Variations in the Earth’s orbit mark the biological evolution on the planet – Central Valley Business Journal

12/06/2021 at 12:30 CET

Scientists at Frances National Center for Scientific Research (CNRS) have found that when the Earths orbit is more circular, equatorial regions show little seasonal variation and unspecialized species dominate all oceans. Instead, as the orbital eccentricity and more pronounced seasons appear near the equator, species diversify and influence the carbon cycle and the determination of ocean chemistry.

In principle, we must bear in mind that the Earth describes annually around the Sun a elliptical path called orbit. Earths orbit has a perimeter of 940 million kilometers, while the planet moves in outer space at an average speed of 107,227 kilometers per hour.

The earth orbit It is not perfectly circular, but rather describes an ellipse of great eccentricity. However, the maximum variation of the distance to the center that marks the Earths orbit is 1.39%: this means that on an imaginary scale of 10 centimeters the distance between the longest and shortest axes would reach a maximum of 0.14 millimeters, an imperceptible difference to the human eye.

Although the orbital changes are not so pronounced from our point of view, they do seem to mark strong variations in planetary dynamics. According to a press release, the study of a variety of microscopic algae called coccolithophores seems to indicate that changes in the Earths orbit could have a direct impact on the biological evolution of the Earth.

As French researchers indicate in a new study published recently in the journal Nature, while the role of Earths orbital variations In driving global climate cycles, its effect on biological evolution is unknown until now.

In order to determine this possible influence, the scientists focused on the coccolithophores, a vital part of plankton: these tiny algae make up small plates of limestone, called coccoliths, around their individual cells. The configuration and dimensions of coccoliths vary by species.

At the end of their life cycle, coccolithophores sink to the depths of the ocean and coccoliths accumulate in sediments: these elements faithfully record the detailed evolution of these organisms over geological time, providing valuable information to researchers. Now, they seem to indicate the crucial role of changes in Earths orbit in the planetary biodiversity.

Related topic: Earths orbit is associated with the extinction of some species.

Specialists have managed to verify that during the last 2.8 million years the morphological evolution of coccolithophores was forced by the Earths orbital eccentricity, with rhythms of around 100,000 years to 405,000 years, in periods different from those marked by contemporary global climatic cycles.

The diversity of coccolithophores species increases markedly when the Earths orbit is more eccentric, due to a clearer variation between the seasons in the equatorial regions. The opposite happens when the Earths orbit is more circular and regular: the seasons tend to be more even at the climatic level in areas close to the equator and biodiversity decreases.

On the other hand, the impact of earth orbit and the biological evolution of these microalgae could have set the rhythm of ancient climates, determining abrupt climatic variations that until now could not be explained.

As coccolithophores are responsible for half of the limestone produced in the oceans, they play a crucial role in the carbon cycle and in the characteristics of ocean chemistry. According to the researchers, in the absence of ice the biological evolution of these microalgae could have marked the rhythm of climates and determined its variations.

Cyclic evolution of phytoplankton forced by changes in tropical seasonality. Beaufort, L., Bolton, CT, Sarr, AC. et al. Nature (2021). DOI: https: //doi.org/10.1038/s41586-021-04195-7

Photo: coccolithophores, an important component of plankton, evolved following the rhythm of Earths orbital eccentricity. Credit: Luc BEAUFORT / CNRS / CEREGE.

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Variations in the Earth's orbit mark the biological evolution on the planet - Central Valley Business Journal