I think researchers know what they're talking about when they talk about the development of modern food crops. There's a lot of evidence to work with and it makes sense that natural plants over the course of hundreds of generations would gradually develop into the domesticated plants that we know today through a process of artificial selection.
Wild carrots are unrecognizable today. Found in Persia and Asia Minor around the 10th century, they were purple or white root-like structures. Its seeds made their way as far as Europe about 5,000 years ago and it is still found today in temperate regions. The orange-ish vegetable we know today was domesticate in the 1900s, which started as a golden ball and transformed into the long orange carrot today. The modern carrot has also become an annual winter crop, compared to its ancestors that thrived in warmer climates.
LINK:
http://www.dailymail.co.uk/sciencetech/article-3428689/What-fruit-vegetables-look-like-Researchers-banana-watermelon-changed-dramatically-ancestors-ate-them.html