Thomas is notable for a number of
scientific publications in the fields of human demographic and
evolutionary history inference,
molecular phylogenetics of
extinct species using
ancient DNA, Cultural evolutionary modelling, and
molecular biology. In 1994 Thomas was one of the first people to read the DNA sequence of the extinct woolly mammoth and in 1998 he coauthored a paper providing
genetic support to the claim of recent
patrilineal common ancestry among the Jewish priestly caste known as
Kohanim (singular "Kohen", "Cohen", or Kohane). Between 2000 and 2003 Thomas coauthored several other papers on the origins of various
Jewish and Judaic groups, including the
Lemba, otherwise known as the "Black Jews of Southern Africa". In 2002 Thomas coauthored a paper providing
Y chromosome evidence for a very high
Anglo-Saxon component of patrilineal
ancestry in central England. This result proved unpalatable for many archaeologists and led to Thomas developing the "apartheid-like social structure" model to explain the discrepancy between
archaeological and genetic estimates of the scale of Anglo-Saxon migration. Thomas has also worked extensively on the evolution of lactase persistence (see
Lactose intolerance), the ability of some humans to produce the enzyme
lactase throughout their adult life and thus to consume appreciable quantities of fresh
milk without the discomforts of lactose malabsorption. In 2004 he led a study to show that most lactase persistent Africans did not have the same mutation causing it as Europeans. In 2007, in collaboration with
Joachim Burger's group in Mainz, Germany, he showed that the genetic variant that causes lactase persistence in most Europeans (-13,910*T) was rare or absent in early farmers from central Europe. In 2009 Thomas led a computer simulation study indicating that lactase persistence started to co-evolve with the culture of dairying in the
LBK (
Linearbandkeramik) culture. In 2009 – in collaboration with Prof Stephen Shennan and Dr Adam Powell – Thomas published a study in the journal
Science showing that population density and or migratory activity are likely to be a major determinants in the maintenance or loss of culturally inherited skills, and that this seemed to explain a number of curious features of the appearance of
behavioural modernity in humans at different times in different parts of the world. Together with
Kristian Kristiansen at the
University of Gothenburg and Kurt Kjaer at the
University of Copenhagen, Thomas was awarded a major
European Research Council synergy grant in 2020, totalling €10 million over six years. This project (titled 'COREX: From correlations to explanations: towards a new European prehistory') will study human biological and cultural evolution from the Neolithic to the Bronze Age through a combination of genomic, archaeological, environmental and isotopic datasets. ==Selected scientific publications==