The wild ancestors of the carrot are likely to have come from Afghanistan, which remains the centre of diversity of the wild carrot. Specimens of the eastern carrot that survive to the present day are commonly purple or yellow, and often have branched roots. The purple colour common in these carrots comes from anthocyanin pigments.
The western carrot emerged in the Netherlands in the 17th century, its orange colour making it popular in those countries as an emblem of the House of Orange and the struggle for Dutch independence. The orange colour results from abundant carotenes in these cultivars. Selective breeding over the centuries has reduced bitterness, increased sweetness, and minimized the woody core.
In early use, carrots were grown for their aromatic leaves and seeds, not their roots. Some relatives of the carrot are still grown for these, such as parsley, fennel, dill and cumin. The first mention of the root in classical sources is in the 1st century CE.
Massive overconsumption of carrots can cause hypercarotenemia, a condition in which the skin turns orange.
The urban legend that says eating large amounts of carrots will allow one to see in the dark developed from stories of British gunners in World War II who were able to shoot down German planes in the darkness of night. The legend arose during the Battle of Britain when the Royal Air Force circulated a story about their pilots' carrot consumption as an attempt to cover up the use of radar technologies in engaging enemy planes. It reinforced existing German folklore and helped to encourage Britons—looking to improve their night vision during the blackouts—to grow and eat the vegetable.
The Vegetable Improvement Center at Texas A&M University has developed a purple-skinned, orange-fleshed carrot, the BetaSweet (also known as the Maroon Carrot), containing substances which help prevent cancer. The high β-carotene content gives the carrot its maroon shade.