Mothers and Infants in the Prehistoric Santa Clara Valley: What Stable Isotopes Tell Us about Ancestral Ohlone Weaning Practices

Breast-feeding and weaning are a part of childhood in all human populations, but the exact timing of these milestones varies between groups. As infants incorporate the nutrients from breast milk into their growing bones, chemical evidence is captured in the form of higher stable nitrogen (δ15N) isotope values. This study interprets δ15N values in the bone collagen of children (n = 24) buried at the Yukisma Mound (CA-SCL-38), in Santa Clara County, California. Radiocarbon dates for this site span 2200-250 B.P., but primarily fall during the Late period (740-230 B.P.). In the one probable mother-infant pair available for study, a 2.9 per mil enrichment of δ15N values was observed, consistent with the expected trophic level enrichment of breast-feeding infants. δ15N values of children under seven years old suggest the introduction of weaning foods between 1.5 and 2 years of age, and cessation of breast-feeding by 3 to 3.5 years of age. These results differ from the practices reported in the ethnohistoric literature. This paper includes photos of human remains, taken during excavation at CA-SCL-38 by Ohlone Family Consulting Services, the CRM arm of the Muwekma Ohlone Tribe (which also served as the Most Likely Descendant tribal group for this project). The images were provided to the authors by the tribe, and specific permission was granted to include them in this publication

Matrilocality in the Middle Period in San Francisco Bay? New Evidence from Strontium Isotopes at CA-SCL-287

We explore strontium (Sr) isotope analysis as a means to reconstruct ancient migration patterns of individuals at SCL-287, a Middle Period site in southern San Francisco Bay. Comparison of Sr isotopes from rst molars to that of bone suggests that males frequently immigrated to the site, while all females were born at or near the site. This pattern is consistent with a preference for matrilocal post-marital residence patterns. At the same time, analysis of third molars indicates that individuals frequently shifted residence during early teenage years, even those who were born and lived as adults at SCL-287. While adult residence shifts are commonly reported in the ethnography of Central California, matrilocality is not. In this respect, isotopic analyses allow us to generate new hypotheses about ancient migration patterns in prehistory independent of those reported in the ethnographic literature

Matrilocality in the Middle Period in San Francisco Bay? New Evidence from Strontium Isotopes at CA-SCL-287

We explore strontium (Sr) isotope analysis as a means to reconstruct ancient migration patterns of individuals at SCL-287, a Middle Period site in southern San Francisco Bay. Comparison of Sr isotopes from rst molars to that of bone suggests that males frequently immigrated to the site, while all females were born at or near the site. This pattern is consistent with a preference for matrilocal post-marital residence patterns. At the same time, analysis of third molars indicates that individuals frequently shifted residence during early teenage years, even those who were born and lived as adults at SCL-287. While adult residence shifts are commonly reported in the ethnography of Central California, matrilocality is not. In this respect, isotopic analyses allow us to generate new hypotheses about ancient migration patterns in prehistory independent of those reported in the ethnographic literature

Detection of subsurface eddies from satellite observations

International audienceThis study aims to develop an index that allows distinguishing between surface and subsurface intensified eddies from surface data only, in particular using the sea surface height and the sea surface temperature available from satellite observations. To do this, we propose the use of a simple index based on the ratio of the sea surface temperature anomaly (SSTa) and the sea level anomaly (SLA). This index is first derived using an academic approach, based on idealized assumptions of geostrophic balance and Gaussian-shaped vortices. This index depends on the vertical extent (or decreasing rate) of the eddy and because of its sensitivity to the exact shape of the vortex, we were not able to evaluate these depths from the surface fields and our results remain qualitative. Then, in order to examine the pertinence and validity of the proposed index, SSTa and SLA were computed using outputs of a realistic regional circulation model in the Peru-Chile upwelling system where both surface and subsurface eddies coexist. Over a seven year simulation, the statistics shows that 71% of eddies are correctly identified as surface or subsurface intensified. Multi-core eddies are also largely present and represent an average of 37% of all vortices. These multi-core eddies contribute to a large number of the wrong identification (15%). Finally, the index was successfully applied on in-situ data to detect a previously observed subsurface-intensified Swoddy (slope water eddy) in the Bay of Biscay. This study suggests that the index can be successfully used to determine the exact nature of mesoscale eddies (surface or subsurface- intensified) from satellite observations only

Detection of subsurface eddies from satellite observations

International audienceThis study aims to develop an index that allows distinguishing between surface and subsurface intensified eddies from surface data only, in particular using the sea surface height and the sea surface temperature available from satellite observations. To do this, we propose the use of a simple index based on the ratio of the sea surface temperature anomaly (SSTa) and the sea level anomaly (SLA). This index is first derived using an academic approach, based on idealized assumptions of geostrophic balance and Gaussian-shaped vortices. This index depends on the vertical extent (or decreasing rate) of the eddy and because of its sensitivity to the exact shape of the vortex, we were not able to evaluate these depths from the surface fields and our results remain qualitative. Then, in order to examine the pertinence and validity of the proposed index, SSTa and SLA were computed using outputs of a realistic regional circulation model in the Peru-Chile upwelling system where both surface and subsurface eddies coexist. Over a seven year simulation, the statistics shows that 71% of eddies are correctly identified as surface or subsurface intensified. Multi-core eddies are also largely present and represent an average of 37% of all vortices. These multi-core eddies contribute to a large number of the wrong identification (15%). Finally, the index was successfully applied on in-situ data to detect a previously observed subsurface-intensified Swoddy (slope water eddy) in the Bay of Biscay. This study suggests that the index can be successfully used to determine the exact nature of mesoscale eddies (surface or subsurface- intensified) from satellite observations only

Detection of subsurface eddies from satellite observations

International audienceThis study aims to develop an index that allows distinguishing between surface and subsurface intensified eddies from surface data only, in particular using the sea surface height and the sea surface temperature available from satellite observations. To do this, we propose the use of a simple index based on the ratio of the sea surface temperature anomaly (SSTa) and the sea level anomaly (SLA). This index is first derived using an academic approach, based on idealized assumptions of geostrophic balance and Gaussian-shaped vortices. This index depends on the vertical extent (or decreasing rate) of the eddy and because of its sensitivity to the exact shape of the vortex, we were not able to evaluate these depths from the surface fields and our results remain qualitative. Then, in order to examine the pertinence and validity of the proposed index, SSTa and SLA were computed using outputs of a realistic regional circulation model in the Peru-Chile upwelling system where both surface and subsurface eddies coexist. Over a seven year simulation, the statistics shows that 71% of eddies are correctly identified as surface or subsurface intensified. Multi-core eddies are also largely present and represent an average of 37% of all vortices. These multi-core eddies contribute to a large number of the wrong identification (15%). Finally, the index was successfully applied on in-situ data to detect a previously observed subsurface-intensified Swoddy (slope water eddy) in the Bay of Biscay. This study suggests that the index can be successfully used to determine the exact nature of mesoscale eddies (surface or subsurface- intensified) from satellite observations only

Detection of subsurface eddies from satellite observations

International audienceThis study aims to develop an index that allows distinguishing between surface and subsurface intensified eddies from surface data only, in particular using the sea surface height and the sea surface temperature available from satellite observations. To do this, we propose the use of a simple index based on the ratio of the sea surface temperature anomaly (SSTa) and the sea level anomaly (SLA). This index is first derived using an academic approach, based on idealized assumptions of geostrophic balance and Gaussian-shaped vortices. This index depends on the vertical extent (or decreasing rate) of the eddy and because of its sensitivity to the exact shape of the vortex, we were not able to evaluate these depths from the surface fields and our results remain qualitative. Then, in order to examine the pertinence and validity of the proposed index, SSTa and SLA were computed using outputs of a realistic regional circulation model in the Peru-Chile upwelling system where both surface and subsurface eddies coexist. Over a seven year simulation, the statistics shows that 71% of eddies are correctly identified as surface or subsurface intensified. Multi-core eddies are also largely present and represent an average of 37% of all vortices. These multi-core eddies contribute to a large number of the wrong identification (15%). Finally, the index was successfully applied on in-situ data to detect a previously observed subsurface-intensified Swoddy (slope water eddy) in the Bay of Biscay. This study suggests that the index can be successfully used to determine the exact nature of mesoscale eddies (surface or subsurface- intensified) from satellite observations only

Ancient human parallel lineages within North America contributed to a coastal expansion.

Little is known regarding the first people to enter the Americas and their genetic legacy. Genomic analysis of the oldest human remains from the Americas showed a direct relationship between a Clovis-related ancestral population and all modern Central and South Americans as well as a deep split separating them from North Americans in Canada. We present 91 ancient human genomes from California and Southwestern Ontario and demonstrate the existence of two distinct ancestries in North America, which possibly split south of the ice sheets. A contribution from both of these ancestral populations is found in all modern Central and South Americans. The proportions of these two ancestries in ancient and modern populations are consistent with a coastal dispersal and multiple admixture events

Ancient human parallel lineages within North America contributed to a coastal expansion.

Little is known regarding the first people to enter the Americas and their genetic legacy. Genomic analysis of the oldest human remains from the Americas showed a direct relationship between a Clovis-related ancestral population and all modern Central and South Americans as well as a deep split separating them from North Americans in Canada. We present 91 ancient human genomes from California and Southwestern Ontario and demonstrate the existence of two distinct ancestries in North America, which possibly split south of the ice sheets. A contribution from both of these ancestral populations is found in all modern Central and South Americans. The proportions of these two ancestries in ancient and modern populations are consistent with a coastal dispersal and multiple admixture events