Analysis of 430,000-year-old fossils, unearthed in northern Spain, shows that the evolution of human body’s shape and size took place in four major stages. Recently published in the journal, Proceedings of the National Academy of Sciences (PNAS), the study, titled “Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain”, was conducted by an international research team, including anthropologist Rolf Quam of Binghamton University, Love Dalén of the Swedish Museum of Natural History and Anders Götherström of Uppsala University.
For the research, the scientists examined the skeletal remains, retrieved from Sima de los Huesos (meaning, “Pit of bones” in Spanish). Located in Spain’s Sierra de Atapuerca, this Paleolithic cave site preserves the world’s largest collection of human fossils, belonging to the hominim species, known as Sima de los Huesos hominim. In comparison to Neanderthals, these Atapuerca individuals were found to be taller, and more muscular, with relatively less brain mass.
Analysis of the 430,000-year-old bones reveals that these humans shared a number of anatomical features, not found in modern Homo sapiens, with the later Neanderthals. Furthermore, a comparative study of the fossils, of different species in the genus Homo, suggests that the evolution of the human body took place in four main stages, from arboreality (i.e living in trees) all the way to bipedalism (or walking on two legs).
The Atapuerca humans belonged to the third stage, with their tall, broad and robust bodies exhibiting terrestrial bipedalism with no signs of arboreality. According to the team, earlier members of the genus, like Homo erectus, as well as later individuals, such as Neanderthals, possessed a similar body form. Thus, the Atapuera humans provide the best, and most precise, representation of the general human body size and shape, in the last one million years, before the emergence of the taller and narrower Home sapiens. Speaking about the discovery, Quam said:
This is really interesting since it suggests that the evolutionary process in our genus is largely characterized by stasis (i.e. little to no evolutionary change) in body form for most of our evolutionary history.