antelopes and wildebeest and warthogs and giraffes and elephants
and zebras and baboons, ancestors of those. He only found two fossils of early
humans, a tooth and a pinkie bone. That's it. Early human fossils
are exceptionally rare. They are very, very difficult to find. Now this was frustrating to him. And so he embarked on a new
strategy to find fossils. Instead of going back to the
same sites over and over again, let's find new sites. And what he took advantage of
was this new technology that was available to the world at
the time called Google Earth. And anyone who has used Google
Earth, one of the first things you do is you look on to your own house. You look at a landscape
that you know very well. Well, he knew this landscape well. And he decided to dive into this
landscape using Google Earth. So here's an animation where
we fly into South Africa, into the Cradle of Humankind. And when we get there,
it's pretty brown. It's pretty dry, arid landscape,
tall grassland environment. But every once in a
while on this landscape, there's going to be a
cluster of trees that's illustrated with these red stars. And the question that he and
his geology team was asking were where were these trees-- they were mostly olive
trees and stinkwood trees-- where were these trees
getting their water, how were they getting
enough water to grow. And what they figured out was that these
trees were growing out of vertical cave shafts, that water was pooling
at the base of these caves, seeds would come blowing in, and
they would sprout out of the caves, meaning that the tree clusters
were acting as bull's eyes for where there might be
additional cave sites, where there might be additional fossils. And using this approach, he
discovered close to 500 new caves on a very well explored landscape
that nobody had known about before. And one of these caves, one that the
animation is circling around right now, is known as Malapa. And that's where we took
our students, and that's where I do a lot of my research. Now from the sky, Malapa
doesn't look very impressive. It just looks like a cluster of trees. And from the ground, it
looks equally unimpressive. It's just a hole in the ground. There is just a pit there. This is the kind of place I probably
would have walked right past, expecting fossils to be preserved in a
much more extraordinary landscape or within a cave that
was just beautiful. And this isn't. It's just a pit in the ground. And yet that pit yielded to of the
most complete early human skeletons, including this one here,
that we've ever discovered in the history of our science. But what I love about
this discovery story is that the very first
fossil wasn't discovered by the paleoanthropologist Lee Berger. I'll let the discoverer
himself tell you what happened. Matthew Berger, Lee
Berger's 9-year-old kid found the first fossil
of what turned into one of the most extraordinary discoveries
in the history of our science. It is a wonderful,
wonderful discovery story that loops in the public really
well into our science and certainly gets the students really
excited about fossil discovery. Because if a nine-year-old can
do it, then anyone can, right? And so right place,
right time for Matthew. But one of the questions
that's often asked is how did they know this
was an early human just based on a clavicle or a collar bone. Well, Lee Berger had studied that
shoulder girdle for his dissertation. He knew this area of
anatomy very, very well. But still there might have been doubts. And when they flipped over
the rock to the other side, there was the lower jaw sticking
out with a canine tooth. And, remember, the canine is
small and blunt in humans, and it's sharp and pointy in
some of the other primates. And so they knew right
away that they had made a really extraordinary discovery. And within five minutes of being at
Malapa, Matthew Berger, the 9-year-old, had made as many fossil
discoveries as his dad had made it Gladysvale in 20 years. So a wonderful, wonderful
discovery by Matthew. But that wasn't the end of it. As we started excavating this site,
more and more fossils were revealed. They were all stuck in chunks of rock. I have one of these chunks
of rock here that folks are welcome to look at afterwards. Fossils are rarely found just
lying there Indiana Jones style. They're found stuck
within chunks of rock. And these chunks of rock have to
go back to the laboratory, where under a very, very careful eye, usually
through a microscope and a steady hand, researchers will slowly grain
by grain, use a tiny little mini jackhammer to relieve the fossil
from its surrounding matrix and free up those fossils. So here's an example of a chunk of rock
that has a fossil sticking out of it. That's an upper arm bone. That's the humerus. And to the far right, it's
sort of broken abruptly. That's actually an open growth plate. So we could tell from that bone
that this was from a child. This was from a young individual. Now a careful eye might spot in
the upper right hand corner-- I'm trying to point it
out there-- a tooth. Oh, thanks, Nate. So there's a tooth sticking
out of that chunk of rock. Now when you see a
tooth, oftentimes you're hopeful that there might be more there. Sometimes there's not. Sometimes there just an isolated tooth. And you could spend months and
months and months and months hacking away at that rock with
your tiny little mini jackhammer and find nothing. So it sure would be nice if
we could speed up the process. And that's exactly what happened. This chunk of rock was snuck out of the
laboratory in the middle of the night and brought to the hospital. And at the hospital, Lee Berger's,
Jackie, happens to be a radiologist. And she gave it an x-ray. And when she gave it an x-ray,
this is the image that appeared. There is a skull in there. That's the tooth sticking
out right over there. Thanks, Nate. And then the silhouette of the skull
is pretty clear from this side. Now with more information,
our preparators knew exactly where to
hack away at the rock to reveal what turned out to be one of
the most complete early human skulls ever discovered. It's absolutely magnificently preserved. Usually when we find fossilized
skulls, they're in pieces and we have to glue them
back together again. In this one, no gluing
required whatsoever. This was in one piece-- an absolutely
beautiful, beautiful specimen. But a specimen of what? What is this thing? And as more and more of
these rocks were prepared, we revealed, not just a skull
or a clavicle and a jaw, but two partial skeletons. On the left we think is an adult
female, female because of her size and the size of her teeth. But she is an adult. She has
wisdom teeth erupted already, and they're pretty worn down. And on the right, we think
is a juvenile male, who would have been about
eight to 10 years old when he died based on his
tooth eruption patterns and his growth plate fusion patterns. These two individuals are not the
only ones we found at the cave. I'll tell you about
others in just a second. But head to toe, their anatomy
was different from anything we had ever seen before. They were an Australopithecus. They were like Lucy in many, many ways. But they were different in
other ways, and different in a combination of ways
that was entirely unexpected. Their heads, for instance, were small. Their brains were small. But they were organized a lot
like a modern human brain. Their arms were long and their shoulders
were shrugged upright like an apes, suggesting they would have been
quite comfortable in the trees. And yet at the end of those long
arms was an amazing human-like hand with a long, robust thumb that would
have been capable of precision grip. Most of my research
on these skeletons had to do with the lower limb, and
the lower limb of a species that we called Australopithecus sediba. It was named a new species in 2010. And that's around when I started
working with this team on this project. From the hips down, the hips and the
knees and the ankles and the feet, were indicative of something
that walked on two legs but differently than anything
I'd ever seen before. It walk differently than we do. It walked differently than
an upright chimpanzee would. And it worked differently
than Lucy would have walked. And so we studied this. I worked with a physical
therapy team, and we studied exactly how this skeleton
would have walked around its world and why it would have
walked the way it did. We think that because it
was really good at climbing trees, when it did come
down from the trees, that would have impacted the mechanics of
its gait when it was on the ground. And we think that its
bones tell us a story of an animal that walked with a
gate that we call hyper-pronation. And we published this in the journal
Science in 2011 and again in 2013 our analysis of the foot and ankle
and knee and hip of this creature and how they would have
worked together to help us understand how this creature walked. Now I can tell you with
words how this happened, or I can work with a
really talented Dartmouth student who can visualize this for us. There is a woman at Dartmouth who
just graduated named Amy Zhang. And Amy works with the DALI
Lab where their interest is in combining art and science. And Amy has been working
with me for a year and a half now to bring that skeleton back to life. After two million
years, how did she walk? And Amy has now prototyped, using
Hollywood animation software, using what Pixar uses in
order to animate their movies, she's now getting
Australopithecus sediba walking after two million
years of being in the ground. This thing is now walking again. It walks a lot like we do, but there
are subtle differences as well. And those differences
are going to help us understand the evolution of bipedalism. What we're finding is
that there must have been these different experiments
of bipedalism happening at this time period in human evolution. There wasn't one way to walk. There were all these different
ways to walk around the world. Now the last thing that
I'll mention about this site is that we found more remains. It's not just these two individuals. It appears as though we have
the remains of an infant. There's an elbow from an infant. There's a shinbone from an adult,
and there's an ankle from a toddler. So we have an infant,
a toddler, a preteen, and two adults, which looks very
much like this may be a family group. But we've got lots and lots of questions
and lots of fossils still to discover. And in fact, what you're
hear about a little bit later is that when we took
students to Malapa, they did make a discovery of
one of these fossils. So with that as an introduction
into my research and what I do and the really cool stuff
that I get to work on, I'm going to turn it over to Professor
Dominy to talk about his research as well. NATE DOMINY: OK, thank you, Jerry. So I want to now move us from the lower
limb up to the skull and particularly the teeth. So one of the curious
aspects about hominin teeth is that the relief on the
teeth is relatively low. So if you run your own tongue over
the surface of your chewing teeth, your molar teeth, you'll note
that it's relatively flat, there's some minimal relief
to the tooth surface, and the enamel is relatively thick
compared to other non-human primates. And so it's long been
argued that the thick enamel of the teeth of our human
ancestors and our own teeth is an adaptation to eating something
relatively hard or difficult to chew. And this assumption was bolstered by
the discovery of another type of hominin species in South Africa at the time. And this thing is called
Paranthropus robustus. And I'll just note the
flaring cheekbones here. And those cheekbones would have served
as attachment points for the masseter muscle, this muscle on
the side of the face, that when you really clench your teeth,
you can feel that muscle just pop out. That muscle is important. If you're chewing
something really difficult, maybe like pizza crust
or something like that, you can really feel that
muscle working hard to chew. These animals, we can infer,
had a massive masseter muscle. In addition, you'll see that
they have this little crest at the top of the head. That serves as the attachment point for
another muscle on the side of the head. So if you clench your teeth, you
can feel another muscle appear. That's called the temporalis muscle. It's responsible for closing your jaw. So it also contributes to chewing. And that muscle passes through this
hole here called the zygomatic foramen. And because the force of
a muscle is proportional to its cross-sectional
area, we can actually calculate the bite force of
this animal and it was immense. It would have had a bite force
that was equal to or greater than a gorillas bite force. But this thing was
about three feet tall. So imagine something three feet tall
with massive chewing muscles capable of doing something
very difficult to chew. And so these observations of
these large chewing muscles has led to a variety of different
hypotheses, the first of which was called the osteo odonto
keratoprosthesis, which is sort of a mouthful, but it argued
that these early human ancestors were probably using bone tools or stone tools
and that they were moving bipedally across the landscape. And they may have been maiming
and clubbing small animals and then eating their flesh. This was an idea that sort have
argued that early human ancestors were prominent hunters, and this is an
idea that prevails in the discipline today, that the shift from an ape-like
ancestor to a bipedal human ancestry may have involved some
important dietary shift and maybe the greater inclusion
of meat was a central factor. But the mechanics of those
teeth with a thick enamel and the low relief and
the big chewing muscles has led paleoanthropologists
over the years to conclude that, whatever they
ate, it must have been hard. And so here are some
descriptions of the hominin diet. It was tough and abrasive, hard foods,
hard and brittle, something very hard, a veritably tough diet, hard, tough,
tough food, so on and so forth. So we've been stuck with these
mechanical descriptions of the diet. But we've been struggling to
identify what those objects were. And that's been an important
area of my own research. And here, the power of
comparative biology may be useful. This is a map of the teeth of ourselves,
humans, chimpanzees, gorillas, and orangutans. And this three dimensional map
is showing you enamel thickness. So the warmer the color, the redder
the area, the thicker the enamel. So we humans have
incredibly thick enamel compared to chimpanzees, gorillas,
and to some extent a orangutan. Now that is probably an anachronism. We're not consuming hard things now. We spend a lot of time processing
food, cooking it mainly to soften it. So we really don't
need this thick enamel. So it's a bit of a puzzle. Why do we have thick enamel and why
do our ancestors have thick enamel? Chimpanzees, remember, 90% of their
diet is ripe fruit, something very soft. So this is the kind of tooth you'd
expect for consuming ripe fruit. So there was a shift. There's some shift
from ripe fruit eating, we think, to something very hard. Now orangutans may be informative. Look, their molar tooth
looks rather similar to ours. And through the 1960s
and 1970s, orangutans were considered the
sister taxon to humans. And it was widely viewed
that humans may have had-- their origin story may have occurred
somewhere in Southeast Asia, where orangutans live. Now of course with the
molecular revolution, we know that chimpanzees are
the sister taxon to humans and the fossil record verifies that
human origins happened in Africa. So there is a puzzle here--
what dietary shift could account for that change in human origins? And the other puzzle comes
with the chemical signature. These teeth that we see in
Australopithecus sedeba and others of her ilk is that they have this
C4 signal, this chemical signal that suggests that a lot of their food
is somehow derived from grass, which uses C4 photosynthesis. Now it could mean that these
hominins were eating grass directly, they were grazing. And that seems improbable. Animals that eat grass don't
have relatively large brains. Or these animals were consuming
the animals that consumed grass, and they were hyper-carnivores. But then, again, those teeth are
not well-suited for chewing meat. Our teeth are just way too flat
for efficiently processing meat. In fact, back of the envelope
calculations of chimpanzees-- occasionally they'll kill monkeys,
and they'll chew the meat. They spend more energy acquiring
the monkey and then chewing it then they actually get
from the meat itself. So for an organism
that can't cook, there is a negative energetic
benefit to consuming meat. And we think the main reason why
chimpanzees might consume meat is for solidarity, group cohesion
maybe, or blood is pretty salty. There's not a lot of salt
in their environment. So maybe they just like
the taste of salty blood. We're not entirely sure. But one idea for something that
could be both hard, physically hard, that could explain the
morphology of the teeth and also have a C4 signature to explain
the chemical composition of the teeth are these underground storage organs. Now South Africa has a
rich biological diversity of plants that have these
underground storage organs. Globally, the Mediterranean has a lot. California comes in second, and
South Africa comes in third, and Western Australia comes in fourth. So Mediterranean climates,
Mediterranean habitats tend to favor this kind of growth form. And South Africa is relatively rich. And here's some photographs of
the different kinds of forms. So this is an example of a corm,
where botanically the stem is enlarging and swelling underground. So it's like a safety deposit box. The plant is putting its
resources, its sugars underground to protect it during
times that are unfavorable for growth. So this is a corm here. This is a bulb here. And a bulb is just simply a
leaf that's put underground. So it's a modified leaf. So when you consume an onion
and you slice through the onion and you see those
concentric layers, those are actually swollen leaves that
have been put underground and wrapped around each other. Tubers are another form of
underground store organ. And so a carrot, for example,
is an underground storage organ. And a potato is actually
a swollen rhizome. It's an underground root that
connects to plants that are identical. So there is multiple types of
underground storage organs, but they all share the same
function for the plant, and that is to store
resources underground. And so provided you're
smart enough, provided you can move on the landscape bipedally
and identify a particular species and you understand that
there's something underground, you have a big advantage
over other organisms on the landscape that might be
also looking for sugary resources. Now there is another competitor
that lives in South Africa. This thing is called the mole rat. Now this is part of my research. I love mole rats. They're neither moles nor rats. They're Bathyergids. They're more closely related
to Guinea pigs and porcupines than they are two moles and rats. These animals are eusocial. There's a single reproductive female. All the other females suppress
their reproductive interests in the service of a colony. These animals are basically blind. They use seismic communication. They patter their feet to
communicate with other individuals. There was recently a
Nature paper that showed that some animals don't work as hard
as others, and they get unusually fat. And that seems unfair. That animal's violating
a social contract. It's not contributing to
foraging for the group. And it turns out that those
animals are the dispersers. So it seems like every
other member of the group recognizes that individual
has a tough life ahead of it, and its chances of
survival are pretty low. And so they allow it to get fat. And then when the rains come
and the ground gets softer, it tunnels its way off to who knows
and maybe it'll be lucky maybe not. In any case, these animals
live in South Africa, and they consume these underground
storage organs exclusively. That's the only thing that they eat. And here's an example. This is what South
Africans called volcano. And it's where the animals ejected dirt
from its tunnel out onto the surface. And if you go across the South African
landscape, you can see these volcanoes. And usually right next to one
is a tuber or some other plant with an underground storage organ. And this one has actually been
consumed a bit by a mole rat. You can see where the
flesh has been excavated. And these animals, it turns out,
are very courteous foragers. They'll take soil, and they'll
patch in the wound of the plant. They won't kill it. They want to save it for later. So they're like sustainable
harvesters, super smart. They're also magneto receptive. They're the only mammal that's
known to detect magnetic fields and orient towards magnetism-- so
just super, super cool animals. I love this photo. It looks like it's got like a
victory sign here or something. I don't know. It's pretty neat. This is a naked mole rat. So they're sort of famous. Cornell has a colony, and they learned
quickly that you cannot keep them in concrete containers because they
can chisel through the concrete. So they now have to use Pyrex. So pretty neat. In any case, there's a lot of
mole rats across South Africa. So here's a map of South Africa. And each of these colored
symbols represents an area where we sampled some
mole rats in addition to mole rats from the
same fossil localities where some of these hominin
ancestors were found. And so we did some research
to look at the stable isotope composition of these different species. So here are the two hominin species,
Paranthropus and Australopithecus. And this shows their values. These mole rats are far away
isotropically from these animals, and they're the tuber specialists. This animal comes from
Cape Town, and it eats the rhizomes of what we in the
United States call Bermuda grass. And then this animal is the
corm and bulb specialist. And it has an isotopic signature that
overlaps those of the two hominins. And so I think these data
are pretty cool because they show that you can consume these
underground storage organs and get the same isotopic signature
as the two hominin species. And so I think these
Underground towards organs are, therefore, pretty viable
foods for these hominins. These data come from
fossil mole rats that were found in the same
assemblage as those hominins. And again, those stable isytope
data overlap the hominins. So you don't need to eat meat,
which was the original explanation for the chemical signature. You can get the same chemical
signature from eating plant foods. Now humans have evolved
the capacity to use fire. And fire is one of the
hallmarks of human evolution. It's a major milestone because
we think humans could even then use fire to reduce the difficulty of
chewing foods, and that the use of fire may explain why our jaws got so much
smaller, why our teeth got so much smaller, because we can now chew
things to a much lesser extent and that gives us free
time to do other things and then brain expansion
may be associated with that. So we can work with modern
people who are consuming tubers and other kinds of
underground storage organs, and we can study the effects of cooking. And this is a project
that sort of confirms the obvious because we cook underground
storage organs all the time. We cook tubers. We bake potatoes for example, and
we already know that cooking them softens their properties. And we verified this with field data. So we think that one
of the major reasons to evolve controlled fire use is
to cook these plant resources, and this will come back, this theme,
will come back a bit later when we talk about the course. Now an additional aspect of South Africa
is that you get these bored stones. So it's a piece of granite
or schist where a hole has been bored through the middle. And these bored stones are
common across South Africa. They're also found in North
America-- so the only two places in the world where
indigenous populations would bore stones are in South
Africa and North America. Now in North America, we think
there were mainly fishing weights. In South Africa, it's
been a bit of a mystery. And it's been argued that the
San, an indigenous group of people that live in southern Africa, were
never indigenous to South Africa. This is a convenient argument
for the current Bantu population living in South Africa. But this discovery, that was
published a few years ago, where they found a bored stone dating
to 40,000 years ago Border Cave does a lot to dispute that argument. And these bored stones are everywhere. Farmers in South Africa regularly
find them in their fields, and they bring them home and they
use them mainly as doorstops. And so I've done some crowd
work in South Africa where I've worked with farmers and
I collect their bored stones and I measure their mass and everything. Here's one that was
only partially bored. Here is a sense of what it
looks like on the inside. And that is granite. That would have taken a lot
of work to bore that stone. Now it's been argued that
these bored stones were mainly used to add weight to a digging stick. So here's an image of rock art showing
a woman with her collecting bag. Here's a stick with
a stone on the stick, and here is a plant with an
underground storage organ. And here's a photograph from the 1880s. It's a staged photograph showing a
woman with this bored stone on a stick. And here is another staged
photograph from the 1980s. So we've never actually
directly observed people using these bored stones. It's just assumed, based on the rock
art, and the nature of the stick, that it was advantageous for digging. Now consider this. These women weighed about 100 pounds. The average weight of the stone is about
three pounds, and these women we think moved about 18 kilometers a
day in the search for food. So that is a non-trivial mass to
lug around the landscape with you. So there must be some mechanical
advantage to using these stones. Here's another image of rock art
from an area where we did our work. It's in the southern
coast of South Africa. And it shows some women
on a collecting party we think with the stick and the stone. And there's a little plug to keep
the stone from moving downwards. And so that's a clue that-- again, another clue to suggest that
the stone was meant to weight a digging stick. We actually used bored stones from the
archeological record from this area. So these are actual bored stones that
were found in that same area where that rock art was found. And in those same
archeological sites, you see these rich beds of
this botanical tissue. Now this botanical tissue
comes from an iris. So the irises that you plant
at home come from South Africa, and there's a tunic
around that corm's tissue. And this is the tissue that you'd
remove from the corm to consume it. And so this is refuse in
the archeological site. So we can do an experiment
where we create a stick. Here's a stone. We know the mass of the stick. We know the mass of the stone. And these little tapes tell us
the distance between segments. So there are increments on
the stick and the stone. And we can work with women
in this same landscape. And we can measure how much force is
generated every time the stick strikes the soil because, through film analysis,
because we know the speed of the stick and because we know the mass of the
stick and the stone and everything and we can calculate
the weight of gravity, we can estimate how much force
and translational momentum was put into the ground. And so this is just-- mute this. You just see what it's like. So the plant, the target
plant, is right here. And these plants grow right next to
large rocks probably to protect-- they're not conscious of this. But mole rats are on that landscape. So the closer it is to a large
rock, the safer the plant is. And you see the attitude of the
stick is constantly changing. That's why we needed
the tape on the stick because that distance will never change. So in our film analysis we
always know how fast it's moving. So the velocity and the force-- so the velocity and the mass will
give us an estimate of the force. And then this is the final outcome. This is the corm itself. This is the edible tissue. It's about 80% starch. So it's comparable to a
domestic potato, and there's that tunic tissue that gets removed. Now the analysis shows that
we can do the experiment with and without the stone as a weight. And without the stone, you
have to really use your muscles to hammer the ground with the stick. And so using the stone
is actually beneficial. So yeah, you pay a cost to
lift the stick and the stone against the force of gravity. But you make up that cost with
increased force every time you hammer. So the overall efficiency
of using a stone is seven times greater
than not using a stone. And I tell you, this project only
came to me because I moved to Vermont and I had to start chopping wood. And I went to Dan and Whit's in Norwich,
and I was asking, what kind of axe do I need? And I didn't know. And I got like a thin axe. And they said, no, no, no. You need like the heavy axe
with the triangular head. And I thought it was crazy. And then they worked with me. There's eight pound
weights and 10 pounds. And they worked with me to
figure out the ideal one because, yeah, you lift it up and
you pay a cost to lift that mass, but then you just relax your arms
and you let gravity and the mass do all the work for you. So it's more efficient to have a
heavier axe when you're chopping wood. And so it's the same principle here. And so we think we figured it
out, by doing this experiment, by working with local South
Africans, we know exactly why these bored stones were made. Yeah, it took a lot of time to
make them and you lugged them around the landscape. But you make it up. You make up that energetic cost
with improved forging efficiency. So there we've given you a little
glimpse of our research interests. We have a shared
interest in South Africa. Those are complimentary
interests-- diet, forging behavior,
complements, locomotion. You have to move efficiently on the
landscape to acquire food resources. So these are related concepts. And these concepts tell us a lot about
human origins and human behavior. And South Africa is just great for
giving students that same experience that we had when we were undergrads. We were fortunate to have
advisors that took us to the field, exposed us to field work. And for the first time, we realized the
professors had these interesting lives outside the classroom. And Dartmouth is the perfect place to
start to give these same opportunities to undergraduate students. So right as Jerry came
to Dartmouth in 2015, remember, the fall quarter
shifted forward in time. So now the fall quarter
ends right at Thanksgiving, which leaves this little window of time
between Thanksgiving and Christmas. And students are now calling
that window the winterim. And so now faculty are
realizing there's an opportunity here to extend an ordinary course. So we conceived of a typical fall
quarter course that happened on campus, and then there's this
three week extension that happened in South Africa. And so students could then go to see
the areas that inform our own research and then inform paleoanthropology. And honestly there's just no
substitute for seeing it yourself. Now Dartmouth, with support
from President Hanlon, with support from DCAL, the Dartmouth
Center for the Advancement of Learning. And because of the
infrastructure that we have, the Guarini Institute for
International Education, we were able to conceive
of an opportunity to go to South Africa with
these resources in hand. And I don't know any
other institution that would have precisely this perfect storm
of opportunity and faculty interest to do something like this. So our class occurred in
Dartmouth Hall right here. We spent the fall quarter
reading the literature associated with each of these
different concepts in South Africa. And so each week was devoted to a
particular topic that would then inform and enhance their understanding
of that topic and those materials when we got on site. So we arrived initially in Johannesburg. And, Jerry, you should just
jump in anytime you want to. JERRY DESILVA: Sure. NATE DOMONY: And the beauty of the
fossil resources in Johannesburg is that they show the entirety of
the fossil record in South Africa, from the Triassic all the
way up to modern times. And so the students start to appreciate
the magnitude of this time depth with the kinds of fossils available
at the University of Witwatersrand. JERRY DESILVA: So then the
students got to see the fossils that we had found at Malapa. And many of them had designed their
own projects around these fossils. One of the requirements
that we had in this class was that the students had to
design their own research project. We had 15 students. They designed their own
research project that couldn't be answered unless they went
to South Africa and collected some data and measured something or asked
people something, something that we didn't know the
answer to and couldn't find the answer to if you just kept
reading papers, kept reading books. We didn't have the answer. You had to go and do
the research yourself. And so several of the students worked
on the fossils that are shown here. This is Karabo, this is the young
male Australopithecus sediba. And there's nothing like
seeing the original fossils to see the kind of anatomical
detail that many of them had their questions centered around. And I can't even tell
you-- to sort of mirror what Nate said earlier, I can't
even tell you how many times I've been in that room, working
on fossils, and I wished my students were with me where I could
show them stuff and say, hey, check this out. Check out this anatomy. This is what we were
talking about in class. But they're not there. Or at Malapa and I'm digging
and I'm working at the site and we're finding things, or not
finding things as is often the case, and I wish my students were there. Or I'm in the classroom
and I'm talking to them about the work I do and I wish
I could just bring them suddenly to South Africa. And we could start seeing the original
fossils or going to this site. And this class allowed us to do that. So Katie and Lauren, they did
their project on that skeleton. So that image is capturing
them talking about breaks on the skeleton that help us
understand how these individuals died. What they were interested in was
how did these individuals die and what evidence do we have for
cause of death two million years ago. Michael and Erica are looking
at a skeleton of a baboon in this particular image in the museum. So the museum was this wonderful
place, or the University Museum, was this wonderful place where students
could see the fossils themselves and handle them and get a
sense of what kind of research happens once you get the
thing out of the ground. But then we went to the Cradle,
and we went to the site of Malapa to dig ourselves. And I've got to tell you that
one of the intentions of going to the Cradle of Humankind
and going to Malapa and having the students dig
at Malapa was to teach them how difficult paleontology. So many students want to
become paleontologists. And we said, oh, yeah, do you want
to stay in a tent for five days where there are bugs flying through at
night that are bigger than your hand and some of them freaked
out at that a little bit, that we could hear hyenas at night. The hyenas were very vocal at
night, and that upset a few folks. But the landscape itself allowed
us, or gave us an appreciation, of not only what the hominids
were facing when they were alive but how the landscape
has changed over time as well because some of
the fossils we're finding were of creatures that
simply aren't there any more. But honestly when we got to the
site of Malapa and started digging-- and we dug for 3 and 1/2 days-- the intention-- and
this is a little cruel-- but the intention was for them to fail. I didn't want them to
find fossils necessarily. I wanted them to see how hard this is. And you have to dig and dig and
dig and dig and dig and dig, and very often you find
absolutely nothing. And we showed them that
this is a fossil rich site and how, in certain spots of the rock,
where her skeleton was discovered, we still have parts of her in there. We can still see those fossils. So we have some targeted
areas of excavation. Here's Kathy using some
of the equipment that we use at the site to document
exact placement of the fossils. When you find something we
need to know the exact GPS coordinates of that fossil. We worked in these gridded off squares
where the students, for three days, just had to slowly,
slowly, slowly scrape dirt and sift it into or shovel it into
buckets that then went into sifts. And they shook and shook
and shook and shook. And I don't know if you'd agree
with this Nate, but many of them I think were bored to tears
of this after a day or two. And I was like, excellent. Great. You're learning how this works. And then of course, on day
three, they found a fossil. And they not only find a fossil. It's got to be an antelope, right? That's all we ever find. They found a piece of her pelvis. They found a piece of the female
Australopithecus sediba pelvis. And it is a critical
piece because it helps us understand what the
pelvic shape was like, and the pelvis is really
important for bipedal locomotion. But also because we
think this is a female, this is going to help us reconstruct
what birth, what childbirth, was like the mechanics of
childbirth were like in something that lived two million years ago. Because childbirth in humans
today involves rotation, the baby is often facing
backwards and childbirth is often a social event in humans,
whereas in chimpanzees they go off into a tree by
themselves and give birth to a baby that's facing forward. They can deliver a baby
themselves, whereas in human it can be much more difficult than that. In Australopithecus
sebida, we're not sure. And having this piece now, now
allows us to ask that question that we were able to ask before. And then we went to other
sites within the Cradle. This is the site of Sircatene,
where the timing was perfect. We did coordinate this to meet up with
an alumni group that was traveling through South Africa at the time. And so our students got to interact with
a group of Dartmouth alumni at-- this is the Cave of Sturk-Fontaine where
many famous fossils were discovered. And without us even
needing to prompt this, it was just this really
wonderful moment for Nate and I, as teachers, that we walked
into a museum that preceded the tour of the Sturk-Fontaine cave. And there were fossil
replicas all over the place, and our students became the teachers. And our students started
teaching these Dartmouth alumni about what they had been learning about,
how they would see certain displays and say, well, that's not quite accurate
anymore because new discoveries have shown this, this, and this. And we were able to just
step back into the shadows and let our students
become the teachers. And it made us incredibly proud
of how they took ownership over this experience at Sturk-Fontain. So we spent a good five days
in the Cradle of Humankind. And then to really flesh
out what the landscape would have been like of Australopithecus
sediba two million years ago, we needed to travel to
a national park to see some of the animals that
would have been coexisting in the landscape, or at least the
modern descendants of those animals two million years after the
existence of an Australopithecus. Nate, I don't know if you want to jump
in and talk about Pilanesburg at all. NATE DOMONY: Sure. Well, one of the common refrains
we heard from the students was just how alarming and
unnerving and unsettling it is to move through this landscape
with these large animals on it because, of course, when you have a
complete assemblage of herbivores, you also have a complete
assemblage of predators. And so I think there was just no
substitute for this kind of experience for the students, to realize that,
yeah, being bipedal makes you efficient, but it also makes you slow. And there is no way we can
outrun a potential predator. And so the students got to
see these predators firsthand. And they actually saw a predation event. So here's a lion with a small impala. And the poor thing was
just bleeding and calling while the lion commenced eating it. It was pretty arresting
for the students. But nonetheless, Katie-- she's 19. She wanted this photo
in the presentation because she felt like this
look on her face captures how she looked all the
time during this course. She just so so enjoyed it. But we also got together at
night around the campfire and other students did their
projects on each other. So there was an engineering student
who was using these portable blood pressure monitors because
it's been argued-- one of the benefits of
evolving controlled use of fire is not only for cooking, but it
also reduces your blood pressure. It relaxes you. And that could be a
selective advantage, too. And so sure enough, her analysis show
that these students were getting more relaxed as they were watching the fire. And it's thought that there's something
about the rhythm, the fluidity, of the flicker of the fire that maybe
is very calming and mesmerizing. And then from Pilanesburg,
we moved to a site called Wonderwerk, Wonderwerk, rather. JERRY DESILVA: Where there is
the first evidence of fire. So we talked all about
fire in the class. And then we had a student who
was doing a project on fire. And then we said, hey,
let's go to where we have the earliest evidence of controlled
fire in the human fossil record. And it happens to be at this site
of Wonderwerk Cave in Central South Africa. We got a little lost getting there,
but we eventually did get there. And down in those deposits
is a layer of ash, and it's been dated to
1 million years old. So long after Australopithecus
but long before us, presumably something like a Homo
erectus, had controlled fire. It wasn't yet making
fire, we don't think. But it was controlling an actual fire,
and it was using it to cook its food and perhaps just sit around
and tell stories at night and lower its blood pressure
the same way we do today. In that same cave the
students noticed rock art on that cave wall as well,
which has been dated to I believe early Holocene, late
Pleistocene, early Holocene. And so this is a cave that's been
occupied for the last million years and perhaps even further back
than that as they dig down and find older and older and older spots. NATE DOMONY: And then
we had an opportunity to meet the makers,
presumed makers of that rock art, a population of
indigenous peoples called the San that live in this northern part
of South Africa in the Kalahari Desert. So this was a radically
different habitats from what they'd experienced before. So it was a true proper desert habitat. And this particular
population has sovereignty over an area of a trans-frontier
national park, which means that the park goes
into different countries. And they built a lodge on this site. And so we thought it was important for
the students to interact with the San as much as they could. So we visited this particular lodge. And this entailed working closely
with the San to go on nature walks, to see the different
kinds of plants and animals that were important to their survival
and ecology in this particular habitat. Some of the students decided
to do projects with the San to wrestle with this tension that in
anthropology is called essentialism-- what is your innate
behavior and to what extent do you change your innate behaviors
in association with others. And so they were interested with how
the San navigate this complexity of how their essential behaviors are
changed when outside groups try to commodify or commercialize their
behaviors for their own purposes. And so the students worked
directly with the San to ask these kinds of complex questions. And here's an example of one of their
informants, another informant here, another here. And it was such a moving
and profound experience for them because the San said that
no American students had ever come and asked these kinds of questions. And some of our students
were native themselves, and they felt a strong, just,
camaraderie that, I think, can't be replicated by
reading the literature. The academic literature that we
assigned in class has a dry, muted tone. It doesn't have any of these more
emotional, more complex elements that the students experienced firsthand. And on our way to Cape Town, they
met another individual of San descent He was easily recognizable. He was a waiter at this one-- I don't know, it was almost like a
roadside attraction type of deal. And they pulled him aside, and they
asked him similar kinds of questions. And they got very similar
kinds of responses. And so the students recognized
that the indigenous identity and indigenous thoughts
are not necessarily being filtered into popular media
and in the academic literature. So for the first time,
the students realized that they were learning
something new and different, that they were directly
understanding a situation that wasn't necessarily being portrayed
that way through other sources. And there's no way to get that
experience without going yourself. So from the Kalahari, we
shot way down to Cape Town. JERRY DESILVA: It was a huge change of
scenery to go from the Kalahari Desert to Cape Town in 24 hours. And the students-- one of the
things that was important to us was to make sure that the
students had an appreciation for being in South Africa, not
just for the science that we do and the science that has
been done for decades, but to understand that science
is not done in a vacuum and that science is
always done in a world or in a sociopolitical climate that
has an impact on those scientists. And so we wanted them to
understand, to some degree-- this wasn't a history class. This wasn't a political
science class-- but we wanted them to understand
the history of South Africa, and we wanted to them to
understand apartheid and the effect that that had on South Africa
and South African scientists and continues to today. So the students-- we
went to Robben Island. And we spent time in Robben Island
learning from one of the prisoners himself that talked about the
experience of being in Robben Island with Nelson Mandela. That's Nelson Mandela's cell
over there on the right. And it was an incredibly moving
experience for all of us to be there and to think about, again,
how science is done today in this country that is
changing so rapidly politically and how it was done in the past. I think about a colleague
of mine, Philip Tobias, who was in South Africa during apartheid
and fought the regime from within. So he would had enough power that
he was able to make some changes so that black students could be
admitted to the medical school during the apartheid regime. And so when apartheid finally fell,
he was seen as a national hero. And this was a paleoanthropologist. This was somebody that I
saw as a scientific hero, but he's more than that. And we were able to appreciate
that to much more degree I think by spending time in Cape Town,
spending time on Robben Island, and then eventually of course
going across to Table Mountain, where the students got all geared
up to climb Table Mountain. I don't know what they're doing here. This photograph has meaning to them. But they're excited because it's
the only place in the world where you can see one UNESCO World Heritage
site from another UNESCO World Heritage site. So the Robben Island is a World
Heritage site and Table Mountain is one. So I'm not sure exactly
what they're doing here. Are they something out? They're spelling something out maybe. NATE DOMINY: Oh, are they? JERRY DESILVA: They're
sending us a code. NATE DOMINY: I didn't realize that. OK, all right. And then of course, they
wanted to climb Table Mountain. So this is they're looking
really fierce and ready, and they're ready to
tackle this mountain. JERRY DESILVA: And they did. They're in much better shape than I am,
it turns out, because I went with them and it was painful. NATE DOMINY: And in addition to
seeing these cultural monuments, they also went to the
coastline to explore how baboons consume coastal
resources because an emerging thought in anthropology
is that there's something about the South African
coastline because you have a rich marine resources. Formerly about 200,000 years ago
the sea levels were much lower, and there was this broad savanna. So there was an area of land about
the size of Israel or New Jersey, whatever your frame of reference
might be, that's now submerged, and that was flat. It was a savanna. And so the idea was that, in addition
to underground storage organs-- reliable sugar-- in addition to the marine foods and
savanna resources-- reliable protein-- that this was a perfect storm,
a trifecta of resources, that allowed humans to forge
especially efficiently. So there's something really special
about the South African coastline. And one particular student wanted to do
a project on baboon human interactions. And so I just want to show you very,
very briefly what a final project looks like at Dartmouth now. So you may be familiar with term papers. So in this particular
class we were more focused on term projects that would
have an online capability, and some students really
took this very far. Like her project entails maps where she
interviewed subjects about their views on baboons. It's color coded based on how
tolerant they are to baboons. She has all sorts of data on perceptions
and human baboon interactions. So she compiles all this into a
website that is then turned into us. And then there's a
project reflection piece where they think about
their experience and think about how the experience
transformed their conceptualization of the material. So we're trying to move
away from the term paper and provide a medium
that allows students to expand their conceptualization
of particular topics and of course as a whole. JERRY DESILVA: And I'll
to that, Nate, that one of the things that we wanted them to
be able to do is feel able to fail. We wanted them to be able
to go to South Africa and realize that the projects they
had come up with were untenable or that the hypothesis
they had was actually wrong and that the data that
they were collecting was either different than they
expected or so much more complex than they once thought that
their original projects just couldn't be done. And over the course of the
three weeks we were there, many students expressed
frustration to us because these are Dartmouth students. They've never failed before. They're good at everything. And they came in and they say,
oh, my project is falling apart. And we're thinking in the
back of our heads, good. Your project is falling apart. You're learning. Now pick yourself back up
and turn it into something. How are you going to now turn
this into something different? How are you going to reflect
back on this experience and have it change you and change how
you would tackle the project next? And we'll see some in just a second. NATE DOMINY: And they were. They were resilient. They really were, which was
a great experience for us. From Cape Town, we
moved to Agulhas point. So if you can imagine an area about
this large that was now submerged but was formerly a savanna like habitat. So we wanted students to see the
remnants of that now submerged savanna. So we went down to the
coastline at this site. This is the point where the Indian
Ocean meets the Atlantic Ocean. They were thoroughly
impressed with that site. So they got to see both the marine
resources-- the limpets and the muscles and the clams that
are on the coastline-- and they could envision
the savanna habitat. Some of that botanical aspects
of that habitat still remain. So they could see it
all, and they could start to understand why this habitat
may have particular importance. One of the most meaningful
events for the students was a group dinner that
we had in our house. And I don't know if
you want to add that. They constantly talk
about this night as being one of the highlights of the trip. JERRY DESILVA: It was towards the end,
and there was a lot of reflection that happened that night of,
OK, we're just about done, and now you reflect back on everything
that happened because, boy, we really packed it in. We did a lot of stuff
in those three weeks. And it was a moment for
them to sort of think back and reflect on that
experience because they knew they'd be leaving soon. NATE DOMINY: And one of the
exciting outcomes of this project. So here's the second to last
day where we are at a cave site called Pinnacle
point which is important because it has some of the earliest
evidence for potential language, the earliest evidence for using
a spear thrower, so projectiles. So Neanderthals, remember--
yeah, they were smart. But they had thrusting spears. And modern humans coming to Europe with
spears that you can actually throw. So we think it was a
big technical advantage. We see the earliest
evidence of symbolic culture engravings, artwork, that sort of thing,
in South Africa, on the coastline. So something exciting is
happening on the coastline. Pennicle point has the evidence
for a lot of the emergence of this important kinds of behavior. And so one student really got
just turned on by these caves and thinking about the importance
of caves and human evolution. And so he's now a
Presidential Scholar and he's developing his own independent projects
looking at this one hominin that has extremely curved fingers. And typically we associate her
fingers with wrapping the fingers around branches. So orangutans and gibbons
have very curved fingers. But this hominid has greater finger
curvature than even orangutans. And yet the wrist and proportions
of the hand are just like ours. So I don't know. It's a big shoulder-shrug. What was it doing with his hands? We don't know. And he thinks maybe it was in
caves rock climbing because he himself is a rock climber. He's the president of the
Dartmouth mountaineering club. And so here he is trying
to unite his passions for climbing with
anthropology to explore another project in South Africa. JERRY DESILVA: Another Presidential
Scholar Olivia Weiner shown here. She's going to be working
with me this summer looking at a lot of the fragmentary fossils that
we have from these South African cave sites. Very often they're not sound complete. They're found in pieces. And she's going to look at
how we can take those pieces and reconstruct them
into a whole skeletons. So if we had a whole
series of skeletons, which we do-- we have access
to those sorts of things-- what if you only had a
fragment of that bone? Would you be able to
reconstruct its entire length? And so she's going to be doing a
project like that with me this summer, in part, inspired by what she
saw in South Africa of all these fragmentary
remains and saying, geez, it'd be great if we could squeeze
more information out of these fossils. Another Presidential Scholar from
last year, Jessica Kittelberger, who just did-- I think she did two different projects,
maybe three different projects when she was in South Africa. She could not get enough. She's also been working with me on
a lesser known idea in our science, that brains have actually gotten
smaller in the last 30,000 years. Most people think brains have gotten
bigger and bigger and bigger and bigger and bigger and bigger. And they haven't. Brains got bigger, and
in the last 30,000 years, they're actually heading
in the other direction. And there are about 15% smaller
than they were 30,000 years ago. We don't know why. We don't know when this started. Lots of folks have their own little
jokes on human intelligence today, and it keeps going down,
down, down perhaps. I like to think it's actually a
result of collective intelligence, that one individual doesn't
need to know everything there is to know about being
a human anymore for survival because we rely on other individuals. And so we're becoming a little eusocial. But she realized that there was a huge
gap in our understanding of brain size at certain places at certain points. And while we were in South
Africa, she took advantage of this and measured the brain
size of several skulls from a cave site in South Africa
that are about 5,000 years old, which is not very old for
a paleoanthropologist. And yet for this particular question,
it actually fills in key time period that we don't know very
well for brain evolution. So she's been working on
that particular project. NATE DOMINY: So I think I'll
just take a minute to summarize, and you should add something. Just to say that in some respects I
feel like this presentation to you is a bit premature because what's
so exciting about these students is that they're now doing their
own individual projects inspired by the content of the class. So I just can't wait for a year
from now or two years from now when the true arc of the
outcome will be revealed. And Michael Everett-- it's so funny
because he came into your office and he said, I just don't see
the need for any more classes. I just want to stop taking classes and
go to South Africa and do as much work as I can. And in some part of me-- part of me felt like that
was just a terrific outcome. JERRY DESILVA: And he's
a second year student. It's not like he's a senior. No, I totally agree. And not only a year from
now or two years from now, I want to 20 years from
now what kind of impact this experience had on their
educational trajectory. So when they come back for
reunions 20 years from now or so, I hope we're still here doing
some sort of talk on our research, and I want to know how that impacted
them because it impacted us enormously. It totally changes how I think
about teaching in the classroom and how I can use-- maybe not
take every class to South Africa, but there's got to be a means
by which we can incorporate more of this experiential learning
approach into all of our classes given how effective I think it
was with this particular group. [APPLAUSE] Thank you. MARIANNE HUNT: Time for a few questions. Well, firstly, the microphone. So wait for the microphone so
everybody can hear your question. And while Alice is coming
down, I just wanted to mention that Jessica spoke to
some of our alumni before the trip. She was talking that specific project. And she was measuring the capacity
of the cranium with like wheatberries or something. JERRY DESILVA: The question-- it was
about how Jessica was measuring brains. And we were running around South
Africa going to grocery store at a grocery store looking for
millet seed to fill up the skulls. And we ended up using little pieces
of rice that did the same thing. So we able to measure volume that way. AUDIENCE: Yeah, can you hear me? My question is this. You're talking about humanoids or
hominids from two million years ago. Do you run into students who
40% of the American population thinks people came on the
earth 6,000 years ago? Does Dartmouth have students like that? They probably don't take this course. And then how do you contend with that? JERRY DESILVA: So it's unusual. It's unusual to encounter a
student like that, but I have. And oftentimes, the student comes
to me with a legitimate struggle that they're really trying to negotiate
these different pieces of information that they're getting in their heads. And I say, hey, that's one of
the beauties of being a human and having this brain is to take
these different kinds of information that you're getting and rattle around in
there and come up with your own ideas. However, my job as an instructor
in biological anthropology is to teach people about what
science is, how science works, what the nature of evidence is,
what we know about our ancestry based on these methods. And so if they leave that class
still not believing in evolution, I don't really care. To me, it's not about convincing anyone. It's about making sure that they
know at least how we do our work. And if they can then go out into the
world and know at least what we do and how we do it and not spread
misconceptions about what we do, then I think we've done
our science a service. But I don't think we're-- at least I'm not in the position
of trying to convince anyone. I think if we present them with
the evidence we have and we give them experiences like this and
show them, look, these things are real. They existed. And we have the physical
evidence of them. And here's how we date them. We don't just make up dates. We understand the geology and
the chemistry of the rock, and here's where the data come from. If they can understand that
more and more and more, then I think they'll realize
that any rejection of this idea kind of flies in the face of
the evidence that we have. NATE DOMINY: That was good. AUDIENCE: A question for Dr. Dominy. Do you know the dating
of your phangeal hominid, or the curvature of the phalanges
and where this was found? NATE DOMINY: The hominin
with the curved phalanges. It's called-- the question was
about the particular hominin that I mentioned that was the focus
of study by Michael Everett at 19. He's interested in a
hominid called Homo naledi. It was recently discovered. Jerry's a co-author on those papers. So he's better suited
than me to talk about it. The date was just published
about two weeks ago. And it's about 200,000 years old. So this thing Homo naledi lived
on the landscape as the same time as us, our species. So there were at least two
versions of homo living in the same place at the same time,
one with extremely curved fingers, and one with fingers like ours. So presumably that curvature
means something biologically. It was doing something with its hands. Personally, I think it was
digging and without a bored stone. Think about it. If you have to dig with a
stick with no extra weight, you have to grip that stick very
hard to dig in that rocky soil. So I kind of think maybe it
was a digging adaptation. But I don't know. But Michael thinks it's rock climbing. JERRY DESILVA: But we'll see. We all thought it was tree
climbing when we first found it. We all thought it was, OK,
curved fingers, climbing trees. That's what curve fingers
tell us in the fossil record. But that's what is important about
having collaborators like Nate is that I mentioned to
him it's climbing trees, you say not if it's 200,000 years old. There are no trees. Or they're Acacia trees and
who wants to go up in those. So knowing the landscape
at that time and working with somebody who
understands landscape ecology becomes incredibly valuable to
paleontologists trying to reconstruct what these creatures were doing. NATE DOMINY: So the landscape you saw
was fundamentally the same 200,000 years ago, mostly Acacia trees. Acacia trees produce pods. That's not something a
human would eat normally. So there's no ecological incentive to
climb a tree to consume those things. And besides, trees are relatively
sparse on the landscape. So it's that kind of thinking that
led Michael to think creatively about what other kinds of things
could this thing have been doing. Rock climbing maybe is one of them. AUDIENCE: Golf. NATE DOMINY: Golf. [LAUGHS] But, see, the hip
swing would be your area. JERRY DESILVA: Oh, there we go. We'd have to look at it. It does have some interesting
rotation going on. AUDIENCE: As a one time Dartmouth
cross country and track runner, I was fascinated by
your work in locomotion. And it appeared to me from
the animated simulation that you showed us that the subject
there was moving really flat footed. I couldn't see much flexibility
in the foot, and as a consequence, must have been very slow, a lot
slower than a Dartmouth runner. JERRY DESILVA: That's a great question. So we don't have her complete foot. So there are lots of pieces of
her foot that remain a mystery. And I can't wait for us to
get more of her foot anatomy. But what we do have
from her would suggest that she is more flat footed than
the majority of humans today. But compared to a chimpanzee,
she would have a partial arch. So her foot would be somewhat
arched compared to a chimp. But compared to most
humans today, we would say she's definitively flat
footed and even more flat footed than folks that consider
themselves to be flat footed. Oftentimes the architecture
of your bony anatomy in there is still kind of curved,
and it's soft tissue that is producing that flat foot. However, with her mid-foot in the
middle of her foot-- and the animation was probably moving too
quickly to see this. We're going to produce another
version that slows her down-- she does have a bend in her foot
in the middle portion of her foot called a midtarsal break, which
most humans do not produce. Chimpanzees do. Other primates do. When they lift their heel, the
middle portion of their foot actually bends in half,
and then they roll on to the sole of their
foot and their toes bend, whereas most humans lift their
heel and their foot is quite rigid, in part because of the arch and all
the soft tissues make the foot rigid. And when you lift your heel, it
works as a lever, an effective lever, that raises the foot onto the ball
which then you can push off and propel yourself into the next step. There are some humans who do
produce a midtarsal break. And we discovered this somewhat
accidentally collecting data at the Boston Museum
of Science on a bunch of visitors who would walk
across a plantar pressure device and produce a digital footprint. And I would see these
footprints and they looked like, in some ways, looked like ape feet. They had this midtarsal break. And I'd asked the people to do
it again-- can you walk again? And they'd do it again, and they're
produced another one of these. I'd say, this is awesome. This is imposs-- no one
knew humans could do this. And it turns out a good percentage
of the human population can do this. They have weak enough feet that
they produce some floppiness in the middle portion of their foot. So we MRIed a bunch of those people. And it turns out, they're bony
anatomy, the bones of their feet, tell us they can do
this, and that anatomy matches what we see in the skeleton. So we think this skeleton also
had that flexible midfoot, which would have been great
for tree climbing, would have been really beneficial
for getting up that tree, grabbing onto that tree, which we
think these things were still doing. But it comes at the expense
of how well it could walk. And most likely-- I agree with you-- most likely on that flat
foot that's very floppy, this thing would not be able to
walk as efficiently as we do today, or as quickly as you phrased it. AUDIENCE: I'd like to ask about the
level of what kind of the scholarship that you have in the scientific
community in South Africa. And did you interact with
them and what were they doing? I ask because I was bureau chief for
The New York Times for four years when Mandela got out of jail. And I never heard of any of this. Didn't have time. It's a fascinating. NATE DOMINY: We made a very concerted
effort that, at each location, we wanted to work with
local South Africans and interact with their students. So at each stop on this
extension, this embedded course, we were interacting with students. And in Cape Town, I remember
vividly we went to dinner with faculty and their students. And the nature of the conversations
just went in all directions. So yeah, for us, it was a top priority
to reach out to our colleagues there and students there and to make
sure that our Dartmouth students could interact with South Africans students. MARIANNE HUNT: OK, well if you don't-- NATE DOMINY: One more someone. MARIANNE HUNT: If you
guys are game for it. JERRY DESILVA: I'm game. AUDIENCE: Is this turned on? JERRY DESILVA: Yeah. AUDIENCE: OK. My question is why is it that
South Africa happens to be the so-called Cradle of Humankind? Is it because of lack
of volcanic activity? Because there might be other places in
the world where there were even earlier records that were
destroyed by metamorphism. JERRY DESILVA: Sure,
it's a great question. So each country where early
human fossils have been found has laid some claim to being
the cradle of human kind. And in South Africa that region
that UNESCO World Heritage site happens to be called
the Cradle of Humankind. But I don't think any
of us would necessarily make the case that it was South Africa
where all of this was happening. Instead what South Africa
does is it produces this window of these
different time periods where we see some key innovations
in human evolution happening. We even talked about, could we have done
the same kind of course in Tanzania, could we have done it
in Kenya and Ethiopia. And the answer is yes. We could have done this course
in those countries as well. We could have done it in Uganda. And in each of those places, there
would be this special unique flavor that each country provides
to our view of human origins. But we couldn't have done a human
origins class outside of Africa. Africa is where our lineage evolved. It's where the splint with chimpanzees,
the very earliest hominins, were in Africa. We know our genus homo
evolved in Africa. And we have very good
evidence that the species homo sapiens evolved in Africa as well. So any class that purports to look
at human origins is going to Africa. It's just a matter of
which which country it is. And South Africa, for us, given the
research we do, was the obvious fit. But I could see this kind
of class happening in Kenya. MARIANNE HUNT: Well, great. I'm sure you can all see why I
enjoy working with Professor DeSilva and Dominy so much. Their enthusiasm and their scholarship
and dedication to the students is really unparalleled. And I thank you and invite
everybody else to thank you as well. [APPLAUSE]
