Vavilov’s name is indelibly associated with the concept of Centres of Diversity. These are the geographical locations where agriculture took root. Originally, Vavilov listed five, then 7, and ultimately 12. He further distinguished primary centres, where domestication first occurred, from secondary centres, where there was a flowering of selection and a resultant explosion in diversity.
The idea has been adopted, expanded, reviled, and treated as dogma. New kinds of evidence have promoted new kinds of conclusion. But it remains a very powerful organizing principle. Here is how Vavilov himself presented centres of diversity in Five Continents. I plan to annotate and add to this to bring it — and keep it — up to date. Your contributions are welcome.
The main agricultural areas of the world are at present determined to cover approximately 850 million hectares, making up about 7% of all areas. The total number of cultivated species, not including the decorative ones, is estimated by us to be around 1500-1600. Our investigation of the geography of these species and their provenance from certain territories has revealed that the great majority of cultivated plants is linked to seven basic geographical centres of origin:
I. The Tropical Centre includes the territories of tropical India, Indochina, southern China, and the islands of southeastern Asia. One third of the plants cultivated at present originated initially from this centre. This is the native land of rice, sugarcane and the majority of tropical fruit and vegetable crops. Not less than one-fourth of the world’s population (more than half a billion people) lives at present in tropical Asia. In the past the comparative population of this territory was even more significant.
II. The East Asiatic Centre includes the central and western parts of China, Korea, Japan and the major portion of the island of Taiwan. This is the native land of such plants as soyabeans, different species of millet, many vegetable crops and an enormous number of fruits. According to our estimate, about 20% of all the world’s cultivated flora comes originally from eastern Asia. Within this territory lives approximately one-fourth of the inhabitants of the world.
III. The Southwest Asiatic Centre embraces the territory of the interior mountains of Asia Minor (Anatolia), Iran, Afghanistan, Inner Asia and northwestern India. This is joined by the Caucasus, the cultivated flora of which is genetically related to that of the Near and Middle East, as shown by its investigators. This centre can be subdivided into the following zones:
(a) the Caucasian Centre with a large number of the original species of wheat, rye and fruit trees. As shown by comparative studies, this is the most important centre of specific origin in the world as.far as wheat and rye are concerned.
(b) the Near East Centre, comprising Asia Minor, interior Syria and Palestine, Trans¬Jordania, Iran, northern Afghanistan, and Inner Asia, together with Chinese Turkestan.
(c) the Northwestern Indian Centre, including, besides Peshawar and the adjacent provinces of northern India and Kashmir, also Beluchistan and southern Afghanistan. About 14-15% of all the cultivated plants in the world came initially from this territory. Here the wild relatives of wheat, rye and many European fruit trees are concentrated in an exceptional variety of species and here it is still possible to trace an unbroken line from the cultivated species back to the wild forms, i.e. to establish the links preserved between the wild and the cultivated strains.
IV. The Mediterranean Centre covers the countries distributed along the coast of the Mediterranean. This remarkable geographical centre, characterized in the past by great ancient civilizations, furnished originally 10-11 % of all species of cultivated plants. Among these are such kinds as olives, the carob tree and a multitude of vegetable and forage crops.
V. The small area of Abyssinia seems to be an independent geographical centre, characterized by a number of endemic species and even genera of cultivated plants. Among these are the grain called teff [Eragrostis abyssinica Link.], the peculiar oil plant named ramtil or niger seed [Guizotia abyssinica Cass.], a special kind of banana [Ensete ventricosum (Welty.) Cheesman], and the coffee tree [Coffea arabica L.]. The total number of species of cultivated plants, linked to Abyssinia with respect to their origin, does not exceed 3-4% of the world’s cultivated flora.
Within the area of the New World two strikingly localized centres of species formation of cultivated plants have been established:
VI. The Central American Centre, covering a rather large portion of southern North America, including southern Mexico. Within this centre it is possible to distinguish three sub-centres:
(a) the mountains of southern Mexico;
(b) the Central American Centre; and
(c) the West Indian islands.
About 8% of cultivated plants came originally from the Central American centre, e.g. maize, long-staple cotton and other American cottons, a number of bean species, pumpkins, the cocoa or chocolate tree and many fruit crops, such as guava, cherimoya, and avocados.
VII. The Andean Centre is in South America and associated with the Andean mountain range. This is the native land of many tuber-bearing crops — first and foremost potatoes. The quinine tree and the coca bush, too, came originally from there.
Original map of seven Vavilov centres
As can be seen from the geographical centres enumerated, the predominant number of plants taken into cultivation are associated not only with floristic areas distinguished by a rich flora, bur also with those having ancient civilizations. Only comparatively few plants were taken into cultivation in the past from the wild flora outside the geographical centres mentioned. The seven geographical centres enumerated correspond to those of ancient agricultural civilizations.
The South Asiatic tropical centre is associated with the very old Indian and Indo-Chinese civilizations. The most recent excavations have demonstrated the great antiquity of these civilizations, synchronous with those of the Middle East. The East Asiatic centre is linked to the ancient Chinese civilizations and the Southwest Asiatic one to the ancient civilizations of Iran, Asia Minor, Syria, Palestine and that of the Assyro-Babylonia. Thousands of years before our era, the Mediterranean was the centre of the Etruscan, Hellenic and Egyptian civilizations. The unique Abyssinian civilization had deep roots and coincided with the Egyptian civilization. Within the New World, the Central American centre is linked to the outstanding Mayan civilization, which attained enormous success in both science and arts before Columbus. The Andean centre coincides in development with the striking pre-Incan and Incan civilizations.
Of course, there is no correlation between the quantity of the species of wild plants in the different territories of the world and the number taken into cultivation. The rich flora of tropical South America, numbering more than 50,000 species of flowering plants (i.e. one-fourth of the worldwide flora), has furnished rather few cultivated plants. Tropical Africa, also characterized by a rich flora (more than 13,000 species), has provided very few plants for cultivation. The Cape Province with its strikingly rich flora, estimated at 7000-8000 species, has only recently been utilized, mainly within the field of decorative plants.
In the past, the qualitative composition of the flora, the development of agricultural civilizations and the presence of a large number of agricultural populations played a decisive role in the utilization of the wild flora. Many species of cultivated plants, characteristic of geographical centres, have not dispersed beyond the limits of their original areas of species formation. The majority of these species are still utilized mainly by the natives, who first took them into cultivation. Out of the total number of cultivated plants (as mentioned above, estimated at between 1500 and 1600 species, not including the decorative ones) not more than one fourth have dispersed beyond the borders of the original centres where they were first taken into cultivation.
These facts are of primary importance and should be used for exploratory work. It is a matter of investigating entire species but also, to an even greater extent, of varieties and smaller intraspecific taxonomic units, represented by local strains.
In my book, Centres of Origin of Cultivated Plants, Leningrad, 1926, I outlined the initial plan for exploratory work as a result of the basic phytogeographical facts mentioned above. Different plants, long since dispersed by people migrating far beyond the borders of their native land, have been subjected to the effects of natural and artificial selection so that they have produced new forms and sometimes new subspecies and species, which are of great interest. Thus, for instance, wheat and barley brought from southwestern Asia into China have, owing to the effects of the monsoon climate (heavy summer rains), produced special subspecies there which are sharply different from the original forms.
Thanks to the persistent work of plant breeders in many countries, who have crossed varieties obtained from different localities, new strains of great practical interest have been produced. Of course, we ourselves utilize first and foremost varieties from countries close to ours with respect to climate: Canada, the USA and western Europe. When searching for varietal material it is necessary to proceed on a broad base, while taking into consideration data on phytogeography, the history of civilizations and the history of ancient and modem plant breeding.
We are interested mainly in plants suitable for cultivation in our own country. Therefore the main attention is focussed on countries with a temperate climate but also on mountain areas of tropical and subtropical territories characterized by temperate climates. In connection with the interests of the Soviet plant industry, expeditions were directed accordingly. The basic idea for the organization of such expeditions takes into consideration the regularities of the phytogeographical evolution of cultivated plants and its profound connection with the history of the agricultural crops. For a radical improvement of our own varieties, it was necessary to organize a wide-ranging collection of varieties from the plant resources of other countries. It is natural that, in particular, attention was directed toward knowledge of our own country and especially of the adjacent Caucasian and Central Asiatic republics with their rich mountain floras and outstanding localities of varietal material, but it was also directed toward acquaintance with the cultivated plants of neighbouring countries. Owing to the development of the exploratory work, the investigations went far beyond the borders of our own country and embraced, in fact, all the main agricultural territories of the entire world.
