IIt's easy to see how the price of a chocolate bar can correlate with weather conditions in Africa. Most cocoa is grown in Africa, so if bad weather changes the volume of cocoa harvest there, it will affect global supplies. The price may change in the future.
You might be even more surprised to learn that the specific path that the blazing Sun takes through the galaxy may have a direct impact on fluctuations in microplankton diversity in Earth's oceans. These are the conclusions new preprint under the direction of Peter Ozvart at the Hungarian Academy of Sciences in Budapest. This is because the flux of cosmic rays hitting Earth varies, and this affects the mutation rate of microplankton, Ozsvart and his colleagues found.
Microplankton form the basis of the marine food web and support all higher marine life such as fish and whales, so the findings suggest that tiny changes in the dynamics of our vast solar system could have had a profound impact on the evolution of life on Earth.
The Sun is located about 26,000 light-years from the center of our galaxy, also known as the Milky Way, and its orbit is nearly circular, taking about 230 million years to complete one revolution. In orbit around the center of the galaxy, the Sun undergoes vertical oscillations with an amplitude of about 200 light years.
Tiny changes in the dynamics of our vast solar system may have had a profound impact on the evolution of life on Earth.
And these fluctuations affect the flow of cosmic rays entering the solar system. Cosmic rays are energetic particles, mainly protons and other ions, that are accelerated to very high speeds either by the Sun itself or by more distant galactic and extragalactic sources. When these cosmic rays collide with molecules in our atmosphere, they create cascades of other particles that fall to Earth and its vast oceans. These “showers” of particles tend to lose their steam once they pass through about 30 feet of water, which is the territory of marine plankton.
Marine plankton are a huge and diverse group of small organisms that include phytoplankton, which belongs to the plant kingdom, and zooplankton, which belongs to the animal kingdom. Ozsvart and his colleagues focused on four groups of microplankton about which we already know a lot about their evolutionary history, including how the number of species and genera has changed over geological time.
Four groups of organisms—radiolaria, nannoplankton, dinoflagellates, and planktonic foraminifera—have skeletons ranging in size from 2 to 300 microns (the size of very finely ground coffee beans) and are found across a wide range of latitudes and water temperatures. Scientists have data on radiolarians that are 500 million years old, and three others that are 250 million years old.
High-energy radiation damages genetic information, most often breaking DNA strands. Cells are designed to repair their own DNA, but the repair process is imperfect. This leads to mutations. The rate of mutation depends on the amount of restoration required, which in turn is affected by the flow of cosmic rays.
Ozsvart and his colleagues calculated the number of new genera of species for each of the groups over geological time and compared it with data on the flux of cosmic rays on Earth. Their hypothesis was that the distribution of new microplankton genera should be higher during periods when cosmic ray flux was higher, and the data seemed to support this to a statistically significant extent.
Plankton is the largest source oxygen in our atmosphere and play a key role in nutrient cycling and maintaining healthy marine ecosystems. What would be the “downstream” consequences of increasing microplankton biodiversity? Like the weather in Africa affecting the price of chocolate, it is possible (though difficult to predict) that such changes could spread from local ecosystems throughout the ocean and have a profound impact on the evolution of life as we know it.
Do seemingly distant, small changes in our cosmic environment play a central role in the evolution of life on Earth? Previous studies have suggested that galactic wobbles may correlate with mass extinction events, but such claims have been refuted. However, the new findings show that when searching for impact forces and massive impacts that may have influenced evolution, it's important to look beyond dinosaur-killing asteroids and megavolcanoes to an even more powerful force in our galaxy: the Sun.
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