As the Earth orbits around the sun, we know that it stays in its perfectly circular loop. However, every 400,000 years, the Earth's orbit stretches to become 5% more elliptical before returning to its normal even path.
Understanding Orbital Eccentricity
For generations, scientists have been well versed in the orbital eccentricity cycle, which is known to drive various changes in global climates. However, its impact on life on the planet wasn't quantified until now.
According to Swinburne Astronomy, Orbital eccentricity is a measure of how squashed the planet's elliptical orbit becomes. One key element must first be specified for researchers to completely define both the shape and orientation of an elliptical orbit.
Today, a recent study suggests that the Earth's fluctuating orbit could be impacting biological evolution on the planet.
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How the Earth's Orbital Fluctuations Impacts Biological Evolution
In a study published in the journal Nature, titled "Cyclic Evolution of Phytoplankton Forced by Changes in Tropical Seasonality," researchers led by Luc Beaufort, paleoceanography from the French National Centre for Scientific Research, found evidence that the planet's eccentricity is driving evolutionary bursts in species, at least in the photosynthesizing variety of plankton--phytoplankton.
Coccolithophores are small sunlight-eating algae that are responsible for creating plates of limestone surrounding their single-cellular bodies. The said limestone shells, coccoliths, have become extremely prevalent in fossil records--appearing for the first time roughly 215 million years in the past during the Upper Triassic.
The microscopic ocean drifters became so abundant that they massively contributed to the planet's nutrient cycles, forces that alter their presence can, in fact, have huge implications on the planet's biological systems.
Beufort and his team measured an impressive 9 million coccoliths across a span of 2.8 million years of evolution both in the Indian and Pacific oceans, using the help of an AI automated microscopy. Using dated oceanic sediment samples, the team obtained a detailed resolution of roughly 2,000 years. The team used size ranges of the microscopic ocean drifters to estimate the numbers of the species; as previous genetic studies confirm, different species in the Noelaerhabdaceae family can be told apart through the species' cell size.
Researchers uncovered that the average length of coccoliths followed a cycle in line with the 400,000-year orbital eccentricity cycle of the planet. The largest average size found appeared a slight time lag after the recorded highest eccentricity. This was irrespective of whether the planet was experiencing an interglacial or glacial state, reports ScienceAlert.
In line with recent findings, the team suggests that the lag between different orbital eccentricity and climate changes could hint that the coccolithophores drive--rather than respond-- to carbon cycle changes. Simply put, these microscopic ocean drifters, along with other types of phytoplankton, may help change the planet's climate in response to the said orbital events. Although further investigation is needed to solidify the discovery, researchers are sure it hints at a new understanding of evolutionary biology.
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