Geophagia

Geophagia is widespread in the animal kingdom. Galen, the Greek philosopher and physician, was the first to record the use of clay by sick or injured animals in the second century AD. This type of geophagia has been documented in "many species of mammals, birds, reptiles, butterflies and isopods, especially among herbivores". Birds Many species of South American parrots have been observed at clay licks, and sulphur-crested cockatoos have been observed ingesting clays in Papua New Guinea. Analysis of soils consumed by wild birds show that they often prefer soils with high clay content, usually with the smectite clay families being well represented. The preference for certain types of clay or soil can lead to unusual feeding behaviour. For example, Peruvian Amazon rainforest parrots congregate not just at one particular bend of the Manu River but at one specific layer of soil which runs hundreds of metres horizontally along that bend. The parrots avoid eating the substrate in layers one metre above or below the preferred layer. These parrots regularly eat seeds and unripe fruits containing alkaloids and other toxins that render the seeds and fruits bitter and even lethal. Because many of these chemicals become positively charged in the acidic stomach, they bind to clay minerals which have negatively charged cation-exchange sites, and are thereby rendered safe. Their preferred soils have a much higher cation-exchange capacity than the adjacent, rejected layers of soils because they are rich in the minerals smectite, kaolin, and mica. The preferred soils surpass the pure mineral kaolinate and surpass or approach pure bentonite in their capacity to bind quinine and tannic acid. It is unclear which factor is driving avian geophagy. However, evidence is mounting that sodium is the most important driver among parrots in southeastern Peru. Parrots are known to eat toxic foods globally, but geophagy is concentrated in very specific regions. Researchers Lee etal. show that parrot geophagy in South America is positively correlated to a significant degree with distance from the ocean. This suggests that overall lack of sodium in the ecosystem, not variation in food toxicity, is a better predictor of the spatial distribution of geophagy. This work, coupled with the recent findings of consistently high sodium levels in consumed soils, Non-human primates (Propithecus candidus) eating earth There are several hypotheses about the importance of geophagia in bats and primates. Chimpanzees in Kibale National Park, Uganda, have been observed to consume soil rich in kaolinite clay shortly before or after consuming plants including Trichilia rubescens, which possesses antimalarial properties in the laboratory. Geophagy is a behavioural adaptation seen in 136 species of nonhuman primates from the suborder Haplorrhini (81%) and Strepsirrhini (19%). The most commonly ingested soils are soils from mounds, soils from tree bases, soils from termite mounds, 'Pong' soils, and forest floor. Studies have shown many benefits of geophagy such as protection from parasites (4.9%), mineral supplements (19.5%), and helping to metabolize toxic compounds from leaves (12.2%) nonexclusive. Geophagic behaviour plays an important role in nonhuman primates' health. In other cases, geophagy is used by the Ring-Tailed Lemurs as a preventive and therapeutic behaviour for parasite control and intestinal infection. The study was done at the salt licks in Veun Sai-Siem Pang Conservation Area, a site that is visited by various species of nonhuman primates. Therefore, mineral supplementation is unlikely to be the primary reason for geophagia in bats. Additionally, bat presence at salt licks increases during periods of high energy demand. ==Humans==

Anthropological and historical evidence Evidence for the likely origin of geophagy was found in the remains of early humans in Africa: Geophagia is nearly universal around the world in tribal and traditional rural societies (although apparently it has not been documented in Japan or Korea). The textbook of Hippocrates (460–377 BCE) mentions geophagia, and the famous medical textbook titled De Medicina edited by A.Cornelius Celsus (14–37 CE) seems to link anaemia to geophagia. The existence of geophagy among Native Americans was noted by early explorers in the Americas, including Gabriel Soares de Sousa, who in 1587 reported a tribe in Brazil using it in suicide, and Cameroon), calaba, and calabachop (in Equatorial Guinea), is eaten for pleasure or to suppress hunger. Consumption is greatest among women, especially to cure nausea during pregnancy, in spite of the possible dangerous levels of arsenic and lead to the unborn child. Another example of geophagia was reported in Mangaung, Free State Province in South Africa, where the practice was geochemically investigated. s being prepared In Haiti, poor people are known to eat bonbon tè made from soil, salt, and vegetable shortening. These biscuits hold minimal nutritional value, but manage to keep the poor alive. However, long-term consumption of the biscuits is reported to cause stomach pains and malnutrition, and is not recommended by doctors. Some Southern African American communities consume kaolin as a supplement and traditional medicine, particularly for pregnant women. The practice was reportedly declining by 1984 but has continued In some communities well into the 21st century. In Central Java and East Java, Indonesia a food made of soil called ampo is eaten as a snack or light meal. It consists of pure clay, without any mixture of ingredients. Impact on health in the soil that has been eaten by a woman shows up as white on this plain X-ray Clay minerals have been reported to have beneficial microbiological effects, such as protecting the stomach against toxins, parasites, and pathogens. Humans are not able to synthesize vitamin B12 (cobalamin), so geophagia may be a behavioral adaptation to obtain it from bacteria in the soil. Mineral content in soils may vary by region, but many contain high levels of calcium, copper, magnesium, iron, and zinc, minerals that are critical for developing fetuses which can cause metallic, soil, or chewing ice cravings in pregnant women. To the extent that these cravings, and subsequent mineral consumption (as well as in the case of cravings for ice, or other cold neck vasoconstricting food which aid in increasing brain oxygen levels by restricting neck veins) are therapeutically effective decreasing infant mortality, those genetic predispositions and the associated environmental triggers, are likely to be found in the infant as well. Likewise, multigenerationally impoverished villages or other homogenous socioeconomic closed genetic communities are more likely to have rewarded gene expression of soil or clay consumption cravings, by increasing the likelihood of survival through multiple pregnancies for both sexes. There are obvious health risks in the consumption of soil that is contaminated by animal or human feces; in particular, helminth eggs, such as Ascaris, which can stay viable in the soil for years, can lead to helminth infections. Tetanus poses a further risk. as well as health risks associated with zinc exposure can be problematic among people who eat soils on a regular basis. Gestational geophagia (geophagia in pregnancy) has been associated with various homeostatic disruptions and oxidative damage in rats. ==See also==