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117-464: The Codex Zouche-Nuttall or Codex Tonindeye is an accordion-folded pre-Columbian document of Mixtec pictography , now in the collections of the British Museum . It is one of about 16 manuscripts from Mexico that are entirely pre-Columbian in origin. The codex derives its name from Zelia Nuttall , who first published it in 1902, and Baroness Zouche, its donor. The Codex Zouche-Nuttall

234-433: A butterfly may produce offspring with new mutations. The majority of these mutations will have no effect; but one might change the colour of one of the butterfly's offspring, making it harder (or easier) for predators to see. If this color change is advantageous, the chances of this butterfly's surviving and producing its own offspring are a little better, and over time the number of butterflies with this mutation may form

351-607: A different social structure. Until the accurate dating of Watson Brake and similar sites, the oldest mound complex was thought to be Poverty Point , also located in the Lower Mississippi Valley . Built about 1500 BCE, it is the centerpiece of a culture extending over 100 sites on both sides of the Mississippi . The Poverty Point site has earthworks in the form of six concentric half-circles, divided by radial aisles, together with some mounds. The entire complex

468-741: A group of expert geneticists and biologists , who have the responsibility of establishing the standard or so-called "consensus" sequence. This step requires a tremendous scientific effort. Once the consensus sequence is known, the mutations in a genome can be pinpointed, described, and classified. The committee of the Human Genome Variation Society (HGVS) has developed the standard human sequence variant nomenclature, which should be used by researchers and DNA diagnostic centers to generate unambiguous mutation descriptions. In principle, this nomenclature can also be used to describe mutations in other organisms. The nomenclature specifies

585-413: A healthy, uncontaminated cell. Naturally occurring oxidative DNA damage is estimated to occur 10,000 times per cell per day in humans and 100,000 times per cell per day in rats . Spontaneous mutations can be characterized by the specific change: There is increasing evidence that the majority of spontaneously arising mutations are due to error-prone replication ( translesion synthesis ) past DNA damage in

702-1018: A larger percentage of the population. Neutral mutations are defined as mutations whose effects do not influence the fitness of an individual. These can increase in frequency over time due to genetic drift . It is believed that the overwhelming majority of mutations have no significant effect on an organism's fitness. Also, DNA repair mechanisms are able to mend most changes before they become permanent mutations, and many organisms have mechanisms, such as apoptotic pathways , for eliminating otherwise-permanently mutated somatic cells . Beneficial mutations can improve reproductive success. Four classes of mutations are (1) spontaneous mutations (molecular decay), (2) mutations due to error-prone replication bypass of naturally occurring DNA damage (also called error-prone translesion synthesis), (3) errors introduced during DNA repair, and (4) induced mutations caused by mutagens . Scientists may sometimes deliberately introduce mutations into cells or research organisms for

819-497: A major source of raw material for evolving new genes, with tens to hundreds of genes duplicated in animal genomes every million years. Most genes belong to larger gene families of shared ancestry, detectable by their sequence homology . Novel genes are produced by several methods, commonly through the duplication and mutation of an ancestral gene, or by recombining parts of different genes to form new combinations with new functions. Here, protein domains act as modules, each with

936-502: A minor effect. For instance, human height is determined by hundreds of genetic variants ("mutations") but each of them has a very minor effect on height, apart from the impact of nutrition . Height (or size) itself may be more or less beneficial as the huge range of sizes in animal or plant groups shows. Attempts have been made to infer the distribution of fitness effects (DFE) using mutagenesis experiments and theoretical models applied to molecular sequence data. DFE, as used to determine

1053-638: A much later date, probably no more than 2,000 years ago, moving across the ice from Siberia into Alaska. The North American climate was unstable as the ice age receded during the Lithic stage . It finally stabilized about 10,000 years ago; climatic conditions were then very similar to today's. Within this time frame, roughly about the Archaic Period , numerous archaeological cultures have been identified. The unstable climate led to widespread migration, with early Paleo-Indians soon spreading throughout

1170-572: A number of beneficial mutations as well. For instance, in a screen of all gene deletions in E. coli , 80% of mutations were negative, but 20% were positive, even though many had a very small effect on growth (depending on condition). Gene deletions involve removal of whole genes, so that point mutations almost always have a much smaller effect. In a similar screen in Streptococcus pneumoniae , but this time with transposon insertions, 76% of insertion mutants were classified as neutral, 16% had

1287-404: A particular and independent function, that can be mixed together to produce genes encoding new proteins with novel properties. For example, the human eye uses four genes to make structures that sense light: three for cone cell or colour vision and one for rod cell or night vision; all four arose from a single ancestral gene. Another advantage of duplicating a gene (or even an entire genome)

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1404-762: A population of over 20,000. Other chiefdoms were constructed throughout the Southeast, and its trade networks reached to the Great Lakes and the Gulf of Mexico. At its peak, between the 12th and 13th centuries, Cahokia was the most populous city in North America. (Larger cities did exist in Mesoamerica and the Andes.) Monks Mound , the major ceremonial center of Cahokia, remains the largest earthen construction of

1521-486: A significantly reduced fitness, but 6% were advantageous. This classification is obviously relative and somewhat artificial: a harmful mutation can quickly turn into a beneficial mutations when conditions change. Also, there is a gradient from harmful/beneficial to neutral, as many mutations may have small and mostly neglectable effects but under certain conditions will become relevant. Also, many traits are determined by hundreds of genes (or loci), so that each locus has only

1638-579: A single unified empire. The Mixtecs would eventually be conquered by the Aztecs until the Spanish conquest. The Mixtecs saw the Spanish conquest as an opportunity for liberation and established agreements with the conquistadors that allowed them to preserve their cultural traditions, though relatively few sections resisted Spanish rule. The Totonac civilization was concentrated in the present-day states of Veracruz and Puebla . The Totonacs were responsible for

1755-463: A variety of tools, including distinctive projectile points and knives, as well as less distinctive butchering and hide-scraping implements. The vastness of the North American continent, and the variety of its climates, ecology , vegetation , fauna , and landforms, led ancient peoples to coalesce into many distinct linguistic and cultural groups. This is reflected in the oral histories of

1872-471: A whole. Changes in DNA caused by mutation in a coding region of DNA can cause errors in protein sequence that may result in partially or completely non-functional proteins. Each cell, in order to function correctly, depends on thousands of proteins to function in the right places at the right times. When a mutation alters a protein that plays a critical role in the body, a medical condition can result. One study on

1989-631: Is Y-chromosome haplogroup Q1a3a . Researchers have found genetic evidence that the Q1a3a haplogroup has been in South America since at least 18,000 BCE. Y-chromosome DNA , like mtDNA , differs from other nuclear chromosomes in that the majority of the Y-chromosome is unique and does not recombine during meiosis . This has the effect that the historical pattern of mutations can easily be studied. The pattern indicates Indigenous peoples of

2106-415: Is a major pathway for repairing double-strand breaks. NHEJ involves removal of a few nucleotides to allow somewhat inaccurate alignment of the two ends for rejoining followed by addition of nucleotides to fill in gaps. As a consequence, NHEJ often introduces mutations. Induced mutations are alterations in the gene after it has come in contact with mutagens and environmental causes. Induced mutations on

2223-468: Is accepted that the majority of mutations are neutral or deleterious, with advantageous mutations being rare; however, the proportion of types of mutations varies between species. This indicates two important points: first, the proportion of effectively neutral mutations is likely to vary between species, resulting from dependence on effective population size ; second, the average effect of deleterious mutations varies dramatically between species. In addition,

2340-444: Is called a de novo mutation . A change in the genetic structure that is not inherited from a parent, and also not passed to offspring, is called a somatic mutation . Somatic mutations are not inherited by an organism's offspring because they do not affect the germline . However, they are passed down to all the progeny of a mutated cell within the same organism during mitosis. A major section of an organism therefore might carry

2457-478: Is important in animals that have a dedicated germline to produce reproductive cells. However, it is of little value in understanding the effects of mutations in plants, which lack a dedicated germline. The distinction is also blurred in those animals that reproduce asexually through mechanisms such as budding , because the cells that give rise to the daughter organisms also give rise to that organism's germline. A new germline mutation not inherited from either parent

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2574-445: Is in a coding or non-coding region . Mutations in the non-coding regulatory sequences of a gene, such as promoters, enhancers, and silencers, can alter levels of gene expression, but are less likely to alter the protein sequence. Mutations within introns and in regions with no known biological function (e.g. pseudogenes , retrotransposons ) are generally neutral , having no effect on phenotype – though intron mutations could alter

2691-411: Is nearly a mile across. Mound building was continued by succeeding cultures, who built numerous sites in the middle Mississippi and Ohio River valleys as well, adding effigy mounds , conical and ridge mounds, and other shapes. The Woodland period of North American pre-Columbian cultures lasted from roughly 1000 BCE to 1000 CE. The term was coined in the 1930s and refers to prehistoric sites between

2808-406: Is that this increases engineering redundancy ; this allows one gene in the pair to acquire a new function while the other copy performs the original function. Other types of mutation occasionally create new genes from previously noncoding DNA . Changes in chromosome number may involve even larger mutations, where segments of the DNA within chromosomes break and then rearrange. For example, in

2925-422: Is that when they move within a genome, they can mutate or delete existing genes and thereby produce genetic diversity. Nonlethal mutations accumulate within the gene pool and increase the amount of genetic variation. The abundance of some genetic changes within the gene pool can be reduced by natural selection , while other "more favorable" mutations may accumulate and result in adaptive changes. For example,

3042-593: Is the Olmec. This civilization established the cultural blueprint by which all succeeding indigenous civilizations would follow in Mexico. Pre-Olmec civilization began with the production of pottery in abundance, around 2300 BCE in the Grijalva River delta. Between 1600 and 1500 BCE, the Olmec civilization had begun, with the consolidation of power at their capital, a site today known as San Lorenzo Tenochtitlán near

3159-670: The Archaic period and the Mississippian cultures . The Adena culture and the ensuing Hopewell tradition during this period built monumental earthwork architecture and established continent-spanning trade and exchange networks. This period is considered a developmental stage without any massive changes in a short period but instead has a continuous development in stone and bone tools, leatherworking, textile manufacture, tool production, cultivation, and shelter construction. Some Woodland people continued to use spears and atlatls until

3276-702: The Cliff Palace of Mesa Verde National Park in Colorado and the Great Houses in Chaco Canyon , New Mexico . The Puebloans also constructed a road system that stretched from Chaco Canyon to Kutz Canyon in the San Juan Basin . The Ancestral Puebloans are also known as "Anasazi", though the term is controversial, as the present-day Pueblo peoples consider the term to be derogatory, due to

3393-535: The Homininae , two chromosomes fused to produce human chromosome 2 ; this fusion did not occur in the lineage of the other apes , and they retain these separate chromosomes. In evolution, the most important role of such chromosomal rearrangements may be to accelerate the divergence of a population into new species by making populations less likely to interbreed, thereby preserving genetic differences between these populations. Sequences of DNA that can move about

3510-697: The Maya script . Other accounts also suggest that the Huastecs migrated as a result of the Classic Maya collapse around the year 900 CE. The Zapotecs were a civilization that thrived in the Oaxaca Valley from the late 6th century BCE until their downfall at the hands of the Spanish conquistadors. The city of Monte Albán was an important religious center for the Zapotecs and served as the capital of

3627-664: The Olmec , Teotihuacan , Mayas , Zapotecs , Mixtecs , Huastecs , Purepecha , Toltecs , and Mexica / Aztecs . The Mexica civilization is also known as the Aztec Triple Alliance since they were three smaller kingdoms loosely united together. These Indigenous civilizations are credited with many inventions: building pyramid temples, mathematics , astronomy , medicine, writing, highly accurate calendars , fine arts , intensive agriculture, engineering , an abacus calculator, and complex theology . They also invented

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3744-978: The Spanish conquest of El Salvador , Cuzcatlan was forced to surrender to conquistador Pedro de Alvarado in 1528. Mutations In biology , a mutation is an alteration in the nucleic acid sequence of the genome of an organism , virus , or extrachromosomal DNA . Viral genomes contain either DNA or RNA . Mutations result from errors during DNA or viral replication , mitosis , or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining ), cause an error during other forms of repair, or cause an error during replication ( translesion synthesis ). Mutations may also result from substitution , insertion or deletion of segments of DNA due to mobile genetic elements . Mutations may or may not produce detectable changes in

3861-531: The Tilantongo kingdom, especially under the leadership of the warrior Lord Eight Deer Jaguar Claw (who died in the early twelfth century at the age of fifty-two). The codex probably reached Spain in the 16th century. It was first identified at the Monastery of San Marco, Florence , in 1854 and was sold in 1859 to John Temple Leader who sent it to his friend Robert Curzon, 14th Baron Zouche . A facsimile

3978-463: The Tlingit , Haida , Chumash , Mandan , Hidatsa , and others, and some established large settlements, even cities, such as Cahokia , in what is now Illinois . Mesoamerica is the region extending from central Mexico south to the northwestern border of Costa Rica that gave rise to a group of stratified, culturally related agrarian civilizations spanning an approximately 3,000-year period before

4095-506: The founding population . The microsatellite diversity and distributions of the Y lineage specific to South America indicate that certain Amerindian populations have been isolated since the initial colonization of the region. The Na-Dené , Inuit , and Indigenous Alaskan populations exhibit haplogroup Q-M242 (Y-DNA) mutations, however, and are distinct from other Indigenous peoples with various mtDNA mutations. This suggests that

4212-409: The product of a gene , or prevent the gene from functioning properly or completely. Mutations can also occur in non-genic regions . A 2007 study on genetic variations between different species of Drosophila suggested that, if a mutation changes a protein produced by a gene, the result is likely to be harmful, with an estimated 70% of amino acid polymorphisms that have damaging effects, and

4329-429: The "Delicious" apple and the "Washington" navel orange . Human and mouse somatic cells have a mutation rate more than ten times higher than the germline mutation rate for both species; mice have a higher rate of both somatic and germline mutations per cell division than humans. The disparity in mutation rate between the germline and somatic tissues likely reflects the greater importance of genome maintenance in

4446-569: The Americas experienced two very distinctive genetic episodes: first with the initial peopling of the Americas and second with European colonization of the Americas . The former is the determinant factor for the number of gene lineages and founding haplotypes present in today's Indigenous populations . Human settlement of the Americas occurred in stages from the Bering Sea coastline , with an initial 20,000-year layover on Beringia for

4563-604: The Americas, diversifying into many hundreds of culturally distinct tribes. The Paleo-Indians were hunter-gatherers , likely characterized by small, mobile bands consisting of approximately 20 to 50 members of an extended family. These groups moved from place to place as preferred resources were depleted and new supplies were sought. During much of the Paleo-Indian period, bands are thought to have subsisted primarily through hunting now-extinct giant land animals such as mastodon and ancient bison . Paleo-Indian groups carried

4680-473: The DFE also differs between coding regions and noncoding regions , with the DFE of noncoding DNA containing more weakly selected mutations. In multicellular organisms with dedicated reproductive cells , mutations can be subdivided into germline mutations , which can be passed on to descendants through their reproductive cells, and somatic mutations (also called acquired mutations), which involve cells outside

4797-474: The DFE of advantageous mutations may lead to increased ability to predict the evolutionary dynamics. Theoretical work on the DFE for advantageous mutations has been done by John H. Gillespie and H. Allen Orr . They proposed that the distribution for advantageous mutations should be exponential under a wide range of conditions, which, in general, has been supported by experimental studies, at least for strongly selected advantageous mutations. In general, it

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4914-422: The DNA. Ordinarily, a mutation cannot be recognized by enzymes once the base change is present in both DNA strands, and thus a mutation is not ordinarily repaired. At the cellular level, mutations can alter protein function and regulation. Unlike DNA damages, mutations are replicated when the cell replicates. At the level of cell populations, cells with mutations will increase or decrease in frequency according to

5031-477: The Europeans arrived, Indigenous peoples of North America had a wide range of lifeways from sedentary, agrarian societies to semi-nomadic hunter-gatherer societies. Many formed new tribes or confederations in response to European colonization. These are often classified by cultural regions , loosely based on geography. These can include the following: Numerous pre-Columbian societies were sedentary, such as

5148-668: The Hohokam, they constructed kivas and great houses as well as ballcourts . Several of the Sinagua ruins include Montezuma Castle , Wupatki , and Tuzigoot . The Salado resided in the Tonto Basin in southeastern Arizona from 1150 CE to the 15th century. Archaeological evidence suggests that they traded with far-away cultures, as evidenced by the presence of seashells from the Gulf of California and macaw feathers from Mexico. Most of

5265-734: The Maya city of Chichen Itza . The Toltecs established vast trading relations with other Mesoamerican civilizations in Central America and the Puebloans in present-day New Mexico . During the Post-Classic era, the Toltecs suffered a subsequent collapse in the early 12th century, due to famine and civil war. The Toltec civilization was so influential to the point where many groups such as the Aztecs claimed to be descended from. With

5382-454: The Maya civilization cannot be overstated: it transformed political power, artistic depictions, and the nature of economics. Within the city of Teotihuacan was a diverse and cosmopolitan population. Most of the regional ethnicities of Mexico were represented in the city, such as Zapotecs from the Oaxaca region. They lived in apartment communities where they worked their trades and contributed to

5499-841: The Mississippian groups had vanished, and vast swaths of their territory were virtually uninhabited. The Ancestral Puebloans thrived in what is now the Four Corners region in the United States. It is commonly suggested that the culture of the Ancestral Puebloans emerged during the Early Basketmaker II Era during the 12th century BCE. The Ancestral Puebloans were a complex Oasisamerican society that constructed kivas , multi-story houses, and apartment blocks made from stone and adobe, such as

5616-483: The Olmec resulted in a power vacuum in Mexico. Emerging from that vacuum was Teotihuacan, first settled in 300 BCE. By 150 CE, Teotihuacan had risen to become the first true metropolis of what is now called North America. Teotihuacan established a new economic and political order never before seen in Mexico. Its influence stretched across Mexico into Central America, founding new dynasties in the Maya cities of Tikal , Copan , and Kaminaljuyú . Teotihuacan's influence over

5733-744: The Olmecs, Teotihuacan, the Toltecs, the Mexica, and the Mayas. These civilizations (except for the politically fragmented Maya) extended their reach across Mesoamerica—and beyond—like no others. They consolidated power and distributed influence in matters of trade, art, politics, technology, and theology. Other regional power players made economic and political alliances with these civilizations over 4,000 years. Many made war with them, but almost all peoples found themselves within one of their spheres of influence. Regional communications in ancient Mesoamerica have been

5850-459: The Spanish colonists. The Wichita people were a loose confederation that consisted of sedentary agriculturalists and hunter-gatherers who resided in the eastern Great Plains . They lived in permanent settlements and even established a city called Etzanoa , which had a population of 20,000 people. The city was eventually abandoned around the 18th century after it was encountered by Spanish conquistadors Jusepe Gutierrez and Juan de Oñate . When

5967-619: The Tlaxcalans for preserving their culture and for their assistance in defeating the Aztecs. The Tlaxcalans would once again assist to the Spaniards during the Mixtón War and the conquest of Guatemala . Cuzcatlan was a Pipil confederacy of kingdoms and city-states located in present-day El Salvador . According to legend, Cuzcatlan was established by Toltec migrants during the Classic Maya collapse in approximately 1200 CE. During

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6084-495: The adaptation rate of organisms, they have some times been named as adaptive mutagenesis mechanisms, and include the SOS response in bacteria, ectopic intrachromosomal recombination and other chromosomal events such as duplications. The sequence of a gene can be altered in a number of ways. Gene mutations have varying effects on health depending on where they occur and whether they alter the function of essential proteins. Mutations in

6201-518: The appearance of skin cancer during one's lifetime is induced by overexposure to UV radiation that causes mutations in the cellular and skin genome. There is a widespread assumption that mutations are (entirely) "random" with respect to their consequences (in terms of probability). This was shown to be wrong as mutation frequency can vary across regions of the genome, with such DNA repair - and mutation-biases being associated with various factors. For instance, Monroe and colleagues demonstrated that—in

6318-557: The calendar, were bequest from the former inhabitants of Tula, the Toltecs. The Mexica-Aztecs were the rulers of much of central Mexico by about 1400 (while Yaquis , Coras, and Apaches commanded sizable regions of northern desert), having subjugated most of the other regional states by the 1470s. At their peak, the Valley of Mexico where the Aztec Empire presided, saw a population growth that included nearly one million people during

6435-439: The category of by effect on function, but depending on the specificity of the change the mutations listed below will occur. In genetics , it is sometimes useful to classify mutations as either harmful or beneficial (or neutral ): Large-scale quantitative mutagenesis screens , in which thousands of millions of mutations are tested, invariably find that a larger fraction of mutations has harmful effects but always returns

6552-512: The city's economic and cultural prowess. Teotihuacan's economic pull impacted areas in northern Mexico as well. It was a city whose monumental architecture reflected a monumental new era in Mexican civilization, declining in political power about 650 CE—but lasting in cultural influence for the better part of a millennium, to around 950 CE. Contemporary to Teotihuacan's greatness was that of the Maya civilization. The period between 250 CE and 650 CE

6669-528: The civilizations in its area, the Tarascan Empire was the most prominent in metallurgy, harnessing copper, silver, and gold to create items such as tools, decorations, and even weapons and armor. Bronze was also used. The great victories over the Aztecs by the Tarascans cannot be understated. Nearly every war they fought in resulted in a Tarascan victory. Because the Tarascan Empire had little links to

6786-747: The cliff dwellings constructed by the Salado are primarily located in Tonto National Monument . The Iroquois League of Nations or "People of the Long House" was a politically advanced, democratic society, which is thought by some historians to have influenced the United States Constitution , with the Senate passing a resolution to this effect in 1988. Other historians have contested this interpretation and believe

6903-404: The coast in southeast Veracruz . The Olmec influence extended across Mexico, into Central America , and along the Gulf of Mexico . They transformed many peoples' thinking toward a new way of government, pyramid temples, writing, astronomy, art, mathematics, economics, and religion. Their achievements paved the way for the Maya civilization and the civilizations in central Mexico. The decline of

7020-494: The colonization of the Americas dates from between 40,000 and 13,000 years ago. The chronology of migration models is currently divided into two general approaches. The first is the short chronology theory with the first movement beyond Alaska into the Americas occurring no earlier than 14,000–17,000 years ago, followed by successive waves of immigrants. The second belief is the long chronology theory , which proposes that

7137-438: The comparatively higher frequency of cell divisions in the parental sperm donor germline drive conclusions that rates of de novo mutation can be tracked along a common basis. The frequency of error during the DNA replication process of gametogenesis , especially amplified in the rapid production of sperm cells, can promote more opportunities for de novo mutations to replicate unregulated by DNA repair machinery. This claim combines

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7254-544: The comparison of genes between different species of Drosophila suggests that if a mutation does change a protein, the mutation will most likely be harmful, with an estimated 70 per cent of amino acid polymorphisms having damaging effects, and the remainder being either neutral or weakly beneficial. Some mutations alter a gene's DNA base sequence but do not change the protein made by the gene. Studies have shown that only 7% of point mutations in noncoding DNA of yeast are deleterious and 12% in coding DNA are deleterious. The rest of

7371-407: The complementary undamaged strand in DNA as a template or an undamaged sequence in a homologous chromosome if it is available. If DNA damage remains in a cell, transcription of a gene may be prevented and thus translation into a protein may also be blocked. DNA replication may also be blocked and/or the cell may die. In contrast to a DNA damage, a mutation is an alteration of the base sequence of

7488-553: The de Soto expedition wandered the American Southeast for four years, becoming more bedraggled, losing more men and equipment, and eventually arriving in Mexico as a fraction of its original size. The local people fared much worse though, as the fatalities of diseases introduced by the expedition devastated the populations and produced much social disruption. By the time Europeans returned a hundred years later, nearly all of

7605-672: The decline of the Toltec civilization came political fragmentation in the Valley of Mexico . Into this new political game of contenders to the Toltec throne stepped outsiders: the Mexica . They were also a desert people, one of seven groups who formerly called themselves "Azteca", in memory of Aztlán , but they changed their name after years of migrating. Since they were not from the Valley of Mexico , they were initially seen as crude and unrefined in

7722-404: The dedicated reproductive group and which are not usually transmitted to descendants. Diploid organisms (e.g., humans) contain two copies of each gene—a paternal and a maternal allele. Based on the occurrence of mutation on each chromosome, we may classify mutations into three types. A wild type or homozygous non-mutated organism is one in which neither allele is mutated. A germline mutation in

7839-479: The destruction, a few original documents have survived, and others were transcribed or translated into Spanish, providing modern historians with valuable insights into ancient cultures and knowledge. Before the development of archaeology in the 19th century, historians of the pre-Columbian period mainly interpreted the records of the European conquerors and the accounts of early European travelers and antiquaries. It

7956-431: The distribution of fitness effects was done by Motoo Kimura , an influential theoretical population geneticist . His neutral theory of molecular evolution proposes that most novel mutations will be highly deleterious, with a small fraction being neutral. A later proposal by Hiroshi Akashi proposed a bimodal model for the DFE, with modes centered around highly deleterious and neutral mutations. Both theories agree that

8073-659: The earliest migrants into the northern extremes of North America and Greenland derived from later populations. Asian nomadic Paleo-Indians are thought to have entered the Americas via the Bering Land Bridge (Beringia), now the Bering Strait , and possibly along the coast. Genetic evidence found in Indigenous peoples ' maternally inherited mitochondrial DNA (mtDNA) supports the theory of multiple genetic populations migrating from Asia. After crossing

8190-435: The effects of the mutations on the ability of the cell to survive and reproduce. Although distinctly different from each other, DNA damages and mutations are related because DNA damages often cause errors of DNA synthesis during replication or repair and these errors are a major source of mutation. Mutations can involve the duplication of large sections of DNA, usually through genetic recombination . These duplications are

8307-548: The empire from 700 BCE to 700 CE. The Zapotecs resisted the expansion of the Aztecs until they were subjugated in 1502 under Aztec emperor Ahuitzotl . After the Spanish conquest of the Aztec Empire , the Zapotecs resisted Spanish rule until King Cosijopii I surrendered in 1563. Like the Zapotecs, the Mixtecs thrived in the Oaxaca Valley. The Mixtecs consisted of separate independent kingdoms and city-states, rather than

8424-595: The end of the period when they were replaced by bows and arrows . The Mississippian culture was spread across the Southeast and Midwest of what is today the United States, from the Atlantic coast to the edge of the plains, from the Gulf of Mexico to the Upper Midwest, although most intensively in the area along the Mississippi River and Ohio River . One of the distinguishing features of this culture

8541-462: The establishment of cities, such as El Tajín as important commercial trading centers. The Totonacs would later assist in the Spanish conquest of the Aztec Empire as an opportunity to liberate themselves from Aztec military imperialism. The Toltec civilization was established in the 8th century CE. The Toltec Empire expanded its political borders to as far south as the Yucatán peninsula , including

8658-403: The first Cazonci, Tariacuri, united these communities and built them into one of the most advanced civilizations in Mesoamerica. Their capital at Tzintzuntzan was just one of the many cities—there were ninety more under its control. The Tarascan Empire was among the largest in Central America, so it is no surprise that they routinely came into conflict with the neighboring Aztec Empire . Out of all

8775-462: The first group of people entered the hemisphere at a much earlier date, possibly 50,000–40,000 years ago or earlier. Artifacts have been found in both North and South America which have been dated to 14,000 years ago, and accordingly humans have been proposed to have reached Cape Horn at the southern tip of South America by this time. In that case, the Inuit would have arrived separately and at

8892-400: The former Toltec Empire , they were also quite independent in culture from their neighbors. The Aztecs, Tlaxcaltec , Olmec, Mixtec, Maya, and others were very similar to each other, however. This is because they were all directly preceded by the Toltecs, and they therefore shared almost identical cultures. The Tarascans, however, possessed a unique religion, as well as other things. Tlaxcala

9009-458: The genome, such as transposons , make up a major fraction of the genetic material of plants and animals, and may have been important in the evolution of genomes. For example, more than a million copies of the Alu sequence are present in the human genome , and these sequences have now been recruited to perform functions such as regulating gene expression . Another effect of these mobile DNA sequences

9126-399: The germline than in the soma. In order to categorize a mutation as such, the "normal" sequence must be obtained from the DNA of a "normal" or "healthy" organism (as opposed to a "mutant" or "sick" one), it should be identified and reported; ideally, it should be made publicly available for a straightforward nucleotide-by-nucleotide comparison, and agreed upon by the scientific community or by

9243-596: The impact was minimal or did not exist, pointing to numerous differences between the two systems and the ample precedents for the constitution in European political thought. The Calusa were a complex paramountcy/kingdom that resided in southern Florida . Instead of agriculture, the Calusa economy relied on abundant fishing. According to Spanish sources, the "king's house" at Mound Key was large enough to house 2,000 people. The Calusa ultimately collapsed into extinction at around 1750 after succumbing to diseases introduced by

9360-484: The indigenous peoples, described by a wide range of traditional creation stories which often say that a given people have been living in a certain territory since the creation of the world. Throughout thousands of years, paleo-Indian people domesticated, bred, and cultivated many plant species, including crops that now constitute 50–60% of worldwide agriculture. In general, Arctic, Subarctic, and coastal peoples continued to live as hunters and gatherers, while agriculture

9477-687: The influence that astronomical activities had upon Mesoamerican people before the arrival of Europeans. Many of the later Mesoamerican civilizations carefully built their cities and ceremonial centers according to specific astronomical events. The biggest Mesoamerican cities, such as Teotihuacan , Tenochtitlan , and Cholula , were among the largest in the world. These cities grew as centers of commerce, ideas, ceremonies, and theology, and they radiated influence outwards onto neighboring cultures in central Mexico. While many city-states, kingdoms, and empires competed with one another for power and prestige, Mesoamerica can be said to have had five major civilizations:

9594-616: The land bridge, they moved southward along the Pacific coast and through an interior ice-free corridor. Throughout millennia, Paleo-Indians spread throughout the rest of North and South America. Exactly when the first people migrated into the Americas is the subject of much debate. One of the earliest identifiable cultures was the Clovis culture , with sites dating from some 13,000 years ago. However, older sites dating back to 20,000 years ago have been claimed. Some genetic studies estimate

9711-472: The late Aztec period (1350–1519). Their capital, Tenochtitlan , is the site of modern-day Mexico City . At its peak, it was one of the largest cities in the world with population estimates of 200,000–300,000. The market established there was the largest ever seen by the conquistadores on arrival. Initially, the lands that would someday comprise the lands of the powerful Tarascan Empire were inhabited by several independent communities. Around 1300, however,

9828-607: The late twentieth century, archeologists have studied, analyzed, and dated these sites, realizing that the earliest complexes were built by hunter-gatherer societies, whose people occupied the sites on a seasonal basis. Watson Brake , a large complex of eleven platform mounds, was constructed beginning in 3400 BCE and added to over 500 years. This has changed earlier assumptions that complex construction arose only after societies had adopted agriculture, and become sedentary, with stratified hierarchy and usually ceramics. These ancient people had organized to build complex mound projects under

9945-549: The molecular level can be caused by: Whereas in former times mutations were assumed to occur by chance, or induced by mutagens, molecular mechanisms of mutation have been discovered in bacteria and across the tree of life. As S. Rosenberg states, "These mechanisms reveal a picture of highly regulated mutagenesis, up-regulated temporally by stress responses and activated when cells/organisms are maladapted to their environments—when stressed—potentially accelerating adaptation." Since they are self-induced mutagenic mechanisms that increase

10062-513: The observable characteristics ( phenotype ) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution , cancer , and the development of the immune system , including junctional diversity . Mutation is the ultimate source of all genetic variation , providing the raw material on which evolutionary forces such as natural selection can act. Mutation can result in many different types of change in sequences. Mutations in genes can have no effect, alter

10179-470: The observed effects of increased probability for mutation in rapid spermatogenesis with short periods of time between cellular divisions that limit the efficiency of repair machinery. Rates of de novo mutations that affect an organism during its development can also increase with certain environmental factors. For example, certain intensities of exposure to radioactive elements can inflict damage to an organism's genome, heightening rates of mutation. In humans,

10296-516: The only true writing system native to the Americas using pictographs and syllabic elements in the form of texts and codices inscribed on stone, pottery, wood, or perishable books made from bark paper. The Huastecs were a Maya ethnic group that migrated northwards to the Gulf Coast of Mexico. The Huastecs are considered to be distinct from the Maya civilization, as they separated from the main Maya branch at around 2000 BCE and did not possess

10413-657: The people abandoned their settlements, likely due to drought. The Mogollon resided in the present-day states of Arizona , New Mexico, and Texas as well as Sonora and Chihuahua . Like most other cultures in Oasisamerica, the Mogollon constructed sophisticated kivas and cliff dwellings. In the village of Paquimé , the Mogollon are revealed to have housed pens for scarlet macaws , which were introduced from Mesoamerica through trade. The Sinagua were hunter-gatherers and agriculturalists who lived in central Arizona. Like

10530-416: The prehistoric Americas . The culture reached its peak in about 1200–1400 CE, and in most places, it seems to have been in decline before the arrival of Europeans. Many Mississippian peoples were encountered by the expedition of Hernando de Soto in the 1540s, mostly with disastrous results for both sides. Unlike the Spanish expeditions in Mesoamerica, which conquered vast empires with relatively few men,

10647-479: The protein product if they affect mRNA splicing. Mutations that occur in coding regions of the genome are more likely to alter the protein product, and can be categorized by their effect on amino acid sequence: A mutation becomes an effect on function mutation when the exactitude of functions between a mutated protein and its direct interactor undergoes change. The interactors can be other proteins, molecules, nucleic acids, etc. There are many mutations that fall under

10764-415: The relative abundance of different types of mutations (i.e., strongly deleterious, nearly neutral or advantageous), is relevant to many evolutionary questions, such as the maintenance of genetic variation , the rate of genomic decay , the maintenance of outcrossing sexual reproduction as opposed to inbreeding and the evolution of sex and genetic recombination . DFE can also be tracked by tracking

10881-487: The remainder being either neutral or marginally beneficial. Mutation and DNA damage are the two major types of errors that occur in DNA, but they are fundamentally different. DNA damage is a physical alteration in the DNA structure, such as a single or double strand break, a modified guanosine residue in DNA such as 8-hydroxydeoxyguanosine , or a polycyclic aromatic hydrocarbon adduct. DNA damages can be recognized by enzymes, and therefore can be correctly repaired using

10998-431: The reproductive cells of an individual gives rise to a constitutional mutation in the offspring, that is, a mutation that is present in every cell. A constitutional mutation can also occur very soon after fertilization , or continue from a previous constitutional mutation in a parent. A germline mutation can be passed down through subsequent generations of organisms. The distinction between germline and somatic mutations

11115-453: The sake of scientific experimentation. One 2017 study claimed that 66% of cancer-causing mutations are random, 29% are due to the environment (the studied population spanned 69 countries), and 5% are inherited. Humans on average pass 60 new mutations to their children but fathers pass more mutations depending on their age with every year adding two new mutations to a child. Spontaneous mutations occur with non-zero probability even given

11232-413: The same mutation. These types of mutations are usually prompted by environmental causes, such as ultraviolet radiation or any exposure to certain harmful chemicals, and can cause diseases including cancer. With plants, some somatic mutations can be propagated without the need for seed production, for example, by grafting and stem cuttings. These type of mutation have led to new types of fruits, such as

11349-657: The single-stranded human immunodeficiency virus ), replication occurs quickly, and there are no mechanisms to check the genome for accuracy. This error-prone process often results in mutations. The rate of de novo mutations, whether germline or somatic, vary among organisms. Individuals within the same species can even express varying rates of mutation. Overall, rates of de novo mutations are low compared to those of inherited mutations, which categorizes them as rare forms of genetic variation . Many observations of de novo mutation rates have associated higher rates of mutation correlated to paternal age. In sexually reproducing organisms,

11466-408: The skewness of the distribution of mutations with putatively severe effects as compared to the distribution of mutations with putatively mild or absent effect. In summary, the DFE plays an important role in predicting evolutionary dynamics . A variety of approaches have been used to study the DFE, including theoretical, experimental and analytical methods. One of the earliest theoretical studies of

11583-416: The structure of genes can be classified into several types. Large-scale mutations in chromosomal structure include: Small-scale mutations affect a gene in one or a few nucleotides. (If only a single nucleotide is affected, they are called point mutations .) Small-scale mutations include: The effect of a mutation on protein sequence depends in part on where in the genome it occurs, especially whether it

11700-573: The studied plant ( Arabidopsis thaliana )—more important genes mutate less frequently than less important ones. They demonstrated that mutation is "non-random in a way that benefits the plant". Additionally, previous experiments typically used to demonstrate mutations being random with respect to fitness (such as the Fluctuation Test and Replica plating ) have been shown to only support the weaker claim that those mutations are random with respect to external selective constraints, not fitness as

11817-564: The subject of considerable research. There is evidence of trade routes starting as far north as the Mexico Central Plateau , and going down to the Pacific coast. These trade routes and cultural contacts then went on as far as Central America . These networks operated with various interruptions from pre-Olmec times and up to the Late Classical Period (600–900 CE). The earliest known civilization in Mesoamerica

11934-425: The template strand. In mice , the majority of mutations are caused by translesion synthesis. Likewise, in yeast , Kunz et al. found that more than 60% of the spontaneous single base pair substitutions and deletions were caused by translesion synthesis. Although naturally occurring double-strand breaks occur at a relatively low frequency in DNA, their repair often causes mutation. Non-homologous end joining (NHEJ)

12051-543: The time of the establishment of the first permanent European colonies, around the late 16th to early 17th centuries, and are known primarily through archaeological research of the Americas and oral histories. Other civilizations, contemporaneous with the colonial period, were documented in European accounts of the time. For instance, the Maya civilization maintained written records, which were often destroyed by Christian Europeans such as Diego de Landa , who viewed them as pagan but sought to preserve native histories. Despite

12168-759: The type of mutation and base or amino acid changes. Mutation rates vary substantially across species, and the evolutionary forces that generally determine mutation are the subject of ongoing investigation. In humans , the mutation rate is about 50–90 de novo mutations per genome per generation, that is, each human accumulates about 50–90 novel mutations that were not present in his or her parents. This number has been established by sequencing thousands of human trios, that is, two parents and at least one child. The genomes of RNA viruses are based on RNA rather than DNA. The RNA viral genome can be double-stranded (as in DNA) or single-stranded. In some of these viruses (such as

12285-451: The vast majority of novel mutations are neutral or deleterious and that advantageous mutations are rare, which has been supported by experimental results. One example is a study done on the DFE of random mutations in vesicular stomatitis virus . Out of all mutations, 39.6% were lethal, 31.2% were non-lethal deleterious, and 27.1% were neutral. Another example comes from a high throughput mutagenesis experiment with yeast. In this experiment it

12402-555: The visits to the Caribbean by Christopher Columbus. Mesoamerican is the adjective generally used to refer to that group of pre-Columbian cultures. This refers to an environmental area occupied by an assortment of ancient cultures that shared religious beliefs, art, architecture, and technology in the Americas for more than three thousand years. Between 2000 and 300 BCE, complex cultures began to form in Mesoamerica. Some matured into advanced pre-Columbian Mesoamerican civilizations such as

12519-500: The ways of the Nahua civilization. Through political maneuvers and ferocious martial skills, they managed to rule Mexico as the head of the 'Triple Alliance' which included two other Aztec cities, Tetxcoco and Tlacopan . Latecomers to Mexico's central plateau , the Mexica thought of themselves, nevertheless, as heirs of the civilizations that had preceded them. For them, arts, sculpture, architecture, engraving, feather-mosaic work, and

12636-420: The wheel, but it was used solely as a toy. In addition, they used native copper , silver , and gold for metalworking. Archaic inscriptions on rocks and rock walls all over northern Mexico (especially in the state of Nuevo León ) demonstrate an early propensity for counting. Their number system was base 20 and included zero . These early count markings were associated with astronomical events and underscore

12753-667: The word tracing its origins to a Navajo word meaning "ancestor enemies". The Hohokam thrived in the Sonoran desert in what is now the U.S. state of Arizona and the Mexican state of Sonora . The Hohokam were responsible for the construction of a series of irrigation canals that led to the successful establishment of Phoenix, Arizona via the Salt River Project . The Hohokam also established complex settlements such as Snaketown , which served as an important commercial trading center. After 1375 CE, Hohokam society collapsed and

12870-493: Was a Nahua republic and confederation in central Mexico. The Tlaxcalans fiercely resisted Aztec expansion during the Flower Wars ever since the Aztecs expelled them from Lake Texcoco . The Tlaxcalans would later ally with the Spanish conquistadors under Hernán Cortés as an opportunity to liberate them from the Aztecs and managed to successfully conquer the Aztecs with the help of the conquistadors. The Spaniards would reward

12987-416: Was a time of intense flourishing of Maya civilized accomplishments. While the many Maya city-states never achieved political unity on the order of the central Mexican civilizations, they exerted tremendous intellectual influence upon Mexico and Central America. The Maya built some of the most elaborate cities on the continent and made innovations in mathematics, astronomy, and calendrics. The Maya also developed

13104-583: Was adopted in more temperate and sheltered regions, permitting a dramatic rise in population. After the migration or migrations, it was several thousand years before the first complex societies arose, the earliest emerging about seven to eight thousand years ago. As early as 5500 BCE, people in the Lower Mississippi Valley at Monte Sano and other sites in present-day Louisiana , Mississippi , and Florida were building complex earthwork mounds , probably for religious purposes. Beginning in

13221-569: Was not until the nineteenth century that the work of people such as John Lloyd Stephens , Eduard Seler , and Alfred Maudslay , and institutions such as the Peabody Museum of Archaeology and Ethnology of Harvard University , led to the reconsideration and criticism of the early European sources. Now, the scholarly study of pre-Columbian cultures is most often based on scientific and multidisciplinary methodologies. The haplogroup most commonly associated with Indigenous Amerindian genetics

13338-439: Was probably made in the 14th century and is composed of 47 sections of animal skin with dimensions of 19 cm by 23.5 cm. The codex folds together like a screen and is vividly painted on both sides, and the condition of the document is by and large excellent. It is one of three codices that record the genealogies, alliances and conquests of several 11th and 12th century rulers of a small Mixtec city-state in highland Oaxaca ,

13455-545: Was published while it was in the collection of Baron Zouche by the Peabody Museum of Archaeology and Ethnology , Harvard in 1902, with an introduction by Zelia Nuttall (1857–1933). The British Museum was loaned the manuscript in 1876 and acquired it in 1917. Pre-Columbian During the pre-Columbian era, many civilizations developed permanent settlements, cities, agricultural practices, civic and monumental architecture, major earthworks , and complex societal hierarchies. Some of these civilizations had declined by

13572-432: Was shown that the overall DFE is bimodal, with a cluster of neutral mutations, and a broad distribution of deleterious mutations. Though relatively few mutations are advantageous, those that are play an important role in evolutionary changes. Like neutral mutations, weakly selected advantageous mutations can be lost due to random genetic drift, but strongly selected advantageous mutations are more likely to be fixed. Knowing

13689-538: Was the construction of complexes of large earthen mounds and grand plazas, continuing the mound-building traditions of earlier cultures. They grew maize and other crops intensively, participated in an extensive trade network, and had a complex stratified society. The Mississippians first appeared around 1000 CE, following and developing out of the less agriculturally intensive and less centralized Woodland period. The largest urban site of these people, Cahokia —located near modern East St. Louis, Illinois —may have reached

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