Little Bethany asked Eli why carrots are orange, why, said Eli, that's because the Dutch took knarly yellow, white and purple proto-carrots and made them orange to honor their King (maybe, maybe not, but she's a kid and it's a wonderful day)
Why are carrots orange? - Carrots are orange because they absorb certain wavelengths of light more efficiently than others. Beta-carotene is the main pigment and is mainly absorbs in the 400-500nm region of the visible spectrum with a peak absorption at about 450nm. Carotenoids are one of the most important groups of natural pigments. They cause the yellow/orange colours of many fruit and vegetables. Though beta-carotene is most abundant in carrots it is also found in pumpkins, apricots and nectarines. Dark green vegetables such as spinach and broccoli are another good source. In these the orange colour is masked by the green colour of chlorophyll. This can be seen in leaves; in autumn, when the leaves die, the chlorophyll breaks down, and the yellow/red colours of the more stable carotenoids can be seen.The most likely theory, in the opinion of the Carrot Museum, is that of Heywood 1983 - After the comparison of several arguments of various highly speculative theories regarding the origin of the western orange carrot, he postulated its selection was from a genepool involving yellow rooted eastern carrots, cultivated white-rooted derivatives of wild carrot (Daucus carota subspecies carota, grown as medicinal plants since classical times) and wild unselected populations of adjacent Daucus Carota subspecies in Europe and the Mediterranean. (V H Heywood - Relationship and Evolution in the Daucus Carota Complex - 1983)
Banga 1963 considers that the purple carrot spread into the Mediterranean in the 10th century where it is thought a yellow mutant appeared. The purple and yellow carrots both gradually spread into Europe in subsequent centuries. It is considered that the white carrot is also a mutant of yellow varieties.
Nevertheless cultivation of carrot in ancient times is still much disputed, mainly because daucus carota inter-crosses freely with other carota types, producing many and varied variations,
One theory proposes that orange was a characteristic of western carrots selected in Southern Europe or Asia Minor. A hybridisation theory supposes crosses between cultivated and wild germaplasm may have played a part in the enhanced pigment types. (Small 1978) Another states that orange-rooted carrots occurred in the Mediterranean, around Turkey, where cultivated carrot diversity was particularly prominent. (Mackevic 1932).
Another theory, (Banga) which has subsequently been discounted, is that, on the basis of the appearance in European oil paintings of the 16th and 17th centuries is it considered that the Dutch selected and fixed orange varieties from yellow, developing its colour from gradual selections of yellow carrots. The orange cultivars "late horn" and "half long horn" originated in the Netherlands during the seventeenth century. (Banga and Simon). Oddly white roots began to appear in pictures about the same time, perhaps implying that there had been little attempt by western Europeans to domesticate the wild, white rooted carrot until Moorish invaders came along with their coloured roots.
A tale, probably apocryphal, has it that the orange carrot was bred in the Netherlands in the sixteenth century to honour William of Orange. Though the development and stabilisation of the orange carrot root does appear to date from around that period in the Netherlands, it is unlikely that honouring William of Orange had anything to do with it! Some astute historian managed to install the myth that the work an unexpected mutation was developed especially to thank King William I as a tribute to independence from Spain. Dr T Fernie (Herbal Simples1875) reported - "The Dutch Government had no love for the House of Orange: and many a grave burgomaster went so far as to banish from his garden the Orange lily, and Marigold; also the sale of Oranges and Carrots was prohibited in the markets on account of their aristocratic colour."It has been argued that the depiction of orange carrots in art works of the period proves that this was their first appearance. Art works alone are not considered to be good enough evidence as the colours used are not always true to type, and artists use colour effects in arranging their subjects. So in paintings, the differences between yellow and orange roots could be due to artistic features rather than to differences between cultivars. One can probably say with certainty that orange varieties were grown in the Netherlands at this time but this does not prove their origin in that locality. (Brandenberg) Also, well before this time, there are clearly visible orange rooted carrots appearing in an ad 512 manuscript, an 11th century document, 14th century scripts and wall paintings in Italy in 1517. (see below)