Ethiopian and American scientists have recently discovered the remains of an early hominid, a primitive ancestor of humans, they say lived up to four million years ago. Scientists are hoping the discovery will help them to understand more about the human evolutionary process.
The team of scientists from the Cleveland, Ohio Museum of Natural History returned from their research trip to Ethiopia's Afar region at the beginning of this week with the news of their discovery.
The scientists found a lower leg bone, pelvis, femur fragments, several ribs, a collarbone, and a complete shoulder blade belonging to an early hominid believed to have lived between 3.8 and four million years ago.
The remains are even older than those of the famous hominid dubbed "Lucy," who is 3.2 million years old. Lucy, discovered in 1974 some 60 kilometers from the current find, is famous primarily because scientists found almost half of her skeleton, which is very rare and which has yielded vital clues about human evolution.
Scientists are hoping the latest find will increase their knowledge of evolution, as many as one million years before Lucy's life.
"Given its age, it's going to be very significant in terms of connecting the dots between the earlier Ardipithecus ramidus at 4.4 [million years ago] and the younger species Australopithecus afarensis, which is Lucy's species," explained team member and curator of the Cleveland Museum of Natural History's department of physical anthropology, Yohannes Haile-Selassie. "So it's going to be very critical when we finish the study. It's going to give us a lot of information and I'm sure a lot of scientists involved in this research would be interested to know what this species was."
But, unlike in Lucy's case, the excavation did not yield a skull, jawbone or teeth. Mr. Haile-Selassie says, without these, it will be difficult to determine the hominid's exact species, but much can still be learned from the remains.
"When you have isolated teeth, you can't really say much, but when we have the leg bone, the arm bone, the head, then you can look at proportions of the body. You can also look at how long the arm was compared to the leg, and this has to do with locomotion and how things evolved," he said.
Mr. Haile-Selassie says he and his team will return to the site next year to see if they can find the hominid's skull and jaw.
The hominid could be a member of Lucy's species, Australopithecus afarensis, or Australopithecus anamensis, a species that lived up to 4.2 million years ago.
What Mr. Haile-Selassie and his colleagues do know from the remains they just found is that the hominid was bipedal, or walked on two legs, and was larger than Lucy.
There have been other remains discovered in eastern Africa from the same time period and earlier, all pointing to bipedalism.
A professor of anthropology at the University of Nairobi, Simiyu Wandibba, explains that the oldest hominid fossil, found in Chad, dates back seven million years. He says six million-year-old remains were located in the Kenyan areas of Lake Turkana, Baringo District and Tugen Hills.
Mr. Wandibba says hominids living between 3.4 million to 4.2 million years ago were likely to have created some form of crude technology.
"Our ancestors at that time will have relied on wood, and wood doesn't preserve in the archaeological record," he said. "So they probably made wooden tools for digging up roots, for breaking hard fruits or nuts in order to make them more easily edible, and so on. We can assume that these people made tools out of wood, and that these tools have not preserved."
Mr. Wandibba says stone tools first appeared some 2.5 million years ago.
The "homo" species line producing modern human beings occurred a little more than two million years ago with the emergence of Homo habilis. Homo erectus then came on the scene, followed by Homo sapiens, Homo sapiens neandertalensis, and humankind's present species, Homo sapiens sapiens.
Those in the homo line have a greater cranial capacity than their earlier hominid ancestors, suggesting increased intelligence, and an opposable thumb, which Mr. Wandibba says aided greatly in the evolutionary process.
He says hominids living between 3.5 million to 4.2 million years ago were not as sophisticated as members of the Homo species.
"They must have invented things, otherwise they will not have survived. These people utilized ready-made objects as tools. So you find a stone, you pick it up, and you use it, and then abandon it. The difference between them and homo is that homo sat down and said, 'I want to make a tool that looks like this,' and then made it. And, if need be, if the material is not available, then you look for that material," he said.
Scientists are unsure of the origins of the Homo species line. Some argue that Lucy's species, which died out about a million years ago, gave rise to the homo line. Findings at Lake Turkana in Kenya indicate that the Homo and Lucy's species, Australopithecus, actually co-existed.