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Preface

Third Edition, 2021

Since the second edition of Crops and Man was published some 30 years ago, germplasm collections have expanded greatly, molecular genetics has taken root and is being used to answer age‐old questions, and archaeological research has discovered many ancient plant and animal remains, uncovered new sites, and expanded our knowledge of the movement of man and his crops throughout the world. Many of the early studies are no longer possible to continue because hunter‐gatherers have all but disappeared except in a few relatively isolated regions.

Crop plant evolution involves an understanding of human behavior, as well as extensive knowledge about plants, what happens to plants as man selects traits that he values, and the importance of these plants in varying societies. The process of evolution takes place over both time and space, and as Jack Harlan so eloquently points out, there is no one model or answer to all questions. In this edition, we made every effort to maintain the basic structure of the previous volumes, while updating information that has evolved during the past 30 years. Most of the original references are still used because evolution of particular plants and many theories have not changed, and the older literature presents the foundation for current work.

Jack Harlan did not formulate his theories and concepts by sitting in an office or library and daydreaming; he explored many regions of the world’s centers of diversity. He collected more than 12,000 accessions of cereals, forages, legumes, trees, and fruits from more than 45 countries. Many of these have been extensively used as the sources for disease and insect resistances and to introduce genetic variability to modern production agriculture. He made taxonomic revisions of the genera Cynodon and Sorghum and studied the evolution of many other species, especially the cereals. He was also involved in archaeological research and had firsthand knowledge of ancient plant types.

Dr. Harlan formulated five concepts as related to crop plant evolution: first, the “Compilospecies” concept where related species intermate to form hybrid swarms with high levels of fitness and aggression, and which are able to expand their ecological range. Secondly, he understood the relationships between crops and companion weeds, and the importance of introgression to maintain diversity in a species. Third, Vavilov’s Centers of Origins, which were more centers of diversity than origin, were revised into larger areas. Dr. Harlan recognized that not all crops had distinct centers and that the center of origin is not necessarily (and is more often not), the center of diversity. Fourth, he understood that the origin of crop domestication occurred for different reasons by various peoples and no one concept fits all situations. Thus, he developed a no‐model model to incorporate the array of theories for crop domestication. Lastly, a natural classification of cultivated plants was proposed that consisted of gene pools rather than the classical method of morphological descriptions. This allows the thousands of variants of a crop to be lumped together into a single genetically and reproductively unified gene pool.

For his masterful accomplishments and service to the agriculture community, Dr. Harlan received many highly prestigious recognitions and awards, both nationally and internationally. His contributions have been recognized in symposia and in Europe a conference series named after him continues to bring together scientists to discuss topics in crop plant evolution.

Jack Harlan was a brilliant scientist and a true scholar. He stimulated all those who knew him to explore new avenues of learning and to never stop acquiring knowledge, not only in their specialty, but in related fields as well. Jack R. Harlan was my mentor, graduate advisor, and friend.

Harlan’s use of the word “man” to describe all people was commonplace at the time of his writing. We have left this gender non‐descript word use in our attempt to maintain the original flavor of his entertaining story style, and trust our readers understand we mean no disrespect.

In this revision, we hope that young plant scientists will broaden their views of the world around them to better understand the evolution of humans and the plants that feed the world. The book does not present the genetics of speciation, polyploidy, or plant breeding. But rather, it is intended to present views of evolution through the personal experiences of Jack Harlan and set the foundations for patterns of crop diversity.

H. Thomas StalkerRaleigh, North Carolina