Since several karst caves northwest of Johannesburg, South Africa, were declared a “World Heritage Site” in 1999, this region has been declaring the area with the term “cradle of mankind” – “the cradle of mankind”. The reason: In an area of only 25,000 hectares, a large number of fossils of early and early humans were found in 15 caves. with AustralopithecusAnd the Paranthropus And the to turn down Two million years ago, three different hominin species lived there at the same time. Roughly a third of all known pre-human finds come from this relatively small area, which is about twelve times the size of Frankfurt Airport.
However, there is a problem. bones and skulls AustralopithecusThe specimens don’t really fit into the classic picture of human history. Accordingly, the gender to turn down Thus also anatomically modern humans evolved from australopithecines. In the cradle of humanity must Australopithecus That is, he lived long before his descendants. As new dating has now been revealed, that was apparently exactly the case, explained Daryl Granger of Purdue University in the US state of Indiana and his team. in PNAS magazine.
The working group examined the finds from the Sterkfontein Cave that set the record for the volume of storage AustralopithecusKeeps fossils in one place. In detail, the five researchers and one researcher looked at the layer in which most of the pre-human artifacts appeared. Traditionally, the layer in which it is found is dated from 2.1 to 2.6 million years ago due to sintering deposits. So the finds must be of the same age. At least that was the assumption so far. But Daryl Granger and his team wanted to know more and analyzed the Brescia rock in which the fossils were embedded.
Dating using radioactive decay
Particles of very high energy of radiation, constantly falling into the Earth’s atmosphere from space, repeatedly collide with rubble lying on the surface. Natural radioactive isotopes such as aluminum 26 and beryllium 10 are constantly formed. “If the rock was later located underground in a cave, for example, much less cosmic radiation would arrive and fewer such isotopes would be formed,” explains archaeologist and dating specialist Daniel Richter of the University of Mainz, who co-authored the study at PNAS. Not involved. Then the radioactive clock starts to appear: Over millions of years, beryllium 10 and aluminum 26 decay very evenly to form boron 10 and magnesium 26. Granger and his team used the amount of isotopes to calculate when the breccia got into around the underground fossils: they think the rock wasn’t Exposed 3.4 to 3.7 million years ago – that’s millions of years longer than previously thought.
“Alcohol buff. Troublemaker. Introvert. Student. Social media lover. Web ninja. Bacon fan. Reader.”
More Stories
University development: DHV positions itself to address the challenges facing science
Your most successful tips and tricks
Black Hole: A powerful, organized magnetic field discovered at the center of the Milky Way Galaxy