I admit that I haven’t read this book, but someone sent me an excerpt about the ancestry of corn. The excerpt is below. First of all, it wouldn't be "food scientists" that attend a conference about corn evolution, but rather plant geneticists. Then he claims that "nothing like it has been attempted since", but in fact a second conference was held a few years later at Harvard.
There is no longer doubt that corn evolved from teosinte, a grass native to Mexico, based on genetic evidence. The author might have learned about that with a little effort just by searching on the internet, but he writes about it as if it's still a mystery.
Corn, and other crop plants were not bred intentionally be early people, but rather the ancestral plants changed over time simply because people were harvesting them. Take wheat for example. The ancestral plant released its seeds, or course, which is how it reproduced. However, when people started collecting seeds, saving them over the winter, and planting them in spring, they selected for a variety of plant that did not release its seeds. Plants that tended to hang on to their seeds were the most successful, because their seeds would be most likely to be collected by people and planted. Over time, this artificial selection resulted in plants that didn't release their seeds at all, which means that the they could not reproduce without people. Because the seeds were firmly attached to the stem, people had to thresh the plants to remove the seeds. Threshing tears the seed from the stem, and leaves a ragged edge, however when seeds are released by natural grasses it leaves a smooth edge. This difference has made it possible to determine quite accurately when wheat was domesticated: archaeologists go back in time by digging down through layers of soil, and examine stems of wheat to determine when the smooth edge became ragged. Fascinating stuff.
Corn was bred from teosinte the same unintentional way. People collected the kernals from teosinte, and so selected for plants that did not release their kernals. Corn therefore is not capable of dispersing its seeds, and only exists because people plant it. There is very good archaeological evidence of the evolution of corn, with numbers of kernals (and ear size) gradually increasing over time. Of course, that is because plants that produced the greatest numbers of kernals were the ones that were most successful, thanks again to people.
"It is beyond us to divine how any people could have bred cobs of corn from such a thin and unpropitious plant—or even thought to try. Hoping to settle the matter once and for all, food scientists from around the world convened in 1969 at a conference on the origin of corn at the University of Illinois, but the debates grew so vituperative and bitter, and at times so personal, that the conference broke up in confusion and no papers from it were ever published. Nothing like it has been attempted since. Scientists are now pretty sure, however, that corn was first domesticated on the plains of western Mexico, and are in no doubt, thanks to the persuasive wonders of genetics, that somehow it was coaxed into being from teosinte, but how it was done remains as much of a mystery as it ever did."