Sponsored by nordvpn Let's take a look at a map of some key Asian
archaeological sites that are between 100 and 200,000 years old, roughly. A time period
called the middle to late pleistocene. A cold time in the earth's climate.
A period of frequent glaciations, woolly mammoths, the whole
shebang. It's the Ice Age. Over in modern Israel and Palestine you have
Skhul and Qafzeh caves. Humming with the activity of homo sapiens. Groups like these were probably
hunting and fishing along the shores of an ancient lake, now the Nefud desert in Saudi Arabia.
Leaving behind nothing but their footprints. North and east in modern Iraq and Iran
neanderthals are making their home in Shanidar cave and the Zagros Mountains. Hunting
wild goats, which can't have been easy, for sure. Further east in the mountains of Uzbekistan, Teshik Tash cave became the final resting
place of this young Neanderthal child. To the north of here neanderthals and
denisovans occupied Denisova cave, sometimes on their own sometimes
together evolutionary cousins raising hybrid families. Though they almost
certainly didn't think about it like that, I would bet. Denisovans lived further east too,
according to the proteins recovered from this jaw found in Baishiya Karst cave. Breathing
in the thin air of the Tibetan plateau. In warmer climates though, tucked away on the
island of java, Homo erectus was still living along the Solo River. No doubt living a similar
life to their ancestors who entered the region well over a million years before. Probably unaware
that they were just over the seas from two other groups of hominin, Homo floresiensis and Homo
luazonensis, from Flores and Luzon respectively. As you can see this is a really incredible
moment in the evolution of our species, there's just so much going on, so
many different forms of hominin leading slightly different lives in in
different regions, all Around the World. In between all of these finds, all these
various forms of ancient human sits South Asia. Modern India, Pakistan, Nepal,
Bangladesh, Sri Lanka. So who lived there? For the past three months I've
been working away at this problem, reading paper after paper, interviewing experts
from different fields, and uh it's complicated, it's really complicated. I think South Asia
is often sidelined in discussions of human evolution. For some reason it just doesn't
get the same attention as Africa or Europe or southeast Asia but I have come to believe that
it is in many ways the most interesting region. A region that gives us a real insight into just
how messy and convoluted human evolution was. Obviously the first line of evidence we
have when we're trying to discuss who was living in a specific region, what kind of
human, what kind of hominin are the fossils, the literal remains of humans that
lived in that place in that time, and this is what makes studying
South Asia so challenging. Hominins have lived in the region for probably
two million years, maybe even 2.6 million years and yet from that early time down through
to when modern Homo sapiens arrived. We only have one cranium, one fossil. The
Narmada cranium. Fortunately for me and this video I got to chat to Professor
Sheela Athreya who's studied it in depth. [Stefan] okay let me share
my screen here so we can see, so yep, so who is this who are we looking at here? [Sheela] We are looking at a hominin
from the pleistocene in central India and those are the three most definitive
things that I can say about it. [Stefan narration] At 1300 kilometers long
the Narmada is India's fifth longest river. The source of the River springs from the
ground at the Narmada Kund temple in Madhya Pradesh before winding its way down through
the mountains, into the state of Gujarat, and out into the Indian Ocean. On December
5th 1982, outside the village of Hathnora, Arun Sonakia unearthed the only archaic human
remains found in South Asia. Unfortunately the skull was found in a secondary deposit which
means the river had washed it away from its original location and deposited it elsewhere, so
it's been removed from its original context and as a result the date range for this skull is really
quite broad, between 46 and 236,000 years old. [Stefan] Even though it's the only fossil
that we have, it's a sample size of one, I think we are fortunate it does
seem to be a really interesting fossil though there does seem
to be a lot going on with it. [Sheela] Yeah that's definitely fair to say. I
mean one of the uh the first morphometric study of it that, you know, did a complete statistical
multivariate statistical analysis of the specimen by Kenneth Kennedy at Cornell University,
demonstrated that it has one of the highest cranial heights and that's measured from the
base of the cranium at a point called basion at the back of the foramen magnum, up to the top
of the cranium. It has one of the highest basion bregma heights, so one of the highest crania
of, if it's a homo erectus of homo erectus, it's outside the range actually. But at the same
time you can see it has a very sloping frontal bone behind those big brow ridges and it has um a
very rounded kind of angular back of the cranium. So living humans have a more vertical back of
the cranium and that's what makes our skulls look so round and this one, even though it's
got very rounded features at the top which do make it seem globular, at the back it's still
angular which is more like Homo erectus. This individual is inferred to be a female but that's
that's based on a limited reference sample, it is assuming that there are more robust individuals
out there and then this is less robust. [Stefan narration] The cranial capacity is also
within the range of modern humans, the average of different estimates works out to about 1288 cubic
centimeters which is basically the average for a modern woman now. So where does narmada fit on our
evolutionary tree, approximately, you know these things are nuanced but where approximately
does it fit on our evolutionary tree? [Sheela] If we treat treat the African Homo
erectus as one group and we treat the Asian Homo erectus as a completely separate group and the
Europeans as a third group, Narmada is not typical of any of them. But it's not so different that we
want to come up with yet another species name, and so when the analyses are run that both the African
and Asian specimens from a certain time period are called Homo erectus, Narmada the fits right,
in it has some African and some Asian features. [James] But also just thinking about
how how you might have interactions between adjacent populations South Asia is
kind of interesting, because to the West it can get cut off during arid phases
because the deserts. It's very difficult to move east west. On the Eastern
side you've got the other problem, you've got some of the wettest landscapes in
the world and when they get wetter that must be very difficult, you've got mountainous
really humid forest to try and traverse, but those areas might be accessible during more
arid phases. So you've got this pulse , when you know when you might have interactions from either
side and that could fit well with what Sheela would suggest of that oh actually you've got
some some Western contact some Eastern contact. [Stefan] What do you think that says about
South Asia's position in our human evolution? [Sheela] You know the title of the paper I
think South Asia was a geographic crossroads the other thing I think it says is more
about how we partition variation. And so if we partition variation based on the
geographic um you know, things that are very geographically disparate. We're going
to say lo and behold they are very different and if you ignore all the all the population
areas, so South Asia and Central Asia, um then your you know your models are obviously
lacking something but you're also missing the point of what we're supposed to be studying
which is how did humans vary in the past, I think that's what we're supposed to be
studying, I don't think we're supposed to be asking how many categories were there
in the past. What we should be asking, what is interesting to ask, if we really want
to understand the evolutionary history of humans isn't the labels again, it's the processes
what are that evolutionary processes that are shaping us, right? To me that's more
fascinating. I would love to know what environmental and climatic factors, maybe even
technological factors, raw material availability, subsistence patterns, what were the things that
were shaping these populations in the past? [Stefan] So there we go, the only human cranium
from the middle pleistocene in South Asia really shows it to be a bridge between two groups of
distant hominins, what's going on in Africa, what's going on in in East Asia. It's
mix of features East and West, modern, archaic really resists an easy classification and
that's probably the point we should be taking away from it. Whoever lived in South Asia during the
middle pleistocene was really at a crossroads both in in time and geography. They're
going to be influenced by a lot of factors, some of them external but also some of them
internal, this was no evolutionary dead end. With only one fossil we have to look elsewhere
for Clues as to what was going down in South Asia. Naturally, this being the Stone Age we're
going to look at stone tools. Now assigning stone tools to a particular hominin in
the absence of fossils is really tough, absolutely fraught with nuance but we
can paint with some really broad strokes. In this middle Pleistocene there are two
families of tools that really stand out. The first are Achulean stone tools,
the absolute classic achelean artifact are these large bifacial hand axes,
but they did also produce cleavers, they did also use flakes, but the
hand axe is really characteristic. Early examples start to appear around
1.75 million years ago in Africa and are associated with the evolution of bigger
brained hominins like Homo erectus and later homo heidalbergensis. That's family
number one, that's the Acheulean. The next family of stone tools the next
development occurred between 400 and 200,000 years ago these are called middle Paleolithic
tools. The idea here is that now flakes are the star of the show. The knapper would create
a striking platform on the bottom of the rock, they would then shape the core to create the
outline of a tool, then with one precise bosh the perfectly shaped flake is removed and now
you have your spear point or whatever you wanted. Archaeologists call this the levallois
technique and it's associated with the evolution of homo sapiens, neanderthals
and denisovans. Multiple groups used them. These changes may seem kind of small to
us but as archaeologist Gopesh Jah and James Blinkhorn will explain, these are legit
technological breakthroughs, no doubt about it. [James] To explain and particularly
this shift from Acheulean technology to accomplish levallois and middle politic
technology. Acheulean tools are bifaces, you can imagine it a bit more like a sculpture,
in that you start off your block of marble, you chip things away until you realize this is
the shape that I wanted in the end. Whereas, you're doing a lot of that shaping of levallois
technology but then you've got this one final strike which is make or break it, into the thing
that you're you've been preparing towards. So it's cognitively more complex to do that, you've got to
think the steps in advance and all the different parameters you can control, but it gives you a lot
more control of the shape and size of the flake that you're removing. Presumably because that's
desirable for the tool that you want to make. [Gopesh] and throughout the middle pleistocene
you have so many industries where people are shifting from this heavy tools to the lighter
tools, and that may have something to do with localized adaptation. Like when there is a
huge scarcity of resources, I don't want to travel with these huge artifacts. I I want to
be more efficient in terms of adaptation and hence I rather focus on these smaller flakes than
these heavy artifacts and these smaller flakes can be of an amount of types like that made in
different technique, this and that, this and that. [Stefan] Okay let's look at some South Asian stone
tools. These are stone tools from Attirampakkam, these are argued to be middle Paleolithic tools,
those levallois stone tools. These are cores that have had flakes removed. In the middle here we've
got these levallois points and at the bottom here we've still got some hand axes being produced.
What's so tantalizing about Attirampakkam is that the oldest layer where these stone tools have
been excavated dates to 385,000 years ago which is extremely old. Making it one of the oldest
middle Paleolithic sites in the entire world, maybe even the oldest middle Paleolithic site in
the entire world. These are some more stone tools from slightly further north in Andhra Pradesh,
apologies for almost certainly saying that wrong. Again here we've got some cores here, G and H
some levallois points. C, D, E and F are again hand axes, that tradition is still going on here.
Quick note here though, notice how E and F are very small hand axes, that's going to be important
later. These all date to 247,000 years ago. So there you go we have very early
levallois technology in South Asia probably made by a hominin that was
like us Homo sapiens, like neanderthals, like denisovans. The hard thing is without human
remains we can't really say much more than that. [James] There's absolutely no reason why,
you know, the middle middle pleistocene homo population that we've got at Narmada is
broadly similar to Neanderthals to denisovans, and to my mind probably not that different from
Homo sapiens either. So probably under the right circumstances would have would be in a position
to innovate similar sorts of technologies. [Stefan narration] As you can see though
these industries are kind of transitional there's still some Acheulean tools being
produced alongside middle Paleolithic tools. This suggests that this is really a local
innovation, independent innovation going on down here in South Asia. But how long that
transition lasted and the factors influencing it is uh subject to huge debate because the
picture is actually even more complicated. [Stefan] Do the Acheulean and the middle
Paleolithic overlap for a long time in South Asia? [James] Yeah, yeah that's one of the key areas
where South Asia is really quite weird. It's got the youngest Acheulean industries in the
world. So in East Eastern Africa it's at Mieso around 214,000 years ago is the youngest latest
Acheulean there. In Arabia you see something slightly younger around Dawadmi it's 170, 180
uh. At Bamburi and Patpara in the middle of Son Valley uh, which is in central India, you're
dating to 140 to 120,000 years ago. So that's, you know a hundred thousand years ago
after it's disappeared from Eastern Africa. [Stefan Narration] So we have a site
with the earliest examples of middle Paleolithic technology, other sites
with the youngest examples of Acheulean technology. What kind of forces
could have driven this variation ? [James] So and I think one of the things that
kind of muddies this issue and even, again I'll probably refer quite a lot to Eastern Africa
here but actually even in the young Acheulean, like some of the most recent Acheulean in Eastern
Africa you find the appearance of levallois Technology, this key key aspect of the middle
paleolithic, but often in low frequencies compared to this focus on bifacial technology which is
still the dominant aspect of the assemblage. At some point that's that switches, so it's not just,
it's not always just a presence or absence sort of argument is my point. Sometimes it's proportional
with reference to the assemblage that it's in. [Stefan narration] The existence of
these two technologies alongside each other for such a long time is challenging though. [James] and this is where the findings from
Attirampakkam kind of jar with that otherwise quite simple model as it's suggesting that
there's perhaps within the region what 250,000 years of overlap between Acheulean technology
and middle paleolithic technology yeah um [Stefan] which is just such a colossal,
it's easy to get lost in the numbers, but that's such a colossal amount of time. [James] I mean uh it's almost as long as we
would, you know, recognize our species to exist, existed for, that there could have
been this overlap, which is is huge and it I find it difficult, I
find that difficult to explain. [Stefan narration] My first instinct upon
learning that there was two different technological traditions surviving
for a long time alongside each other was that there was multiple
different hominins producing them. [James] I don't see the immediate need to jump
that they must be different populations doing that. um I think that's partly because, you
know, without either genetics or some fossils to go on we can keep on populating with more and
more different hominins if we like. So for me, it's why was it happening down on the south
east, and why didn't it spread elsewhere and that's that question of was it a was it really
an enduring thing, that always persisted there or was it momentary and related
to some very specific conditions? [Stefan narration] Climate
and environment obviously two huge factors that could have played a role. [Gopesh] So India or South Asia comes under
this school called oriental z,one Oriental okay which is which has just so many pockets of natural
resources which are evergreen, okay. In a way like even when there's certain kind of a table turning
environmental shift is happening around the globe, becoming super arid conditions but you always
have these pockets which can support hominin populations and India has, not India I would say
south Asia, has multiple set of these pockets. We are not traveling for sake of traveling, we
are traveling in search of resources or better habitats but when you have one which supports
your needs, which nourishes you, caters you what you seek, which you don't need to go far off
regions. You can be or you can build that cocoon or ecological cocoon where you grow and grow
and grow and does not have to be in contact. [Stefan narration]as I said at the start Homo
erectus was still around at this time one hundred thousand years ago on Java. But that's sort of
easy to explain because Java is so tucked away on the southeast of Eurasia. It wasn't an island
at this time but it's still extremely remote, extremely mountainous region. So their survival
in that area is sort of simple to explain in a way. But explaining the Persistence of Acheulean
technologies in South Asia uh is more difficult. [James] uh because when you note 250,000 years
of overlap or potential overlap between middle paleolithic in the southeast and late Acheulean in
kind of north and west, what was separating them? Even after the disappearance
of Acheulean it doesn't get any easier to untangle what's going on.
Archaeologist Praveen Kumar talked me through some of the most important sites at
this time one hundred thousand years ago. [Praveen] That is the middle Son valley,
right now I'm working in this area, this eastern part of the India. [Stefan narration] Sites like Sandhav, which has
pretty good evidence of a homo sapiens population. [Praveen] it's an interesting Discovery
from the Sandhav because tanged point is in Africa North Africa, Aterian points
are actually associated with modern humans. [Stefan narration] The tanged points
that Praveen and others excavated here at Sandhav called Aterian points are
especially interesting because at the same time they're found across North
Africa and are associated with modern Homo sapiens. Could this population also have
been present at the same time in South Asia? [Praveen] Yeah so in in Western India
and coastal region this time discovery of this tanged point uh a date, the date
of this tanged point is very interesting. So this tanged point is byproduct of modern
human? I I don't know it's it's big question? [Stefan narration] This point is great
evidence of homo sapiens in South Asia at that time but at other locations middle
Paleolithic assemblages still have small diminutive bifaces, just like the ones from
Andhra Pradesh that was 247,000 years old. The youngest of these diminutive bifaces was found just down the road from Sandhav
and dates to 69,000 years old. [Gopesh] it's 69 kilo years [Stefan]oh wow that's really young [Gopesh] 1.5 to 69. yeah that's
what we are talking about. [Stefan]damn. I think the real archeology nerds in my
audience out here can see why this region is so interesting. At every single step
it just forbids us from forming any simple conclusion. It's like oh we have Aterian
points so homo sapiens are in the region, right? Well maybe but somebody's also
still producing bifaces and they're found alongside middle Paleolithic tools. It's just
a it's just so complex, I absolutely love it. There's probably only one technology which is really going to help us get to
grips with all this diversity. Okay this paper is what started my whole obsession
my whole South Asian rabbit hole, deep dive, 'Using hominin integration to trace modern human
dispersals'. Basically using evidence of archaic genetics in modern populations, modern Asian
and Oceanian populations to try and peel back history a little bit and and understand
what was going on deep in pre-history. I reached out to Joao Teixeira
author of the paper to learn more. [Joao] The paper we wrote was essentially
focusing, or the idea was to focus on Island Southeast Asia. When we, when we try to unpack
sort of the signals of Archaic introgression in island southeast Asia we realized, we just have
to, you know, pull the movie backwards and sort of like look of what what was happening before,
to try to fit it all together and one thing that I want to make clear is that there's a myriad
of alternative models that could explain the data and we have to sort of combine the pieces
that we find with models that make sense from an archaeological point of view. Because this
is a perspectives paper it's really taking other people's work and sort of combine
different lines of evidence to sort of make, try and make a cohesive you know view. But I
mean it's mostly going to be wrong. Probably somebody's gonna show us that they're very wrong
in maybe you know, one year or two years but for now I would say most things that are there
genetically, I think they're they're holding. [Stefan] As you can see from all of those
caveats the picture is very complex, but the clues that geneticists have
unearthed are really intriguing. [Joao] There are a couple of papers that had come
out just before we wrote our paper, one of them by Browning et al in in cell provided evidence
for two episodes of admixture with Denisovans, uh and the way they saw this or the
way they infer these two episodes is that the the admixing Denisovan
populations were genetically distinct. So they found that mixture with like a
high affinity population to the altai genome, right? From the fossil or from the
pinky finger. But we yeah but they also found evidence for a more distant sort of real
distantly related Denisovan like group which they reported in Australopapuans, so people from
New Guinea and Australia, but also South Asians, Gujarati you know Punjab. Okay so that's one
paper, and then another paper tried to model Neanderthal and Denisovan admixture with modern
humans using multiple demographic modelling and deep learning and so they tested like different
plausible scenarios given what we know, more or less, you know with these processes
or like sort of limiting to a decent amount of models that would would be plausible, and they
they found support for two distinct models which both included admixture from a group which was
equidistant between neanderthals and denisovans, in the ancestors of South Asians,
East Asians and Australopapuans. So you can imagine as that sort of
radiation of modern humans went East in Eurasia and before they split they sort of
received this genetic input from a population that sort of, you know, was genetically
in between neanderthals and Denisovans. [Stefan narration] So there you have it, possible
genetic signals of a denisovan-like population or something in between a denisovan and a
neanderthal, equally related to those groups. They gave this group The placeholder name extinct
hominin one and based on the modern populations that have this admixture they propose that extinct
hominin one lived in the region of of South Asia, everyone east of that point seems to have uh that
genetic signal. So that makes a lot of sense . When we consider South Asia's position
geographically it does sit right in between where we know neanderthals are living, where we know
denisovans are living. So some population that is is related to both is entirely plausible. It's
entirely plausible that extinct hominin one was making those tools in South Asia, though obviously
we do have to interpret these results cautiously. [Joao] But now people move. [Stefan] yeah [Joao] So we're most likely wrong, but what I
think it's important is that yes that that is possible that some of the the these mixing events
that we're detecting are not necessarily like from these discrete groups from which we have
like sort of a couple of genomes or a handful of Neanderthals, but it's there's more to it
than this. It gets more reticulated than that, and we need, Now is that a fossil group that's
going to correspond to that? Maybe, maybe not. What this really shows is that neanderthals
and denisvans are not really a separate species they're like two points on a spectrum
and in between those two points is obviously going to be a group that is related to both
of them and that group may well have lived in South Asia, that group may well have been
producing these middle Paleolithic tools. I've had to come for a walk to process all
my thoughts about this issue. This has been the hardest video I've ever had to make, bar none.
You can see how long it's taken me by how often my facial has changed, how often the background's
changed. I've tried to maintain a consistent facial hair for the whole time and absolutely
failed. Every time I tried to create like a simple but but honest narrative about
what was going on in South Asia, I failed, I absolutely failed. I couldn't construct
all of this information into a simple tale and I realized that's because what makes South
Asia so special is the complexity. Sometimes we can get so focused on what a neanderthal is
doing, what were Homo sapiens doing, what was Homo erectus doing blah blah blah blah. We focus
in on one group doing something at one particular time and it sort of creates this false impression
in our mind that these were truly distinct groups. When we study South Asia, when we study the
literal geographic bridge between all of these populations we can see human evolution
for the truly complex Beast that it was. From the Narmada cranium which is archaic and
modern and like Homo sapiens and like Homo erectus, and to the tools where the transition
from Acheulean to Middle Paleolithic is so drawn out over hundreds of thousands of years. DNA
evidence of admixture with a population that isn't a neanderthal or a denisovans,
something in between these two groups, you know. With South Asia there's no
easy answers, there's no simple models, you have to confront the reality of evolution the
complexity of evolution, there's no way around it. There's absolutely no line of evidence
will provide you with a simple conclusion. It's incredible, I love it, it's
fantastic. Imagine what we're gonna learn in 20 years more studying this
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