How many domesticated animals are there in the world

Domesticated species are not wild. Plant Domestication People first domesticated plants about 10, years ago, between the Tigris and Euphrates rivers in Mesopotamia which includes the modern countries of Iran, Iraq, Turkey, and Syria. People collected and planted the seeds of wild plants.

They made sure the plants had as much water as they needed to grow, and planted them in areas with the right amount of sun. Weeks or months later, when the plants blossomed, people harvested the food crops. The first domesticated plants in Mesopotamia were wheat , barley , lentils, and types of peas. People in other parts of the world, including eastern Asia, parts of Africa, and parts of North and South America, also domesticated plants.

Other plants that were cultivated by early civilizations included rice in Asia and potatoes in South America. Plants have not only been domesticated for food. Cotton plants were domesticated for fiber , which is used in cloth. Some flowers, such as tulips, were domesticated for ornamental , or decorative, reasons.

Animal Domestication About the same time they domesticated plants, people in Mesopotamia began to tame animals for meat, milk, and hides. Hides, or the skins of animals, were used for clothing, storage , and to build tent shelters. Goats were probably the first animals to be domesticated, followed closely by sheep. In Southeast Asia, chickens also were domesticated about 10, years ago.

Later, people began domesticating larger animals, such as oxen or horses, for plowing and transportation. These are known as beasts of burden. Domesticating animals can be difficult work.

The easiest animals to domesticate are herbivores that graze on vegetation, because they are easiest to feed: They do not need humans to kill other animals to feed them, or to grow special crops. Cows, for instance, are easily domesticated. Herbivores that eat grains are more difficult to domesticate than herbivores that graze because grains are valuable and also need to be domesticated. Chickens are herbivores that eat seeds and grain.

Some animals domesticated for one purpose no longer serve that purpose. Some dogs were domesticated to assist people in hunting, for instance. There are hundreds of domestic dog species today.

Many of them are still excellent hunters, but most are pets. Throughout history, people have bred domesticated animals to promote certain traits. Domestic animals are chosen for their ability to breed in captivity and for their calm temperament. Their ability to resist disease and survive in difficult climates is also valuable. By clicking 'Got It' you're accepting these terms. A first-of-its-kind study published Monday shows that, when it comes to impacting life on Earth, humans are punching well above our weight.

The study, published in Proceedings of the National Academy of Sciences , is the first ever comprehensive census of the distribution of the biomass, or weight of living creatures, across classification type and environment. It found that, while humans account for 0.

According to the study, human impacts are due to the combined effects of the agricultural and industrial revolutions. In particular, the domestication of livestock has caused a shift in the relative biomass of different species of mammals. Humans account for about 36 percent of the biomass of all mammals.

Domesticated livestock, mostly cows and pigs, account for 60 percent, and wild mammals for only 4 percent. The same holds true for birds.

The biomass of poultry is about three times higher than that of wild birds. In the prey pathway, humans have initiated domestication, perhaps as a response to depletion of local stocks of prey animals that humans had hunted for thousands of years [ 31 ], to enhance the yield or predictability of a resource meat or hides [ 29 ].

Over time and under certain circumstances, these game management strategies developed into actual herd management and, eventually, the controlled breeding of managed animals [ 28 ]. The main species that followed this pathway are sheep Ovis aries , goat Capra hircus , or cattle Bos taurus [ 29 ]. In the direct pathway, humans deliberately set out to domesticate a species [ 28 , 31 ].

This pathway skips the early phases of habituation and management and starts with the capture of wild animals with the deliberate intention of controlling their reproduction [ 29 ]. This pathway occurred more rapidly and was accompanied by a dramatic bottleneck [ 29 ]. The main species are horse Equus caballus , donkey Equus asinus , and dromedary Camelus dromedarius [ 28 ].

Species that followed either commensal or prey pathways tend to possess more traits that make them appropriate candidates for domestication. Conversely, species on directed pathways likely possess barriers to domestication that require more knowledge on the part of humans to overcome [ 28 , 31 ].

Whatever the pathway followed, captive animals began to be domesticated at some point. Yet, as for domestication, there is no consensus today about what a domesticated species is see [ 27 ] for a review of the main definitions. Nevertheless, most authors considered that a domesticated species is a group of animals reproduced in captivity and modified from their wild congeners [ 27 ]. In other words, there is not a clear biological separation between wild and domesticated animals [ 33 ].

In addition, a domesticated animal is neither in a final nor a static status, and thus farmed species are still evolving today, particularly in response to changes in technology and husbandry practices, which themselves are evolving and constantly improving [ 34 ]. Conversely, domesticated species can sometimes return to nature, a process known as feralization [ 35 ]. During domestication, five main genetic processes were involved [ 15 , 28 , 34 ], including inbreeding and genetic drift two uncontrolled processes , natural selection in captivity and relaxation of natural selection two partially controlled processes , and active selection one controlled process [ 34 , 35 ].

The two uncontrolled processes are due to the limited size of the population known as inbreeding and the random changes in gene frequencies genetic drift. The two partially controlled processes are natural selection in captivity that accounts for selection imposed on captive populations that cannot be attributed to active or artificial selection and relaxation of natural selection expectably accompanying the transition from wild to captive environments [ 35 ].

At last, the fifth genetic process is controlled, known as active selection, because changes are directional [ 34 , 35 ]. Domesticated animals have been profoundly modified during domestication. Indeed, the variation range of certain traits within a domesticated species occasionally exceeds that in whole families or even orders [ 36 , 37 ]. Modifications resulting from domestication concern morphoanatomy, physiology, behavior, and genetics [ 31 , 35 , 38 , 39 , 40 ].

Behavior is probably the first to have been modified during domestication [ 35 ]. Nevertheless, behavioral traits neither appeared nor disappeared during domestication but rather are the response thresholds that changed [ 34 , 35 ].

One of the most remarkable behavioral changes shared by all domesticates is their tolerance of proximity to or complete lack of fear of people [ 31 , 37 , 39 ]. Besides, because humans provide shelter, food, and protection against predators, domesticated animals most often express a lower incidence of antipredator behaviors and show lower motivation for foraging [ 34 ]. More generally, mood, emotion, agnostic and affiliative behavior, as well as social communication all have been modified in some way by domestication [ 39 ].

Most domesticated animals are also more precocious than their wild counterparts [ 34 ]. The activity of their reproductive system became enhanced and relatively uncoupled from the environmental photoperiod, and they all acquired the capacity to reproduce in any season and more often than once a year [ 37 ]. At last, the most spectacular and obvious changes concern morphology, among which are the animal size dwarfs and giants , proportions fewer vertebrae, shorter tails , color, length and texture of coat, wavy or curly hair, rolled tails, and floppy ears or other manifestations of neoteny the retention of juvenile features into sexual maturity [ 37 , 39 ].

In most domesticated species, head or brain size has decreased [ 34 ]. The most illustrative example of such considerable changes is the morphological variations in dogs [ 37 ].

At the beginning of the twentieth century, modern breeding programs were initiated, leading to dramatic changes in productivity, e. Even though the decision to consider farmed or captive animals as domesticated is subjective and arbitrary [ 35 , 41 ], most authors agree that about 40 species around the world that directly or indirectly contribute to agriculture are domesticated; this number varies between 20 and 50 following the definitions used for a domesticated animal [ 36 , 42 , 43 , 44 ].

Several of those domesticated species have a distinct scientific name than their wild ancestors [ 25 ]. For the five most valuable species, the domestication resulted in the creation of hundreds of breeds, particularly in the past centuries [ 42 , 45 , 46 ].

In France, the article D. Breeds have therefore both a biological sense common features and a social acceptance group of breeders ; the relative importance of the latter increased in the past years, for scientists as well as in the application of policies [ 47 ]. The wild ancestor of cattle is a group of races of the now extinct aurochs Bos primigenius [ 48 , 49 , 50 ]. The aurochs, the last specimen of which died in a Polish park in , had a very wide geographic distribution, which extended from East Asia to Europe and North Africa [ 42 , 48 , 50 ].

Traditionally, two major types of domestic cattle are considered: zebu Bos indicus which have a prominent thoracic hump and taurine Bos taurus , which do not [ 40 , 42 , 49 , 50 ]. However, these two species fully interbreed, and a meta-analysis of different microsatellite datasets revealed taurine-zebu admixture over Europe, southwest Asia, and Africa [ 40 , 45 , 49 , 50 ]. Molecular evidence suggest that these two species came from two independent domestication events: zebu cattle were domesticated in the Indus valley region ca.

However, Larson and Burger [ 29 ] recently suggested that only the latter was domesticated, while zebu may have resulted from the introgression of wild zebu populations into taurine cattle that were transported eastward.

During several millennia, extensive gene flow among different groups of domestic cattle, as well as with aurochs until its extinction, was possible, leading to relatively high effective population sizes and preventing genetic drift at the regional scale [ 40 , 48 , 50 , 51 ]. This might partly explain the relatively large cattle gene pool despite a likely bottleneck at the time of domestication [ 50 ]. Besides, it is also possible that other species were crossed with cattle in some areas of the world, including the yak Bos grunniens in Nepal or banteng Bos javanicus in Southeast Asia and Indonesia, which also contribute to maintain or increase genetic variability [ 40 ].

The large size of cattle and its low growth, as well as the early use for milk or traction, imply relatively low levels of directed selection during millennia [ 51 ]. However, this situation changed dramatically about years ago with the emergence of breed concept [ 50 ]. The first cattle herd book was published in Britain in [ 49 ]. Since that time, stronger selection pressures have been applied to local populations followed by standardization of the desired conformation and performance, such as high milk yield for dairy cattle breeding programs [ 49 ].

This led to an isolation of breeds from each other ca. Nevertheless, gene flow between neighboring regions did not completely stop, as deliberate upgrading was realized in order to increase production characteristics by using bulls of other populations from the same or a different country [ 45 ]. More recently, the number of males involved in reproduction schemes has drastically decreased with the expansion of artificial insemination, leading to another strong reduction of effective population size of breeds and inexorably to a genetic drift and loss of alleles [ 46 , 50 , 63 ].

For example, at the worldwide level, the Holstein cattle has an effective population size of about 50 [ 50 ]. This strong decrease of the effective population size might explain the strong reduction in fertility as well as the genetic diseases observed in this breed [ 50 ].

An even more extreme result was found in Japan, where the Japanese black cattle had an effective population size of Another extreme case of low genetic variability is a feral British breed, Chillingham cattle, for which 24 out of 25 microsatellite loci were found homozygous [ 46 ].

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