Dylan S. Davis

Climate change is perhaps one of the greatest threats facing humanity in the 21st century. As such, the focus of the environment’s effects on human settlement is of great importance to the modern world and helps to advance NASA’s Earth Science Directive. Madagascar is a perfect case study of severe environmental change and its effects on humans through time because of its high levels of ecological diversity and longstanding history of climate change. Past patterns of human settlement can reveal important connections between demographic and environmental change, which in turn can prepare society for similar circumstances today. Environmental change is already affecting coastal communities on Madagascar and understanding these drivers can assist in developing environmental policies and preparing for future demographic shifts. Specifically, this project will investigate the socio-environmental mechanisms that influenced settlement strategies on Madagascar over the past 3,000 years. The proposed research will demonstrate how researchers can combine remote sensing datasets with spatial statistics to iteratively investigate human behaviors over time.

We propose to use satellite-based remote sensing, machine learning and oxygen isotope records from fossil corals to reconstruct changes in human settlement distribution, land and sea use and climate in southwest coastal Madagascar over the course of the Holocene. We will develop open-source AI tools and build local capacity for reconstructing and analyzing long-term landscape-level human-climate-environment dynamics, so that our approach can be scaled up beyond southwest Madagascar. By harnessing the power of remote sensing and machine learning, this project will generate and analyze large datasets on long-term landscape change and past human response that are vital for understanding and successfully tackling critical threats to local livelihoods, cultural heritage and biological diversity today.

Establishing definitive chronologies is a longstanding challenge for archaeologists, and this is particularly true in the tropics, where high temperatures and humidity degrade materials that are useful for radiocarbon (14C) dating. In Madagascar and other tropical landmasses, eggshell frequently becomes an important component of the archaeological record. However, the customary 14C dating of the mineral (calcium carbonate) fraction of eggshell is often complicated by the fact that carbon in this fraction can be derived from both contemporary atmosphere and relatively “old” (14C-depleted) carbon from bedrock. This problem of “old carbon” complicates the interpretation of 14C data from eggshell and associated organic material such as charcoal and bone. To address this issue, I am developing a refined method of extracting the minor protein fraction present in eggshell for 14C analysis, which will improve the reliability and accuracy of eggshell 14C data. The proposed work with eggshell from Madagascar will help clarify the island’s human settlement chronology, which is poorly resolved yet essential to many of the environmental and political narratives in the western Indian Ocean. Despite being the fourth largest island in the world, the earliest concrete archaeological evidence for humans on Madagascar dates to about 1350 years before present (B.P.). There is some evidence provided from stone tools that humans were present on the island as early as 5000 B.P., and recently-described cut marks on endemic animal bone suggests a human presence on the island as early as 11000 B.P.Previous eggshell carbonate 14C work supported by EESL indicates that many eggshells found within archaeological contexts are approximately between 1000 and 9000 years old. Robust chronologies that tie together archaeological and paleoenvironmental data from Madagascar will allow us to learn more about past adaptation to environmental change. Such learning from the past will be important as forest clearance and climate change continue to threaten many lifeways in Madagascar. The proposed work with eggshell will immediately contribute to our understanding of Madagascar’s past and has the potential to strengthen archaeological chronologies on many other tropical landmasses. Improving our knowledge about the temporal context of human settlements can form the basis of studies on human-environmental interactions in the past, which will yield important conclusions for modern day conservation and environmental policies.

Environmental change is an increasing threat around the world. On Madagascar, such change has affected humans for thousands of years. To better understand the impacts of environmental change on human mobility, we require a systematic understanding of past settlement distributional patterns. However, Madagascar remains largely unexplored archaeologically. This study attempts to create and analyze a robust archaeological dataset and paleoclimate record. Specifically, I will investigate when and where the earliest communities were located on Madagascar and to what degree environmental resources influenced settlement. I will address these questions using remote sensing survey and paleoclimate reconstruction using fossil coral proxies.

Understanding the impacts of climate change on human behavior is of increasing importance. Madagascar is acknowledged as a high-risk nation for climate change related threats and has undergone similarly drastic changes in the past. Understanding human-environmental relationships requires high-resolution datasets and comprehensive archaeological surveys. Here, I will create a high-resolution environmental proxy dataset comprised of fossil-corals and speleothems and conduct a systematic archaeological remote sensing survey. This will permit for the evaluation of spatio-temporal relationships between environmental change and human settlement.

Understanding the drivers behind human movement has challenged social scientists – and anthropologists in particular – for decades. Today, environmental change poses significant risks to hundreds-of-millions of people, and the number of environmental refugees worldwide is unprecedented. Madagascar is a perfect case study of severe environmental change and its effects on humans through time because of its ecological diversity and history of climate fluctuation. This project will investigate human-environmental dynamics as they pertain to settlement choice in early coastal foraging populations on Madagascar. Studying past patterns of human settlement can help uncover drivers of demographic change related to environmental conditions, which in turn can prepare society for similar circumstances today. Climate change is already affecting coastal communities on Madagascar and understanding these drivers can assist in developing environmental policies and preparing for future demographic shifts. This study attempts advance comprehension of these relationships by analyzing a systematically acquired archaeological dataset and robust paleoclimate record.

Archaeology can yield important insights that improve modern society. As the world faces increased risk from environmental disasters, questions concerning how people have successfully coped in similar circumstances elevate insignificance. Sea-level rise threatens to displace coastal populations numbering in the hundreds-of-millions in the next several decades. As such, studying the effects of climate change on human migration patterns can help to prepare the modern world for the consequences of similar events. Madagascar represents an exceptional location to address human-environmental interconnectivity, as it contains a widely diverse set of ecological conditions which have changed through time and current populations are at increased risk from such change. Studying the effects of climate change on demographics can assist in developing future environmental policies. Because Madagascar remains largely unexplored, systematic investigations are required to address biases. However, funding limitations, large unexplored areas, and a small number of active archaeologists present substantial research barriers. This study attempts advance comprehension of these relationships by analyzing a systematically acquired archaeological dataset via remote sensing and a robust paleoclimate record.

As the world faces increased risk from environmental disasters, questions concerning how past peoples successfully coped with similar dilemmas elevate in significance. In Madagascar, climate change impacts have been and will continue to be severe. Thus, there is a largely untapped record of human response to climate change at risk of disappearance. To address questions concerning mobility and its adaptive utility in variable environments, a systematic landscape-scale understanding of the archaeological record is required. In this dissertation, I aim to address landscape scale mobility and settlement and its relationship with environmental change in coastal Southwest Madagascar. To accomplish this task, I will develop a predictive model using remote sensing data to detect cultural materials in the Morombe district of Madagascar. Identified deposits will be surveyed using satellite remote sensing and ground-based methods to look at shifts in settlement patterns since the Late Holocene (~10,000 B.P. –1500 B.P.)and their environmental context. Then, I will construct a multiproxy marine paleoclimate dataset using fossil corals. Paleoclimate records applied to archaeological data, to date, have only utilized terrestrial information, but to understand coastal populations, marine data are essential. As such, this project will contribute to our understanding of how coastal communities respond to shifting resource availability via settlement choice and mobility.

Madagascar is the fourth largest island in the world(~500,000 km2) and represents an exceptional location to address human-environmental interconnectivity, as it contains a widely diverse set of environmental conditions which have changed through time. Questions concerning settlement and its connection to environmental change are particularly important for the local communities living along the coasts of Madagascar. The Vezo people –a Malagasy population whose name roughly translated to “people of the sea”–are inseparable from maritime lifeways. Yet, Madagascar’s coasts are actively threatened by sea level rise, erosion, and anthropogenic development. By systematically investigating the cultural heritage of southwest Vezo communities via remote sensing, this study will: 1)improve the ability for scholars and local communities to conserve and protect Malagasy history at risk from extractive industry development and climate change; and 2) will permit for a landscape scale analysis of settlement and mobility patterns as adaptive mechanisms to environmental fluctuation.

Here, we propose the first automated archaeological remote sensing survey of Southwest Madagascar with the goal of improving our understanding of past settlement patterns and the factors that influence settlement mobility. The human settlement of Madagascar, the fourth largest island in the world,remains one of the most hotly contested questions in island archaeology. Our ability to answer the question of when and how this large island was settled is, however, constrained by the combination of vast stretches of archaeologically unexplored territory, high costs associated with traditional approaches to archaeological survey, and a relatively small contingent of active field archaeologists. These limitations also present an important opportunity to apply remote sensing techniques to the island’s archaeological landscapes, in order to expand the inventory of archaeological sites and elucidate regional settlement patterns. Remote sensing is an important tool for archaeological research as these approaches offer the ability to systematically evaluate archaeological signatures at the landscape scale. The massive datasets generated through remote sensing, however,require the development of machine learning algorithms and image analysis software to effectively and systematically study this information and improve our knowledge of the archaeological record. We will use spectral signatures of known archaeological deposits in Madagascar to develop an automated classification method. We will then ground-truth all identified locations and determine the accuracy of the technique. Subsequently, all confirmed sites will be sampled for the purpose of building a settlement chronology of the Velondriake area. This research is particularly critical on Madagascar given current trends in development and extractive industry (e.g. mining and logging) on the island, as the proposed work will help to more quickly identify and protect cultural heritage that is at risk. It will also set the stage for future studies attempting to understand the complex dynamics between human behavior and its influences (e.g., environmental change) through time. More broadly, the creation of a machine learning algorithm for use in African and Malagasy archaeology is an innovative contribution,as very few studies have been published on automated remote sensing survey for archaeology in this part of the world. Using a similar procedure to the one outlined above, we also propose to identify fossil coral beds off the coast of the study area. These fossil corals can be used to create a high-resolution paleoclimate record, which will improve our understanding of human- environmental relationships, specifically with regard to human migration as a response to climate change.

On Madagascar, much of the island’s archaeological settlement history is unknown, and little- to-no research has been conducted applying spaceborne technologies to the investigation of human settlement or its environmental context. This leaves our understanding of Madagascar’s earliest settlement patchy and largely biased towards areas with more recent historical significance. To alleviate this shortcoming, remote sensing –specifically spaceborne satellite datasets can be used to locate prehistoric cultural deposits at landscape scales. This type of analysis has successfully led to the discovery of hundreds-of-thousands of archaeological sites worldwide. In this project, I will develop a remote sensing model situated firmly within frameworks stemming from the geosciences and anthropology. I will develop a remote sensing algorithm that includes culturally important environmental variables – including coral reefs, waterbodies, and vegetative health – in order to identify areas with a high probability of containing archaeological materials within the Velondriake region of Southwest Madagascar. Culturally important environmental resources listed above will be identified and quantified using machine learning and vegetative indices.

Risks posed by climate change are not new, and archaeology can shed light on how humans have coped with these stressors in the past, and thereby shed light on potential solutions in the present. Madagascar provides a good case study for studying these relationships. To study human-environmental relationships in Southwestern Madagascar, two distinct projects are needed that integrate into a larger study. The first project involves the use of machine learning algorithms and remote sensing data to identify the locations of new archaeological sites in Southwest Madagascar. This will allow for a more complete understanding of settlement distributions in this part of the island and the history of human occupation. The deposits identified by this survey will be ground-tested during field visits and all confirmed archaeological deposits will be sampled for datable materials. This will serve to construct a chronological sequence of human settlements of this area through time. The second project will center around the creation of a high-resolution environmental proxy for Southwestern Madagascar using fossil corals. During preliminary field visits to Madagascar, I will identify the locations of fossil corals –with the help of local divers –that can be cored to produce a climate record for Southwestern Madagascar over the past several thousand years. The locations of potential sites have been suggested by Douglas and Zinke (2015) but must be confirmed by field visits. Linking these two projects will involve the use of quantitative modeling to understand the correlation and causal relationships (if thereare any) between environmental conditions and changes in settlement patterns through time. Together, this dissertation project will produce one of the highest-resolution paleoenvironmental proxies for this part of the world to date and will undertake the first semiautomatic remote sensing survey for Malagasy archaeology.

The timing and nature of human settlement in Madagascar remains among the most contested questions in Island Archaeology. Timings of these arrivals range from~ 1500 B.P. to as early as 11,000 B.P. Studies thus far indicate that the earliest occupations are in the Southwest, and recent archaeological survey work in this region has resulted in the identification of several thousand eggshells from elephant birds (ratite genera Aepyornis and Mullerornis) with archaeological associations. These samples can yield C14 determinations to assist in dating the associated cultural deposits and may yield ages that exceed those of other known archaeological sites. As such, this new information may push back the date of initial human colonization of the island. This study will contribute to the ongoing debate surrounding the history of human presence in this region.