John Relethford, Anthropology, is senior author of a paper entitled “Cranial measures and ancient DNA both show greater similarity of Neandertals to recent modern Eurasians than to recent modern sub Saharan Africans,” in the American Journal of Physical Anthropology (with Fred Smith, Illinois State University, as coauthor).
Neandertals are ancient humans that died out about 40,000 years ago, but form part of the ancestry of modern humans (Homo sapiens). Fossil and genetic evidence show that modern humans first evolved in Africa about 200,000 years ago, and about 100,000 years ago began to disperse throughout the rest of the world, where they encountered earlier humans such as Neandertals.
In the past decade, studies of ancient DNA have shown that there is a small amount of Neandertal ancestry in present-day people of Eurasian ancestry but not in present-day people of sub-Saharan African ancestry. This geographic difference is because interbreeding of Neandertals and modern humans took place after the initial dispersion of modern humans out of Africa.
Relethford and Smith tested the hypothesis that the same pattern can be found when comparing cranial measures of present-day humans with those of Neandertals. They examined a multivariate measure of cranial similarity based on 37 craniofacial measures and compared 2,413 crania of present-day humans around the world to an average Neandertal (based on the same measures from fossils).
They found that although all recent modern humans are very similar to each other and quite distinct from Neandertals, individuals of Eurasian descent were closer to Neandertals, as expected from the ancient DNA results. They also showed that other factors, such as differences relating to climatic adaptation, did not affect the conclusions.