Eske Willerslev (born 5 June 1971) is a Danish evolutionary geneticist notable for his pioneering work in molecular anthropology, palaeontology, and ecology.

He is director of the Centre of Excellence in GeoGenetics, a research associate at the Wellcome Trust Sanger Institute, and a professorial fellow at St John's College, Cambridge.

[3] Willerslev is a foreign associate of the National Academy of Sciences (US) and holds the Order of the Dannebrog issued by her Majesty Queen Margrethe II of Denmark in 2017.

[22][23] His team has also used environmental DNA to reveal forested refugia in Scandinavia during the last interglacial,[24] and that forbs rather than grasses were dominating the steppe environments of the northern hemisphere during the Pleistocene and were an important food source for the megafauna.

[25] Using environmental DNA, Willerslev and collaborators estimated that woolly mammoth in mainland Alaska survived more than 3,500 years earlier than previously thought, thereby dismissing the Blitzkrieg and Impact hypotheses for megafauna extinction.

[26] They also clarified the importance of climate change as a driver of megafauna population dynamics,[27] and the decline of protein rich forbs during the Pleistocene extinctions.

[25] In 2017 Willerslev's team was the first to apply a metagenomic approach to environmental DNA, reconstructing the biological succession of North America's interior Ice-Free Corridor.

Willerslev and his team obtained and identified two-million-year-old environmental DNA sequences from the Kap København Formation in Greenland that indicated that the region once had a forested ecosystem with a wide variety of animal life.

[31] They did not find any genetic signature or any distinctive range dynamics distinguishing extinct (woolly mammoth and rhino) from surviving species (horse, musk ox, and reindeer), revealing the challenges associated with predicting future responses of extant mammals to climate and human-derived change to their habitats.

[34] This was the first genetic evidence for cultural change happening in isolation through the spread of ideas within a population rather than through meetings between different groups of peoples as seen e.g. during the European Neolithisation.

[36] In 2014 his team sequenced the Clovis-age genome from the 12,600-year-old Anzick boy from Montana and found it to be ancestral to many contemporary Native Americans thereby rejecting the Solutrean theory for early peopling of the Americas.

In a paper in the scientific journal Nature in 2016 Willerslev and co-authors showed that this ice-free corridor could not sustain humans until much later thereby making it most likely that the early Americans migrated along the Pacific coast.

[43] Willerslev's team sequenced the genome of one of the earliest anatomically modern humans from Europe, Kostenki 14 from Russia, dated to be between 36-38,000 years old.

They also found evidence for major population movements and replacements in both Europe and Asia during the Bronze Age time and that significant parts of contemporary European and Asian genetic diversity were created during this period.

[46] In 2018, Willerslev and colleges published 2 papers in Nature and Science the same day addressing the population history of Central and Southern Asia.

Later, Scythians admixed and were replaced by steppe nomads from the east coming out of the Xiongnu confederations of Mongolia and China, including the westward-expanding Huns (fourth–fifth century AD).

A second theory, referred to as the ‘two-layer model’, favours the view that migrating rice farmers from what is now China replaced the indigenous Hòabìnhian hunter-gatherers.

Genotypes that today are typical of Africa and Asia, as well as a subgenotype from India, are shown to have an early Eurasian presence with humans, revealing a complexity of HBV evolution that is not evident when considering modern sequences alone.

[56] Willerslev appears regularly in media such as magazines, newspapers, radio and TV when discussions turn to human evolution, migration, and the role of science in society.

He and his staff at the Centre for GeoGenetics[57] have participated in documentaries including The Great Human Odyssey (PBS/CBC/DR), Code Breakers (CBC/DR) and Equus - Story of the Horse (CBC/PBS/DR/ZDF), First Peoples (PBS), Search for the Head of John the Baptist and How to Build and Ancient Man (both National Geographic).

[58] His father's education of Eske and his brother was rather authoritarian, and included frequent physical challenges, such as obstacle paths and swimming in ice water, already at the age of six.

[60] However, influenced by numerous experiences living with native people, Willerslev came to respect, and to some extent believe, in supernatural powers unknown to science.