Remains found in China may belong to third human lineage

Paleontologists from the Chinese Academy of Sciences have discovered proof of a previously undiscovered human lineage while cooperating with colleagues from Xi'an Jiaotong University, the University of York, the University of Chinese Academy of Sciences, and the National Research Center on Human Evolution. The crew examined the ancient jawbone, partial skull, and some leg bones of a hominin that lived 300,000 years ago for their study, which was published in the Journal of Human Evolution.

The fossils were discovered in Hualongdong, which is currently in East China. They were then evaluated geometrically and morphologically, with the jawbone receiving particular attention since it had an unusual curve and a bottom edge that was triangular.

According to the study team, the jawbone's distinctive characteristics are similar to those of both contemporary people and Late Pleistocene hominids. However, scientists also discovered that it lacked a chin, indicating that it was more closely linked to previous species. They discovered other characteristics that were similar to those of Middle Pleistocene hominins, which when combined revealed the person most resembled a Homo erectus species. They come to the conclusion that this points to a cross between contemporary humans and early hominids.

The fact that these characteristics have never before been seen together in East Asian hominids, according to the researchers, suggests that traits present in modern humans first emerged as early as 300,000 years ago.

The current team studied the skull, which a previous team had determined to be the earliest Middle Pleistocene human skull ever discovered in southeast China, and discovered that the bones in its face were more comparable to those in contemporary humans than was the case for the jawbone.

The scientists ruled out Denisovan in an effort to identify the species of the bones. They were thus left with the possibility that the fossils reflect a third lineage, one that is more closely related to modern humans than Denisovans or Homo erectus. And if this is the case, the species most likely shared certain evolutionary ties and traits with hominins from the Middle or Late Pleistocene.