Fecal Explosion: A New Theory of Complex Life Development on Earth
Publication Date: August 5, 18:00
An international group of scientists from Australia and Germany has proposed a new hypothesis about the causes of the Cambrian explosion, which occurred approximately 540 million years ago. The study, published in the journal Trends in Ecology & Evolution, suggests that the so-called fecal revolution could have been the driving force behind this significant stage in the evolution of life. According to the new theory, mass deposition of nutrient-rich excrement accelerated the development of oceanic ecosystems.
Evolution of Complex Life Forms
For nearly 4 billion years after the emergence of primordial life, evolution remained at the level of single-celled and simplest organisms. However, a vast diversity of complex life forms appeared at the end of the Ediacaran and the beginning of the Cambrian periods over approximately 25 million years. It was previously believed that the main factors driving this process were:
- increasing levels of oxygen in the water and atmosphere;
- formation of the ozone layer;
- influx of nutrients from the melting of global glaciation.
Evolutionary biologist Russell Bicknell from Flinders University and his colleagues noted the role of fossilized excrement, or coprolites, in shaping new ecosystems. The emergence of animals with fully developed digestive systems and anal openings radically changed the nutrient cycling in ancient oceans. The oldest coprolites, which date back to the same period as the Cambrian explosion, consist of microscopic clumps or thin threads.
With the complexity of digestive systems, fossils several millimeters long appear in the fossil record, often containing crushed remains of shells. Excrement enriched with carbon, nitrogen, iron, and phosphorus was massively deposited in deeper layers of water, creating a flow of nutrients. This process formed stable trophic links, accelerated the development of oceanic ecosystems, and initiated positive feedback, which in turn could have contributed to the development of complex life on Earth.
This new theory may significantly change the understanding of the evolution of life on Earth, as it focuses on the biological impact of excrement on ecosystem development. Understanding the role of coprolites may aid further investigations into evolutionary processes as well as studying ecological changes that occurred in ancient times. The scientists' findings highlight the complexity of evolutionary interactions and may serve as a basis for further research in this area.