Cleopatra is one of the most well-known figures of the ancient world, standing beside Julius Caesar, Alexander the Great and Hannibal. It’s an impressive accomplishment considering the male dominated age in which she lived. She was the last of the Ptolemaic rulers, a dynasty descended from Alexander the Great’s general Ptolemy I, which lasted for nearly three centuries. Her downfall has been told and retold, most notably by Shakespeare. It is a tale of power, intrigue and sex. A tragedy of epic proportions, this tale has, until now, been exclusively a human one.
This is often the case with history – we see it through the lens of the academic. A historian tells us about the people, whereas a paleoclimatologist tells us about the climate, or a paleontologist tells us about animal life. These areas are each interesting but only provide single threads of a wider tapestry that, if woven together, can create a more representative picture. Interdisciplinary studies are one way of bringing these seemingly disparate strands together. Recently an interdisciplinary study from historians and climate scientists has been published in Nature Communications shedding new light on natural factors that may have impacted upon the political and economic stability of Egypt, and perhaps ultimately also contributed to the downfall of Cleopatra and the Ptolemaic dynasty.
In these studies, researchers investigated the effects of volcanic eruptions on the flooding of the Nile. They did this using the Nilometer and ice core records between 622 CE to 1902 CE. The Nilometer is a collection of three ancient buildings on the Nile that measured the height of each year’s summer flood, allowing farmers to predict how well their crops would grow, and for the state to know how much tax to levy on farmers. Records go from the year 622 CE until the early twentieth century, when the damming of the Nile moderated the annual flood. The ice cores contain measurable amounts of sulphate from the atmosphere, originating from eruptions. This sulphate is what provides a timeline of past volcanic events. Comparing these two sources of information allowed the researchers to show that the explosive injection of volcanic sulphates into the atmosphere caused a reduction in the monsoon rainfall, that drove the annual summer flooding of the Nile.
Once this was confirmed, the next step was to examine whether the eruptions during the Ptolemaic era and the likely low flooding of the Nile in the following years could be connected to historical evidence of unrest such as the issuing of priestly decrees, revolt or interstate warfare. The researchers found that there was a statistically significant connection between these events and the eruptions, which led them to conclude that the low flooding of the Nile affected the political stability of the region.
However, this study only looked at the short-term effects of volcanic eruptions on the Nile. The Nile also has its own cycles over longer periods of decades to centuries. If flooding increased or reduced over these time periods, the effects of the volcanic eruptions may have been diminished or exacerbated. Dr Francis Ludlow, a climate historian based in Trinity College Dublin who worked on this study says that as of now “not enough is known about the Nile’s patterns on a multi-decadal to centennial scale”, illustrating just how much more there is still to learn.
We’ve known about the significance of the Nile to Egypt for a long time. With hardly any local rainfall, the water of the Nile was the lifeline of Egypt. Fed by the monsoon rains over the Ethiopian highlands and drained by the Blue Nile, the Nile’s annual summer flooding is what allowed Egypt to be the agricultural giant it was in ancient times. Farmers would plant their crops after the annual flood and many of the population were drafted into helping with the process. Known as the breadbasket of Rome, the floods allowed the growth of grain that not only supported the population but also solidified Egypt’s power. Unsurprisingly, the floods held religious significance as well. It was said that the floods were the tears of Isis and the quality of each year’s flood was linked to the quality of the Pharaoh’s governance. It is thus understandable how a change in the floods could lead to increased unrest and difficulties for Ptolemaic rulers. What this study brings us, for the first time, is statistical evidence of that effect.
An issue with any study of the past is that they are very often focused on a single aspect of their subject. Historical events are rarely caused by a single factor, but instead are almost always the result of a confluence of factors. This can be seen today in Syria. It would be foolish to say drought caused the region’s ongoing issues but it would be equally foolish to say that the severe drought that occurred in the years immediately leading up to the Syrian conflict played no part in it. In Egypt’s case there were many aggravating factors leading to the series of revolts against Ptolemaic rule. Egyptians had reasons to be unhappy with their Ptolemaic rulers, and ethnic tensions were high, given the Greek origins of the Ptolemies. They had also pushed for a greater focus on the growth of free threshing wheat, a cash crop of the ancient world, that was less resistant to drought than the wheat and barley traditionally grown by the Egyptians.
However, should the rulers have known better? It is studies such as this which show us some of the collective constraints that these rulers faced. Allowing us to understand their dilemmas in all their complexity could help to reveal examples of our present in their past.
It is also possible that interdisciplinary studies could allow for greater accessibility. A real problem for scientists is communicating information effectively. Most communicators agree that people learn through narratives. Bringing together different disciplines achieves just that – it allows people to look at the real effects of environmental change within an accessible human story. It shows us change in a context we can relate to. People, farming, food and water can be understood, whereas charts, figures and the abstract language of scientific papers remove us from many narratives.
Another benefit is suggested by Dr Francis Ludlow’s assertion that interdisciplinary studies are better for ‘hitting more areas of interest’ for the general populace. Drawing historians into science and vice versa. There is the possibility that interdisciplinary studies could also improve people’s critical thinking processes. There are a few preliminary studies that show the effects of an interdisciplinary approach on students, with results ranging from an increased interest in their studies to an improved ability in critical thinking skills. If this is true, and I stress that we are a long way from knowing whether it is, more studies like this could be a way of not only improving science communication, but also people’s underlying ability to understand it.