Publications by authors named "Ricardo A Guichón"

5 Publications

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Ancient genomes in South Patagonia reveal population movements associated with technological shifts and geography.

Nat Commun 2020 08 3;11(1):3868. Epub 2020 Aug 3.

Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA.

Archaeological research documents major technological shifts among people who have lived in the southern tip of South America (South Patagonia) during the last thirteen millennia, including the development of marine-based economies and changes in tools and raw materials. It has been proposed that movements of people spreading culture and technology propelled some of these shifts, but these hypotheses have not been tested with ancient DNA. Here we report genome-wide data from 20 ancient individuals, and co-analyze it with previously reported data. We reveal that immigration does not explain the appearance of marine adaptations in South Patagonia. We describe partial genetic continuity since ~6600 BP and two later gene flows correlated with technological changes: one between 4700-2000 BP that affected primarily marine-based groups, and a later one impacting all <2000 BP groups. From ~2200-1200 BP, mixture among neighbors resulted in a cline correlated to geographic ordering along the coast.
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http://dx.doi.org/10.1038/s41467-020-17656-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400565PMC
August 2020

Eco-geographic adaptations in the human ribcage throughout a 3D geometric morphometric approach.

Am J Phys Anthropol 2018 06 8;166(2):323-336. Epub 2018 Feb 8.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales, Madrid, Spain.

Objectives: According to eco-geographic rules, humans from high latitude areas present larger and wider trunks than their low-latitude areas counterparts. This issue has been traditionally addressed on the pelvis but information on the thorax is largely lacking. We test whether ribcages are larger in individuals inhabiting high latitudes than in those from low latitudes and explored the correlation of rib size with latitude. We also test whether a common morphological pattern is exhibited in the thorax of different cold-adapted populations, contributing to their hypothetical widening of the trunk.

Materials And Methods: We used 3D geometric morphometrics to quantify rib morphology of three hypothetically cold-adapted populations, viz. Greenland (11 individuals), Alaskan Inuit (8 individuals) and people from Tierra del Fuego (8 individuals), in a comparative framework with European (Spain, Portugal and Austria; 24 individuals) and African populations (South African and sub-Saharan African; 20 individuals).

Results: Populations inhabiting high latitudes present longer ribs than individuals inhabiting areas closer to the equator, but a correlation (p < 0.05) between costal size and latitude is only found in ribs 7-11. Regarding shape, the only cold adapted population that was different from the non-cold-adapted populations were the Greenland Inuit, who presented ribs with less curvature and torsion.

Conclusions: Size results from the lower ribcage are consistent with the hypothesis of larger trunks in cold-adapted populations. The fact that only Greenland Inuit present a differential morphological pattern, linked to a widening of their ribcage, could be caused by differences in latitude. However, other factors such as genetic drift or specific cultural adaptations cannot be excluded and should be tested in future studies.
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http://dx.doi.org/10.1002/ajpa.23433DOI Listing
June 2018

Pre-Columbian tuberculosis in Tierra del Fuego? Discussion of the paleopathological and molecular evidence.

Int J Paleopathol 2015 Dec 17;11:92-101. Epub 2015 Nov 17.

Instituto de Bioantropología, Museo de la Naturaleza y el Hombre, Tenerife, Islas Canarias, Spain.

This work contributes to ongoing discussions about the nature of tuberculosis in the Western Hemisphere prior to the time of European contact. Our example, from the extreme south of South America was, at the time of our study, without firm temporal association or molecular characterization. In Tierra del Fuego, Constantinescu (1999) briefly described vertebral bone lesions compatible with TB in an undated skeleton from Myren 1 site (Chile). The remains of Myren are estimated to represent a man between 18 and 23 years old at the time of death. The objectives of this research are to extend this description, to present molecular results, to establish a radiocarbon date, and to report stable isotopic values for the remains. We provide further description of the remains, including tuberculosis-like skeletal pathology. Radiocarbon dating of 640±20 years BP attributes this individual to the precontact fourteenth-fifteenth centuries. Isotopic ratios for nitrogen and carbon from bone collagen suggest a mixed diet. Molecular results were positive for the rpoB quantitative PCR (qPCR) assays but negative for two independent IS6110 and IS1081 qPCR assays. Further testing using genomic methods to target any mycobacteria for specific identification are needed.
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http://dx.doi.org/10.1016/j.ijpp.2015.09.003DOI Listing
December 2015

Pre-Columbian mycobacterial genomes reveal seals as a source of New World human tuberculosis.

Nature 2014 Oct 20;514(7523):494-7. Epub 2014 Aug 20.

1] Department of Archaeological Sciences, University of Tübingen, Ruemelinstraße 23, 72070 Tübingen, Germany [2] Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Tübingen 72070, Germany [3] Max Planck Institute for Science and History, Khalaische Straße 10, 07745 Jena, Germany.

Modern strains of Mycobacterium tuberculosis from the Americas are closely related to those from Europe, supporting the assumption that human tuberculosis was introduced post-contact. This notion, however, is incompatible with archaeological evidence of pre-contact tuberculosis in the New World. Comparative genomics of modern isolates suggests that M. tuberculosis attained its worldwide distribution following human dispersals out of Africa during the Pleistocene epoch, although this has yet to be confirmed with ancient calibration points. Here we present three 1,000-year-old mycobacterial genomes from Peruvian human skeletons, revealing that a member of the M. tuberculosis complex caused human disease before contact. The ancient strains are distinct from known human-adapted forms and are most closely related to those adapted to seals and sea lions. Two independent dating approaches suggest a most recent common ancestor for the M. tuberculosis complex less than 6,000 years ago, which supports a Holocene dispersal of the disease. Our results implicate sea mammals as having played a role in transmitting the disease to humans across the ocean.
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http://dx.doi.org/10.1038/nature13591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4550673PMC
October 2014

Quantitative paleoparasitology applied to archaeological sediments.

Mem Inst Oswaldo Cruz 2006 Dec;101 Suppl 2:29-33

Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Buenos Aires, Argentina.

Three techniques to extract parasite remains from archaeological sediments were tested. The aim was to improve the sensibility of recommended paleoparasitological techniques applied in archaeological remains. Sediment collected from the pelvic girdle of a human body found in Cabo Vírgenes, Santa Cruz, Argentina, associated to a Spanish settlement founded in 1584 known as Nombre de Jesús, was used to search for parasites. Sediment close to the skull was used as control. The techniques recommended by Jones, Reinhard, and Dittmar and Teejen were used and compared with the modified technique presented here, developed to improve the sensibility to detect parasite remains. Positive results were obtained only with the modified technique, resulting in the finding of Trichuris trichiura eggs in the sediment.
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http://dx.doi.org/10.1590/s0074-02762006001000006DOI Listing
December 2006