Origin and Diffusion
Origin and Diffusion
The tobacco of worldwide commerce belongs to the species Nicotiana tabacum. It belongs to the family Solanaceae, which includes the potato, tomato, eggplant, petunia, and many other cultivated and ornamental plants. The genus Nicotiana is one of about ninety genera in the family and consists of about sixty-five species in the world, three-fourths of them native to North and South America, one-fourth native to Australia, and a single one, N. africana, discovered in the 1970s on a few mountain tops in the Namibian Desert of Namibia. In Africa, the continent where Homo sapiens evolved, the human interaction with this genus was nonexistent until the sixteenth century. Humankind became aware of these plants and their psychoactive properties about 50,000 years ago when Australia was populated, and approximately 10,000 to 15,000 years ago when the Americas south of the Arctic were being populated.
Perhaps a dozen species of Nicotiana have been actively used by humankind, but the remainder have evidently never been seriously used for smoking or chewing, because initial experimentation likely revealed the low nicotine content or the presence of other bitter or more immediately poisonous alkaloids.
The various species of Nicotiana range along a spectrum from strictly wild species to a completely domesticated one. Nicotiana tomentosiformis, which grows in the Andes, is a wild species that grows and propagates entirely on its own, without any deliberate intervention on the part of humans (although human modification of habitats in the last 10,000 years may affect its distribution). Conversely, Nicotiana tabacum, which is by far the most widespread and important of the tobaccos in an economic sense, depends entirely on humankind for its continuing existence, and cannot persist for more than a generation or two without being deliberately planted and protected from weeds.
In Australia, at least the following native species have been used for chewing tobaccos before the arrival of Europeans (and the New World tobaccos): N. gossei, N. ingulba, N. simulans, N. benthamiana, N. cavicola, N. excelsior, N. velutina, and N. megalosiphon. Agriculture never developed in Australia; but whether or not any of these were sometimes deliberately planted is not known, and none were truly domesticated. In addition, since the mid-1800s N. glauca has become widely naturalized and has been used for chewing. In the 2000s, N. tabacum is widely cultivated.
North and South America
In North America and Mexico, Amerindians used certain of the native Nicotiana species for their psychoactive effects. The range where these wild tobaccos can be found may involve some spread beyond their original native ranges due to human influence. In North America, one species, N. quadrivalvis (previously called N. bigelovii), was "semi-domesticated," which means it evolved because of human selection for particular traits, but with only a few modifications, so that it could probably exist in the wild; after generations of cultivation by Amerindians, selection had taken place to produce plants with larger flower parts, the parts richest in nicotine. All wild species of Nicotiana have the fruit divided into two chambers, but in N. quadrivalvis, the number of cells had been increased to three or four. This intensive use also expanded its original range from California eastward to the Great Plains from Texas to the upper Missouri River, and it was the tobacco that the explorers Meriwether Lewis and William Clark encountered being cultivated by the Mandan Indians.
Only two species, N. rustica and N. tabacum, spread out from a single continent of origin in prehistoric times, and these are the only ones to spread around the world in general cultivation. The introduction of these two into Europe after Christopher Columbus' explorations can be dated quite precisely by both printed descriptions and illustration because they were grown and noted by botanists of the day. N. tabacum, for example, was first illustrated in 1571 by Pierre Pena and Mathias de l'Obel (1571), and this provides incontrovertible evidence of the species that had reached Europe by this time.
Investigating the spread of N. rustica and N. tabacum in America up to the time of Columbus presents serious difficulties because of the lack of a written record, and because these soft-bodied plants are mostly absent from the archeological record except under the most favorable circumstances for preservation. The presence of pipes or representations of smoking on pottery or murals can demonstrate the existence of tobacco (or other plants used for the same purposes) at a certain place or time, but usually not the species being used. Researchers are fairly certain that, in general, by the time of Columbus N. tabacum was present in eastern South America, Central America, Mexico, and the West Indies; while N. rustica was being cultivated in Mexico and the eastern United States as well as the Andes of South America.
Researchers have proposed a number of theories for the origin of these two species, placing their origin in various areas. The origin of both N. rustica and N. tabacum in Andean South America had been more or less firmly established by 1954 with the publication of the botanist Thomas Harper Goodspeed's careful treatment of the entire genus, "The Genus Nicotiana," based on his thorough knowledge of the morphology of the species, their genetic behavior, and the areas where they were found. An important consideration is that both N. rustica and N. tabacum have twenty-four pairs of chromosomes, and are termed tetraploids, because they have twice the number of chromosomes as their nearest relatives, termed diploids, which have twelve pairs. Scientists soon realized that these two species must have resulted from the hybridization of two other species with the subsequent doubling of the chromosome number in the hybrid.
With traditional breeding experiments and modern DNA sequence analysis, the origins of N. rustica can be more carefully elucidated. Before Columbus, N. rustica occurred in the United States and northern Mexico, as well as in the Andes from Ecuador to Bolivia. However, it has never been found as a truly wild-growing plant in Mexico or the United States as it is in the Andes around human habitations. Since it is a hybrid, with subsequent chromosome doubling between N. paniculata and N. undulata, its area of origin must be within the natural range of these two wild species in Peru, Bolivia, and Argentina (see Map).
N. paniculata is an annual herbaceous or slightly woody species up to 2 meters or more tall, found in a wide altitudinal range, from 300 to 3,000 meters, in western Peru. N. undulata is a fleshy, sticky annual herb up to 2 meters tall, from very dry, barren areas, from 2,700 to 4,200 meters altitude in Peru, Bolivia, and Argentina, and is especially common in weedy areas around settlements. The original hybridization almost certainly must have taken place in Peru, with subsequent spread due to humans. It is impossible to know whether the hybrid N. rustica developed before or after human arrival in the Andes. The fact of a human presence may have inadvertently led to the hybridization of N. paniculata with N. undulata to create N. rustica. Humans may have modified the range of the wild species (for example, by gathering certain specimens) and created exactly the sort of habitats in which N. rustica prospers: disturbed soil rich in nutrients (especially nitrogen). Such habitats occur around human habitations and the pens of their animals, and in the 2000s N. rustica grows in such sites without deliberate planting.
The time and route of dispersal of N. rustica north to Mexico and the eastern United States is difficult, if not impossible, to reconstruct, but it was well established in many cultures by the time of Columbus. None of the higher altitude Andean domesticated tubers like the potato (Solanum tuberosum) or oca (Ullucus tuberosus), for example, ever made it to suitable habitats in the highlands of Central America or Mexico because of the impossibility of passing through the lowland tropical jungles of Panama if the plants were to be travel by the slow route of being traded from village to village. Some domesticated plants that could be grown in the humid tropical lowlands easily passed through this area, the prime example being corn (or maize, Zea mays), which spread easily from its area of origin in Mexico throughout the tropical and temperate parts of the Americas, including into South America. More direct dispersion via pre-Columbian Pacific trade routes by boats is the likely means that N. rustica arrived in Mexico from the northern Andes.
Although N. rustica was in use in eastern North America by Amerindians at the time of Europeans' arrival and was even the first commercial tobacco to form the economic basis of the Virginia colony, it would become overshadowed by N. tabacum, which is the overwhelmingly predominant cultivated tobacco throughout the world in the twenty-first century. The prehistory of N. tabacum was somewhat similar to that of N. undulata in that it is a hybrid with chromosome doubling, and had spread widely enough to be the tobacco which Columbus probably encountered in the West Indies on his first trip to the region.
One of the parental species of N. tabacum is N. sylvestris, native to northwestern Argentina and southern Bolivia. It is an annual herb with long, narrowly tubular white flowers that open at night and are pollinated by hawk moths. The leaves are large, somewhat similar to those of tobacco, but its only use is as an ornamental in flower beds. The other parent must belong in the Tomentosae, a group of six Andean species from Peru to northwestern Argentina which are short-lived shrubs or small trees with short pinkish flowers open in the day and pollinated by bees and hummingbirds (the majority) or open mainly at night and pollinated by bats (N. otophora). The prime suspect for the second parent has been N. otophora, a shrub from central Bolivia to northwestern Argentina, which grows in seasonally dry forests or along washes in more arid areas of desert thorn-scrub. It is the only species of the group that also grows in the range of N. sylvestris. Nicotiana otophora has leaves that look very much like those of tobacco, and in Bolivia they are even used occasionally for smoking when tobacco from N. tabacum is not available. Based on the morphological characters, and on crossing experiments, Goodspeed concluded that N. otophora was the likely second parent of N. tabacum.
However, studies conducted in the 1990s of the DNA sequences have indicated that the second parental species is not N. otophora but rather N. tomentosiformis, a soft-woody shrub or small tree 1.5 to 5 meters tall, from the humid montane forests of northern Bolivia and southern Peru on the slope facing the Amazon lowlands. N. tomentosiformis has large, tobaccolike leaves, and even smells like tobacco both when fresh and when dried. How and when N. tomentosiformis and N. sylvestris came in contact to hybridize is a mystery, and it is unclear how the hummingbird-pollinated N. tomentosiformis would have hybridized naturally with the hawk-moth-pollinated N. sylvestris. Even during the climatic changes during the Pleistocene Age, it is highly unlikely that the range of the two species could have allowed them to come into contact naturally.
Scientists have hypothesized that N. tabacum originated several million years ago, but this seems almost impossible because of the biology of the species: N. tabacum is not known to exist as a wild plant anywhere in the world, despite the fact that it is cultivated on a vast scale worldwide and has the opportunity to escape and become naturalized in innumerable possible habitats. A species formed millions of years ago and capable of persisting until humans could begin cultivating it would certainly continue to exist to this day as a wild plant in some area.
A much more likely possibility is that the second parent of N. tabacum is a currently unknown species of Nicotiana similar to N. tomentosiformis, but growing in southern Bolivia. Vast areas in southern Bolivia have not been explored botanically; there are series of parallel mountain ranges where the more humid forested ridges could easily harbor a species of Tomentosae, which would be in position to occasionally hybridize with N. sylvestris, known to grow in the intervening dry valleys.
In the 1990s, researchers discovered that two other cultivated plants have their origin in this region. The tree tomato, Solanum betaceum (also known as Cyphomandra betacea), was discovered in the 1990s to grow wild in this region, finally solving the question of the origin of a species which had long been cultivated in the Andes of Ecuador and Colombia. The origin of the peanut, Arachis hypogaea, presents a parallel situation to that of tobacco since it is a cultivated plant not known in the wild, and botanists have long known that it must be a tetraploid hybrid of two wild diploid species. It was only in the 1990s that researchers definitively established the origin of the peanut. The peanut is descended from A. duranensis, a widespread species from northwestern Argentina, southeastern Bolivia, and westermost Paraguay, and from A. ipaensis, a species only known from two collections in southern Bolivia made in 1971 and 1977.
See Also Missionaries; Sailors.
▌ MICHAEL NEE
Goodspeed, Thomas H. "The Genus Nicotiana." Chronica Botanica 16 (1954): 1–536.
Krapovickas, Antonio, and William C. Gregory. "Taxonomía del Género Arachis (Leguminosae)" (Taxonomy of the genus Arachis [Leguminosae]). Bonplandia 8 (1994): 1–186.
Peterson, Nicolas. "Aboriginal uses of Australian Solanaceae." In The Biology and Taxonomy of the Solanaceae. Edited by John G. Hawkes, Richard N. Lester, and A. D. Skelding. London: Academic Press, 1979.
psychoactive a drug having an effect on the mind of the user.
alkaloid an alkaloid is an organic compound made out of carbon, hydrogen, nitrogen, and sometimes oxygen. Alkaloids have potent effects on the human body. The primary alkaloid in tobacco is nicotine.
hybridization the practice of cross-breeding different varieties of plants or animals to produce offspring with desired characteristics.