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KATANDA, ON THE BANKS of Africa's Semliki River, seems an unlikely place for a great civilisation. It's a sleepy, unspoiled spot where hippos cool themselves in the muddy waters.
Yet archaeologists have discovered that this remote part of the Democratic Republic of Congo was once home to a flourishing society. Men and women made elegant bone harpoons, knives, fish hooks and other finely carved tools; trawled for catfish during the spawning season; and constructed homes along the river bank.
That is intriguing enough. But Katanda holds an even greater secret. Research carried out here, and at other newly discovered African sites, has revealed startling evidence about the nature of our species and the roots of its inventiveness, not long after its emergence from sub-Saharan Africa.
These studies show that Homo sapiens displayed profound intellectual and cultural gifts far earlier than experts had realised.
A hundred thousand years ago, we had already evolved complex language which helped hold large tribes together; used symbols to express ourselves artistically; and created sophisticated tools - new weapons, special fish hooks and other implements - to boost hunting and the gathering of food. Human inventiveness, it turns out, is a far more ancient quality than previously supposed.
And just as well, for at this time Africa's climate underwent a series of paroxysms that triggered catastrophic alterations to the environment. Deserts spread, forests vanished and human populations plummeted. We hung on, but only just, thanks to the flexibility our newly evolved intellect allowed.
Our distant past was really a battle of brains versus climate. And for evidence we need to look no further than Katanda.
Consider those elegantly carved harpoons, discovered in 1988 by the American husband-and-wife team Alison Brooks and John Yellen. When tested, these were found to be more than 80,000 years old - a level of antiquity that caused considerable surprise.
Until then the world's oldest harpoon, found in Europe, had been dated as being a mere 25,000 years old. It was "as if a Pontiac car had been found in the attic of Leonardo da Vinci," as one observer put it.
Nevertheless the dating is correct, insists Brooks, an archaeologist based at George Washington University in Washington DC. "We have tested those implements in many different ways and we get a consistent result. We think they still are more than 80,000 years old."
This antiquity is significant; for it indicates humans were capable of sophisticated thinking from the moment they appeared on the African savannah (see box at end of article).
"Until relatively recently, scientists have argued that humans went through further recent changes to the wiring of their brains and continued to evolve intellectually long after they left Africa," adds Brooks. "Our work indicates those ideas are wrong. A hundred thousand years ago, humans were identical, mentally, to men and women today."
It is a controversial proposal but it has powerful support - supplied by archaeologists and palaeontologists who have poured into southern Africa with the fall of apartheid.
For example, at Ntolana Tsoana in Lesotho, a group led by Peter Mitchell, professor of African archaeology at the University of Oxford in England, has excavated 60,000-year old razor-sharp points, called Howieson Poort tools. Made from the mineral opaline, these appear to have been used for butchery, as spearheads, and possibly even arrows - a truly sensational idea.
"It was thought the bow and arrow was invented 10,000 years ago in Europe," said Mitchell, but here in this remote part of Africa there is compelling evidence that archery was practised 60,000 years ago.
And there is more. At Blombos Cave, over 300 km east of Cape Town, an excavation directed by Chris Henshilwood of the University of the Witwatersrand in Johannesburg, South Africa, has uncovered pieces of ochre, a form of iron ore whose surfaces have been carefully smoothed and covered with cross-hatched lines to create complex geometric patterns.
Dated at more than 70,000 years old, these are humankind's oldest pieces of art and are twice the age of previous works found in southern France, indicating that humans had clearly evolved the power to think abstractly and symbolically in those distant days.
In addition, Henshilwood's team has dug up dozens of shells of the tiny snail Nassarius kraussianus. Each has a hole drilled through its centre, suggesting a very clear use as beads on a necklace. Intriguingly, traces on these shells suggest they may have lain against skin painted with red ochre, a body pigment still used in Africa.
It is a striking assembly of talent -art, harpoons, fish hooks, jewellery - indicating that, 100,000 years ago, Homo sapiens possessed not only a modern anatomy but behaviour that was relatively comparable with people today. "It is clear that African people, from whom we are all descended, were modern in their behaviour long before they got to Europe and replaced Neanderthals,'' says Henshilwood.
This point is critical. Only a decade ago, it was assumed Homo sapiens had continued to evolve mentally until around 40,000 years ago, after we had migrated from Africa, and had begun to take over Europe and Asia (see box at end of article). Only then did we reach our full intellectual potential.
Now this idea has been shown to be "Eurocentric nonsense", as Mitchell puts it. When humanity appeared on the savannahs of Africa, we were already armed with all the cultural, intellectual, symbol-using apparatus we have today.
This intriguing story raises two immediate questions: what factors led to the evolution of those powerful attributes and what was their direct impact? Let us turn to the first, more difficult question, a task that takes us to the very dawn of Homo sapiens.
Researchers are still searching for the precise place and time of our appearance, though tantalising results have been unearthed at the Ethiopian sites of Herto and Omo Kibish. There scientists have dug up pieces of modern human skeletons dated at 160,000 and 195,000 years respectively.
Palaeoclimatologists have also discovered that around 200,000 years ago a major, long-lasting drought affected most of sub-Saharan Africa, suggesting not just a date but also a causative agent for our evolution.
The resulting pressures on our hominid ancestors would have led to the development of abilities vital to our survival: complex language that allowed us to maintain ties with more individuals, for example. "We became a bit like bees or ants, with bigger and bigger social groupings with whom we could share resources,'' says Brooks.
Similarly, our growing resourcefulness would have provided new ways to gather food. Consider those Katanda harpoons again. They demonstrate the ingenuity of their makers first, in their delicate construction, and secondly, in their use to hunt catfish as they spawned, a behaviour called 'seasonal mapping', which implies knowledge, reasoning and anticipation and that was previously thought to typify only modern humans.
This takes us to our second question: what were the consequences of those skills that we developed? The short answer is that we thrived - but only in fits and starts. Around 70,000 years ago, Africa went through another climatic downturn, one that triggered droughts and famine and would have wiped out many communities. Around the same time, on the other side of the world, Mount Toba in Sumatra erupted.
The most powerful volcanic blast in two million years, it dusted a thick layer of vegetation-killing ash across the globe. Genetic evidence shows that the Homo sapiens population shrank to an alarming 1,000 individuals or fewer. We only just hung on; intellectual prowess being our saving grace.
"In the end, humans prevailed. We are here to tell the tale, after all," says archaeologist Steve Shennan, of University College London in Britain who has used complex mathematical models to estimate our fluctuating numbers in those times. "However, it is difficult to say whether that was due to the climate improving or whether inventions accumulated sufficiently to give us an edge that allowed us to turn the tide. Probably it was a bit of both."
Either way, the effect was dramatic. Humanity spread across Africa. Then, some 60,000 years ago, a group crossed the Mandab Strait to Asia in tiny boats, probably in search of new food sources. It was a monumental act.
Homo sapiens had left its home continent. Two thousand generations on, descendants of these African emigrants have settled our entire planet and reached a population of 6.5 billion.
That Red Sea crossing, arguably the greatest journey ever undertaken, is one of the key discoveries produced by the US$40 million (A$62 million) Genographic Project, backed by the National Geographic Society and IBM, which involves scientists collecting DNA samples from 250,000 volunteers from different continents to create a detailed map of humanity's great diaspora.
Instead of studying the bones and tools of the dead, these researchers are probing the blood of the living to unravel our past. To do this, they exploit two types of genetic material: mitochondrial DNA, which is passed down from mother to daughter, and the Y chromosome, which is inherited only through the male line.
Over the millennia, mutations build up in these DNA sequences. Scientists can work out when they first appeared and so trace the path of humanity as it carried these mutations through the Old World en route to global conquest.
"As the ultimate ancestor begat son, who begat son and so on, they picked up mutations in their DNA that we can now pinpoint by gene analysis," says geneticist Stephen Wells, leader of the Genographic Project based at the National Geographic Society in Washington DC. "When we look at these markers' distributions, we can see how our ancestors moved about."
The Genographic Project scientists have created a map of the routes taken by humankind on this great migration, one that resembles a global road map.
Consider the group whose descendants ended up in Australia. After emerging from Africa into the Arabian Peninsula, they travelled north on a route christened M-168 by project scientists, before taking route M-130 along the south Asian coast to reach Australia, arriving some 50,000 years ago.
In contrast, those whose descendants became Europeans and South Americans headed east on route M-9 across the steppes of central Asia and then headed north on the M-45.
Then, around 30,000 years ago, this group split. One cluster turned west on the M-173 and then the M-343 to emerge in Europe as the Cro-Magnons. The other headed east on M-242, across the land bridge that then connected Asia with America, and travelled south through North and South America on the M-3. In this way, the world was conquered.
We should note that these various markers - the European marker is known as the R1b haplogroup, for example - say nothing about the overall genetic make-up of Homo sapiens.
They merely tell people how their paternal or maternal ancestors reached their homeland. The question of the general genetic make-up of our species is important, nevertheless. Without knowing what is special about our DNA, we will never pinpoint the key evolutionary features that enabled our ancestors to survive the vicissitudes of African life 60,000 years ago and to triumph over several other hominid species.
To achieve that, we need two sets of information: a full data set of our genes and a comparison set from one of the groups of hominids who succumbed to the arrival of Homo sapiens 50,000 years ago.
Then, by locating those bits of DNA possessed by humans but not by the other species, and by examining the function of these pieces of genetic material, we may learn the secrets of global success.
Of course, we already possess one of these data sets. In 2003, scientists of the Human Genome Project published the first complete genetic sequence of a human being. Equally importantly, geneticists are also homing in on the sequence of another hominid species: the Neanderthals.
This remarkable project is housed in the huge glass and concrete Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany.
Against one wall of its central concourse a four-storey climbing wall has been erected while at its foot, someone has placed a baby grand piano. And nearby, in the staff restaurant, huge screens beam live TV pictures of chimpanzees grooming and playing at nearby Leipzig Zoo.
"We are encouraged to breakfast, lunch and dine here and to swap ideas," explains renowned geneticist Svante Pääbo. "Hence the piano, climbing wall and the other amusements. We need to take our minds off things occasionally."
And researchers at the institute certainly have had a lot on their minds, for they have just put the finishing touches to a program in which Pääbo and colleagues have analysed DNA from Neanderthal skeletons found at a site, called Vindija Cave in Croatia, and used it to sequence an entire draft genome of those ancient rivals of our own species.
Announced at the 2009 annual meeting of the American Association for the Advancement of Science (AAAS), in Chicago in February, the Leipzig team's achievement has been hailed as an amazing advance in evolutionary science.
As Pääbo put it: "Now that we have the Neanderthal genome, we can look for areas in the human genome where a change seems to have swept rapidly through us since we separated from the Neanderthals. There, something special may have happened to us. The cool thing is, now that we have the whole genome, we can look for these changes without bias."
Neanderthals and humans diverged from a common ancestor about 500,000 years ago, according to a preliminary examination of Pääbo's results, which also indicate that the ability to speak complex languages was shared by both species.
A gene known as FOXP2 is involved in regulating speech and language centres in the human brain. Crucially, Pääbo has found that Neanderthals also possessed the same variations in this gene as Homo sapiens. "There is no reason to believe that they could not speak like us," adds Pääbo. "However, there are many other genes involved in speech
and language, so there are many more studies to be done."
The project has not yet had time to produce major breakthroughs in our understanding of these mysterious folk, or to reveal new insights into our own intellectual development. So far we have only had tantalising hints.
However, science has been supplied with the means to make those discoveries in the near future. The next decade promises to be an extraordinarily exciting time for studying human evolution, although Pääbo is quick to pour cold water on one prospect: that the sequencing of the Neanderthal genome implies we may also be able to clone it in the near future. "We are talking about a very complex animal. I don't think technology will improve fast enough to make this possible in my lifetime. It is more in the realm of science fiction."
Out of Africa
TWO MAJOR THEORIES compete as explanations for humanity's spread across the globe: the Out of Africa theory and Multi-regionalism. The former suggests our African roots are recent. The latter argues they are ancient and deep and maintains that an even earlier species of humans - known as Homo erectus, a tall, athletic species of hominid with modestly sized brains - left Africa around one million years ago. Across the Old World, its members evolved into various species - such as the Neanderthals in Europe - and then later into the various races of modern humans. For their part, followers of the Out of Africa accept that Homo erectus emerged from Africa more than one million years ago but maintain that around 200,000 years ago, a second hominid species - large-brained Homo sapiens - appeared in Africa and, around 60,000 years ago, moved into the Old World, displacing all rival human species. Today, most genetic, linguistic, archaeological and anatomical evidence indicates the Out of Africa theory is the most accurate.
The 'Great Leap Forward'
MANY ARCHAEOLOGISTS BELIEVE that around 40,000 years ago, there was a final creative flourishing among members of Homo sapiens after they emerged from Africa and were moving into Europe and Asia. As evidence, they point to the sophisticated new types of stone tools and superb cave paintings that have been uncovered from this period. Some argue this 'Great Leap Forward' was a cultural awakening that was triggered when our ancestors encountered the Neanderthals in Europe. Others argue that a genetic mutation produced a radical rewiring of our neural processes and this set loose that wave of innovation. However, scientists such as Brooks, Yellen, Mitchell and others say the latest evidence from Africa shows such ideas are untenable. They argue that humans were already in possession of their full intellectual evolutionary powers, as can be seen from finds made at Katanda, Blombos and Ntolana Tsoana.
Star Wars bar
TODAY, EARTH HAS only one species of human: Homo sapiens. However, for virtually all our evolutionary history there have been several different species of hominid on the planet. Fifty thousand years ago there were at least two others, the Neanderthals and Homo fl oresiensis, the Hobbit folk of Flores in Indonesia (see "Bones of contention", Cosmos 17, p80). Scientists also believe other descendants of Homo erectus may have survived at this time, though their remains have yet to be discovered. It now seems clear the planet was packed with different hominids at this time. "Think of that scene from Star Wars - in the bar where you see all kinds of aliens playing and talking together," says palaeontologist Yoel Rak, from Tel Aviv University in Israel. "I believe that image gives a better flavour of our evolutionary past."
Robin McKie is a contributing editor of Cosmos, based in London. He is the author of The Dawn of Time and co-author of African Exodus: The Origins of Modern Humanity.
