Why are carrots orange?

Your carrot used to be a different colour

Pick up a carrot in your kitchen and it is almost certainly orange. But wild carrot, the roadside plant also known as Queen Anne's lace, has slender roots that are white or pale yellow and have an unpleasant, sharp taste¹.

When people began farming carrots, the first crops were purple or yellow^{1, 2}. A large genetic study of 630 carrot samples, wild and cultivated, suggests this happened in the Early Middle Ages, somewhere between western and central Asia². Purple carrots get their colour from pigments called anthocyanins, which turn brown when cooked and stain hands and pots¹.

How orange took over

Purple and yellow carrots spread west. Between the twelfth and fifteenth centuries they were eaten in Spain, Italy, France, Germany, England and the Netherlands². In Europe the yellow ones became more popular, likely because of their taste³.

Then came orange. The genetic study concludes that orange carrots were selected during the Renaissance, probably in western Europe². In its family tree, yellow carrots from the Netherlands (and Poland) sit at the base of all western orange carrots. That supports an old idea of a Dutch, or perhaps Belgian, origin². One idea is that orange carrots came from crossing white and yellow ones³.

Dutch growers shaped the result. 'Horn' carrots, named after the town of Hoorn, were developed in Holland¹. By 1763 carrots were sorted into four types: 'Long Orange' and three Horn carrots. Modern western orange carrots descend from these four¹.

The chemistry of orange

The orange colour comes from alpha- and beta-carotene, pigments that orange carrots store in large amounts². Surprisingly, getting there meant switching genes off. Deep orange needs the recessive versions of three genes at once; each was selected separately and then became fixed^{2, 3}.

One of them, called Or, carries a small change that was missing in every wild carrot sample studied but is nearly universal in orange cultivated carrots⁴. A candidate for a further colour gene, called Y (not one of the three above), turned up in 2016, when researchers published the first carrot genome sequence^{3, 5}.

So, what about William of Orange?

A popular story says Dutch farmers bred orange carrots to honour William of Orange, a leader of the Dutch Revolt, which began in 1566⁶. John Stolarczyk, curator of the online World Carrot Museum, says there is no documentary evidence that the Dutch invented orange carrots to honour their royal family⁶.

What does fit: the orange carrot does seem to have been developed and stabilised in the Netherlands around that time, and it grew very well in the Dutch climate⁶. But orange carrots were not only Dutch. An orange carrot appears next to a purple root in ceiling decorations in a villa in Rome, made between 1515 and 1517 (the picture caption says 1518)¹. Later, the Dutch state may have used orange carrots to underline its national colour, and that may be where the royal link comes from⁶.

Stolarczyk calls the story simply not true; in his account the orange carrot came first and the independent Dutch state second⁶. And the old colours never fully vanished. Purple and yellow carrots are making a comeback, and many shops sell mixed 'rainbow' bags of red, yellow, white, purple and orange carrots¹.