Bhubaneswar: A new study suggests that radiation from an ancient supernova may have impacted evolution on Earth, specifically influencing virus diversity in Lake Tanganyika around 2.5 million years ago.
Researchers found that an increase in virus diversity in the lake coincided with a period when Earth was bombarded with cosmic rays from a nearby supernova explosion.
The team analyzed core samples of deep-sea sediments to identify spikes in the radioactive isotope iron-60, which is produced during supernova explosions. They traced these spikes to a supernova event that occurred between 2 and 3 million years ago, likely originating from the Scorpius-Centaurus group of young stars. Simulations showed that this supernova would have exposed Earth to elevated levels of cosmic radiation for approximately 100,000 years.
While the study cannot definitively prove a direct link, the timing of the supernova radiation and the increased viral diversity in Lake Tanganyika is intriguing. The researchers emphasize that radiation is a known driver of mutation and evolution, and the supernova event could have played a role in nudging changes along.
This research highlights the potential for distant cosmic events to influence life on Earth and underscores the interconnectedness of our planet with the broader universe. The research has been published recently in The Astrophysical Journal Letters.
ABSTRACT OF THE STUDY
The abstract of the study says the following.
- The Earth sits inside a 300 pc-wide void that was carved by a series of supernova explosions that went off tens of millions of years ago, pushing away interstellar gas and creating a bubble-like structure.
- The Fe (radioisotope of iron) peak deposits found in the deep-sea crust have been interpreted by the imprints left by the ejecta of supernova explosions occurring about 2–3 and 5–6 Myr ago.
- It is likely that the Fe peak at about 2–3 Myr originated from a supernova occurring in the Upper Centaurus Lupus association in Scorpius Centaurus (≈140 pc) or the Tucana-Horologium association (≈70 pc), whereas the ≈5–6 Myr peak is likely attributed to the solar system's entrance into the bubble.
- Our study shows that the supernova source responsible for synthesizing the Fe peak deposits ≈2–3 Myr ago can consistently explain the cosmic-ray spectrum and the large-scale anisotropy between 100 TeV and 100 PeV.
- The cosmic-ray knee could then potentially be attributed entirely to a single nearby "PeVatron" source.
- Matching the intensity and shape of the cosmic-ray spectrum allows us to place stringent constraints on the cosmic-ray energy content from the supernova as well as on the cosmic-ray diffusion coefficient.
- Making use of such constraints, we provide a robust estimate of the temporal variation of terrestrial ionizing cosmic radiation levels and discuss their implications in the development of early life on Earth by plausibly influencing the mutation rate and, as such, conceivably assisting in the evolution of complex organisms.
