Cotton (Gossypium sp.) belongs to the Malvaceae  family and is one of the most important and earliest domesticated plants in the world. It was domesticated independently both in the Old World and in the New World.
The word "cotton" originated from the Arabic term al qutn, which became in Spanish algodón and cotton in English.
Among the different domesticated species, the most widespread are G. arboreum L. and G. herbaceum L. domesticated in the Old World; and G.hirsutum and G. barbadense domesticated in the New World.
Old World Cotton
Cotton was first domesticated in the Old World about 7,000 years ago. The two main species, G. arboreum and G. herbaceum, are genetically very different and probably diverged well before domestication. Cultivation of G. arboreum began in the Indus Valley of India and Pakistan, and then spread over Africa and Asia, whereas G. herbaceum was first cultivated in Arabia and Syria.
Specialists agree that the wild progenitor of G. herbaceum was an African species, whereas the ancestor of G. arboreum is still unknown. Regions of possible origin of the G. arboreum wild progenitor vary from Madagascar and the Indus Valley, where the most ancient evidence of cultivated cotton was found.
G.herbaceum
This type of cotton traditionally grew in African open forests and grasslands. Characteristics of its wild species are higher plant, compared to the domesticated shrubs, smaller fruit and thicker seed coats. Unfortunately, no clear domesticated remains of G. herbaceum have been recovered from archaeological contexts. However, the distribution of its closest wild progenitor suggests a northward distribution toward North Africa, and the Near East.
G. arboreum
Abundant archaeological evidence exists for the domestication and use of G. arboreum. Mehrgarh, the earliest agricultural village of the Indus Valley, presents evidence of cotton seeds and fibers dating to ca 6000 B.C. At Mohenjo-Daro, the famous archaeological site on the Indus river, fragments of cloth and cotton textiles have been dated to the fourth millennium B.C., and archaeologists agree that most of the trade that made the city grow was based on cotton exportation. In the second millennium B.C. from India, cotton reached the Babylonian kingdoms, Egypt and, later on, Europe.
Among the different domesticated species, the most widespread are G. arboreum L. and G. herbaceum L. domesticated in the Old World; and G.hirsutum and G. barbadense domesticated in the New World. Among the American species, G. hirsutum was apparently cultivated first in Mexico, and G. barbadense in Peru. Some archaeologists believe, alternatively, that the earliest type of cotton was introduced into Mesoamerica as an already domesticated form of G. barbadense from coastal Ecuador and Peru. However, most believe that G. hirsutum was independently domesticated in Mesoamerica.
New World Cotton
Among the American species, G. hirsutum was apparently cultivated first in Mexico, and G. barbadense in Peru. Some archaeologists believe, alternatively, that the earliest type of cotton was introduced into Mesoamerica as an already domesticated form of G. barbadense from coastal Ecuador and Peru. However, most believe that G. hirsutum was independently domesticated in Mesoamerica.
G. hirsutum
The oldest evidence of Gossypium hirsutum in Mesoamerica comes from the Tehuacan valley and has been dated between 3400 and 2300 BC. In different caves of the area, archaeologists affiliated to the project of Richard MacNeish found remains of fully domesticated examples of this cotton.
Recent studies have allowed the comparison of bolls and cotton seeds from excavation in Guila Naquitz Cave, Oaxaca, with living examples of wild and cultivated G. hirsutum punctatum, showing that they might come from the same species, originally domesticated in the Yucatan Peninsula.
In different eras and among different Mesoamerican cultures, cotton was a highly demanded good and a precious exchange item. Maya and Aztec merchants traded cotton with other luxury items, and nobles adorned themselves with preciously woven and colored mantles.
Aztec kings often offered cotton products to noble visitors as gifts and to army leaders as payment.
G. barbadense
The first clear evidence of domestication of this type of cotton comes from Ancon, a site on the Peruvian coast where archaeologists found remains of cotton bolls dating to 4200 BC. By 1000 BC Peruvian cotton bolls were indistinguishable from modern cultivars of G. barbadense.
Archaeological examples of this type of cotton has been found in different sites of Peru and Ecuador, especially Ancón, in the central coast of Peru.
Sources
This glossary entry is a part of the guide to the Domestication of Plants, and the Dictionary of Archaeology.
Hancock, James, F., 2004, Plant Evolution and the Origin of Crop Species. Second Edition. CABI Publishing, Cambridge, MA
Mannion A.M., 1999, Domestication and the origins of Agriculture: an appraisal, in Progress in Physical Geography 23, 1, pp. 37â€"56.
Murphy, Denis J., 2007, People, Plants, and Genes. The Story of Crops and Humanity, Oxford University Press.
Pearsall Deborah M., 2008, Plant Domestication and the Shift to Agriculture in the Andes, in The Handbook of South America Archaeology, edited by Helaine Silverman and William Isbell, Springer, pp.105-120.
Stephens, S.G., and M. Edward Moseley, 1974, Early Domesticated Cottons from Archaeological Sites in Central Coastal Peru, American Antiquity, Vol. 39, No. 1, pp. 109-122.
Wendel, Jonathan F., Curt L. Brubaker, and Tosak Seelanan, 2010, The Origin and Evolution of Gossypium, in Physiology of Cotton, edited by James McD. Stewart, Derrick M. Oosterhuis, James J. Heitholt and Jackson R. Mauney, Springer, pp. 1-18
Images of the canid from