New Age Estimate for Early Human Skull Produces Surprising Discovery
2020-04-13
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1Scientists say a new age estimate for the skull of an early human is raising questions about modern human ancestry.
2The fossilized skull was considered a major discovery when it was found in Zambia in 1921.
3It was the first fossil of an extinct human species to be discovered in Africa.
4The skull was named after the area in which it was discovered: Broken Hill. Researchers say a new examination of the fossil suggests that it is much younger than previously thought.
5The fossil was difficult for scientists to date.
6That is because the skull was recovered in a mine that later became completely destroyed from mining operations.
7Researchers now say that two new complex dating methods have estimated the Broken Hill skull to be about 299,000 years old.
8Past scientific examinations had estimated the fossil was likely about 500,000 years old.
9The team of researchers said their examination efforts involved years of work that included direct dating of the skull itself as well as other human and non-human materials found near the discovery area.
10Rainer Gruen of Australia's Griffith University led the examination efforts.
11He was also the lead writer of a study on the process, which recently appeared in the publication Nature.
12Gruen said in a statement that the new age estimate changes earlier opinions on both "the tempo and mode" of modern human ancestry.
13Gruen and his team believe the findings show that human evolution in Africa around 300,000 years ago "was a much more complex process" than other evidence has suggested.
14Scientists now believe the process involved the co-existence of several human lineages.
15Instead of linear evolution, in which each new species replaced the old one, Africa may have been a place where different human species mated with each other.
16The new estimate means the species represented by the skull was unlikely to have been a direct ancestor of Homo sapiens, the species of human that exists today.
17Our species first appeared in Africa more than 300,000 years ago before spreading worldwide.
18Scientists first thought the skull belonged to a new species they named Homo rhodesiensis.
19But most scientists now believe it is part of the Homo heidelbergensis group.
20This species is thought to have appeared about 600,000 years ago in parts of Africa and Europe.
21Chris Stringer is an anthropologist with the Natural History Museum in London.
22He told the Reuters news agency the latest research suggests "that the facial shape of Homo heidelbergensis fossils does not fit an ancestral pattern for our species."
23Stringer said the age of the fossil suggests that at least three human species lived in Africa around 300,000 years ago.
24Homo sapiens, he said, were likely present in places like Morocco and Ethiopia.
25The Homo heidelbergensis is thought to have lived in south-central Africa.
26The third is called Homo naledi, and was recently discovered in South Africa.
27"We already knew that Eurasia contained diverse human lineages about 300,000 years ago," Stringer said.
28"Now, the same applies to Africa."
29When the skull was discovered in 1921, it provided the first evidence of a prediction that British naturalist Charles Darwin made 50 years earlier.
30Darwin theorized that Africa was the place where humans broke off from other animals, because African apes are our closest living relatives.
31Prehistoric human fossils until that time had all been found in Europe and Asia.
32I'm Bryan Lynn.
1Scientists say a new age estimate for the skull of an early human is raising questions about modern human ancestry. 2The fossilized skull was considered a major discovery when it was found in Zambia in 1921. It was the first fossil of an extinct human species to be discovered in Africa. 3The skull was named after the area in which it was discovered: Broken Hill. Researchers say a new examination of the fossil suggests that it is much younger than previously thought. 4The fossil was difficult for scientists to date. That is because the skull was recovered in a mine that later became completely destroyed from mining operations. 5Researchers now say that two new complex dating methods have estimated the Broken Hill skull to be about 299,000 years old. Past scientific examinations had estimated the fossil was likely about 500,000 years old. 6The team of researchers said their examination efforts involved years of work that included direct dating of the skull itself as well as other human and non-human materials found near the discovery area. 7Rainer Gruen of Australia's Griffith University led the examination efforts. He was also the lead writer of a study on the process, which recently appeared in the publication Nature. 8Gruen said in a statement that the new age estimate changes earlier opinions on both "the tempo and mode" of modern human ancestry. 9Gruen and his team believe the findings show that human evolution in Africa around 300,000 years ago "was a much more complex process" than other evidence has suggested. 10Scientists now believe the process involved the co-existence of several human lineages. Instead of linear evolution, in which each new species replaced the old one, Africa may have been a place where different human species mated with each other. 11The new estimate means the species represented by the skull was unlikely to have been a direct ancestor of Homo sapiens, the species of human that exists today. Our species first appeared in Africa more than 300,000 years ago before spreading worldwide. 12Scientists first thought the skull belonged to a new species they named Homo rhodesiensis. But most scientists now believe it is part of the Homo heidelbergensis group. This species is thought to have appeared about 600,000 years ago in parts of Africa and Europe. 13Chris Stringer is an anthropologist with the Natural History Museum in London. He told the Reuters news agency the latest research suggests "that the facial shape of Homo heidelbergensis fossils does not fit an ancestral pattern for our species." 14Stringer said the age of the fossil suggests that at least three human species lived in Africa around 300,000 years ago. Homo sapiens, he said, were likely present in places like Morocco and Ethiopia. The Homo heidelbergensis is thought to have lived in south-central Africa. The third is called Homo naledi, and was recently discovered in South Africa. 15"We already knew that Eurasia contained diverse human lineages about 300,000 years ago," Stringer said. "Now, the same applies to Africa." 16When the skull was discovered in 1921, it provided the first evidence of a prediction that British naturalist Charles Darwin made 50 years earlier. Darwin theorized that Africa was the place where humans broke off from other animals, because African apes are our closest living relatives. Prehistoric human fossils until that time had all been found in Europe and Asia. 17I'm Bryan Lynn. 18Bryan Lynn wrote this story for VOA Learning English, based on reports from Reuters, Nature, Griffith University and the Natural History Museum in London. Ashley Thompson was the editor. 19We want to hear from you. Write to us in the Comments section, and visit our Facebook page. 20__________________________________________________ 21Words in This Story 22skull - n. the part of the head that is made of bone and protects the brain 23fossil - n. part of an animal or plant from thousands of years ago, preserved in rock 24extinct - adj. no longer living or existing 25tempo - n. the speed at which something happens 26mode - n. a way of doing something 27evolution - n. the way in which living things gradually change and develop over millions of years 28species - n. a set of plants or animals in which the members have similar characteristics to each other 29anthropologist - n. a person who studies human development and society or different societies 30pattern - n. a particular way something is done, is organized or happens 31diverse - adj. including many different kinds