User:Glasshn/Anzick-1

Anzick-1 is the name given to the skeletal remains of Paleo-Indian male infant found in Western Montana in 1968 that date to 12,707-12,556 years BP. Anzick-1 is the only human that has been discovered from the Clovis Complex, and is the first ancient Native American genome to be fully sequenced.

Paleogenomic analysis of the remains revealed Siberian ancestry and a close genetic relationship to modern Native Americans. These findings support the hypothesis that modern Native Americans are descended from Asian populations who crossed Beringia between 32,000 and 18,000 years ago, and discredits the Solutrean Hypothesis.

Anzick-1's discovery and subsequent analysis is controversial because although the researchers did not violate the Native American Graves Protection and Repatriation Act (NAGPRA), many Montana tribal members believe they should have been consulted before the analysis of the infant's skeleton and genome.

Discovery
The Anzick site was accidentally discovered by a construction worker in a collapsed rock shelter near Wilsal, Montana. The site contained hundreds of of stone projectile points, blades, and bifaces as well as two juveniles Some of the artifacts were covered in red ochre. The stone points were identified as part of the Clovis Complex because of their distinct shape and size. Originally, the two human skeletons were both thought to contemporaneous with the Clovis Complex stone points, but later carbon dating revealed that only one of the human skeletons, Anzick-1, was from the Clovis period. Anzick-1 predates the other skeleton by two millennia.

Osteological Findings
Anzick-1's skeletal remains included 28 cranial fragments, the left clavicle, and several ribs. These bones were discovered in highly fragmented states; however, partial reconstruction of the crania allowed for age estimation, investigation of basic health indicators, and some information about cultural practices. Originally, investigators thought the left clavicle showed evidence of cremation, but further analysis revealed that the discoloration was the result of groundwater staining and not fire. Additionally, all of the Anzick-1 remains were stained with ocher, which masks the natural color of the infant's bones.

Age estimation
The age at death of an individual can be determined from several skeletal markers including cranial suture closure, tooth eruption rates, rates of epiphyseal fusion on long bones, and others. Cranial bones fuse together along suture lines throughout the life of every human, and can be used to estimate the age at death of human remains. The small size and lack of suture closure of Anzick-1's crania revealed that the individual was 1-2 years old. The metopic suture is also present in the frontal bone of Anzick-1. This suture is present in most human infants but closes well before adulthood. The presence of a frontal suture in Anzick-1's remains corroborates the age estimation of 1-2 years old.

Skeletal markers of health
Cranial bones can also be useful for detecting evidence of physiological perturbations. Porotic hyperostosis is characterized by porous lesions on the parietal, occipital, and sometimes frontal bones. Cribra orbitalia is another pathological skeletal lesion that manifests as porosity on the orbital roof. Both porotic hyperostosis and cribra orbitalia are indicators of a nutritional deficiency that leads to anemia. The reconstructed frontal, parietal, and occipital bone fragments of Anzick-1 were analyzed for these indicators of health; however, the crania showed no evidence of cribra orbitalia or porotic hyperostosis.

Cranial Vault Modification
Many cultures use wrappings and boards to manipulate the malleable cranial bones of infants into different shapes which may hold cultural significance. This practice has been recorded in several different bioarchaeological contexts throughout the Americas. The shape of Anzick-1's cranial vault revealed no evidence of cultural cranial vault modification.

Paleogenetic Findings
A team of researchers throughout the United States and Europe conducted paleogenetic research on the Anzick-1 skeletal remains. They sequenced the mitochondrial DNA (mtDNA), the full nuclear DNA, and the Y-chromosome, and compared these sequences to those of modern populations throughout the world. The results of these analyses allowed the researchers to make conclusions about ancient migration patterns and the peopling of the Americas.

Mitochondrial DNA Analysis
MtDNA is DNA located in mitochondria, an organelle that is found in human cells. The mitochondria is maternally inherited and analysis of the mtDNA can provide information about maternal ancestry. MtDNA genomes are classified into different haplogroups based on a shared common ancestor, and distinct haplogroups provide information about ancient migration patterns. Morten Rasumssen and Sarah L. Anzick et al. sequenced the mitochondrial DNA of Anzick-1 and determined that the infant represents an ancient migration to North America from Siberia. They found that Anzick-1's mtDNA belongs to the haplogroup D4h3a, a "founder" haplogroup that might represent an early coastal migration route into the Americas. The D haplogroup is also found in modern Native American populations, which provides a link between Anzick-1 and modern Native Americans.

Nuclear DNA Analysis
Human nuclear DNA is located inside the nucleus of every cell and makes up the human genome. Humans inherit half of their nuclear DNA from their mother and half from their father. Throughout human evolution, mutations occur that are inherited in each subsequent generation. Different populations have different frequencies of these mutations, and population histories can be ascertained from these mutations by comparing the mutations of one individual to other genomes from specific ethnic groups. The genome of Anzick-1 was sequenced and analyzed to look for specific mutations that might point shed light on the population history of modern Native Americans. Anzick-1's genome was compared to over 50 Native American genomes for comparison, and researchers found that it was significantly more similar to these Native American genomes than to any modern Eurasian population. Interestingly, however Anzick-1's genome was closer to 44 Native American populations from Central and South America than with 7 Native American populations from North America.

Y-Chromosome Analysis
The y-chromosome is inherited from father to son in each generation. Because males have an x-chromosome and a y-chromosome, and females have two x-chromosomes, the y-chromosome can only be inherited from an male's father. Specific mutations on the y-chromosome can be used to trace the paternal lineage of a male individual. Like mtDNA, these mutations can be grouped and categorized into haplogroups. The y-chromosome of Anzick-1was sequenced and researchers determined that his y-chromosome haplogroup is Q-L54*(xM3), one of the major founding lineages of the Americas.

Implications
Anzick-1's mtDNA, nuclear DNA, and Y-Chromosome analysis revealed a close genetic affinity to modern Native Americans and provided evidence of gene flow from Siberia into the Americas. Some researchers believe that these findings support the Beringia Hypothesis of the peopling of the Americas and refute the Solutrean Hypothesis. However, other researchers believe that these results could support the Solutrean Hypothesis of the peopling of the Americas.

Beringia Hypothesis
The Beringia Hypothesis is a model for the peopling of the Americas that posits a migration of early Amerindians from Siberia across a land bridge that spanned the Bering Strait. This hypothesis is supported by genetic and archaeological evidence that places the migration no earlier than 32 thousand years ago. Ancient Native Americans could have entered the New World through an ice free corridor across the Beringian land bridge or they could have used boats to sail along the coast of Siberia, the Beringia land bridge, and North America. The Anzick-1 paleogenetic analysis lends support to the Beringia Hypothesis theory and supports the idea that there were three waves of migration from ancient Siberia into the New World.

Solutrean Hypothesis
The Solutrean hypothesis posits that modern Native Americans migrated to the New World across the Atlantic Ocean from Europe via "ocean current highways." Some mtDNA evidence supports this hypothesis because haplogroup X, found in some Native American communities in northeastern North America, originated in Europe where the Solultrean culture developed. Proponents of the Solutrean Hypothesis believe that ancient people crossed the Atlantic Ocean during a climatic event that raised glacier levels to a maxima that created a land bridge between Europe and North America. These early migrants to the New World left evidence of their presence through cave paintings and a distinct tool culture that influenced the Clovis Complex tools. Proponents of the Solutrean Hypothesis, like Kyle Bristow who wrote White Apocalypse, believe that Europeans migrated to the New World before ancient Native Americans crossed the Bering Strait.