Socialist Worker

Human evolution and the African Eve

A new TV series shows that all humans are descended from African ancestors who walked the earth some 200,000 years ago, writes Neil Faulkner

Issue No. 2151

The origin of the human species is still a subject of fierce political debate. The question of whether modern day humans evolved together or are in fact separate races has social as well as historical significance.

Frederick Engels and Karl Marx avidly read Charles Darwin’s The Origin of Species when it was first published.

They praised the work as a major rejection of religious creationism – the belief that God created the world.

This influenced their own works on how humans evolved and their relationship to nature.

The fact that humans had the intelligence and ability to work together meant that they survived famine and catastrophe.

The debate about how humans evolved millions of years ago and how they came to leave Africa is still very much alive among archeologists.

All the evidence supports the theory that humans evolved from an ape species more than three million years ago. A 3.2 million year old fossil of an archaic ape found in Ethiopia, nicknamed Lucy, is accepted as being the oldest known human predecessor.

However, how this archaic ape evolved into modern human, and during what period those people first migrated around the world, is still controversial.

Some archeologists argue that humans evolved separately in Asia and Africa over the last million years, developing different physical and mental abilities, before interbreeding.

Journey

A major five-part documentary series on BBC2, The Incredible Human Journey, which started last Sunday, examines the conclusions raised by the discovery of Peking Man.

Dr Alice Roberts, who presents the series, is an anatomist and anthropologist at Bristol University. She is in no doubt about the anti-racist implications of the science.

She said, “The really fantastic and powerful insight we’re getting out of this is that we’re a very young species and that we’re all very closely related to each other. That’s why racism is such nonsense.

“The idea of ‘race’ doesn’t make sense in biology. It’s a concept pulled together from a ragbag selection of physical characteristics, culture and religion, and attachment to place of birth.”

The new evidence shows modern humans are descended from a single African woman, usually called African Eve, who lived about 200,000 years ago.

This date – based on DNA analy­sis – is a perfect match with that of the earliest known fossils of Homo sapiens.

Two skulls and a partial skeleton that were found at Omo in Ethiopia in 1967 have recently been re-dated to approximately 195,000 years ago – the oldest known members of our species.

Such evidence undermines a theory of human development – known as multiregional evolution – which had become quite popular.

Homo erectus, the very first humans, did leave Africa and settle in areas which would become China.

Fossil remains of erectus excavated at Zhoukoudian near Beijing between 1921 and 1937 – dubbed at the time “Peking Man” – probably date between 400,000 and 800,000 years ago.

They are claimed to be the direct ancestors of the modern Chinese. It has even been argued that the archaic skulls have distinctive East Asian features.

The African early human is described as being stronger, taller, with a thick set skull and large jaw. His Peking cousin was in contrast said to be smaller but more agile and intelligent.

This theory, dubbed Out of Africa 2, is even taught in many of China’s schools to support a sense of national identity and superiority.

These descriptions are familiar to anyone who has studied racist caricatures of what African and Asian people are meant to be like today.

This theory assumes parallel evolution in different places, and then interbreeding to achieve a single hybrid species – modern humans.

Biological evidence also shows that “speciation” – the creation of new species – occurs through branching off and separate evolution.

Moreover, a “missing link” – intermediate fossils which prove such a development – do not exist.

The latest DNA evidence has shown once and for all this theory is wrong.

The new findings come from the Chinese professor Jin Li who has used the latest DNA technology to trace the genetics of modern humans.

He took samples from 12,000 Chinese people to see if they could have descended from Peking Man.

The conclusion is stark – he found that we are descended from the same species of early human, which developed in Africa some 200,000 years ago.

It has now been established that Peking Man became extinct and humans evolved from Homo sapiens.

So what do we now know about human evolution based on the evidence we have today?

Early human species evolved from a group of archaic ape species known as australopithecines. This included Lucy, who we can tell from her fossil walked upright.

Labour

This freed her arms and hands for labour and in turn encouraged natural selection in favour of higher brain capacity.

Hand and brain, labour and intellect, skill and thought would have begun that explosive interaction whose evolutionary culmination is modern humans.

About one million years ago Homo erectus migrated from Africa and colonised much of South and East Asia. The standard tool of erectus was the stone hand axe.

Later, a more developed early human – Homo heidelbergensis – settled much of Western Asia and Europe.

Neanderthals evolved out of heidelbergensis. Their tool-kit was dominated by sharp-edged stone flakes.

For well over 100,000 years Homo sapiens did not leave Africa – except for a brief foray into the Middle East.

When the great exodus finally began around 85,000 years ago, it was rapid. Southern Asia and Australia were colonised some 50,000 years ago, Northern Asia and Europe 40,000 years ago, and the Americas just 15,000 years ago.

They probably spread along the coast of southern Asia, only later penetrating the interior.

Almost certainly, as hunter-gatherers, they moved in search of new food supplies, responding to resource depletion, population pressure, and climate change.

They were designed for long-distance movement such as endurance walking and running.

Their manual dexterity made them excellent tool-makers while large brains made them capable of abstract thought, detailed planning, language and social organisation.

They formed small, tight-knit, co-operative groups.

Cultured

They were, in a literal sense, “cultured” – their ways of getting food, of living together, of sharing tasks, of making tools, of ornamenting themselves, of burying their dead, and much else were agreed within the group.

Their society was an early form of primitive communism, as identified by Marx and Engels.

Their species characteristics meant they could adapt to radically varied environments. In the Arctic, they hunted reindeer, in the tropics, pigs, monkeys, and lizards.

Tool-kits varied according to the challenges. Instead of simple hand axes and flakes, they manufactured a range of “blades” – sharp-edged stone tools longer than they were wide.

And they produced art, painting and sculptures of the animals they hunted believing them to be magical.

Above all, the new species experimented and innovated, and successes were shared and copied. Culture was not static, but changeable and cumulative.

Instead of humans either dying out or changing form in the face of new conditions, Homo sapiens found solutions in better shelters, warmer clothes and sharper tools.

Nature and culture interacted. Humans became progressively better at controlling, altering, and exploiting their environments.

This explains the emergence of farming around 10,000 years ago. Hunting turned into herding.

The collection of wild grasses became the cultivation of cereals. Probably some sort of ecological crisis lay behind the change.

It was the uniquely “progressive” character of Homo sapiens as a species that made this possible.

What the DNA evidence proves is that humans are a single species.

Leading geneticist Luigi Luca Cavalli-Sforza, who spearheaded the collection and study of DNA data concludes that, “Studies of human population genetics and evolution have generated the strongest proof that there is no scientific basis for racism.”

As a species – the descendents of African Eve – we have come a long way. But the greatest challenges are still ahead.

The Incredible Human Journey, BBC Two, Sundays at 9.30 pm


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Features
Tue 12 May 2009, 17:19 BST
Issue No. 2151
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