Plant domestication

There have been two major human historical influences on the plants of the world: their genetics (see plant domestication and man-made plants), and distribution under cultivation (see plant cultivation, and cultivated plant globalization).

Introduction

Domesticated plants may be categorized in various ways. The four first-order categories used here relate to groups of plants that belong to different spheres of human activity. There are two major groups associated with food and drink groups. Firstly, there are the temperate (mostly cereal) agricultural crops associated with the Neolithic Agricultural Revolution of prehistory and the settled communities that developed in both East and West. Then there are the subtropical and tropical crops distributed through the tropics during the European colonial expansion of the 18^th and 19^th centuries. Globally there are about 3000 known food plants of which about 150 have been extensively cultivated and traded. However, about 90% of the human diet consists of about 15 species and, of these, only four (wheat, rice, maize, and potatoes) make up much more than half of the world’s food supply. There are a further couple of non-food groups that fall under the umbrella term ‘domesticated plant’ – the ornamental plants used in parks and gardens, and plants of special practical use – for medicine, structural materials etc.

The second-order categories relate to the different kinds of plants themselves: root crops, cereals or grain crops,

Plant domestication

‘Plant domestication’ is an ambiguous expression that generally refers to the human genetic alteration or selection of plants that can occur to a greater or lesser degree. In a strong sense ‘domestication’ includes some of our major cereal crops subjected to anthropogenic alteration on such a scale that they could not survive if reintroduced to nature. In a weak sense ‘domestication’ simply means plants that have been brought into cultivation. Some garden plants do not differ genetically from plants in the wild and, when they escape from gardens into the wild, they may proliferate to invade the natural vegetation. It is possible that in some countries ornamental plants have been brought into cultivation from the wild on only one or a few occasions. Though techncally they do not differ from plants growing in the wild they do represent only one part of the wild gene pool and are still, therefore, genetic selections. Sometimes forms of ornamental interest that are not recognized in their botanical names, for example some flower colour variants, may be brought into cultivation and given special cultivar names under the International Code of Nomenclature for Cultivated Plants.

From a plant-centred or phytocentric perspective it might seem that human impact has been greatest as a consequence of domestication (although some would argue that it was the plants that domesticated humans). Domestication has three key components: moving them out of natural habitats and thus altering the natural plant geography, changing them physically by selection, breeding, and genetic engineering, in this way, and by cultivating them in various ways.

Time of introduction

Records of plant introductions can be misleading. Dates of plant introduction to a non-native country or region may be recorded when the plants were not put into commerce or general cultivation: later introductions might have been the ones that were widely distributed and their introduction may have been continuous or sporadic. Genetics is revealing more and more about the paths of plant geographic redistribution mediated by humans and may one day allow us to pin-point the original populations from which introduced plants were selected. Many countries received exotic plants indirectly from secondary sources rather than directly from their native populations so, for example, most of the plants introduced to the Neo-Europe’s would have come from their European colonial founders. In the early years of colonial settlement Australia’s agricultural crops and ornamental plants would have come almost exclusively from Britain.

La_Boqueria market Barcelona
We are attracted to the luscious colours of luscious fruits
Ripe fruit was a favourite part of the diet of our primate ancestors
Courtesy Wikimedia Commons
Dungodung Accessed 5 May 2017

Historical phases of introduction

Like so many other factors plant globalization began slowly, gathering pace over time through trade between different civilizations. Historically, several important phases of plant globalization can be discerned: the Neolithic Agricultural Revolution (c. 10,000-4000 BCE); the collection and redistributed of plants through the Roman empire (c. 100 BCE-400 CE); distribution by trade in the Islamic Empire (c. 600-1400 CE); then by far the greatest phase of plant dispersal that has been likened to the early phases of homogenization of world vegetation that occurred during the phase of European colonial expansion (c. 1500-1900). This was a period of exchange of tropical crops between the East and West Hemispheres, the introduction of temperate agricultue into new regions of the world and the import into Europe of ornamental plants from its colonies and colonial exploration when botanic gardens played a role in the redistribution of plants of economic importance.

In line with major factors relating to globalization and sustainability it is evident that factors influencing plant globalization include: population numbers, degrees of social organization, and technological developments influencing systems of transport and communication.

Records of domestication

Key information relates to the historical change that has occurred in geographic distribution of the major crops and the extent to which they are geneticaly different from their wild ancestors. The scientific value of the information in the timeline below would be greatly enhanced if all factual claims were referenced, an extended academic exercise taking too much time here. I have done what I can using the references listed and by accessing sources like Wikipedia. Clearly this list of domesticated plants is confined to major economic crops – it cannot extend to ornamental plants.

New World food crops

Food crops native to the New World of South America and the Caribbean included: avocado, cashew, cassava, chili peppers, cocoa, Jerusalem artichoke, peanuts, pineapple, pumpkin, French and runner beans, squash, sunflower, sweet potato, tomato, vanilla, and the staple cereal maize (corn). Crops

Old World and Asia

passing to the New World included: wheat, barley, rye, oats, apples, aubergines (eggplant), citrus, coffee, grapes, mango, olives, onions, peaches, pears, spinach, and tea, and from Africa especially came sorghum, henna, and watermelons.

From SE Asia

Came: banana, breadfruit, coconut, sugar, taro, yams, and plantains. There were additional economically important non-food plants: tobacco from tropical America, the rubber plant from Brazil, quinine from Bolivia, Ecuador and Peru, opium from Eurasia, the fibres hemp and jute from Asia and sisal from South America, and cotton from the tropics and beyond.

Commentary & sustainability analysis

The process of plant domestication has been one of coevolution (see plants make sense) – indeed it may be claimed that plants domesticated humans. Possibly the most momentous change in human social history occurred when societies took up agriculture to live in settled communities. From this time the development of cities with hierarchical societies, division of labour, writing, complex cultures, and rapidly growing populations appear, in retrospect, to be almost inevitable.

Plant domestication timeline

BCE
9400-9200 Fig – Near East – The edible fig was one of the first plants to be domesticated by humans. Sterile (cultivated) figs have been found in the early Neolithic village Gilgal I in the Jordan Valley dating to about 9400–9200 BCE, thus pre-dating the domestication of wheat, barley, and legumes by about 1000 years. Figs were widely grown in Ancient Greece. Theophrastus observed that Greek farmers tied wild figs to cultivated trees to produce the fruit. Also grown by the Romans Cato the Elder lists several varieties (cultivars) in his De Agri Cultura, (c. 160 BCE, ch. 8) based on provenance: the Mariscan, African, Herculanean, Saguntine, and the black Tellanian. From the 15th century on it was grown in Northern Europe and the New World, the first record in the UK appearing to be in the 16th century (Cardinal Reginald Pole, Lambeth Palace, London)
8500 Barley – Near East – Wild Barley (H. vulgare ssp. spontaneum) ranges from North Africa and Crete in the west, to Tibet in the east.[8] The earliest evidence of wild barley in an archaeological context comes from the Epipaleolithic at Ohalo II at the southern end of the Sea of Galilee. The remains were dated to about 8500 BC.[8] Cultivated The earliest domesticated barley occurs at Aceramic Neolithic sites, in the Near East such as the Pre-Pottery Neolithic B layers of Tell Abu Hureyra, in Syria. Barley was one of the first domesticated grains in the Near East,[13] near the same time as einkorn and emmer wheat.[14] Barley has been grown in the Korean Peninsula since the Early Mumun Pottery Period (c. 1500–850 BC) along with other crops such as millet, wheat, and legumes.[15]
8500 Einkorn wheat – Near East – An early dwarf Cultigen of wild wheat found in archaeological sites of the Fertile Crescent and first domesticated approximately 10,000 years BP, the earliest DNA records traced to Karaca Dağ in SE Turkey. Cultivation spread from here to the Caucasus, the Balkans, and central Europe, favoured over Emmer in cooler climates but in the Middle East its use declined in favor of emmer wheat around 2000 BCE. Cultivated in some regions of N Europe through the Middle Ages up to the early 20th century
8500 Emmer wheat – Near East
8500 Chickpea -Anatolia
8000 Rice – Asia
8000 Potatoes – Andes Mountains
8000 Beans – South America
8000 Squash – (Cucurbita pepo) Central America
8000-6000 Bottle gourd – Lagenaria siceraria – Indigenous to Old World Africa, reaching East Asia (China, Japan) by 9,000–8,000 BP, widely dispersed in the New World by 8,000 BP from Asian stock. Not so much a food source but grown for the value of its hard-shelled, buoyant fruits used as containers, musical instruments, and fishing floats^[1]
7000 Maize – Central America
6000 Broomcorn millet – East Asia
6000 Bread wheat – Near East
6000 Manioc/Cassava – South America
5500 Chenopodium – South America
5000 Avocado – Central America
5000 Cotton – Southwest Asia
5000 Bananas – Island Southeast Asia
5000 Beans – Central America
4000 Chili peppers – South America
4000 Amaranth – Central America
4000 Watermelon -Near East
4000 Olives – Near East
4000 Cotton – Peru
3500 Pomegranate – Iran
3500 Hemp – East Asia
3000 Cotton – Mesoamerica
3000 Coca – South America
3000 Squash (Cucurbita pepo ovifera) – North America
2600 Sunflower – Central America
2500 Rice – India
2500 Sweet Potato – Peru
2500 Pearl millet – Africa
2400 Marsh elder (Iva annua) -North America
2000 Sorghum – Africa
2000 Sunflower – North America
1900 Saffron – Mediterranean
1900 Chenopodium – China
1800 Chenopodium – North America
1600 Chocolate – Mexico
1800 Chenopodium – North America
1500 Coconut – Southeast Asia
1500 Rice – Africa
1000 Tobacco – South America
c. 100 Eggplant – Asia
c. 1300-1400 Vanilla – Central America