New research challenges the idea that early humans were smaller and grew taller and heavier over time. The earliest humans (i.e. Between 2.5 million to 1.5 million years ago, heights ranged from 4 feet 8 inches up to 6 feet. This is similar to modern human height. According to fossils discovered in Georgia, southern Europe in the past 1, scientists have known for a long time that Homo Erectus was shorter than 152cm (five feet). They also weighed less than 50kg lbs. 77 millions years ago. However, little was known about the origins and timing of the larger human ancestors, which we associate with modern-day humans. 1.5 million year old Turkana boy (Homo Erectus). Because it is the largest bone in the body and is responsible for a large proportion of its weight, the femur is often used to calculate body size. Photo by Jay Stock. The Journal of Human Evolution published the latest findings. (citation below). Researchers from Tubingen, Germany and Cambridge in England found that human body sizes increased tens of thousand years after Homo sapiens erectus left Africa. This was primarily due to the Koobi Fora area of Kenya. Manuel Will (a PhD student at the Department of Early Prehistory and Quaternary Ecology in Tubingen) is co-author. He said that the evolution of longer legs and larger bodies cannot be considered the primary driving force behind early excursions of the genus Eurasia. The scientists used small fossil fragments of the fossils they found to determine height and mass. This method was similar to modern human beings. Jay Stock from the Department of Archaeology and Anthropology, University of Cambridge said that the findings could be interpreted as a sign of a new characteristic of the species, namely the origins of diversity. These findings are consistent with the recent cranial evidence of great diversity among early members the genus Homo.” This is the first time many tiny fossils, some measuring less than 5cm in length and ankle bones as small as 5cm each, have been used for estimating body size. Source: University of Cambridge. After comparing fossil measurements from sites in Georgia, South Africa, Tanzania and Kenya, the scientists found that there was considerable regional variation in the weight and height of early humans during the Pleistocene (from about 2,588,000 to 11,700 years ago). The average height for some groups such as the ones living in South African caves was 4.8 feet. However, a variety of fossils from Kenya’s Koobi Foresta showed humans to be nearly six feet tall. This is comparable to what the average adult male in Britain stands at today. Dr. Stock stated that “essentially every textbook about human evolution suggests that one lineage of humanity evolved bigger bodies than the rest before they spread beyond Africa.” However, the evidence to support this narrative about our origins and dispersal from Africa is no longer convincing. “The Dmanisi site in Georgia was the first place where we found fossils of small-bodied individuals. 77 millions years ago. Although this has been well known for many years, we know now that a consistently larger body mass evolved in Eastern Africa, after 1.7million years ago. This was in the Koobi Fora area of Kenya. However, it is equally important to reveal the variety that exists. The study revealed that early humans were just like us today. Studies in the past relied only on a small number of fossils. Because techniques to calculate body mass and height required specific pieces of bone, such as the majority of a hip joint or leg bone, previous studies used very few specimens. Dr. Stock used three-time larger samples to estimate body size from over 40 specimens from Africa and Georgia. This is their largest comparison study. Instead of waiting for specific bone fossils to be discovered, researchers tried a new approach: they examined previously unexplored fossils. Stock called it a difficult project and he spent over a year creating new equations to calculate the height and body mass of people using smaller bones. These bones were compared to the measurements from more than 800 modern hunter-gatherers around the globe and various regression equations. The researchers were able estimate the body sizes of several fossils, which had not been examined in this manner before. Dr. Stock stated that body size is an important characteristic in human evolution. By studying these “scrapier” fossils, we can gain a better understanding of how and when human body sizes have changed. Our ancestors lived a relatively small life, being less than 5 feet tall and heavier than average in their body weight. This shift occurred around 1.7million years ago in northern Kenya’s Koobi Fora. This means that we now have the ability to think about how regional conditions influenced this variety, and not just consider body size as an essential characteristic of a species. Citation: Manuel Will and Jay T. Stock. Journal of Human Evolution. Publication 26 March and 2015. April
