Early plant breeding from wild to domesticates-A trek to evolutionary Past
Keywords: Plant Breeding. Domestication. Migration. Centers of Diversity. Neolithic Revolution. Green Revolution. Genetic Engineering. Agriculture. BCE (based on a common era).
Man, ( Homo sapiens ) considered as the accredited engineer of agriculture have been interacting with plants in the last 10,000 years of co-evolution in a mutualistic manner. Archeological evidence revealed that man have used plants in various ways as food, shelter, clothing, in religious rites and offerings among others. Examination of fossil remains in the open middens or dumpsites from human encampment showed plant and animal remain dated from 17,000 to 18,000 years ago. Though it did not indicate whether the remains is the result of the hunting-gathering activity or from domesticated ones.Forensic Botany, a powerful tool aside from carbon dating revealed interesting information as to the diets of our early ancestors that they use plants in a number of ways.
Depictions in cave paintings of animals and hunting and gathering activities, pottery fragments, clay figurines and tools posed as evidence of the past. In some hunting-gathering settlement, charred remains of fruits, seeds, and tubers has been found from 23 plant species and tend to indicate that early man had a remarkable varied plant diet. Nevertheless, man's dependence on plants as a source of food, shelter, and clothing become intense when their numbers grew into tribes to villages and cities to civilization.
From nomadic hunting - gathering to sedentary life style
The early plant breeders lack the knowledge and expertise of the modern day plant breeders. The transition from nomadic hunter -gathering to sedentary lifestyle is a gradual process, however, the lingering question is "why settle when food is plentiful in the wild? There are several theories formulated, but none can give a satisfactory answer. Moreover, one can just surmise the kind of lifestyle that our early ancestors have to a one that is constantly under threat.The early man who submits to this kind of lifestyle must be cognizant of the elements, attack from the wild beast, and hostile groups as they forage in search for food from one place to another. The early man thought that this is not good and decided to settle in one place, a family first then joined by another family to form a band. By doing this, they are able to protect themselves from danger while some members of the group pursue hunting and gathering food..
As their population grew with interbreeding, the need to provide food becomes critical when food from the wild become scarce and herds of game animals receded farther in search for greener pasture. Then, the man decided to produce its own food, at first by observation, experimenting, and eventually domesticating plants and animals for its own needs.The process is gradual and that it required hundreds of generations before they become food secure.During this period, the farmer becomes the early plant breeder whose knowledge was based on the morphological features of plants.A selection of desirable cultigens was based on morphological attributes.
The Neolithic Revolution - the first agricultural revolution
Based on archeological evidence, agricultural development could be accounted in four major locations worldwide: Agriculture in Asia, Agriculture in Fertile Crescent, Agriculture in Africa and Agriculture in the Americas.Major crops during this prehistoric time include the following; wheat and barley(Fertile Crescent), wheat and millet(India), Maize(Mesoamerica), rice(India, SouthEast Asia, china), potatoes, yams(South America), sorghum, millet, rice(Africa) and root crops (Melllanisia).Aside from these staple food crops, a prehistoric man uses at least 25 more plant species to obtain a balanced diet.
The early plant breeders
The early plant breeder of prehistoric time is an ordinary farmer whose knowledge comes from observations, experimentation and domestication of plants. In its primitive form plant breeding started after the invention of agriculture-The Neolithic Revolution, an era of invention and discovery.During this period, the early man discovered the most basic plant breeding techniques-selection, the art of discriminating biological variations in population to identify and select desirable variants.With the practice of domestication of plants, our ancestors were able to observe many plant traits closely as compared during the time when the are in the hunting-gathering lifestyle.Domestication results from the interactions of plants or animals, the environment, and humans (Gepts, 2004). Consequently, plants that have undergone domestication for hundreds of generation were incapable of survival in the wild without the intervention of man. These morphological changes were beneficial to both crops and man in a mutualistic fashion.
Furthermore, after hundreds of generations of selections these morphological traits stabilized permitting early plant breeders to plant wider areas to support the growing population. Some of these crops grown by prehistoric man is presented here.
Categories of crops cultivated during the prehistoric period
Centers of crop diversity, domestication, and cultivation
The early plant breeders are hunter-gatherers who by necessity abandoned their nomadic hunter-gatherer to the sedentary lifestyle. In order to support themselves, it is necessary to farm crops near their settlements called agriculture. The process evolves gradually over thousands of years.Domestication of plants and animals was given priority while some member of the group hunt and gathered food.By observation, experimenting and experience, early plant breeders were able to select desirable plants from their wild counterparts.Fortunately, domesticates responded positively to the machinations of early plant breeders that entirely changed their behavior from the wild, by then early man decided to settle permanently. As man migrated to other parts of the globe, they brought with them their seeds or cultigens and domesticated animals, but most important is the knowledge of different uses of plants, when to plant and how to plant. This agricultural innovation is basic to the growth and development of early human society.
The suite of traits that marks a crop's divergence from its wild ancestors is defined as " domestication syndrome". A domestication syndrome may involve combination of traits: including seed retention(non-shattering), increased in seed/fruit size(bigger), change in branching or stature (low/semi-dwarf), change in reproductive physiology(synchronous flowering), and change in secondary metabolites(eliminates bitter taste). The domestication syndrome may evolve over thousands of generations, as desirable traits are selected for in the agricultural environment and become fixed in the crop's genome( Meyer, R et al 2012). Furthermore, the natural variability which was present when domestication begun and which is still constantly changing in the wild arises from mutation, polyploidy, and recombination of genes following intra-specific crossing and occasional inter-specific crossing (Knight, 1977).
Centers of diversity
Vavilov defined eight centers of origin according to certain criteria: high varietal diversity, co-occurrence of wild ancestors with their domesticated long history of crop use.The eight centers of diversity, according to Vavilov is drawn in world map: 1) The South Mexican and Central American Center(6 species), 2)The South American(Peruvian-Ecuadorian-Bolivian)Center(8 species), 2a)The Chiloe Center (1specie),2b) The Brazilian-Paraguayan Center( 6 species),3) The Mediterranian Center(6 species),4)The Near Eastern Center(20 species),5) The Abyssinian Center(14 species), 6) The Central Asiatic Center(15 species), 7)The Indian Center(15 species),7a)The Indo-Malayan Center(5 species), 8) The Chinese Center(11 species). Accordingly, the number of species vary from location to location. Knight (1977), observed from the lists of species that some crops occurred in more than one center.This is true of many crops of Abysinnia (Ethiopia). It has been suggested that these crops were introduced to Abysinnia from other countries via migration and that environmental conditions in the mountains and valleys of Abyssinia were conducive to the development of variability.
Centers of crop domestication and cultivation
Early plant breeders have practiced selection 8,000 years ago with the beginning of permanent agricultural settlement. At that time, there was a vast array of natural variability following the evolution and natural selection over millions of years. By year 4,000, our ancestors have finished domesticating major crops species upon which human survival is dependent, including rice, maize and wheat (Doebley, F. J, et al.2006). With domestication, cultivation follows there are at least seven major location that domestication had occurred: Mesoamerica, South America, the Sub-Saharan region in Africa, Fertile Crescent in Mesopotamia, China, South Asia-India, and New Guinea among others. Agriculture(Neolithic Revolution) is also the period of discoveries and inventions. New tools and implements were developed to facilitate agricultural development.With food secured, man turns his attention to other pursuits such as arts, craftsmanship, and military.
Spread of domesticates via human migration
As agriculture evolved, crops that were particularly suitable for agriculture slowly spread to surrounding regions as people traded with each other or migrated to new areas bringing their crops with them.This diffusion led to the emergence of principal crops associated with major centres of the world. In the Near East-wheat and barley as their dietary staples, in the Far East -rice, in Africa-sorghum and millet, in Mesoamerica-corn, and in South America-sweet potato and other root crops (Loventin-McMahon,2008).Furthermore, as civilization continued to develop, trading and migration expanded the range of crops from their origin. The genetic interaction with the native population further expands the amount of variations among crops for which early plant breeders have exploited.
Prehistoric plant breeding
Plant breeding is defined as art and science of improving the genetic makeup of plants for the benefit of man. Early plant breeders lack the sciences that support modern plant breeding (eg. Genetics, Botany, Plant Physiology, etc.}, but they have strong intuitive knowledge like what is edible or poisonous from observation with what animals eat when to plant and harvest ( calendar plants). Possess skills ( art ) in selecting superior plants as the source of planting material for next season planting. Have practical knowledge how to bred plant as practiced by Assyrians 4,000 years ago, plants have sex. Though exact methods are lost in antiquity but archeological evidence suggest that it was practiced by early plant breeders.Attendant to the development of early plant breeding is the evolution of agriculture. On the basis of World history, we can connect plant breeding in the evolution of agriculture across time. It appears that around 400 BCE all major food crops have been domesticated and early plant breeders had a significant role in this agricultural innovations.
Timeline of agricultural innovation and world population-10,000 to 500 B.C.E.
Neolithic revolution begins in Southwest Asia and othe areas.Climate change resulted in longer dry season and the end of 100,000years ice age . Abundane of wild grains enable hunter-gatherers to settle in villages. Domestication of dos begins Asia and North America
The "founder crops" of agriculture appears: wheat, barley, peas, lentils, bitter gourd, vetch, chick peas, and flax
Nomadic hunter-gatherer begin to grow food and domesticate animals. Rice in China-7,000BCE, whear in Mesopotamia-8,500BCE, squash in Mexico-7,000BCE, cattle in SWAsia and India-7,000BCE
Domestication of cattle begins in SWAsia , Pakistan, and India
A wooden plow , the Ard.used Iin Mesopotamia and Egypt Permanent villages in established in the banks of Nile River
Domestication of horses begins inUkraine, donkeys in Egypt, buffalo in China, Corn (maize) production in Mexico
Irrigation systems and dams built in Nile River.Crop production increases trade and spread of agriculture. Potatos domesticated in Peru
Iron plow developed in China
Manure used as fertilizer. Iron plow widely used in China and Southwest Asia
Mouldboard plow with a V-shaped iron cutt ing edge developed in China
Recall that the first agricultural innovation was the Neolithic Revolution around 10,000 BC and the second agricultural innovation-the Green Revolution started in 1960's and the third agricultural innovation-Genetic Engineering started around the 1970's. Unlike its predecessor, today's Plant Breeding is back up by knowledge from different sciences.The methods used by early plant breeders may be classified as primitive and yet this primitive cultivars developed by our ancestors 4,000 years ago are still with us giving nourishment to our resource-poor farmers. Off course the scenario is changed, there are more people to feed now than before and it seems that the food supply is at the hands of the few. Of the estimated 30,000 edible plant species, only 15 species supply 90 percent of our food. and 60 percent of our dietary needs comes from the three great kinds of cereal: Wheat, corn (maize) and rice. If the prediction of population growth is true, then by the year 2025, there will be 8 billion mouths coming to dinner.The question now, is the third agricultural innovation-Genetic Engineering, provide the solution to this grim scenario? without sacrificing the ecological balance of the global community? According to Storey (1972) “An unfortunate modern tendency is for the scientific plant breeder to become too much scientific and not enough breeder. he becomes too engross with the theoretical genetical aspect of the problem to give much attention to the practical aspects. In other words, he forgets that the first responsibility of a plant breeder is to breed plants”
Recommendations and Conclusion
Ten thousand years ago, a new breed of people known as the early plant breeders were instrumental in the development of agriculture, lacking the scientific knowledge and armed only with intuitive knowledge, experience, and observations these early plant breeders were able to select and improved many of our food crops and have come down to us unchanged through centuries and some have not improved since. With three agricultural innovations at our fingertips, presently we are still threatened with food insecurity especially in the developing countries Modern plant breeders should be able to find solution to this global problem- food insecurity after all, the early plant breeders have found solution to this problem.
“We cannot solve our problems with the same thinking we used
when we created them”
Quote from Albert Einstein.
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