A fossilized jawbone found in a cave in eastern China bears a curious blend of historical and fashionable features, according to a detailed evaluation that compares it with dozens of other human specimens. The getting, released in the Journal of Human Evolution, suggests that the 300,000-12 months-aged bone could have belonged to an as-nevertheless undescribed species of archaic human.

Researchers excavating a cave called Hualongdong, located in Anhui province in eastern China, have unearthed stays of 16 persons that date to all-around 300,000 years in the past. Various fragments belong to the skull of a 12-to-13-year-old juvenile.

Xiujie Wu, a palaeoanthropologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, and her colleagues very first explained the skull in 2019. But in 2020, while sifting through trays of animal bones uncovered in the cave, they recognized a fragment of a mandible — the lessen element of the jaw — that could be one more piece of the similar cranium.

The discovery has enabled a far more detailed analysis of where by the Hualongdong people today suit on the human family tree. The mandible has a mixture of both equally modern and archaic functions. For illustration, the bone along the jawline is thick, a characteristic shared with early human species, these types of as Homo erectus. It also lacks a legitimate chin, the presence of which is a critical characteristic of Homo sapiens. But the side of the mandible that attaches to the higher jaw is thinner than these of archaic hominins and much more reminiscent of that of modern-day people.

Historical and modern

The assessment deepens the mystery of which historical human species inhabited the region for the duration of the Middle to Late Pleistocene epoch, a time period spanning practically 800,000 several years that preceded the conclude of the past Ice Age, close to 12,000 yrs ago.

A electronic comparison of the newly uncovered mandible with 83 other jawbones confirmed a unusual combine of historical and modern day anatomical attributes. Wu and her colleagues used juvenile and adult bones from Neanderthals (Homo neanderthalensis), which lived in Eurasia until 40,000 decades in the past, H. sapiens from all around the world, and H. erectus, a species whose assortment extended from japanese Africa to the southeast Asian islands of Indonesia amongst 1.9 million and 250,000 many years back.

Wu says that the H. sapiens-like options of the jawbone set it apart from individuals of other hominins from the Center Pleistocene, which include individuals of a 160,000-year-previous Denisovan from Tibet and of the close to 770,000-calendar year-previous continues to be acknowledged as Peking Male. She adds that the Hualongdong folks could signify a beforehand not known ancestor or near relative of early H. sapiens.

But the notion that contemporary individuals arose from ancestors in Asia is not widely approved. The oldest H. sapiens fossils, which date to 230,000 a long time back, are from websites in Ethiopia.

Baffling photograph

The image of human profession in East Asia for the duration of the Pleistocene is a confusing one, says Yameng Zhang, a palaeoanthropologist at Shandong College in Jinan, China. He states that numerous species of archaic hominin inhabited East Asia throughout the Center Pleistocene, a period of time from around 800,000 to 126,000 several years back. It is unclear no matter whether any of these could be ancestors of present day individuals — like Neanderthals and Denisovans, they may just have died out.

The combination of ancient and modern day characteristics in the Hualongdong mandible is equivalent to people of stays located through the early 2000s at the Jebel Irhoud archaeological website in Morocco, says María Martinón-Torres, a palaeoanthropologist at the Countrywide Investigation Heart on Human Evolution in Burgos, Spain, who was element of the group that described the results at Hualongdong. The Jebel Irhoud remains — which include things like quite a few skull fragments and a nearly comprehensive mandible — have an age identical to that of the Hualongdong types and are believed to belong to a single of the earliest users of the evolutionary lineage that includes H. sapiens. “More fossils and scientific studies are needed to fully grasp [the Hualongdong people’s] precise situation in the human loved ones tree,” she states.

Martinón-Torres adds that ancient proteins extracted from the bones could shed more mild on how the Hualongdong folks are connected to fashionable humans, as very well as to a lot more-archaic species.

This article is reproduced with permission and was 1st revealed on Septemer 18, 2023.