Michael F Hammer

Professor, Research Scientist

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Research Interests

The primary research goals in my lab are to better understand the genomic and evolutionary factors shaping patterns of human variation and to test models of human origins. The human genome holds clues to the mystery of human origins. With the completion of the human genome sequence, and those of closely related species, we are now in a position to examine patterns of variation across the entire genome in multiple human populations. Such an undertaking will facilitate an understanding of events that took place tens of thousands of years ago, and the better design of studies to map genes involved in human disease today. In the early to mid 1990s my lab pioneered studies of variation on the Y chromosome as a model system to explore human evolution. Now the lab is comparing patterns of genetic variation across the entire genome to distinguish the footprint of natural selection from the signatures of demographic processes. We are engaged in a long-term collaborative projects to gather new data and design novel analytical methods to answer long-standing questions in human evolution. One focus of this research is on the evolutionary relationships of archaic human groups (such as the Neanderthals in Europe and Homo erectus in Asia) to modern humans. Did archaic forms make any contribution to the contemporary human gene pool, or were Neanderthals and H. erectus completely replaced (without interbreeding) by modern humans as they expanded out of Africa within the last 100 thousand years? Did our ancestors make the transition to modern form in a small, isolated part of Africa, or over a broader geographic range with genetic contributions from divergent populations. Another focus of this research is on human population growth. Although our current population size is more than 6 billion, the long-term average population size was probably substantially less than 1 million. When did human populations begin to expand dramatically in size? Was this growth associated with a particular event in human history, such as the advent of language or the invention of agriculture? We are also interested in the effects of natural selection, particularly local adaptation in human populations. Two model systems are pigmentation genes and genes involved in the resistance to disease.

Selected Publications

Karafet TM, Mendez FL, Meilerman MB, Underhill PA, Zegura SL, Hammer MF. Apr 2008. New binary polymorphisms reshape and increase resolution of the human Y chromosomal haplogroup tree. Genome Res, 18:830-8

Cox MP, Mendez FL, Karafet TM, Pilkington MM, Kingan SB, Destro-Bisol G, Strassmann BI, Hammer MF. Jan 2008. Testing for archaic hominin admixture on the X chromosome: model likelihoods for the modern human RRM2P4 region from summaries of genealogical topology under the structured coalescent. Genetics, 178:427-37

Pilkington MM, Wilder JA, Mendez FL, Cox MP, Woerner A, Angui T, Kingan S, Mobasher Z, Batini C, Destro-Bisol G, Soodyall H, Strassmann BI, Hammer MF. Mar 2008. Contrasting signatures of population growth for mitochondrial DNA and Y chromosomes among human populations in Africa. Mol Biol Evol, 25:517-25