| Project: | Human dispersals and environmental controls during the late Pleistocene / Early Holocene in Mexico |
| Principal Investigator: | Dr. Silvia Gonzalez |
| Co-Investigators: | Dr. Marta Mirazón Lahr, Prof. David Huddart, Dr. Alan Cooper, Dr. Angela Lamb, Dr. Alistair Pike, Dr. Ed Rhodes |
| Collaborators: | Prof. Rainer Grün, Dr. D. Owsley, Dr. José Concepción Jiménez-López |
| Funding: | NERC / EFCHED |
The timing, route and origin of the first colonization of the Americas remains a most contentious topic in human evolution. Most early sites date to the latest Pleistocene, in the US reflecting the expansion of Clovis archaeological tradition, but the fact that the earliest accepted date is in southern Chile (Monte Verde, 12,500 years), where lithic remains differ from Clovis sites, complicates the picture. Few human remains have been directly dated [e.g. the Santa Rosa Island femora (10,960 years BP), Buhl Woman, Idaho (10,700 years BP) and Kennewick Man, (8,800 years BP)], a fact thought to be due to the lack of collagen preservation in the bone and high degree of mineralization. In South America a human with a potential age of 11,500 B.P. has been reported, but the oldest directly-dated humans are not older than 9,720 years BP. However, in recent years this controversy has extended to the affinities and number of colonizing populations. Palaeoamerican remains are diverse morphologically and largely lack characteristic Amerindian traits. In this controversial context, Mexico plays a key role due to its geographical position. A number of Palaeoamerican remains exist. Four of these have been recently 14C AMS-dated to the late Pleistocene and early Holocene, and preliminary studies show important morphological differences to recent populations in the area. Several models have been proposed to explain the differences between early and mid-Holocene remains, from separate waves of migration, with extinction of the early group, to in situ differentiation. However, the Mexican remains suggest that these phenotypically different populations were at least partly contemporaneous. The survival of greater levels of diversity in the Americas may have been reflected in recently extinct population outliers, like the Fueguians or the Pericues, living on the southern tip of Baja California peninsula until the 18th C. Therefore, Mexico is not only at the crossroads of the Americas, but it has crucial Late Pleistocene/ Holocene human remains to explore the evolution of the American population.
The aims of this project are:
a) To build a comparative database of craniofacial features of Palaeoamericans, including the first complete study of dated Mexican remains and include the Pericues collection (150 individuals in the National Museum of Anthropology, Mexico City).
b) To date the Pre-Ceramic human and Pericues collections, using either 14C, U-Series dating on bones which have been unsuccessful with 14C and thermoluminiscence on sediments. The latter two techniques could revolutionise the dating and have a major chronological impact where 14C cannot be used. Dated remains will be added to the craniometric database.
c) Use techniques specifically developed for ancient human DNA on Mexican Palaeoamericans (including the Pericues to test the hypothesis of migration along the Pacific coast), mtDNA to determine geographical origin (SW Asia, Japan, Melanesia). Individuals with exceptional collagen preservation identified during 14C dating and bone biochemistry studies are prime candidates for genetic studies, like the four already dated.
d) To refine the known Late Pleistocene/Early Holocene stratigraphy in the Basin of Mexico using sedimentology, tephrachronology and palaeoenvironmental proxies (d18O, diatoms and ostracods), especially to assess the role of volcanic activity and climatic controls on human dispersals and megafaunal extinctions.