Intra-University Cooperative Laboratories
Laboratory of Isotope Ecology
Isotope ecology, Prehistoric anthropology, Chronology
Diet, Human remains, Osteoarchaaeology
Research interest: The relationship between humans and the environment from the perspective of isotope ecology.
Although we Homo sapience are a kind of animal, we have a unique ecological feature that we have adapted to various environments in a special way called “culture”. My own research is based on natural anthropology, by using isotopes to investigate human uniqueness. In particular, I have been working with archaeologists to reconstruct the life of prehistoric Jomon hunting-gathering-fishing societies that depended on the surrounding environment and natural food resources, from an ecological point of view. On the other side, by studying the plants and animals that lived in anthropogenic niche around human settlements, it is possible to study when and how domestication of animals and plants began. With Japanese archaeology, we can enjoy one of the richest archaeological information in the world. The main goal of our laboratory is to use this information not only within the framework of Japanese history, but also to understand human evolution.
We are also working on the development of isotopic methods to decipher the lives of animals and plants that we cannot observe directly. It is a challenge to apply cutting-edge methods developed in the geosciences to archaeological remains to reconstruct past human activity.
Our laboratory has been some facilities to measure a series of isotope e ratios in a variety of elements (C, N, O and Sr). We use a stable isotope ratio mass spectrometer (EA-IRMS) to measure isotope ratios of carbon and nitrogen, which are major elements in living organisms, TC/EA-IRMS to measure isotope ratios of oxygen and carbon in organic matter, GB-IRMS to measure isotope ratios of oxygen and carbon in carbonate, and GC-C-IRMS to continuously measure organic matter separated by gas chromatography. We mainly use GC-C-IRMS to measure the nitrogen isotope ratios of individual amino acids.
We also operate an accelerator mass spectrometer (AMS) for inter-university use, which can date organic matter up to 50,000 years ago using one milligram of carbon, and we are developing an instrument to measure carbon as small as 10 micrograms. It is now possible to determine the age of trace samples that could not previously be measured.
In addition to the measurement of isotope ratios of these light elements, the isotope ratios of heavy elements such as strontium and lead are measured in collaboration with Department of Earth and Planetary Science.
Using these instruments, we are challenging the following research themes
(1) Revealing the diversity of human adaptation through dietary habits
Ancient human bones found in archaeological excavations contain a great deal of information about the past people life. We are now able to reconstruct individual life histories at the period of thousands of years ago to some extent like, by combining their adult life recorded in bone and their childhood recorded in teeth. We will study the diversity of adaptive strategies of people in the past, focusing on the Japanese archipelago with its diverse environments.
(2) Coevolution of humans, animals and plants and the origin of agriculture
In the Holocene, humans have actively interfered with the surrounding environment to construct more comfortable niches. In this process, certain animals and plants were tamed and used as livestock or domesticated plants. On the other hand, animals and plants have evolved to take advantage of humans and their environment. Considering domestication and cultivation as co-evolution, we are studying the process from both human and animal/plant perspectives.
(3) Considering the complexity of society from individual variabilities in human life history
The life of an individual is greatly influenced by not only the surrounding natural environment but also the social environment. We are conducting research to decipher social changes from individual differences in bone isotope ratios, using samples from the prehistoric (Jomon to Kofun) and historic periods of the Japanese archipelago. A research project is also underway on the background to the emergence of states and civilisations during the Neolithic and Bronze Age in China. Some of our graduates have specialised in the Andean civilisation or the prehistory of Southwestern Asia, so it is possible to study humans from some different regions and periods.