How many redheads are there in the world?
About 200 people took part in the UK's first Ginger Pride march in August, and the world record for the largest gathering of natural redheads was broken last month when 1,600 attended the Redhead Day Festival in the Dutch town of Breda. But how many redheads are there in the world - and where do they live?
Scotland is thought by some to have the highest concentration of redheads in the world, so maybe it was an appropriate location for the Ginger Pride march, led by Canadian comedian Shawn Hitchins.
While they marched through the streets of Edinburgh, he made a startling claim.
"It's a great opportunity to bring together all the redheads in the country that holds 19% of the world's population of redheads," he told BBC Radio.
The claim was initially reported on BBC News too. But can it really be true that Scotland is home to almost a fifth of the world's redheads?
"I can't really believe that figure," says Jonathan Rees, professor of dermatology at the University of Edinburgh and one of a team of scientists to identify the gene responsible for red hair - the melanocortin 1 receptor (MC1R).
So where did Hitchins get the figure from? It turns out it was a mistake.
"It must have been in confusion," he says. "I was walking through Edinburgh with 200 redheads behind me and I was mostly trying not to lead people into traffic. Nobody really knows the exact [number]. There was someone from Glasgow saying it was 19% in just the population of Scotland."
In the heat of the moment, it seems, he simply got his words muddled, and that proportion of redheads in Scotland became something very different.
"I am very sorry. This is what happens when you let comedians be spokespeople," says Hitchins. "Also, I'm a ginger so I'm 10 times more likely to make up a statistic."
So if we can now confidently say that a fifth of the world's redheads do not live in Scotland, do we know what proportion actually do?
"It's fair to say we don't have very detailed information about what the frequency of people with red hair is throughout the world," says Rees.
"I wouldn't say there are no reliable estimates, but the ideal way to do this would of course be like the census, where everybody's examined at various ages and you have robust data.
"We don't have that sort of data, but many different researchers have carried out smaller studies where the selection has not been entirely random in the way you would like."
It is often said that between 1% and 2%, or 70 to 140 million people around the world, have red hair.
In purely numerical terms, it is highly likely that the US has the highest number of people with red hair, because of the size of its population. If just 1% had red hair, for example, that would mean it had three million redheads.
According to Rees, the figure for the UK is about 10%.
If that was the case in Scotland, that would suggest that the country with its population of 5.3 million was home to just over half a million redheads - less than 1% of the global total.
The prevalence of red hair may be slightly higher in Scotland than in England, Rees says, adding that it may be even higher in the Republic of Ireland.
Overall, Northern European countries have a greater proportion of redheads than anywhere else in the world.
"If you're in northern Europe, you get used to seeing people with different hair colour," says Rees.
"But most of the people on this planet don't live in Europe and if you just think about Asia, it's very, very rare to see somebody with red hair. And in most of Africa it is exceedingly rare to see somebody with red hair. It is an unusual trait globally."
To explain this, you have to go back tens of thousands of years, says Rees.
"When humans moved out of Africa… skin lightened and people developed hair with different colours. There seems to be some advantage in having pale skin if you live in parts of the world where there isn't much sunshine," he says.
"The probable reason for that is that we make vitamin D in our skin. We rely on sunshine to make vitamin D and if you have very dark skin, it's harder to make that vitamin D."
Being pale, redheads are more efficient at making vitamin D and do not need so much sunlight in order to get the amount they need, he says.
So, in certain places in the world at least, there's a big advantage to being in this minority.