2-3 million years ago, many new viruses suddenly appeared in Africa’s Lake Tanganyika and affected local fish populations. Scientists believe that this event occurred because of radiation from the explosion of a supernova, which reached our planet at this very period of time.
Lake Tanganyika
Tanganyika is a large lake in Africa, stretching more than 600 kilometers from north to south. It is one of the largest reservoirs of freshwater on Earth, where 16% of the world’s reserves are concentrated. But a while ago, researchers discovered that something strange happened to life in it 2-3 million years ago. The frequency of virus mutations increased dramatically and the number of virus species affecting local fish increased.
A team of researchers from the University of California, Santa Cruz, believe they have solved the mystery. In their paper published in The Astrophysical Journal Letters, they claimed that it was caused by radiation from a supernova explosion occurring between 2 and 3 million years ago.
They base their opinion on another study that found a layer of radioactive iron-60 at the bottom of the world’s oceans. According to how much of it had time to decay, scientists determined that it reached Earth about 2.5 million years ago. This suggests that this event may have something to do with the increase in the number of viruses in Lake Tanganyika.
Local bubble
In fact, two layers of radioactive iron-60 are present at once in the geologic record. One dates back 6 million years, the other 2.5 million years. Both are somehow related with radiation from supernova explosions, but in slightly different ways.
The Earth is inside the so-called Local Bubble. This is a region of space with a relatively low density of interstellar gas. It was formed by a powerful supernova explosion, and the Sun and Earth are inside it.
However, this does not mean that this particular supernova is to blame for the new viruses in the lake. It erupted many millions of years before. And the iron-60 peak was formed when the Sun entered the Local Bubble and crossed the front of the shock wave spreading through space.
Since then, however, another supernova has erupted not far from Earth. As the place where it occurred scientists suggest several stellar associations that are now between 70 and 140 pc away from us. It generated ionizing radiation, which caused enhanced mutations, and after about 100,000 more years came a wave of radioactive dust, which is responsible for the second layer of iron-60 on the ocean floor.
According to phys.org
