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Speaking of human ancestors, everyone is no stranger to the grandmother Lucy, who is about 3.2 million years ago. Lucy is another name for the fossil skeleton of australopithecus afarensis.
Lucy restoration figure Wikipedia
Because of its "regular upright walking" feature, Australopithecus alpha species is often referred to as the ancestor of the genus Homo sapiens, which is the ancestor of our modern man, Homo sapiens. But who is Lucy's ancestor? For too long, there was no definitive answer to this question. On August 27, the journal Nature published a study of new fossils of ancient apes. Can scientists thus further determine the origin of human beings?
Is the lakeside species really Lucy's ancestor?
If we look at the context of temporal development, the oldest australopithecus anamensis (the earliest specimen discovered in 1965 on the shores of Lake Turkana, Kenya) has a mix of modern ape and human characteristics – both upright and tree climbing – in time also just before the Alpha species (about 3 million to 3.8 million years ago), So there seems to be a great possibility that lucy's ancestors.
Unfortunately, due to the fragmentation and rarity of fossil material—only fragments of mandibles, teeth, long bones, and phalanges—academics are curious about the ancestral relationship between lakeside species and alpha species, and even between lakeside species and earlier humans (such as Ardipithecus, also unearthed in Ethiopia), but it is difficult to produce more conclusive evidence.
In 2010, the American Journal of Physical Anthropology and The Philosophical Transactions of the Royal Society B published Yohannes online Haile-Selassie) team in Ethiopia's Woranso-Mille region of the newly discovered Australopithecus lake species of free teeth, jaws, back skull and other fragments, the results of the study can not deny the ancestral relationship between the lake species and the Afa Southern Ape species, it seems to indicate that the lake species is Lucy's ancestor.
However, the answer is not so simple. On August 27, the journal Nature published the latest research by Johnnys' team, announcing their research on new materials for australopithecus species. Once recognized as Lucy's ancestors, the Lakeside Species are now in the spotlight again, are they really Lucy's ancestors?
The new fossils make the truth even more confusing
△ Australopithecus species (MRD-VP-1/1) specimen photo
a Front, b Back, c Top, d Left, E Right, f Bottom Side
(Image source: screenshot of the paper)
It is a nearly intact fossil skull, designated MRD-VP-1/1, also unearthed in the Woranso-Mille region of Ethiopia, belonging to a middle-aged male. The new fossil challenges past knowledge, and its analysis suggests that the lakeside species is not the ancestor of the Alpha species.
In the past, the identification of lakeside species often relied on tooth and jaw morphology. The MRD-VP-1/1 specimen showed a more prominent incisor size, the dentition was U-shaped, and there were also differences between different types of teeth, which was in line with the characteristics of lakeside species.
△ Incisors comparison photo, the left 1 belongs to the Australopithecus alpha species, and the rest belong to the Australopithecus species. (Image source: screenshot of the paper)
Thanks to the preservation of fossils, this study provides more facial identification features. On the positive side, the lakeside species are closer to Australopithecus, while there are significant differences with the other two paleontological species, which undoubtedly belong to australopithecus. But on the side, the braincase is long and narrow, very similar to the Sahelanthropus tchadensis, which predates the lakeside species 3.2 million years ago, and the cheekbones protruding forward resemble the Paranthropus aethiopicus that are 1.3 million years after the lakeside species. The authors speculate that this trait, which converges with young taxa, may be the result of parallel evolution. At the same time, there are significant differences between the lakeside species and the South Afa australopithecus in the suborbital and retroorbital regions, as well as in the position of the masseter muscles.
△ Skull comparison photo, from left to right: Chadian Shach, ground ape, Australopithecus lakeside species, Australopithecus arhas, Australopithecus African species. ((Image source: screenshot of the paper))
△ The yellow part is the reconstruction part, representing the lakeside skull material known to the academic community before the discovery of this specimen, with a scale of 1cm (Image source: screenshot of the paper)
The study also included a 3.9 million-year-old specimen of the frontal bone (BEL-VP-1/1), based on the characteristic of "weak retroorbital narrowing", which advanced the survival of The Affacomonian by 100,000 years to 3.9 million years ago. There is even a possibility that a small number of 4 million-year-old dental specimens that were once found at the Fejej site in Ethiopia belong to the South Afa australis rather than the lakeside species.
MrD-VP-1/1 dating data show that the survival time range of lakeside species can be extended to 3.8-4.2 million years ago, that is, their survival time is extended by 100,000 years, indicating that the Alpha species represented by Lucy once lived in the same area as the lakeside species for nearly 100,000 years. That is to say, the two did not belong to a single branch of the racial change, that is, the Australopithecus species were not Lucy's ancestors.
In fact, the lakeside species is not only separated from the alpha species in craniofacial morphology, but also does not have ancestral relations, and even the brain volume is different. The brain volume of the MRD-VP-1/1 specimen is 365-370 ml, which is closer to the brain volume of the ape (300-350 ml) and the Chadian Shah (320-380 ml) and lower than the brain volume of the Alpha species (about 485 ml) – of course, it is much lower than the modern average (about 1450 ml).
It is known that the species are distributed in four different regions over at least four consecutive periods, and differ in tooth and skull morphology. Based on craniofacial observations and the phylogenetic trees reconstructed in a variety of ways, the lakeside species remains the oldest member of Australopithecus australis, and this genus is located closer to the basal trunk than all Australopithecus and later anthropocenes, consistent with previous findings.
△ Phylogenetic tree, bolded by lakeside species of new fossils MRD-VP-1/1.
For the academic community, the new lakeside species material overturns the long-term assumption of the ancestral relationship between the lakeside species and the Alpha species, but the evolutionary picture of early humans has not become clear, but seems to show the evolutionary trend of bushes, making the truth more confusing.
The origin of mankind, there are still many mysteries waiting to be solved
The article published in Nature is more like an academic debate between Johannes and himself — using new material to break down his own incomplete understanding of the evolution of Australopithecus australis. Of course, constantly using new fossils and new methods to explore the origin of human beings is the original intention that he has adhered to since the moment he began to study ancient humans.
John Ness studies human fossils in his office (Credit: Cleveland Museum of Natural History)
Johannes is a professor in the Department of Physical Anthropology at the University of Cleveland and curator of the Cleveland Museum of Natural History. In his view, the Alpha region of Ethiopia, although it is currently a desert, is a paradise for ancient humans to survive about 3 million to 4 million years ago. The Woranso-Mille area, which is the focus of his attention, is located about 520 kilometers northeast of Addis Ababa (the capital of Ethiopia), and it is self-evident that it is obvious that it is 30 kilometers south to reach the Hadar region where "Lucy" was found.
Since 2005, he has led his team to this area and has carried out many years of field excavations, and so far, he and his team have published several research articles on ancient humans in the Alpha Basin. Challenging the inherent perception of the paleoanthropological community is something he often does. In May 2011, he discovered Australopithecus deyiremeda (Australopithecus deyiremeda) in the Alpha region, 3.3 million to 3.5 million years ago. The new hominid man's jaws, fossil teeth, and bones are markedly different from "Lucy", challenging the academic view that "Lucy was the ancestor of mankind" and "there was only one kind of person in this area at this time". The study was also published in the journal Nature that year, attracting public attention.
△ Johannes displays the fossils of australopithecus he found (Credit: Cleveland Museum of Natural History)
Similarly, the mysterious evolutionary relationship between the lakeside species and the alpha species also made Johannes curious. During a field excavation in 2015, he harvested the precious skull he studied in this paper. The new species on the lakeside undoubtedly provides important information for the study of the earliest Australopithecus australis and its origins. After further research, John Nice once again confirmed that Australopithecus, Australopithecus close relatives, and even Lucy may be just some of the many candidates of our immediate ancestors, and there may be more kinds of hominids living in similar geographical locations at the same time.
△ Photographs of John Nice excavating in the Woranso-Mille area (Credit: Cleveland Museum of Natural History)
In the future, as John Ness once mentioned in his TED talk, there may be more surprises waiting for scientists to discover in this magical land of the Alpha region at a critical time period of about 3-4 million years ago.
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