https://phys.org/news/2023-08-china-human-lineage.html
A team of paleontologists at the Chinese Academy of
Sciences, working 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, has found evidence of a
previously unknown human lineage. In their study,
reported in Journal of Human Evolution, the group
analyzed the fossilized jawbone, partial skull and
some leg bones of a hominin dated to 300,000 years ago.
The fossils were excavated at a site in Hualongdong, in
what is now a part of East China. They were subsequently
subjected to both a morphological and a geometric
assessment, with the initial focus on the jawbone, which
exhibited unique features—a triangular lower edge and a
unique bend.
The research team suggests that the unique features of
the jawbone resemble those of both modern humans and
Late Pleistocene hominids. But they also found that it
did not have a chin, which suggests that it was more
closely related to older species. They found other
features that resemble hominins of the Middle
Pleistocene, which, when taken together, suggested the
individual most resembled a Homo erectus species. And
that, they conclude, suggests a hybrid of modern human
and ancient hominid.
The researchers note that the combination of features
has never before been observed in hominids in East Asia,
suggesting that traits found in modern humans began to
appear as far back as 300,000 years ago.
...
In an effort to determine a species for the remains, the
team ruled out Denisovan. That left them with the
likelihood that the fossils represent a third
lineage—one that is not Denisovan or Homo erectus, and
is closer to Homo sapiens. And if this is the case, the
species would very likely have shared some evolutionary
relationships with hominins of the Middle or Late
Pleistocene, resulting in shared characteristics.
https://www.sciencedirect.com/science/article/abs/pii/S0047248423000908 Morphological and morphometric analyses of a late
Middle Pleistocene hominin mandible from Hualongdong,
China
Abstract
Excavations in Hualongdong (HLD), East China, have
yielded abundant hominin fossils dated to 300 ka.
There is a nearly complete mandible that fits well
with a partial cranium, and together they compose
the skull labeled as HLD 6. Thus far, detailed
morphological description and comparisons of the
mandible have not been conducted. Here we present
a comprehensive morphological, metric, and geometric
morphometric assessment of this mandible and compare
it with both adult and immature specimens of
Pleistocene hominins and recent modern humans.
Results indicate that the HLD 6 mandible exhibits a
mosaic morphological pattern characterized by a
robust corpus and relatively gracile symphysis and
ramus. The moderately developed mental trigone and
a clear anterior mandibular incurvation of the
HLD 6 mandible are reminiscent of Late Pleistocene
hominin and recent modern human morphology. However,
the weak expression of all these features indicates
that this mandible does not possess a true chin.
Moreover, a suite of archaic features that resemble
those of Middle Pleistocene hominins includes
pronounced alveolar planum, superior transverse
torus, thick corpus, a pronounced endocondyloid
crest, and a well-developed medial pterygoid tubercle.
The geometric morphometric analysis further confirms
the mosaic pattern of the HLD 6 mandible. The
combination of both archaic and modern human features
identified in the HLD 6 mandible is unexpected, given
its late Middle Pleistocene age and differs from
approximately contemporaneous Homo members such as
Xujiayao, Penghu, and Xiahe. This mosaic pattern has
never been recorded in late Middle Pleistocene hominin
fossil assemblages in East Asia. The HLD 6 mandible
provides further support for the high morphological
diversity during late Middle Pleistocene hominin
evolution. With these findings, it is possible that
modern human morphologies are present as early as
300 ka and earlier than the emergence of modern humans
in East Asia.
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