Researchers led by geographer Hader Sheisha at Aix-Marseille University in France used paleoecological clues to help reconstruct what Egypt’s Nile River might have looked like over the past 8,000 years. They determined that the pyramid builders likely took advantage of a “now-defunct” arm of the river to move building materials, according to a study published Aug. 24 in the Proceedings of the National Academy of Sciences. Their findings show “that former aquatic landscapes and higher river levels around 4,500 years ago facilitated the construction of the Giza Pyramid Complex,” the study said. The Great Pyramid is approximately 139 meters high and was commissioned by Pharaoh Khufu in the 26th century BC. Consisting of 2.3 million stone blocks with a combined mass of 5.75 million tons (ie 16 times that of the Empire State Building), it is the largest of the group of pyramids at Giza. The other two main pyramids belong to Khufu’s son Khafre and his grandson Menkaure. Built on the Giza plateau bordering Cairo, the structures — surrounded by temples, cemeteries and workers’ quarters — are the oldest of the Seven Wonders of the Ancient World.
ANCIENT ENGINEERS USED FLOODS LIKE HYDRAULIC LIFTS
Scientists have long assumed that the ancient Egyptians must have exploited former parts of the Nile to move the tons of limestone and granite needed to build the giant structures. (The current waterways of the Nile are too far removed from the sites of the pyramids to be useful.) This explanation, known as the “river-port-complex” hypothesis, posits that ancient Egyptian engineers cut a small canal across from the pyramid site on the Khufu Branch of the Nile, along the river’s western edge of the river’s floodplain, and dredged basins to the bottom of the river. The annual floodwaters acted like a hydraulic lift, allowing them to move huge boulders to the construction site, researchers said. But until now, scientists didn’t have a concrete understanding of which landscapes they involved, according to the researchers. Using a combination of techniques to reconstruct the ancient Nile floodplain, the research team found that Egyptian engineers could have used the now-dry Khufu branch of the Nile to move building materials to the site of the Giza pyramids. First, they analyzed the rock layers of cores drilled in 2019 from the Giza floodplain to estimate water levels in the Khufu Branch thousands of years ago. They also examined fossilized pollen grains from clay deposits in the Khufu region to identify areas of rich vegetation indicative of high water levels. Their data showed that the Khufu area flourished during the first half of Egypt’s Old Kingdom period, from about 2700 to 2200 BC, when the three main pyramids were likely built. The branch still had high water levels during the reigns of Pharaohs Khufu, Khafre and Menkaure. “From the third to fifth dynasties, Khufu’s branch clearly provided an environment conducive to the emergence and development of the pyramid site by helping the builders plan for the transport of stone and materials by boat,” the research team noted in the study. But in Egypt’s Late Period, about 525-332 BC, the water level of the Khufu Branch had dropped during a dry phase — a finding consistent with studies of oxygen in the teeth and bones of mummies from the time period reflecting low drinking water, according to the study. When Alexander the Great conquered Egypt in 332 BC, the Khufu branch was just a small canal. Taken together, the data show that these ancient engineers used the Nile and its annual floods “to exploit the plateau area overlooking the floodplain for monumental constructions.” In other words, the ancient Khufu branch of the Nile was indeed high enough to allow ancient engineers to move huge boulders — and build the magnificent pyramids we know today.
PALEOCLIMATOLOGY AFFECTS OUR UNDERSTANDING OF THE PAST AND FUTURE
For Joseph Manning, a classicist historian at Yale University, the “groundbreaking” research is an example of how paleoclimatology is “fundamentally changing our understanding of human history.” “We’re getting a more realistic and more dynamic understanding of human societies further back in time,” he told CNN. These new techniques — like the pollen analysis used in this study — allow scientists to look at societies thousands of years ago, Manning said. “Climate science, as in this paper, gives us fundamentally new information … (that is) very relevant to what is happening today.” Understanding how the climate changed during the Old Kingdom of ancient Egypt, for example, gives scientists a framework for climate change trends today. Previously, historians of ancient Egypt relied primarily on texts to derive their understanding of Egyptian society, Manning said. But increasingly, environmental science is “throwing everything out the door” and allowing new insights into the ancient world. The most novel part of the new research is that it identifies a natural waterway that could have been used to transport pyramid materials, whereas some researchers previously thought an artificial channel was needed, Manning said. Making the most of environmental history will require scientists to collaborate and work with historians, he said. “There’s resistance to it, because it’s a different way of working,” Manning said. But the possibilities, he added, are “super exciting.”
