The Nelson Bay Cave, near the coast of South Africa, was excavated between the 1960s and the 1970s. It contains Stone Age remains and is also an important site to uncover past climate fluctuations, thanks to the traces of past animals (such as shells and teeth) the archaeologists found inside.
Between twenty-three and twelve thousand years ago, the cave was not facing the ocean, as it does today. During this period, known as the Last Glacial Maximum, sea level was 120 meters below what it is now, and the cave was facing the vast grassland now known as the Agulhas Plains. There are a lot of unknowns about what happened between that time and the beginning of the Holocene, when the ocean rose and submerged the Agulhas Plains.
To study these climatic changes, a team of scientists from the University of Cape Town, the Natural History Museum of Utah, and Nelson Mandela University studied the remains of herbivorous animals, related to cattle, found in the cave to look for changes in their diet. When an animal eats, some of its body tissues record the chemical signatures of food it has eaten. Scientists can measure this with isotopes, which are slightly altered versions of standard chemical elements. By measuring carbon and oxygen isotopes in herbivore teeth, the scientists could understand how the environment the food grew in changed over time. They identified a shift in the vegetation available at that time, which seems to have been caused by a change in rainfall patterns. This finding is another piece the puzzle of what climate around the world was like during the Last Glacial Maximum.