1. Madagascar Human-environment interaction & lemur evolutionary ecology
Madagascar’s 100 or so extant lemur species are widely known for their incredible phenotypic and behavioral diversity. Yet, only several thousand years ago lemur diversity was considerably greater. For example, from skeletal remains, we know of at least 17 now-extinct species that lived as recently as 500 years ago. These species are often called the “subfossil” lemurs, as the bones are unmineralized. Each subfossil species was larger than any extant lemur, some substantially so -- up to the size of a male gorilla! Humans arrived to Madagascar within the past several thousand year, and thereafter may have contributed to the extinction of the subfossil lemurs through habitat changes and hunting activities. This phenomenon continues; more than 70% of extant lemurs are considered endangered or critically endangered due to continuing deforestation and hunting.
While humans arrived relatively recently to Madagascar, there is large uncertainty over the actual date. Also, while modern Malagasy have mixed Southeast Asian and mainland African ancestry, the order in which various people arrived is unknown, as is the pace of subsequent population expansions. All of this information is important for reconstructing the history of anthropogenic impacts on the island’s biodivdersity, as (for example) each human group arrived with different technologies and land-use practices. To study these processes, we are using high-resolution population genomic methods to reconstruct and compare the recent demographic histories of both the Malagasy people and various lemur species, and comparing these results to paleoclimate data. We are also working to characterize signatures of recent natural selection in extant lemurs that could reflect adaptations to human habitat disturbance or hunting pressures. Finally, we are testing multiple hypotheses about longer-timescale lemur evolutionary ecology. Our current projects in this area include ancient DNA studies to make inferences about extinct subfossil lemur behavioral ecology (e.g., taste and visual perception), and both behavioral and evolutionary genomic analyses of the foraging ecology of the aye-aye, a cryptic, morphologically specialized extant lemur that extracts insect larvae from dead trees. These projects are funded by grants from the National Science Foundation.
2. Evolutionary ecology of human rainforest hunter-gatherers
Rainforests are incredibly challenging habitats for human hunter-gatherers. They are food limited, structurally dense, extremely hot and humid, and harbor a large number and diversity of parasitic and infectious disease pathogens. Rainforest hunter-gatherers in Africa, Southeast Asia, and South America share a number of cultural and physical traits hypothesized to represent convergent adaptations to this environment. Small body size, or the ‘pygmy’ phenotype, is a captivating example.
The long-term goal of this project is to build a comprehensive picture of rainforest hunter-gatherer evolutionary ecology. One approach is to identify signatures of natural selection in the genomes of both African and Southeast Asian rainforest hunter-gatherers, and then link those signatures to adaptive phenotypes. We are also interested in the antiquity of hunting and gathering behaviors in the rainforest and the history of trade with neighboring agricultural populations. This project involves sample collection and ecological experiments at a field site in Uganda (we have also done some work in Malaysia and the Philippines), as well as functional and evolutionary genomic analyses in the laboratory. This research is funded by a grant from the National Institutes of Health.
3. Parasites AS PROXIES FOR STUDYING human evolution
Many of our parasites flourish only under very specific human behaviors and habitats, are wholly dependent on us, and have evolved with us for thousands or millions of years. Therefore, by asking when and how we first acquired those parasites, under which environmental and cultural conditions we are the most susceptible, and how the parasites have evolved and adapted to us and we in response to them, we can gain considerable insight into our own evolutionary history, beyond that which can readily be obtained by only studying ourselves.
In our lab, we have begun to apply genomic sequencing and ancient DNA tools to study potentially informative human parasites (for ancient DNA, the specimens are from mummies or preserved in coprolites), starting with tapeworms and hookworms. The tapeworm lifecycle is dependent on our consumption of meat, whereas the hookworm larval stage must occur in non-frozen soil. Therefore, the evolutionary and population histories of these parasites are intertwined with critical aspects of human biology and culture related to the origins of meat eating as a regular hominin behavior, and questions concerning the peopling of the Americas over the Bering Land Bridge versus a coastal route, respectively. These projects are just underway and we are looking to push forward and expand this research model to other human parasites. Our tapeworm research is funded by a grant from the Wenner-Gren Foundation for Anthropological Research.
See publications: Perry 2014