Scientists from the University of Madrid and the University of Alcala found a collection of skulls with Neanderthal characteristics and features similar to more primitive humans in Sima de los Huesos, or "Bones Pit," a cave in Atapuerca, Spain.
The team aimed to find out the reason Neanderthals evolved so quickly compared to other hominins, and the pattern of the changes brought by the evolution.
The researchers created an image of the populations thriving in Europe around 400,000 years ago as part of their investigation. The probe was complex because the fossil records for that time got dispersed and mixed with fossil records from other eras.
"The Middle Pleistocene was a long period of about half a million years during which hominin evolution didn't proceed through a slow process of change with just one kind of hominin quietly evolving towards the classic Neandertal," said Juan-Luis Arsuaga, lead author of the study and a professor of Paleontology at the Complutense University of Madrid.
The collection of skulls that included 17 skull species once belonged to a single population of hominin. Researchers have continuously dug on the site since 1984, and have recovered 7,000 human fossils matching the skeletons of around 28 individuals since then.
The analysis of the skull helped the scientists conclude how the Neanderthals developed their features in a progressive manner. Officials expected the data to be useful for evolutionary scientists, as it could be a guide in analyzing evolutionary patterns during the Middle Pleistocene era.
The findings of the research also supported the accretion model theory, which states that the Neanderthal evolved each of their defining features one at a time, in contrast to the theory that they developed their defining features in a very quick period.
Further details of this study were published in the June 20 issue of Science.
