factFiction5The claim

“Hold on, just wait a minute. This is called statistical noise.”

Craig Cobb, on the results of his DNA test, The Trisha Show

The background

“You have a little black in you,” a clearly delighted Trisha told the American white supremacist Craig Cobb.

Through the live audience’s whoops, Mr Cobb protested, “No, no, no”.

A DNA ancestry test, which he’d agreed to do for The Trisha Show’s ongoing Race in America series, showed he was 14 per cent Sub-Saharan African.

Mr Cobb, who reportedly once said “racism is my religion“, has ambitions to build a “white nationalist” community in the North Dakota town of Leith.

He has insisted the DNA test was just “statistical noise”, adding: “Water and oil don’t mix”.

Statistical noise would imply the test results were an unexplained variation or randomness.

Is that fair or was Mr Cobb in DNA denial? FactCheck investigates.

The analysis

The structure of DNA was only discovered 50 years ago. So far humans have developed and exploited the technology to record one whole human DNA sequence: some 3bn letters of genetic code.

But as a spokesman for Genomics England told FactCheck, that’s rather like walking around with 27 different telephone directories and saying you know everyone in London.

We might have the all the numbers, but they are not all known to us. In fact, we are a long way off.

Fossils place the origin of humans in Sub-Saharan Africa, with recent analysis pointing to a single point in south eastern Africa: the Cradle of Mankind.

A minority had previously argued, using skull data, that populations had evolved in other areas.  But a 2007 study of more than 6,000 skulls, by the University of Cambridge’s Department of Zoology, has confirmed the majority’s single origin theory.

Dr Neil Bradman, Chair of University College London’s Centre for Genetic Anthropology, told FactCheck it is futile to argue that we don’t come from Africa.

“All of us have a genetic ancestry that goes back to Africa.  If you go back far enough all of us are descended from animals,” he said.

So why bother looking at African origins?

Dr Chris Tyler-Smith of the Wellcome Trust Sanger Institute said: “Our origins…have an impact on our current health and disease. Biologically, we have adapted to a hunter-gatherer lifestyle in Africa over millions of years, but have only begun to adapt to a modern farming or urban lifestyle for a few thousand. Evolution is slow, and this mismatch underlies many of our health problems.”

Science is hunting for information about how homo sapiens journeyed from Africa to the far corners of the globe.

The story of that journey is written in our genes.

As the National Geographic’s Genographic Project explains: “When DNA is passed from one generation to the next, most of it is recombined by the processes that give each of us our individuality. But some parts of the DNA chain remain largely intact through the generations, altered only occasionally by mutations, which become ‘genetic markers’. These markers allow geneticists to trace our common evolutionary time line back many generations.”

Dr Spencer Wells, the lead scientist at the Genographic Project, has said previously: “Old-fashioned concepts of race are not only socially divisive, but scientifically wrong.”

He explained that evidence shows all humans are 99.9 per cent identical “and do not fall neatly into physical categories some people call races”.

The differences among us evolved as we adapted to different environments. But these differences account for less than 0.01 per cent of our genetic makeup.

Genomics England, set up by the Department of Health to run the 100k Genome Project, investigates rare diseases and cancer in DNA sequences. It will sequence the personal DNA code – or genome – of up to 100,000 patients over the next five years.

A spokesman for Genomics England said this was the “serious side” of DNA testing. Just 3 per cent of our DNA is active protein – which tells us how our health is right now. The rest of the code sets everything out from birth: from our eye colour to the chance of a developing a hereditary disease in later life.

Some people are happy to live in blissful ignorance of what might be in store. Others, such as the actress Angelina Jolie, are not.

Her DNA test informed her that she has an 87 per cent chance of getting breast cancer. Rather than take the risk, she had a mastectomy.

The verdict

Scientists agree that modern man originated from Sub-Saharan Africa. Indeed the lead scientist from the National Geographic’s Genographic Project says all humans are 99.9 per cent identical.

The first modern humans lived in south eastern Africa and migrated out of Africa more than 60,000 years ago.

FactCheck would like to know how Mr Cobb could argue that his DNA doesn’t contain African heritage.

How African we are may differ wildly, and is likely to be higher in those whose relatives have come into greater contact with Africans.

For example, a European with ancestors who lived around established slave centres would have a higher percentage of African DNA than a European from Siberia.

And as Dr Bradman told FactCheck: “Almost none of us know who all our great, great grandparents were.”

DNA tests can whittle it down. But really, it’s besides the point.

Far more interesting than what percentage of us is African, is how we migrated. And how our evolution affects our current health and diseases. That secret is held within our DNA.

As Dr Chris Tyler-Smith of the Wellcome Trust Sanger Institute said: “We still don’t know what turned a rare African species in to a globally-dominant one”.

By Emma Thelwell