Julia Chivu ’23

The Motroto site in Uganda has recently provided new insights on the evolution of the locomotor versatility, diet, and environment of early hominids. The site is estimated to be twenty-one million years old. Associate professor in the Department of Anthropology at Stony Brook University, Dr. James Rossi, is part of a large research team that has recently examined the fossil remains of the Morotopithecus ape species, as well as a smaller unidentified ape from this location. According to the terminal branch forest frugivory hypotheses, hominids forged for fruit on the outskirts of the tropical forest canopies. However, the findings of their research study demonstrate otherwise.

After examining the fossil remains of the two ape species, it was found that the molars of these apes exhibited elongation and well-developed crests that are ideal for breaking apart leaves. Carbon isotope analysis on the tooth enamel further revealed that the apes ate water-stressed plants (C3 plants). The analysis also showed that the apes may have been consuming C4 vegetation, which are widely associated with woodland regions. By studying biogeochemical signals from collected ancient soils and plant-related silica bodies, the research team discovered that the environment was likely composed of many C3 and C4 plants in a broken canopy forest or woodland habitat. It was identified that the environment in which the apes roamed experienced periods of aridity and rain. This provided insight as to what kinds of trees and plants were likely present at the time. The team also learned that the ape species had short and strong femurs. In addition, the species had lumbar vertebrae, suggesting that they had stable dorsal lower backs. These bone findings are consistent with the locomotor characteristics found in ape species living today. Examination of the femur and vertebrae of the fossils demonstrates that the apes were well-adapted to vertical climbing.

 The findings of this study suggest that Moroto is a key site for understanding the development of hominid locomotor adaptability and lifestyle. In addition, the findings do not support the terminal branch forest frugivory hypotheses. Therefore, it is imperative to continue investigating evidence found from this location in order to better understand early hominids.

Works Cited: 
[1] LM. MacLatchy, et al., The evolution of hominoid locomotor versatility: evidence from Moroto, a 21 Ma site in Uganda. Science 380, (2023). doi :10.1126/science.abq2835

[2] Image retrieved from: https://unsplash.com/photos/EP3Xj9Cx_QE