Human Ancestor Size Shifted: Gradual Change & Sudden Growth

Scientists from the University of Reading and University of Oxford in the UK analyzed 386 hominin fossils from 21 species to understand how body size evolved in human ancestors. The research, published in Proceedings of the National Academy of Sciences, reveals a complex picture of both gradual change and rapid increases in body size over millions of years.

Early hominins like Australopithecus weighed around 40kg, similar to a modern child. However, with the emergence of the Homo genus, particularly Homo erectus and Homo ergaster, average weight increased to approximately 60kg, approaching the size of many modern adults. The study clarifies previous debates by integrating a comprehensive fossil record, demonstrating that while some later species like Homo floresiensis remained small due to adapting to different environments, the overall trend involved a significant increase in body size linked to changes in lifestyle, including bipedalism and increased meat consumption.