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Cotton, Gossypium arboreum (Malvaceae)

In our age of synthetic fibers, natural fibers are nevertheless still very much part of our daily life. Did plant fibers, such as flax, sisal and cotton antedate animal fibers such as wool? Which were the first in use? Another question, turning now only to cotton, is that of its geographic origin, single or multiple?

Wool was first in use. Descended from a wild mouflon, the sheep’s domestication occurred about 10,000-11,000 years ago in Mesopotamia. Sheep wool and goat hair, those of other animals as well, were already woven around 6,500 BCE. By 4,500 BCE the raising of wool-bearing sheep was practiced widely within the Fertile Crescent — i.e., modern-day Iraq, Syria, Lebanon, Jordan, Israel, Palestinian terriries, Cyprus, Egypt, the adjoining southeastern part of Turkey and the western fringes of Iran and Kuwait. By 4,000 BCE , Babylonians were wearing clothing of crudely woven fabric.

Cotton can also boast a very ancient history, although not quite as far reaching as that of wool. When did it start? When did mankind start using its fibers and domesticating the plant? As is turns out, the plant has some exceptional features, making for a most varied, an indeed astounding history.

The Gossypium genus has about 50 species. In the wild, they are found in arid and semi-arid regions, all over the planet, including Australia, Madagascar and Hawaï. It appeared 5-10 million years ago, during the Miocene geological era.

There are no fewer than four independently domesticated species, two in the Old World (Africa and Asia), G. arboreum and G. herbaceum, and two in the New World (Mesoamerica), G. hirsutum and G. barbadense. Their chromosomal counts differ, Old World species are diploid (2n=26) while New World species are tetraploid (4n=52).

The New World species originated in migration, within the last million years, of an Old World species that hybridized with an indigenous one; the two genomes becoming a single one. This transoceanic migration had to occur through transoceanic voyage, since the continents lacked any land bridge at the time. Seeds were transported across the oceans by birds and by currents. Gossypium seeds are remarkably resistant to immersion in salt water, even over periods of years, retaining their germinating ability.

What about parts of the plant becoming prime material for textiles? Fibers are derived from seed hairs, a feature of the wild species. Lint-bearing species, from which cultivated cottons were domesticated, have a fuzz of short cylindrical hairs, one to three mm in diameter, complemented by a layer of longer, 10-25 mm, hairs. When these longer lint hairs dessicate at maturity, they form a cylindrical ribbon. Because the cellulose strands are laid down in periodically reversing spirals, the entire hair convolutes and twists. It is this structural feature that enables it to be spun into a yarn.

It may come as a surprise, domestication of cotton did not originate, or not only, in the Fertile Crescent. The earliest archaeological evidence for cotton is from the Neolithic occupation of Mehrgarh, during the sixth millennium BCE. Mehrgarh, the earliest agricultural village of the Indus Valley, presents evidence of cotton seeds and fibers, derived from G. arboreum dating to ca 6000 BCE. At Mohenjo-Daro, an archaeological site on the Indus river, fragments of cloth and cotton textiles have been dated to the fourth millennium BCE. Cotton must have been cultivated by that time. Indeed, archaeologists agree that most of the trade that made the city grow was based on cotton exportation.

Two regions rival for the origin and domestication of G. arboreum, Madagascar and the Indus Valley.

G. herbaceum is endemic in the wild in Southern Africa. Its domestication and cultivation took it along the coasts bordering the Indian Ocean trade routes. It was grown subsequently from Ethiopia to Southern India.

G. barbadense was domesticated in northwest South America, perhaps along the coast or inland near waterways. The earliest archeological remains, consisting of seeds, fibers, yarn, fishing nets and fabrics were recovered from central coastal Peru. They date to 5,500 years ago.

The vast majority, more than 90% of the world cotton, comes from the G. hirsutum cultivar, also known as Upland cotton. It is cultivated in both temperate and tropical regions, from 47° N in the Ukraine and 37° N in the United States, to 32° S in South America and Australia.

Where did this New World species originate, and where did it undergo domestication? G. hirsutum has a large indigenous range, throughout MesoAmerica and the Caribbean. The oldest archeological remains date from between 4,000 and 5,000 years ago, in the Tehuacan Valley of Mexico. Two centers of genetic diversity were identified, in Southern Mexico-Guatemala and in the Caribbean. The former, the Yucatan peninsula, is likely to have been the primary center of diversity, since it is both the center of morphological diversity and the original geographic point of domestication. The Caribbean area represents a secondary center of diversity. Upland cottons are derived from these Yucatan cultivars, that spread along the Mexican gulf coast, reaching as far as some Caribbean islands and Florida.

One has to admire the resourcefulness of Homo sapiens. To have exploited the lint from this plant, to have domesticated it for this purpose, not once, but four times in widely different regions of the globe, is quite a technological feat. As writes one of the experts, Jonathan Wendel, an academic geneticist from Iowa,

‟the effects of human manipulation on the four cultivated species have been so extensive that the evolution of these species can only be understood within the context of domestication. The development of weaving would have let to selection for lint quality characteristics. The requirement of hand-ginning favored smooth-seeded varieties that had easily detached lint fibers. The invention of mechanical gins allowed smooth-seeded varieties to be replaced by fuzzy-seeded variants with higher quality lint and lint percentages.‟

The shared histories of cotton and mankind are definitely not exemplary in every particular. I’ll only remind the reader of the link of cultivated cotton with slavery and imperialism. The former occurred in the American South. The latter is illustrated by the examples of Egypt and India.

In both these countries, Britain exported their raw cotton production to its mills in Lancashire. It acted to monopolize the market, to protect British manufacturers from the world price. Egyptian farmers and consumers bore the burden which, towards the end of World War I, caused considerable unrest in Egypt.

While it was, arguably, the earliest birthplace of the domestication and cultivation of Gossypium, India under British rule had likewise to send its cotton production for processing to England, in the Manchester area. In turn, Indians had to purchase the manufactured cotton fabrics from England. During the 1930s, Gandhi used this logical anomaly as an argument for Indian autonomy, as preparation for independence. This is why he was adamant that the Indian people become self-sufficient and that they spin their own cotton yarn.