Did a star explosion influence virus evolution? 💥

2.5 million years ago, a supernova near Earth may have released intense cosmic radiation. These energetic particles could have altered the DNA of viruses in Lake Tanganyika, leading to rapid diversification. A recent study explores this surprising link between space and terrestrial microbiology.

Supernovas, explosions of massive stars, release cosmic rays capable of traveling interstellar distances. When these radiations reach Earth, they can interact with living organisms. A team of researchers discovered that one of these explosions coincides with a sudden increase in viral diversity in Lake Tanganyika, in East Africa.

Traces of a supernova in sediments

Scientists analyzed samples of marine sediments rich in iron-60, an isotope produced during stellar explosions. These traces indicate that Earth was exposed to cosmic radiation about 2.5 million years ago. This period corresponds to a passage of our Solar System through a region of the Milky Way marked by supernovas. Researchers identified two peaks of iron-60, one dating back 6.5 million years and the other 2.5 million years, suggesting several major cosmic events.

Simulations show that these radiations could have reached the Earth's surface for 100,000 years. Cosmic particles, by damaging DNA, may have favored accelerated mutations in living organisms. This hypothesis is reinforced by the discovery of a peak in viral diversification in Lake Tanganyika at the same time. Models suggest that the supernova responsible for these radiations came from a group of stars located about 460 light-years from Earth.

The study highlights the importance of cosmic events in Earth's evolutionary history. Although the direct link between the supernova and viral diversification remains to be confirmed, the data show a striking temporal correlation. Researchers now plan to explore other geological periods to verify if stellar explosions could have influenced other biological upheavals. These discoveries open new perspectives on the interaction between space and life.

Lake Tanganyika, a natural laboratory

Lake Tanganyika, one of the oldest and deepest freshwater lakes, is home to exceptional biodiversity. More than 2,000 species live there, half of which are endemic. This unique ecosystem offers an ideal study ground to understand the interactions between viruses and their hosts.

Viruses, by mutating more rapidly, may have influenced the evolution of species in the lake. This diversification could have altered the relationships between predators and prey, as well as ecological dynamics. Scientists emphasize that cosmic radiation, by damaging DNA, may have accelerated these mutations. Although the direct link between a supernova and this diversification remains to be confirmed, the data suggest an intriguing correlation.

Lake Tanganyika continues to be a subject of research due to its complexity and geographic isolation. Studies on its sediments and biodiversity provide valuable clues about past events. Cosmic radiation could thus have played an underappreciated role in Earth's evolutionary history. These discoveries pave the way for new research on the impact of astronomical phenomena on biology.

To go further: How do cosmic rays affect Earth?

Cosmic rays are highly energetic particles from space, often originating from supernovas or other violent stellar events. When they reach Earth, they interact with the atmosphere, creating a cascade of secondary particles. Although most of this radiation is absorbed by the atmosphere, a fraction reaches the surface, where it can influence living organisms.

These energetic particles have the ability to penetrate cells and damage DNA. This can lead to genetic mutations, sometimes beneficial, but often harmful. In some cases, these mutations can accelerate evolution by favoring the emergence of new genetic variants.

Cosmic rays are not limited to influencing biology. They can also affect the climate by altering cloud formation or disrupting electronic systems, such as satellites. However, their most intriguing impact remains their potential role in the evolution of species. By better understanding these interactions, scientists hope to shed light on the links between cosmic phenomena and life on Earth.