The Incredible Human Journey

377 Pages·2009·5.38 MB·English

by  Dr Alice Roberts

To Jonathan Musgrave and Kate Robson-Brown,
wise friends and mentors
Contents
Introduction
1 African Origins
Meeting Modern-Day Hunter-Gatherers: Nhoma, Namibia
African Genes: Cape Town, South Africa
The Earliest Remains of Our Species: Omo, Ethiopia
Modern Human Behaviour: Pinnacle Point, South Africa
The First Exodus: Skhul, Israel
An Arabian Mystery: Oman
2 Footprints of the Ancestors: From India to Australia
Archaeology in the Ashes: Jwalapuram, India
Hunter-Gatherers and Genes in the Rainforest: Lenggong, Perak, Malaysia
Headhunting an Ancient Skull: Niah Cave, Borneo
The Hobbit: Flores, Indonesia
A Stone Age Voyage: Lombok to Sumbawa, Indonesia
Footprints and Fossils: Willandra Lakes, Australia
Art in the Landscape: Gunbalanya (Oenpelli), Northern Territory, Australia
3 Reindeer to Rice: The Peopling of North and East Asia
Trekking Inland: Routes into Central Asia
On the Trail of Ice Age Siberians: St Petersburg, Russia
Meeting with the Reindeer Herders of the North: Olenek, Siberia
The Riddle of Peking Man: Beijing, China
An Archaeological Puzzle: Zhujiatun, China
East Asian Genes to the Rescue: Shanghai, China
Pottery and Rice: Guilin and Long Ji, China
4 The Wild West: The Colonisation of Europe
On the Way to Europe: Modern Humans in the Levant and Turkey
Crossing the Water into Europe: the Bosphorus, Turkey
Face to Face with the First Modern European: Oase Cave, Romania
Neanderthal Skulls and Genes: Leipzig, Germany
Treasures of the Swabian Aurignacian: Vogelherd, Germany
Tracking Down the Last Neanderthals: Gibraltar
A Cultural Revolution: Dolni Vistonice, Czech Republic
Sheltering from the Cold: Abri Castanet, France
Visiting the Painted Caves: Lascaux, Pech Merle and Cougnac, France
New Age Mesopotamia: Göbekli Tepe, Turkey
5 The New World: Finding the First Americans
Bridging the Continents: Beringia
Mapping Native American Genes: Calgary, Canada
Exploring the Coastal Corridor: Vancouver, Canada
Finding Arlington Woman: Santa Rosa Island, California
Hunting American Megafauna: La Brea Tar Pits, Los Angeles
Clovis Culture: Gault, Texas
Meeting Luzia: Rio, Brazil
Ancient Hunter-Gatherers in the Amazon Forest: Pedra Pintada, Brazil
Black Soil and Revelations: Monte Verde, Chile
Journey’s End
References
Acknowledgements
A NOTE ON THE AUTHOR
Try to imagine the world in which humans have lived for the overwhelming
majority of our existence, a world without cities, settled villages, or even
permanent residences, a world without farmed fields and crops, without
possessions larger than those which we could easily carry with us, and with
everything we needed in daily life – all of our tools, weapons and clothing –
produced by ourselves or by those within our small social bands. We did not
grow food or have others grow it for us, but instead exclusively relied upon
our own knowledge of the surrounding natural environment to survive,
foraging for plant foods and scavenging, hunting or fishing for meat.1
D. J. Cohen
Introduction
We are very familiar with the idea that humans are everywhere; that wherever
you go in the world you will probably find people there already. We are an
unusual species in that we have a near-global distribution. And although people
around the world may look quite different from each other, and speak different
languages, they can nevertheless recognise each other as distant cousins.
But where and when did our species first appear? What are the essential
characteristics of our species? And how did people end up being everywhere?
These are rephrasings of fundamental questions. Who are we? What does it
mean to be human? Where do we come from? For thousands of years, such
questions have been explored through philosophy and religion, but the answers
now seem to lie firmly within the grasp of an empirical approach to the world
and our place within it. By peering deep into our past and dragging clues out into
the light, science can now provide us with some of the answers to the questions
that people have always asked.
They are questions that have always captivated me. As a medical doctor and
anatomist (I lecture in anatomy on the medical course at Bristol University), I
am fascinated by the structure and function of the human body, and the
similarities and differences between us and other animals. We are certainly apes;
our anatomy is incredibly similar to that of our nearest relations, chimpanzees. I
could put a chimpanzee arm bone, or humerus, in an exam for medical students
and they wouldn’t even notice that it wasn’t human.
But there are obviously things that mark us out – not as special creations, but
as a species of African ape that has, quite serendipitously, evolved in ways that
enabled our ancestors to survive, thrive and expand across the whole world.
There are aspects of anatomy that are entirely unique to us; unlike our arms, our
spines, pelvis and legs are very different from those of our chimp cousins, and no
one would mistake a human skull for that of another African ape. It’s a very
distinctive shape, not least because we have such enormous brains for the size of
our bodies. And we use our big brains in ways that no other species appears to.
Unlike our closest ape cousins, we make tools and manipulate our
environments to an extent that no other animal does. Although our species
evolved in tropical Africa, this ability to control the interface between us and our
surroundings means that we are not limited to a particular environment. We can
reach and survive in places that should seem quite alien to an African ape. We
have very little in the way of fur, but we can create coverings for our bodies that
help to keep us cool in very hot climates and warm in freezing temperatures. We
make shelters and use fire for warmth and protection. Through planning and
ingenuity, we create things that can carry us across rivers and even oceans. We
communicate, not just through complicated spoken languages but through
objects and symbols that allow us to create complex societies and pass on
information from generation to generation, down the ages. When did these
particular attributes appear? This is a key question for anyone seeking to define
our species – and to track the presence of our ancestors through the traces of
their behaviour.
The amazing thing is – it is possible to find those traces, those faint echoes of
our ancestors from thousands and thousands of years ago. Sometimes it could be
an ancient hearth, perhaps a stone tool, that shows us where and how our
forebears lived. Occasionally we find human remains – preserved bones or
fossils that have somehow avoided the processes of rot and decay and
fragmentation to be found by distant descendants grubbing around in caves and
holes in the ground, in search of the ancestors.
I’ve always been intrigued by this search, by the history that can be
reconstructed from the few clues that have been left behind. And at this point in
time, we are very lucky to have evidence emerging from several different fields
of science, coming together to provide us with a compelling story, with a better
understanding of our real past than any humans have ever had before. From the
study of bones, stones and the genes within our living bodies comes the evidence
of our ancestors, of who we are, of where we came from – and of how we ended
up all over the world.
When the BBC offered me the opportunity to follow in the footsteps of the
ancients, to delve into the past, to meet people, see artefacts and fossils for
myself and visit the places that seem most sacred to those searching for real
meanings, I couldn’t wait to get started. I took a year off from teaching anatomy
and looking at medieval bones in the lab, and set off on a worldwide journey in
search of our ancestors.
The Human Family Tree
My journey would take me all around the world, starting in Africa and then
following in the footsteps of our ancestors into Asia and around the Indian
coastline, all the way to Australia, north into Europe and Siberia, and, eventually,
to the last continents to be peopled: the Americas.
Modern humans are just the latest in a long line of two-legged apes,
technically known as hominins. We’ve grown used to thinking of ourselves as
rather special, and a quick glance at the human family tree shows us that we’re
in a rather unusual position at the moment, being (as far as we know) the only
hominin species alive on the planet. Going back into prehistory, the family tree is
quite bushy, and there were often several species knocking around at the same
time. By 30,000 years ago, it seems there were only two twigs left on the
hominin family tree: modern humans and our close cousins, the Neanderthals.
Today, only we remain.
The ancestral home of hominins is Africa, although some species, including
our own, have made it out into other continents at various times. Whether we
actually met up with our ‘cousins’ on our ancient wanderings is something I’ll be
investigating in this book. Certainly, it seems that there was some overlap in
Europe, and that for a good few thousand years modern humans and
Neanderthals were sharing the continent.
It may sound strange but it’s actually quite difficult to know exactly how many
different species of ancient hominins there were. It’s something that prompts a
huge amount of debate. The world of palaeontology – the branch of science that
peers into the past to examine extinct and fossil species – is inhabited by
‘lumpers’ and ‘splitters’. Lumpers use very wide definitions of species to group
lots of fossils together under one species name. Splitters, as the term suggests,
divide them up into lots of different species. But which group is right? It’s hard
to know, and this is one of the debates that enlivens this science. Both lumpers
and splitters are looking at the same evidence – but making different
interpretations.
Trying to decide if two populations really are different enough from each
other to be labelled as separate species is more difficult than it seems. Some
species can even interbreed and produce fertile, hybrid offspring. But, basically,
species are populations that are diagnosably different from each other, in terms
of their genes or their morphology (the way their bodies are constructed) – or
both.
With long-dead fossil animals, all palaeontologists have to go on is the
skeleton, and sometimes only fragments of bones. So the problem of species
definition becomes even more difficult. Looking at the skeletons of living
animals, they can get an idea of the range of morphological variation in a species
(because, even within a species, animals come in a variety of shapes and sizes).
They can also measure the level of morphological difference between species.
This gives them a benchmark for how similar skeletons are within a species, and
how different they need to be to be classed as separate species. Then the
palaeontologist can apply that standard to sort fossil animals into species. It’s a
knotty problem, and it’s not really that surprising that different palaeontologists,
each of whom may have spent a lifetime studying the fossils, can reach different
conclusions.
Indeed, some palaeontologists shy away from talking about ancient ‘species’
at all. The eminent physical anthropologist William White Howells suggested we
call these groupings ‘palaeodemes’ (‘ancient populations’) instead. But we can
recognise evolving lineages in the fossil record, and giving distinct populations a
genus (e.g. Homo) and species (e.g. sapiens) name provides a useful handle and
helps when we’re trying to reconstruct family trees.1
Within palaeoanthropology, the discipline that looks at fossil hominins in
particular, taxonomies range from extreme lumping, with some researchers
calling all hominins from the last million years Homo sapiens, to extreme
splitting, with other scientists finding room for eight or more species. Chris
Stringer, palaeoanthropologist at the Natural History Museum in London, has
recognised four species during and since the Pleistocene (in the last 1.8 million
years): Homo erectus, Homo heidelbergensis (the putative common ancestor of
modern humans and Neanderthals), Homo sapiens and Homo neanderthalensis,2
although the recent discovery of the tiny ‘Hobbit’ skeletons in Indonesia requires
us to make room for Homo floresiensis as well.
Throughout this book I use the word ‘human’ in an inclusive but nevertheless
precise sense to mean any species in the genus Homo, whereas ‘modern human’
refers to our own species, Homo sapiens. In the same way, ‘Neanderthals’ are
Homo neanderthalensis.
Each one of these human species made it out of Africa, to Eurasia. Homo
erectus got all the way to Java and China by about one million years ago. About
800,000 years ago, another lineage formed and expanded: Homo heidelbergensis
fossils have been found in Africa and Europe. The European branch of this
population went on to give rise to Neanderthals, about 300,000 years ago.
Modern humans sprang from the African population, some around 200,000 years
ago – and their descendants spread across the globe.