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134-572: The Caral culture developed between 3000 and 1800 B.C (Late Archaic and Lower Formative periods). In America, it is the oldest of the pre-Hispanic civilizations, developing 1,500 years earlier than the Olmec civilization , the first Mesoamerican complex society. Closely related to the city of Caral was an early fishing city, Áspero or El Áspero , located on the coast near the mouth of the Supe River. There, remains of human sacrifices (two children and

268-570: A rubber tree in the area. The juice of a local vine, Ipomoea alba , was then mixed with this latex to create rubber as early as 1600 BCE. The Nahuatl word for the Olmecs was Ōlmēcatl [oːlˈmeːkat͡ɬ] (singular) or Ōlmēcah [oːlˈmeːkaʔ] (plural). This word is composed of the two words ōlli [ˈoːlːi] , meaning " natural rubber ", and mēcatl [ˈmeːkat͡ɬ] , meaning "people". Early modern explorers and archaeologists, however, mistakenly applied

402-422: A beta particle (an electron , e ) and an electron antineutrino ( ν e ), one of the neutrons in the C nucleus changes to a proton and the C nucleus reverts to the stable (non-radioactive) isotope N . During its life, a plant or animal is in equilibrium with its surroundings by exchanging carbon either with the atmosphere or through its diet. It will, therefore, have

536-588: A colossal head required the efforts of 1,500 people for three to four months. Some of the heads, and many other monuments, have been variously mutilated, buried and disinterred, reset in new locations and/or reburied. Some monuments, and at least two heads, were recycled or recarved, but it is not known whether this was simply due to the scarcity of stone or whether these actions had ritual or other connotations. Scholars believe that some mutilation had significance beyond mere destruction, but some scholars still do not rule out internal conflicts or, less likely, invasion as

670-527: A decade. It was revised again in the early 1960s to 5,730 ± 40 years, which meant that many calculated dates in papers published prior to this were incorrect (the error in the half-life is about 3%). For consistency with these early papers, it was agreed at the 1962 Radiocarbon Conference in Cambridge (UK) to use the "Libby half-life" of 5568 years. Radiocarbon ages are still calculated using this half-life, and are known as "Conventional Radiocarbon Age". Since

804-475: A factor. The flat-faced, thick-lipped heads have caused some debate due to their resemblance to some African facial characteristics. Based on this comparison, some writers have said that the Olmecs were Africans who had emigrated to the New World. But the vast majority of archaeologists and other Mesoamerican scholars reject claims of pre-Columbian contacts with Africa. Explanations for the facial features of

938-423: A few years, but the surface waters also receive water from the deep ocean, which has more than 90% of the carbon in the reservoir. Water in the deep ocean takes about 1,000 years to circulate back through surface waters, and so the surface waters contain a combination of older water, with depleted C , and water recently at the surface, with C in equilibrium with the atmosphere. Creatures living at

1072-442: A fragment of bone, provides information that can be used to calculate when the animal or plant died. The older a sample is, the less C there is to be detected, and because the half-life of C (the period of time after which half of a given sample will have decayed) is about 5,730 years, the oldest dates that can be reliably measured by this process date to approximately 50,000 years ago (in this interval about 99.8% of

1206-408: A given sample stopped exchanging carbon – the older the sample, the less C will be left. The equation governing the decay of a radioactive isotope is: N = N 0 e − λ t {\displaystyle N=N_{0}\,e^{-\lambda t}\,} where N 0 is the number of atoms of the isotope in the original sample (at time t = 0, when

1340-400: A higher δ C than one that eats food with lower δ C values. The animal's own biochemical processes can also impact the results: for example, both bone minerals and bone collagen typically have a higher concentration of C than is found in the animal's diet, though for different biochemical reasons. The enrichment of bone C also implies that excreted material

1474-413: A mass of less than 1% of those on land and are not shown in the diagram. Accumulated dead organic matter, of both plants and animals, exceeds the mass of the biosphere by a factor of nearly 3, and since this matter is no longer exchanging carbon with its environment, it has a C / C ratio lower than that of the biosphere. The variation in the C / C ratio in different parts of

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1608-464: A newborn) have been found. In 2016, the remains were found of a woman, who presumably belonged to the local elite of 4,500 years ago. Caral was inhabited between approximately 26th century BC and 20th century BC , and the site includes an area of more than 60 hectares (150 acres). Caral has been described by its excavators as the oldest urban center in the Americas. This claim has been challenged by

1742-869: A paper in Science in 1947, in which the authors commented that their results implied it would be possible to date materials containing carbon of organic origin. Libby and James Arnold proceeded to test the radiocarbon dating theory by analyzing samples with known ages. For example, two samples taken from the tombs of two Egyptian kings, Zoser and Sneferu , independently dated to 2625 BC plus or minus 75 years, were dated by radiocarbon measurement to an average of 2800 BC plus or minus 250 years. These results were published in Science in December 1949. Within 11 years of their announcement, more than 20 radiocarbon dating laboratories had been set up worldwide. In 1960, Libby

1876-569: A pyramid. These are the "Great Temple/Great Pyramid", "Central Pyramid", "Quarry Pyramid", "Lesser Pyramid", "Pyramid of the Gallery", and "Pyramid of the Huanca". The associated residential structures around each of these pyramids contain evidence of elite living, including food remnants that would have been exclusive to elite lifestyles, such as sea lion bones. In the Upper Half of Caral, many of

2010-629: A sample. More recently, accelerator mass spectrometry has become the method of choice; it counts all the C atoms in the sample and not just the few that happen to decay during the measurements; it can therefore be used with much smaller samples (as small as individual plant seeds), and gives results much more quickly. The development of radiocarbon dating has had a profound impact on archaeology . In addition to permitting more accurate dating within archaeological sites than previous methods, it allows comparison of dates of events across great distances. Histories of archaeology often refer to its impact as

2144-522: A series of photos of Olmec artwork and of the faces of modern Mexican Indians with very similar facial characteristics. The African origin hypothesis assumes that Olmec carving was intended to be a representation of the inhabitants, an assumption that is hard to justify given the full corpus of representation in Olmec carving. Ivan Van Sertima claimed that the seven braids on the Tres Zapotes head

2278-620: Is a method for determining the age of an object containing organic material by using the properties of radiocarbon , a radioactive isotope of carbon . The method was developed in the late 1940s at the University of Chicago by Willard Libby , based on the constant creation of radiocarbon ( C ) in the Earth's atmosphere by the interaction of cosmic rays with atmospheric nitrogen . The resulting C combines with atmospheric oxygen to form radioactive carbon dioxide , which

2412-429: Is also referred to individually as a carbon exchange reservoir. The different elements of the carbon exchange reservoir vary in how much carbon they store, and in how long it takes for the C generated by cosmic rays to fully mix with them. This affects the ratio of C to C in the different reservoirs, and hence the radiocarbon ages of samples that originated in each reservoir. The atmosphere, which

2546-414: Is assumed to have originally had the same C / C ratio as the ratio in the atmosphere, and since the size of the sample is known, the total number of atoms in the sample can be calculated, yielding N 0 , the number of C atoms in the original sample. Measurement of N , the number of C atoms currently in the sample, allows the calculation of t , the age of the sample, using

2680-440: Is contaminated so that 1% of the sample is modern carbon, it will appear to be 600 years younger; for a sample that is 34,000 years old, the same amount of contamination would cause an error of 4,000 years. Contamination with old carbon, with no remaining C , causes an error in the other direction independent of age – a sample contaminated with 1% old carbon will appear to be about 80 years older than it truly is, regardless of

2814-428: Is depleted in C because of the marine effect, C is removed from the southern atmosphere more quickly than in the north. The effect is strengthened by strong upwelling around Antarctica. If the carbon in freshwater is partly acquired from aged carbon, such as rocks, then the result will be a reduction in the C / C ratio in the water. For example, rivers that pass over limestone , which

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2948-400: Is depleted in C relative to the diet. Since C makes up about 1% of the carbon in a sample, the C / C ratio can be accurately measured by mass spectrometry . Typical values of δ C have been found by experiment for many plants, as well as for different parts of animals such as bone collagen , but when dating a given sample it is better to determine

3082-426: Is done by calibration curves (discussed below), which convert a measurement of C in a sample into an estimated calendar age. The calculations involve several steps and include an intermediate value called the "radiocarbon age", which is the age in "radiocarbon years" of the sample: an age quoted in radiocarbon years means that no calibration curve has been used − the calculations for radiocarbon years assume that

3216-409: Is incorporated into plants by photosynthesis ; animals then acquire C by eating the plants. When the animal or plant dies, it stops exchanging carbon with its environment, and thereafter the amount of C it contains begins to decrease as the C undergoes radioactive decay . Measuring the proportion of C in a sample from a dead plant or animal, such as a piece of wood or

3350-459: Is less CO 2 available for the photosynthetic reactions. Under these conditions, fractionation is reduced, and at temperatures above 14 °C (57 °F) the δ C values are correspondingly higher, while at lower temperatures, CO 2 becomes more soluble and hence more available to marine organisms. The δ C value for animals depends on their diet. An animal that eats food with high δ C values will have

3484-415: Is mostly composed of calcium carbonate , will acquire carbonate ions. Similarly, groundwater can contain carbon derived from the rocks through which it has passed. These rocks are usually so old that they no longer contain any measurable C , so this carbon lowers the C / C ratio of the water it enters, which can lead to apparent ages of thousands of years for both the affected water and

3618-438: Is much smaller; hardstone carvings in jade of a face in a mask form. Jade is a particularly precious material, and it was used as a mark of rank by the ruling classes. By 1500 BCE early Olmec sculptors mastered the human form. This can be determined by wooden Olmec sculptures discovered in the swampy bogs of El Manati. Before radiocarbon dating could tell the exact age of Olmec pieces, archaeologists and art historians noticed

3752-444: Is naturalistic. Other art expresses fantastic anthropomorphic creatures, often highly stylized, using an iconography reflective of a religious meaning. Common motifs include downturned mouths and a cleft head, both of which are seen in representations of werejaguars . In addition to making human and human-like subjects, Olmec artisans were adept at animal portrayals. While Olmec figurines are found abundantly in sites throughout

3886-406: Is now generally accepted that these heads are portraits of rulers, perhaps dressed as ballplayers. Infused with individuality, no two heads are alike and the helmet-like headdresses are adorned with distinctive elements, suggesting personal or group symbols. Some have also speculated that Mesoamerican people believed that the soul, along with all of one's experiences and emotions, was contained inside

4020-419: Is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age. Other corrections must be made to account for the proportion of C in different types of organisms (fractionation), and the varying levels of C throughout the biosphere (reservoir effects). Additional complications come from the burning of fossil fuels such as coal and oil, and from

4154-456: Is sometimes called) percolates into the rest of the reservoir. Photosynthesis is the primary process by which carbon moves from the atmosphere into living things. In photosynthetic pathways C is absorbed slightly more easily than C , which in turn is more easily absorbed than C . The differential uptake of the three carbon isotopes leads to C / C and C / C ratios in plants that differ from

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4288-453: Is the main pathway by which C is created: n + 7 N → 6 C + p where n represents a neutron and p represents a proton . Once produced, the C quickly combines with the oxygen ( O ) in the atmosphere to form first carbon monoxide ( CO ), and ultimately carbon dioxide ( CO 2 ). C + O 2 → CO + O CO + OH → CO 2 + H Carbon dioxide produced in this way diffuses in

4422-565: Is usually needed to determine the size of the offset, for example by comparing the radiocarbon age of deposited freshwater shells with associated organic material. Volcanic eruptions eject large amounts of carbon into the air. The carbon is of geological origin and has no detectable C , so the C / C ratio in the vicinity of the volcano is depressed relative to surrounding areas. Dormant volcanoes can also emit aged carbon. Plants that photosynthesize this carbon also have lower C / C ratios: for example, plants in

4556-399: Is where C is generated, contains about 1.9% of the total carbon in the reservoirs, and the C it contains mixes in less than seven years. The ratio of C to C in the atmosphere is taken as the baseline for the other reservoirs: if another reservoir has a lower ratio of C to C , it indicates that the carbon is older and hence that either some of

4690-402: The C has decayed, or the reservoir is receiving carbon that is not at the atmospheric baseline. The ocean surface is an example: it contains 2.4% of the carbon in the exchange reservoir, but there is only about 95% as much C as would be expected if the ratio were the same as in the atmosphere. The time it takes for carbon from the atmosphere to mix with the surface ocean is only

4824-526: The C will have decayed), although special preparation methods occasionally make an accurate analysis of older samples possible. In 1960, Libby received the Nobel Prize in Chemistry for his work. Research has been ongoing since the 1960s to determine what the proportion of C in the atmosphere has been over the past 50,000 years. The resulting data, in the form of a calibration curve ,

4958-489: The C / C ratio in the atmosphere. This increase in C concentration almost exactly cancels out the decrease caused by the upwelling of water (containing old, and hence C -depleted, carbon) from the deep ocean, so that direct measurements of C radiation are similar to measurements for the rest of the biosphere. Correcting for isotopic fractionation, as is done for all radiocarbon dates to allow comparison between results from different parts of

5092-404: The δ C value for that sample directly than to rely on the published values. The carbon exchange between atmospheric CO 2 and carbonate at the ocean surface is also subject to fractionation, with C in the atmosphere more likely than C to dissolve in the ocean. The result is an overall increase in the C / C ratio in the ocean of 1.5%, relative to

5226-475: The 19th century . Among other "firsts", the Olmec appeared to practice ritual bloodletting and played the Mesoamerican ballgame , hallmarks of nearly all subsequent Mesoamerican societies. The aspect of the Olmecs most familiar now is their artwork, particularly the colossal heads . The Olmec civilization was first defined through artifacts which collectors purchased on the pre-Columbian art market in

5360-546: The Aztecs buried it, suggesting such masks were valued and collected as were Roman antiquities in Europe. The 'Olmec-style' refers to the combination of deep-set eyes, nostrils, and strong, slightly asymmetrical mouth. The "Olmec-style" also very distinctly combines facial features of both humans and jaguars. Olmec arts are strongly tied to the Olmec religion, which prominently featured jaguars. The Olmec people believed that in

5494-482: The Formative Period , the stone monuments such as the colossal heads are the most recognizable feature of Olmec culture. These monuments can be divided into four classes: The most recognized aspect of the Olmec civilization are the enormous helmeted heads. As no known pre-Columbian text explains them, these impressive monuments have been the subject of much speculation. Once theorized to be ballplayers, it

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5628-616: The Isthmian script , and while there are some who believe that the Isthmian may represent a transitional script between an earlier Olmec writing system and the Maya script, the matter remains unsettled. The Long Count calendar used by many subsequent Mesoamerican civilizations, as well as the concept of zero , may have been devised by the Olmecs. Because the six artifacts with the earliest Long Count calendar dates were all discovered outside

5762-719: The Juxtlahuaca and Oxtotitlán cave paintings feature Olmec designs and motifs. Olmec influence is also seen at several sites in the Southern Maya area . In Guatemala, sites showing probable Olmec influence include San Bartolo , Takalik Abaj and La Democracia . Many theories have been advanced to account for the occurrence of Olmec influence far outside the heartland, including long-range trade by Olmec merchants, Olmec colonization of other regions, Olmec artisans travelling to other cities, conscious imitation of Olmec artistic styles by developing towns – some even suggest

5896-943: The Tlatilco culture in the Valley of Mexico , where artifacts include hollow baby-face motif figurines and Olmec designs on ceramics. Chalcatzingo , in Valley of Morelos , central Mexico, which features Olmec-style monumental art and rock art with Olmec-style figures. Also, in 2007, archaeologists unearthed Zazacatla , an Olmec-influenced city in Morelos. Located about 40 kilometres (25 mi) south of Mexico City, Zazacatla covered about 2.5 square kilometres (1 sq mi) between 800 and 500 BCE. Teopantecuanitlan , in Guerrero , which features Olmec-style monumental art as well as city plans with distinctive Olmec features. Also,

6030-434: The quipu also may have recorded logographic information in the same way writing does. Gary Urton has suggested that the quipus used a binary code that could record phonological or logographic data. The main temple complex ( Spanish : Templo Mayor ) is 150 meters (490 ft) long, 110 meters (360 ft) wide and 28 meters (92 ft) high. The date of its construction is unknown. Shady's findings suggest it

6164-677: The "radiocarbon revolution". Radiocarbon dating has allowed key transitions in prehistory to be dated, such as the end of the last ice age , and the beginning of the Neolithic and Bronze Age in different regions. In 1939, Martin Kamen and Samuel Ruben of the Radiation Laboratory at Berkeley began experiments to determine if any of the elements common in organic matter had isotopes with half-lives long enough to be of value in biomedical research. They synthesized C using

6298-502: The 2006 find from a site near San Lorenzo shows a set of 62 symbols, 28 of which are unique, carved on a serpentine block. A large number of prominent archaeologists have hailed this find as the "earliest pre-Columbian writing". Others are skeptical because of the stone's singularity, the fact that it had been removed from any archaeological context, and because it bears no apparent resemblance to any other Mesoamerican writing system. There are also well-documented later hieroglyphs known as

6432-472: The Lower Half was designed to house laborers, with the river serving as the division between these groups. This sort of intentional city planning is evidence of structuralized inequality at Caral, which perpetuated existing social stratification. Olmec civilization The Olmecs ( / ˈ ɒ l m ɛ k s , ˈ oʊ l -/ ) were the earliest known major Mesoamerican civilization, flourishing in

6566-712: The Olmec culture is tenocelome , meaning "mouth of the jaguar ". The Olmec heartland is the area in the Gulf lowlands where it expanded after early development in Soconusco , Veracruz. This area is characterized by swampy lowlands punctuated by low hills, ridges, and volcanoes. The Sierra de los Tuxtlas rises sharply in the north, along the Gulf of Mexico's Bay of Campeche . Here, the Olmec constructed permanent city-temple complexes at San Lorenzo Tenochtitlán , La Venta , Tres Zapotes , and Laguna de los Cerros . In this region,

6700-566: The Olmec heartland, continued to be occupied well past 400 BCE , but without the hallmarks of the Olmec culture. This post-Olmec culture, often labeled the Epi-Olmec , has features similar to those found at Izapa , some 550 kilometres (340 mi) to the southeast. The Olmec culture was first defined as an art style, and this continues to be the hallmark of the culture. Wrought in a large number of media – jade, clay, basalt, and greenstone among others – much Olmec art, such as The Wrestler ,

6834-435: The Olmec instituted human sacrifice is significantly more speculative. No Olmec or Olmec-influenced sacrificial artifacts have yet been discovered; no Olmec or Olmec-influenced artwork unambiguously shows sacrificial victims (as do the danzante figures of Monte Albán ) or scenes of human sacrifice (such as can be seen in the famous ballcourt mural from El Tajín ). At El Manatí, disarticulated skulls and femurs, as well as

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6968-414: The Olmec remains unknown, various hypotheses have been put forward. For example, in 1968 Michael D. Coe speculated that the Olmec were Maya predecessors. In 1976, linguists Lyle Campbell and Terrence Kaufman published a paper in which they argued a core number of loanwords had apparently spread from a Mixe–Zoquean language into many other Mesoamerican languages . Campbell and Kaufman proposed that

7102-457: The Olmecs formulated the forerunners of many of the later Mesoamerican deities . Although the archaeological record does not include explicit representation of Olmec bloodletting , researchers have found other evidence that the Olmec ritually practiced it. For example, numerous natural and ceramic stingray spikes and maguey thorns have been found at Olmec sites, and certain artifacts have been identified as bloodletters. The argument that

7236-567: The Sierra de los Tuxtlas. The Tres Zapotes heads, for example, were sculpted from basalt found at the summit of Cerro el Vigía, at the western end of the Tuxtlas. The San Lorenzo and La Venta heads, on the other hand, were probably carved from the basalt of Cerro Cintepec, on the southeastern side, perhaps at the nearby Llano del Jicaro workshop, and dragged or floated to their final destination dozens of miles away. It has been estimated that moving

7370-399: The above-ground nuclear tests performed in the 1950s and 1960s. Because the time it takes to convert biological materials to fossil fuels is substantially longer than the time it takes for its C to decay below detectable levels, fossil fuels contain almost no C . As a result, beginning in the late 19th century, there was a noticeable drop in the proportion of C in

7504-399: The actual calendar date, both because it uses the wrong value for the half-life of C , and because no correction (calibration) has been applied for the historical variation of C in the atmosphere over time. Carbon is distributed throughout the atmosphere, the biosphere, and the oceans; these are referred to collectively as the carbon exchange reservoir, and each component

7638-418: The appropriate correction for the location of their samples. The effect also applies to marine organisms such as shells, and marine mammals such as whales and seals, which have radiocarbon ages that appear to be hundreds of years old. The northern and southern hemispheres have atmospheric circulation systems that are sufficiently independent of each other that there is a noticeable time lag in mixing between

7772-457: The atmosphere as the carbon dioxide generated from burning fossil fuels began to accumulate. Conversely, nuclear testing increased the amount of C in the atmosphere, which reached a maximum in about 1965 of almost double the amount present in the atmosphere prior to nuclear testing. Measurement of radiocarbon was originally done with beta-counting devices, which counted the amount of beta radiation emitted by decaying C atoms in

7906-438: The atmosphere might be expected to decrease over thousands of years, but C is constantly being produced in the lower stratosphere and upper troposphere , primarily by galactic cosmic rays , and to a lesser degree by solar cosmic rays. These cosmic rays generate neutrons as they travel through the atmosphere which can strike nitrogen-14 ( N ) atoms and turn them into C . The following nuclear reaction

8040-547: The atmosphere, is dissolved in the ocean, and is taken up by plants via photosynthesis . Animals eat the plants, and ultimately the radiocarbon is distributed throughout the biosphere . The ratio of C to C is approximately 1.25 parts of C to 10 parts of C . In addition, about 1% of the carbon atoms are of the stable isotope C . The equation for the radioactive decay of C is: 6 C → 7 N + e + ν e By emitting

8174-421: The atmospheric C / C ratio has not changed over time. Calculating radiocarbon ages also requires the value of the half-life for C . In Libby's 1949 paper he used a value of 5720 ± 47 years, based on research by Engelkemeir et al. This was remarkably close to the modern value, but shortly afterwards the accepted value was revised to 5568 ± 30 years, and this value was in use for more than

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8308-425: The biosphere, gives an apparent age of about 400 years for ocean surface water. Libby's original exchange reservoir hypothesis assumed that the C / C ratio in the exchange reservoir is constant all over the world, but it has since been discovered that there are several causes of variation in the ratio across the reservoir. The CO 2 in the atmosphere transfers to the ocean by dissolving in

8442-454: The calibration curve (IntCal) also reports past atmospheric C concentration using this conventional age, any conventional ages calibrated against the IntCal curve will produce a correct calibrated age. When a date is quoted, the reader should be aware that if it is an uncalibrated date (a term used for dates given in radiocarbon years) it may differ substantially from the best estimate of

8576-435: The carbon exchange reservoir means that a straightforward calculation of the age of a sample based on the amount of C it contains will often give an incorrect result. There are several other possible sources of error that need to be considered. The errors are of four general types: In the early years of using the technique, it was understood that it depended on the atmospheric C / C ratio having remained

8710-500: The carbon exchange reservoir, but because of the long delay in mixing with the deep ocean, the actual effect is a 3% reduction. A much larger effect comes from above-ground nuclear testing, which released large numbers of neutrons into the atmosphere, resulting in the creation of C . From about 1950 until 1963, when atmospheric nuclear testing was banned , it is estimated that several tonnes of C were created. If all this extra C had immediately been spread across

8844-431: The cause of the eventual extinction of the Olmec culture. Between 400 and 350 BCE , the population in the eastern half of the Olmec heartland dropped precipitously, and the area was sparsely inhabited until the 19th century. According to archaeologists, this depopulation was probably the result of "very serious environmental changes that rendered the region unsuited for large groups of farmers", in particular changes to

8978-431: The colossal heads include the possibility that the heads were carved in this manner due to the shallow space allowed on the basalt boulders. Others note that in addition to the broad noses and thick lips, the eyes of the heads often show the epicanthic fold , and that all these characteristics can still be found in modern Mesoamerican Indians. For instance, in the 1940s, the artist/art historian Miguel Covarrubias published

9112-519: The complete skeletons of newborns or fetuses, have been discovered amidst the other offerings, leading to speculation concerning infant sacrifice. Scholars have not determined how the infants met their deaths. Some authors have associated infant sacrifice with Olmec ritual art showing limp werejaguar babies, most famously in La Venta's Altar 5 (on the right) or Las Limas figure . Any definitive answer requires further findings. The Olmec may have been

9246-435: The date of the sample. Samples for dating need to be converted into a form suitable for measuring the C content; this can mean conversion to gaseous, liquid, or solid form, depending on the measurement technique to be used. Before this can be done, the sample must be treated to remove any contamination and any unwanted constituents. This includes removing visible contaminants, such as rootlets that may have penetrated

9380-483: The discovery of other ancient sites nearby, such as Bandurria, Peru . Accommodating more than 3,000 inhabitants, Caral is the best studied and one of the largest sites known of the Norte Chico civilization . The city was declared a UNESCO World Heritage Site in 2009. In early 2021, tensions arose between squatters claiming land rights and archaeologists researching the site, as housing construction encroached on

9514-424: The distant past a race of werejaguars was made between the union of a jaguar and a woman. One werejaguar quality that can be found is the sharp cleft in the forehead of many supernatural beings in Olmec art. This sharp cleft is associated with the natural indented head of jaguars. The Kunz axes (also known as "votive axes") are figures that represent werejaguars and were apparently used for rituals. In most cases,

9648-494: The early 20th century hence gives an apparent date older than the true date. For the same reason, C concentrations in the neighbourhood of large cities are lower than the atmospheric average. This fossil fuel effect (also known as the Suess effect, after Hans Suess, who first reported it in 1955) would only amount to a reduction of 0.2% in C activity if the additional carbon from fossil fuels were distributed throughout

9782-610: The early history of Olmec culture. Olmec-style artifacts tend to appear earlier in some parts of Guerrero than in the Veracruz-Tabasco area. In particular, the relevant objects from the Amuco-Abelino site in Guerrero reveal dates as early as 1530 BCE . The city of Teopantecuanitlan in Guerrero is also relevant in this regard. The first Olmec center, San Lorenzo, was all but abandoned around 900 BCE at about

9916-401: The entire carbon exchange reservoir, it would have led to an increase in the C / C ratio of only a few per cent, but the immediate effect was to almost double the amount of C in the atmosphere, with the peak level occurring in 1964 for the northern hemisphere, and in 1966 for the southern hemisphere. The level has since dropped, as this bomb pulse or "bomb carbon" (as it

10050-424: The equation above. The half-life of a radioactive isotope (usually denoted by t 1/2 ) is a more familiar concept than the mean-life, so although the equations above are expressed in terms of the mean-life, it is more usual to quote the value of C 's half-life than its mean-life. The currently accepted value for the half-life of C is 5,700 ± 30 years. This means that after 5,700 years, only half of

10184-471: The errors caused by the variation over time in the C / C ratio. These curves are described in more detail below . Coal and oil began to be burned in large quantities during the 19th century. Both are sufficiently old that they contain little or no detectable C and, as a result, the CO 2 released substantially diluted the atmospheric C / C ratio. Dating an object from

10318-460: The first Mesoamerican civilization emerged and reigned from c.  1400–400  BCE. Pre-Olmec cultures had flourished since about 2500 BCE, and it has been speculated that the Olmecs derived in part from the neighboring Mokaya or Mixe–Zoque cultures which developed during this time. The beginnings of Olmec civilization have traditionally been placed between 1400 BCE and 1200 BCE . Past finds of Olmec remains ritually deposited at

10452-492: The first civilization in Mesoamerica, the Olmecs are credited, or speculatively credited, with many "firsts", including the bloodletting and perhaps human sacrifice , writing and epigraphy , and the invention of popcorn , zero and the Mesoamerican calendar , and the Mesoamerican ballgame , as well as perhaps the compass . Some researchers, including artist and art historian Miguel Covarrubias , even postulate that

10586-646: The first civilization in the Western Hemisphere to develop a writing system. Symbols found in 2002 and 2006 date from 650 BCE and 900 BCE respectively, preceding the oldest Zapotec writing found so far, which dates from about 500 BCE. The 2002 find at the San Andrés site shows a bird, speech scrolls, and glyphs that are similar to the later Maya script . Known as the Cascajal Block , and dated between 1100 and 900 BCE,

10720-908: The former is much easier to measure, and the latter can be easily derived: the depletion of C relative to C is proportional to the difference in the atomic masses of the two isotopes, so the depletion for C is twice the depletion of C . The fractionation of C , known as δ C , is calculated as follows: δ C 13 = ( ( C 13 C 12 ) sample ( C 13 C 12 ) standard − 1 ) × 1000 {\displaystyle \delta {\ce {^{13}C}}=\left({\frac {\left({\frac {{\ce {^{13}C}}}{{\ce {^{12}C}}}}\right)_{\text{sample}}}{\left({\frac {{\ce {^{13}C}}}{{\ce {^{12}C}}}}\right)_{\text{standard}}}}-1\right)\times 1000} ‰ where

10854-496: The ground among circular stone lines near Caral. This image, known as a geoglyph , is located on the desert floor just west of the main site at Caral. The lines form the design of a human face with long, streaming hair and a gaping mouth. This geoglyph is similar to bleeding figures with a similar gaping mouths found etched onto the stone walls at a site called Cerro Sechín , in the Casma Valley 240 kilometres (150 mi) to

10988-457: The head is half the total volume of the figure. All Kunz axes have flat noses and an open mouth. The name "Kunz" comes from George Frederick Kunz , an American mineralogist , who described a figure in 1890. Olmec-style artifacts, designs, figurines, monuments and iconography have been found in the archaeological records of sites hundreds of kilometres outside the Olmec heartland. These sites include: Tlatilco and Tlapacoya , major centers of

11122-478: The head. Seventeen colossal heads have been unearthed to date. The heads range in size from the Rancho La Cobata head, at 3.4 m (11 ft) high, to the pair at Tres Zapotes, at 1.47 m (4 ft 10 in). Scholars calculate that the largest heads weigh between 25 and 55 tonnes (28 and 61 short tons). The heads were carved from single blocks or boulders of volcanic basalt , found in

11256-425: The immediate Maya homeland, it is likely that this calendar predated the Maya and was possibly the invention of the Olmecs. Indeed, three of these six artifacts were found within the Olmec heartland. But an argument against an Olmec origin is the fact that the Olmec civilization had ended by the 4th century BCE, several centuries before the earliest known Long Count date artifact. The Long Count calendar required

11390-454: The initial C will remain; a quarter will remain after 11,400 years; an eighth after 17,100 years; and so on. The above calculations make several assumptions, such as that the level of C in the atmosphere has remained constant over time. In fact, the level of C in the atmosphere has varied significantly and as a result, the values provided by the equation above have to be corrected by using data from other sources. This

11524-404: The inner tree rings do not get their C replenished and instead only lose C through radioactive decay. Hence each ring preserves a record of the atmospheric C / C ratio of the year it grew in. Carbon-dating the wood from the tree rings themselves provides the check needed on the atmospheric C / C ratio: with a sample of known date, and a measurement of

11658-673: The laboratory's cyclotron accelerator and soon discovered that the atom's half-life was far longer than had been previously thought. This was followed by a prediction by Serge A. Korff , then employed at the Franklin Institute in Philadelphia , that the interaction of thermal neutrons with N in the upper atmosphere would create C . It had previously been thought that C would be more likely to be created by deuterons interacting with C . At some time during World War II, Willard Libby , who

11792-715: The late 19th and early 20th centuries. Olmec artworks are considered among ancient America's most striking. The name "Olmec" means "rubber people" in Nahuatl , the language of the Nahuas , and was the Aztec term for the people who lived in the Gulf Lowlands in the 15th and 16th centuries, some 2,000 years after the Olmec culture died out. The term "Rubber People" refers to the ancient practice, spanning from ancient Olmecs to Aztecs, of extracting latex from Castilla elastica ,

11926-498: The modern-day Mexican states of Veracruz and Tabasco from roughly 1200 to 400  BCE during Mesoamerica's formative period . They were initially centered at the site of their development in San Lorenzo Tenochtitlán , but moved to La Venta in the 10th century BCE following the decline of San Lorenzo. The Olmecs disappeared mysteriously in the 4th century BCE , leaving the region sparsely populated until

12060-672: The most prominent Olmec center, lasting from 900 BCE until its abandonment around 400 BCE. La Venta sustained the Olmec cultural traditions with spectacular displays of power and wealth. The Great Pyramid was the largest Mesoamerican structure of its time. Even today, after 2500 years of erosion, it rises 34 m (112 ft) above the naturally flat landscape. Buried deep within La Venta lay opulent, labor-intensive "offerings" – 1000 tons of smooth serpentine blocks, large mosaic pavements, and at least 48 separate votive offerings of polished jade celts , pottery, figurines, and hematite mirrors . Scholars have yet to determine

12194-580: The most valued jade was the Motagua River valley in eastern Guatemala , and Olmec obsidian has been traced to sources in the Guatemala highlands, such as El Chayal and San Martín Jilotepeque , or in Puebla , distances ranging from 200 to 400 km (120–250 miles) away, respectively. The state of Guerrero , and in particular its early Mezcala culture , seem to have played an important role in

12328-526: The name "Olmec" to the rediscovered ruins and artifacts in the heartland decades before it was understood that these were not created by the people the Aztecs knew as the "Olmec" but rather a culture that was 2000 years older. Despite the mistaken identity, the name has stuck. It is not known what name the ancient Olmec used for themselves; some later Mesoamerican accounts seem to refer to the ancient Olmec as " Tamoanchan ". A contemporary term sometimes used for

12462-510: The neighbourhood of the Furnas caldera in the Azores were found to have apparent ages that ranged from 250 years to 3320 years. Any addition of carbon to a sample of a different age will cause the measured date to be inaccurate. Contamination with modern carbon causes a sample to appear to be younger than it really is: the effect is greater for older samples. If a sample that is 17,000 years old

12596-444: The north. What this figure represents is unclear. It is believed to have been constructed around the same time as Caral and to have been associated with a nearby ceremonial site known as Chupacigarro . Another significant find at the site was a collection of musical instruments, including 37 cornetts made of deer and llama bones and 33 flutes of unusual construction. The flutes were radiocarbon dated to 2170±90 BC. The city of Caral

12730-420: The ocean surface have the same C ratios as the water they live in, and as a result of the reduced C / C ratio, the radiocarbon age of marine life is typically about 400 years. Organisms on land are in closer equilibrium with the atmosphere and have the same C / C ratio as the atmosphere. These organisms contain about 1.3% of the carbon in the reservoir; sea organisms have

12864-635: The organism from which the sample was taken died), and N is the number of atoms left after time t . λ is a constant that depends on the particular isotope; for a given isotope it is equal to the reciprocal of the mean-life – i.e. the average or expected time a given atom will survive before undergoing radioactive decay. The mean-life, denoted by τ , of C is 8,267 years, so the equation above can be rewritten as: t = ln ⁡ ( N 0 / N ) ⋅ 8267 years {\displaystyle t=\ln(N_{0}/N)\cdot {\text{8267 years}}} The sample

12998-579: The origins of the Andean civilizations and the development of its first cities. Among the artifacts found at Caral is a knotted textile piece that the excavators have labelled a quipu . They write that the artifact is evidence that the quipu record keeping system, a method involving knots tied in textiles that was brought to its highest development by the Inca Empire , was older than any archaeologist previously had determined. Evidence has emerged that

13132-437: The people living in the Lower Half of Caral consisted mostly of agricultural plants and some fish. These diets were less rich than those of the elites living in the Upper Half. The current explanation for the divided city is that the city was intentionally planned in this way, with the monumental architecture and complexes of the Upper Half designed both to house elites and to physically indicate their political power. Conversely,

13266-440: The plants and freshwater organisms that live in it. This is known as the hard water effect because it is often associated with calcium ions, which are characteristic of hard water; other sources of carbon such as humus can produce similar results, and can also reduce the apparent age if they are of more recent origin than the sample. The effect varies greatly and there is no general offset that can be applied; additional research

13400-413: The pre-existing Egyptian chronology nor the new radiocarbon dating method could be assumed to be accurate, but a third possibility was that the C / C ratio had changed over time. The question was resolved by the study of tree rings : comparison of overlapping series of tree rings allowed the construction of a continuous sequence of tree-ring data that spanned 8,000 years. (Since that time

13534-493: The presence of these core loanwords indicated that the Olmec – generally regarded as the first "highly civilized" Mesoamerican society – spoke a language ancestral to Mixe–Zoquean. The spread of this vocabulary particular to their culture accompanied the diffusion of other Olmec cultural and artistic traits that appears in the archaeological record of other Mesoamerican societies. Carbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating )

13668-510: The prospect of Olmec military domination or that the Olmec iconography was actually developed outside the heartland. The generally accepted, but by no means unanimous, interpretation is that the Olmec-style artifacts, in all sizes, became associated with elite status and were adopted by non-Olmec Formative Period chieftains in an effort to bolster their status. In addition to their influence with contemporaneous Mesoamerican cultures , as

13802-405: The ratios in the atmosphere. This effect is known as isotopic fractionation. To determine the degree of fractionation that takes place in a given plant, the amounts of both C and C isotopes are measured, and the resulting C / C ratio is then compared to a standard ratio known as PDB. The C / C ratio is used instead of C / C because

13936-489: The region and used for recreational and religious purposes. A dozen rubber balls dating to 1600 BCE or earlier have been found in El Manatí , a bog 10 km (6 mi) east of San Lorenzo Tenochtitlan. These balls predate the earliest ballcourt yet discovered at Paso de la Amada , c. 1400 BCE, although there is no certainty that they were used in the ballgame. While the actual ethno-linguistic affiliation of

14070-517: The region, he made some observations about the development of architecture in the Andes. Ruth Shady further explored this 4,000- to 4,600-year-old city in the Peruvian desert, with its elaborate complex of temples, an amphitheater, and ordinary houses. The urban complex is spread out over 150 hectares (370 acres) and contains plazas and residential buildings. Caral was a thriving metropolis at roughly

14204-461: The relocation of settlements due to volcanism, instead of extinction. Volcanic eruptions during the Early, Late and Terminal Formative periods would have blanketed the lands and forced the Olmec to move their settlements. Whatever the cause, within a few hundred years of the abandonment of the last Olmec cities, successor cultures became firmly established. The Tres Zapotes site, on the western edge of

14338-463: The remains of a baby, wrapped and buried with a necklace made of stone beads. Caral was flanked by 19 other temple complexes scattered across the 90 square kilometres (35 sq mi) area of the Supe Valley. The date of 2627 BC for Caral is based on the carbon dating of reed and woven carrying bags that were found on site. These bags were used to carry the stones for the construction of

14472-439: The residents were wealthy elites, whose lives likely were associated with religious and social activities that would have taken place in the temples. By comparison, the residential buildings in the Lower Half have less evidence of elite populations. Instead of the large structures, exclusively elite residential complexes of the Upper Half, these residences are smaller and single rooms are used for more than one purpose. The diets of

14606-405: The rise of an elite class. The elite class created the demand for the production of the symbolic and sophisticated luxury artifacts that define Olmec culture. Many of these luxury artifacts were made from materials such as jade , obsidian , and magnetite , which came from distant locations and suggest that early Olmec elites had access to an extensive trading network in Mesoamerica. The source of

14740-481: The riverine environment that the Olmec depended upon for agriculture, hunting and gathering, and transportation. These changes may have been triggered by tectonic upheavals or subsidence, or the siltation of rivers due to agricultural practices. One theory for the considerable population drop during the Terminal Formative period is suggested by Santley and colleagues (Santley et al. 1997), who propose

14874-415: The same over the preceding few thousand years. To verify the accuracy of the method, several artefacts that were datable by other techniques were tested; the results of the testing were in reasonable agreement with the true ages of the objects. Over time, however, discrepancies began to appear between the known chronology for the oldest Egyptian dynasties and the radiocarbon dates of Egyptian artefacts. Neither

15008-456: The same proportion of C as the atmosphere, or in the case of marine animals or plants, with the ocean. Once it dies, it ceases to acquire C , but the C within its biological material at that time will continue to decay, and so the ratio of C to C in its remains will gradually decrease. Because C decays at a known rate, the proportion of radiocarbon can be used to determine how long it has been since

15142-586: The same time as the great pyramids were being built in Egypt, which is considered one of the earliest civilizations in the world. Caral is the largest recorded site in the Andean region, with dates older than 2000 BC. It appears to be the model for the urban design adopted by Andean civilizations that rose and fell over the span of four millennia. Scholars believe that research conducted in Caral may answer questions about

15276-430: The same time that La Venta rose to prominence. Widespread destruction of many San Lorenzo monuments also occurred around the 950s BCE, which may indicate an internal uprising or, less likely, an invasion. The latest thinking, however, is that environmental changes may have been responsible for this shift in Olmec centers, with certain important rivers changing course. Following the decline of San Lorenzo, La Venta became

15410-412: The sample since its burial. Alkali and acid washes can be used to remove humic acid and carbonate contamination, but care has to be taken to avoid removing the part of the sample that contains the carbon to be tested. Particularly for older samples, it may be useful to enrich the amount of C in the sample before testing. This can be done with a thermal diffusion column. The process takes about

15544-625: The shrine El Manatí near the triple archaeological sites known collectively as San Lorenzo Tenochtitlán moved this back to at least 1600–1500 BCE . It seems that the Olmec had their roots in early farming cultures of Tabasco , which began between 5100 BCE and 4600 BCE . These shared the same basic food crops and technologies of the later Olmec civilization. What is today called Olmec first appeared fully within San Lorenzo Tenochtitlán, where distinctive Olmec features occurred around 1400 BCE. The rise of civilization

15678-410: The site. Paul Kosok discovered Caral in 1948. The site received little attention at the time because it appeared to lack many of the typical artifacts that were sought at archaeological sites throughout the Andes. In 1975, the Peruvian architect Carlos Williams made a detailed record of most of the archaeological sites of the valley of Supe, among which he recorded Caral. Based on what he observed in

15812-401: The surface water as carbonate and bicarbonate ions; at the same time the carbonate ions in the water are returning to the air as CO 2 . This exchange process brings C from the atmosphere into the surface waters of the ocean, but the C thus introduced takes a long time to percolate through the entire volume of the ocean. The deepest parts of the ocean mix very slowly with

15946-590: The surface waters, and as a result water from some deep ocean areas has an apparent radiocarbon age of several thousand years. Upwelling mixes this "old" water with the surface water, giving the surface water an apparent age of about several hundred years (after correcting for fractionation). This effect is not uniform – the average effect is about 400 years, but there are local deviations of several hundred years for areas that are geographically close to each other. These deviations can be accounted for in calibration, and users of software such as CALIB can provide as an input

16080-422: The surface waters, and the mixing is uneven. The main mechanism that brings deep water to the surface is upwelling, which is more common in regions closer to the equator. Upwelling is also influenced by factors such as the topography of the local ocean bottom and coastlines, the climate, and wind patterns. Overall, the mixing of deep and surface waters takes far longer than the mixing of atmospheric CO 2 with

16214-523: The temples. The material is an excellent candidate for high precision dating. The site may date even earlier, however, as samples from the oldest parts of the excavation have yet to be dated. Caral had a population of approximately 3,000 people. However, 19 other sites in the area (posted at Caral), allow for a possible total population of 20,000 people sharing the same culture in the Supe Valley. All of these sites share similarities with Caral, including small platforms or stone circles. Shady believes that Caral

16348-478: The tree-ring data series has been extended to 13,900 years.) In the 1960s, Hans Suess was able to use the tree-ring sequence to show that the dates derived from radiocarbon were consistent with the dates assigned by Egyptologists. This was possible because although annual plants, such as corn, have a C / C ratio that reflects the atmospheric ratio at the time they were growing, trees only add material to their outermost tree ring in any given year, while

16482-404: The two. The atmospheric C / C ratio is lower in the southern hemisphere, with an apparent additional age of about 40 years for radiocarbon results from the south as compared to the north. This is because the greater surface area of ocean in the southern hemisphere means that there is more carbon exchanged between the ocean and the atmosphere than in the north. Since the surface ocean

16616-445: The unique "Olmec-style" in a variety of artifacts. Curators and scholars refer to "Olmec-style" face masks but, to date, no example has been recovered in an archaeologically controlled Olmec context. They have been recovered from sites of other cultures, including one deliberately deposited in the ceremonial altepetl (precinct) of Tenochtitlan in what is now Mexico City . The mask would presumably have been about 2000 years old when

16750-447: The use of zero as a place-holder within its vigesimal (base-20) positional numeral system. A shell glyph – [REDACTED] – was used as a zero symbol for these Long Count dates, the second oldest of which, on Stela C at Tres Zapotes , has a date of 32 BCE. This is one of the earliest uses of the zero concept in history. The Olmec are strong candidates for originating the Mesoamerican ballgame so prevalent among later cultures of

16884-434: The value of N (the number of atoms of C remaining in the sample), the carbon-dating equation allows the calculation of N 0 – the number of atoms of C in the sample at the time the tree ring was formed – and hence the C / C ratio in the atmosphere at that time. Equipped with the results of carbon-dating the tree rings, it became possible to construct calibration curves designed to correct

17018-497: The ‰ sign indicates parts per thousand . Because the PDB standard contains an unusually high proportion of C , most measured δ C values are negative. For marine organisms, the details of the photosynthesis reactions are less well understood, and the δ C values for marine photosynthetic organisms are dependent on temperature. At higher temperatures, CO 2 has poor solubility in water, which means there

17152-451: Was a society built on commerce and pleasure. No indications of warfare, such as battlements, weapons, or mutilated bodies, have been found at Caral. This contrasts with the older site of Sechin Bajo , where depictions of weapons are found. In one of the Caral temples, researchers found 32 flutes made of condor and pelican bones and 37 cornetts of deer and llama bones. One find revealed

17286-485: Was an Ethiopian hair style, but he offered no evidence it was a contemporary style. The Egyptologist Frank J. Yurco has said that the Olmec braids do not resemble contemporary Egyptian or Nubian braids. Richard Diehl wrote "There can be no doubt that the heads depict the American Indian physical type still seen on the streets of Soteapan, Acayucan, and other towns in the region." Another type of artifact

17420-514: Was assisted by the local ecology of well-watered alluvial soil, as well as by the transportation network provided by the Coatzacoalcos river basin. This environment may be compared to that of other ancient centers of civilization such as the Nile , Indus , Yellow River and Mesopotamia . This highly productive environment encouraged a densely concentrated population, which in turn triggered

17554-411: Was awarded the Nobel Prize in Chemistry for this work. In nature, carbon exists as three isotopes . Carbon-12 ( C ) and carbon-13 ( C ) are stable and nonradioactive; carbon-14 ( C ), also known as "radiocarbon", is radioactive. The half-life of C (the time it takes for half of a given amount of C to decay ) is about 5,730 years, so its concentration in

17688-586: Was split into two sections, an "Upper Half" and a "Lower Half". These halves were divided naturally by the Supe River Valley. In the Upper Half there are six monumental complexes, each of which includes a pyramid, open plaza, and assemblage of residential buildings. In the Lower Half there are residential buildings, small pyramids, and one monumental complex called the "Temple of the Amphitheater". The Upper Half complexes were all constructed around

17822-459: Was the focus of this civilization. It is believed to be part of an even more vast cultural complex, trading with the coastal communities and the regions farther inland. She suggests that a depiction of monkeys may be evidence of trade with communities along the Amazon. In 2000, Marco Machacuay (the chief of excavations at the time) and his colleague, Rocío Aramburú, discovered a large shape etched on

17956-785: Was then at Berkeley, learned of Korff's research and conceived the idea that it might be possible to use radiocarbon for dating. In 1945, Libby moved to the University of Chicago , where he began his work on radiocarbon dating. He published a paper in 1946 in which he proposed that the carbon in living matter might include C as well as non-radioactive carbon. Libby and several collaborators proceeded to experiment with methane collected from sewage works in Baltimore, and after isotopically enriching their samples they were able to demonstrate that they contained C . By contrast, methane created from petroleum showed no radiocarbon activity because of its age. The results were summarized in

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