The ancient fossilized teeth discovered in decades of archaeological projects in northeastern Ethiopia indicate that two different types of human, or human ancestors, lived in the same place between 2.6 million and 2.8 million years ago.
This discovery gives us a glimpse into the complex web of human evolution. The ten teeth found between 2018 and 2020 belong to the genus Australopithecus, a relative of ancient human beings. Meanwhile, the three teeth found in 2015 belong to the genus Homo, including modern humans or homo sapiens. The results were published in Nature on Wednesday.
This overlap of two hymonins in the fossil record is rare, leading scientists to believe that HOMO appeared after Australopithecus, rather than the two of their contemporaries. The Australopithecus species stood upright like modern humans, but had relatively small brains and were close to the size of an ape. The emergence of homo species is one with a larger brain, and is easy for people today to consider as an evolutionary upgrade of the species, the path to modern humanity.
However, the coexistence of the two indicates that humans developed and lived in multiple varieties at once. “This new study shows that the image that many of us have in the minds of the apes to Neanderthals is incorrect. “There are two species of humanity here. And human evolution is not linear, it is a bushy tree, and there are life forms that are extinct.”
Since 2002, Reid has been a community member of the Ledi-Geraru research project, with some focusing on searching for evidence of early homo species. In 2015, the team announced the discovery of the oldest known homo johnbone, 2.8 million years old. We also searched for evidence after the Australopithecus afarensis, which first appeared 3.9 million years ago, but there are no indications of these ancient human relatives in the fossil record 2.95 million years ago.
Australianthecus afarensis is best represented in the famous fossilized Lucy ruins discovered in Ethiopia in 1974. Lucy was shorter than the average human, reaching about 3.3 feet (1 meter) tall, with about a third of the size of a human brain having a face and brain that was close to the top. Her fossils introduced a mixture of human-like apella-like properties, providing evidence that ancient human relatives stood upright 3.2 million years ago.
When the team discovered Australopithecus teeth during two separate excavations in 2018 and 2020, they compared them to species such as Afarensis and another human group known as Garhi, but they did not match. Instead, scientists believe that it belongs to a species of Australian species whose teeth walked the Earth after Lucy and which walked the Earth alongside the early homo species.
“When I found a homo, I thought it was all we could find, so one day I was researching, I found an Australopithecus tooth,” Reed said. “Most importantly, it shows once again that human evolution is not linear. There were extinct species. Other species adapt better than others, and others certainly know this for Neanderthals.
The teeth were found in a distant area of Ethiopia. This is an important place for researchers looking for answers about human evolution. Various preserved fossils and some of the earliest stone tools have been discovered, Reed said.
The AFAR region is an active lifting environment. The tectonic plate below that Earth is actively pulled apart, exposing an older layer of sediment that shed light on nearly five million years of evolution, Reed said.
“The continent is literally upset, and that creates a lot of volcanic activity and tectonics,” says Christopher Campazano, a co-author of the study, associate professor at the Institute of Human Origins and associate professor at the School of Human Evolution and Social Change in Arizona. “At 2 1⁄2, three million years ago, these volcanoes spewed ash containing crystals called feldspars.
The Australian coalescence teeth documented in the new study were dated 2.63 million years ago, while the homo teeth date from 2.59 million and 2.78 million years ago. However, the team is cautious about identifying any dental species until there is more data and more fossils.
“We know what early homo teeth and mandibles look like, but that’s it,” Brian Billmore, principal research author and associate professor at the University of Nevada School of Anthropology in Las Vegas, said in a statement. “This potentially highlights the important importance of finding additional fossils to understand the differences between Australopithecus and Homo, and how they can overlap in the fossil records in the same location.”
The Australopithecus teeth were broadly similar to the Afalensis species’ teeth in contour and molar size, but the features of the pointed and canines were not previously seen in Afalensis or Garhi teeth, Villmoare said. The shape of the teeth was different from that of the ancient human relative parantropath, known for its homo species and its larger teeth and chewing muscles.
“Obviously these are just teeth,” Villmoare said. “However, we continue our fieldwork in the hopes of restoring other parts of the anatomy that could increase taxonomy resolution.”
According to Campisano, finding teeth was a complicated task.
“You’re looking at small teeth. You’re looking at individual teeth that seem to literally have many of the small pebbles spread across the landscape,” he said in the video. “So we have a great team of local Afars. It’s a great fossil hunter. They saw their entire lives walking around the landscape. ”
New research is important because it provides insight into the time frame between 3 million and 2 million years ago, a mystical period in human evolutionary studies, according to Dr. Stephanie Merillo, a paleontologist and assistant professor at Mercyhurst University in Pennsylvania. Melilo was not involved in this study, but is involved in the Wansomill Paleontology Research Project, located in a distant triangle in Ethiopia.
Part of the question of learning about this prehistoric spread is how ancient filth layers were deposited over the course of East African history.
“Erosion on the rivers and lakes was low, with a little dirt deposited in the distance,” Merillo wrote in an email. “The deposited dirt contains fossils. They are all animals of our ancestors and all of the animals that lived with us. When there is little deposition, there are very few fossils.”
An important feature that helps archaeologists understand human evolution is the “bowl” on the surface of the Earth, which naturally collects layers of sediment rather than the surrounding landscape. Previous studies found evidence suggesting that Homo and Paranthropus coexisted there 1.5 million years ago.
The new study focuses on distant depression, the northern basin of Turkana.
“This contribution by Villmoare and colleagues shows that there are also several other species around Homo in the distance, but that’s not Paranthropus,” Melillo said. “Instead, they identify this ‘non-homo’ genus as Australopithecus. They do a very convincing job of demonstrating why new fossils are not parantropaths. ”
The study adds to the growing evidence that Australopithecus doesn’t roam just Afar’s depression, she said.
When Australopithecus and Homo were alive, the far-reaching areas were mostly Semidale now, and had far more seasonal variations in rainfall than they do today, Reid said. Millions of years ago, the environment there was still dominated by the dry season, but was interrupted by a short rainy season. The rivers that carried water across the landscape were only present for a portion of the year. Few trees were grown near the river, and the nearby environment was mainly wetlands and grasslands.
“We have fossil giraffe species that were grazing, which probably shows that they are highlighted when eating almost every other place,” Reed said. “Did Hymonin eat the same thing? We’re trying to look into and look at the isotopes of the teeth and microscopic wounds of the teeth.”
Understanding whether Homo and Australopithecus have the same food source can help them paint portraits of how ancient ancestors shared or competed with resources, Reid said. The team is also trying to determine which Hymoninns made the stone tools found on the site.
At this point, it is impossible to tell exactly how the two humans coexist, but Reed said he hopes future findings provide more answers.
“Whenever you have an exciting discovery, if you’re a paleontologist, you always know that you need more information,” Reed said. “We need more fossils. More fossils help us talk about what happened to our ancestors a long time ago, but we are survivors who know that it happened to us.”
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