Adapted from Hans Christian Andersen’s The Princess and the Pea (1835)

Once there was a Prince who wanted to marry a Princess. Only a real one would do. So he traveled through all the world to find her, and everywhere things went wrong. There were Princesses aplenty, but how was he to know whether they were real Princesses? There was something not quite right about them all. So he came home again and was unhappy because he did so want to have a real Princess.

One evening a terrible storm blew up. It thundered and rained. It was really frightful! In the midst of it all came a knocking at the town gate. The old King went to open it.

Who should be standing outside but a Princess, and what a sight she was in all that rain and wind. Water streamed from her hair down her clothes into her shoes and ran out at the heels. Yet she claimed to be a real Princess.

"We'll soon find that out," the old Queen thought to herself. Without saying a word about it she went to the bedchamber, stripped back the bedclothes, and put just one pea at the bottom of the bed. Then she took twenty mattresses and piled them on the pea. Then she took twenty eiderdown feather beds and piled them on the mattresses. Up on top of all these the Princess was to spend the night.

In the morning they asked her, "Did you sleep well?" " Oh!" said the Princess. "No. I scarcely slept at all. Heaven knows what's in that bed. I lay on something so hard that I'm black and blue all over. It was simply terrible."

They could see she was a real Princess and no question about it, now that she had felt one pea all the way through twenty mattresses and twenty more feather beds. Nobody but a Princess could be so delicate. So the Prince made haste to marry her because he knew he had found a real Princess.

As for the pea, they put it in the museum. There it's still to be seen unless somebody has taken it. There, that's a true story.

Text 1:

Genetic investigations into the origins of human life most often focus on mitochondrial DNA. As opposed to nuclear DNA, mitochondrial DNA is transmitted only from the mother. This allows for the tracing of mutations that arise independently of changes that occur because of the combining of the mother’s and father’s DNA. As useful as this is, the high mutation rate of mitochondrial DNA allows scientists to look at only relatively recent prehistory.

Text 2:

Nuclear DNA, on the other hand, has a low mutation rate, making it ideal for looking into the more distant past. Studying the nuclear DNA of fossils now shows a substantial decrease in population size in Europe and Asia approximately 50—80 thousand years ago. No such decrease happened in Africa. This supports the idea that migrants from Africa replaced all previous humans, and did not interbreed with earlier migrants.