Stardust found beneath the surface of the Pacific Ocean has led German researchers to speculate that a supernova that erupted 3 million years ago may have helped advance human evolution.
Stardust found beneath the surface of the Pacific Ocean has led German researchers to speculate that a supernova that erupted 3 million years ago may have helped advance human evolution.
Günter Korschinek (Korschinek) and his colleagues from the Technical University of Munich reported last Wednesday (27/10) that they found the remains of a supernova that exploded and whose echoes caused climate changes on Earth around the same time that man's ancestors began to walk on two.
Depending on the distance of the supernova from us, it could have caused an increase in cosmic radiation for about 300 thousand years. This radiation warmed the earth. wrote the researchers in the last issue of Physical Review Letters.
The timing of the star explosion is more or less similar to the time when the climate change occurred in Africa when drier conditions caused the retreat of forests and the growth of savannah areas. Anthropologists and other experts believe that these changes caused the first humans to come down from the trees and walk on two feet.
The best-known pre-human, a skeleton nicknamed 'Lucy', is also estimated to be 3 million years old. Lucy and the rest of the Austrophytecus afarensis were upright and already walking on two like us.
Korshink's team was the first, five years ago, to find real material from another planet on Earth, in fossil deposits in the Pacific Ocean. This time they searched much deeper for the stellar material. In the middle of the Pacific Ocean near the equator and far from any continent, about south of the Hawaiian Islands. There, at a depth of 4.8 km below sea level, they found a layer of iron-60. It is very easy to date stable layers under the sea. This layer is dated about 2.8 million years old. they say.
Iron-60 is an isotope or chemical variation of iron. This isotope is rare on Earth and scientists believe it did not come from anywhere other than a supernova.
This isotope has a half-life of 1.5 million years, which may give an estimate of when the star exploded, sending out not only solid matter in the form of iron and other elements but also cosmic rays.
Korshink and his colleagues commented that other scientists have hypothesized that cosmic ray bombardment damages the ozone layer and allows more ultraviolet sunlight to penetrate. This phenomenon in turn causes warming and drying in large areas. "It is still not accepted by all scientists that such an increase in the intensity of cosmic radiation could have caused a significant impact on the Earth's climate." They wrote, but they note that the coincidence is interesting: "The climate of the African continent became drier approximately 2.8 million years ago" they write and add. "Some of the main events at the beginning of human evolution seem to correspond to the climatic changes in Africa". They point out.
