How Did First Animals Evolve?

Posted: Aug 20 2017, 12:57am CDT | by , in News | Latest Science News

 

How Did First Animals Evolve?
Dr. Jochen Brocks and Dr. Amber Jarrett with an oil sample taken ancient sedimentary rocks. Credit: Stuart Hay, ANU
 

Scientists claim that an algae bloom 650 million years ago set the stage for first animals including humans

Researchers claim they have solved the mystery of how first animals appeared on Earth. 

Hundreds of millions of years ago Earth went through a frozen period, where the planet was covered in ice, resulting in what they call, “Snowball Earth.” Ice blanketed the entire planet even the oceans.  When the snow melted during an extreme global heating event, high levels of frozen nutrients went into the oceans and created a burst of energy needed for the evolution of a complex life.

While digging ancient sedimentary rocks from Central Australia, researchers have found the evidence of an algae explosion 650 million years ago at the base of the food web in the oceans. It was a large single-celled organism called green algae that later become multi-cellar and larger. The subsequent analysis of rock samples they retrieved led to what they believe is an explanation of evolution of world’s first animals.

The rise of algae triggered one of the most profound ecological revolutions in Earth's history, without which humans and other animals would not exist.

“We crushed these rocks to powder and extracted molecules of ancient organisms from them," said Dr Jochen Brocks from The Australian National University (ANU).

"These molecules tell us that it really became interesting 650 million years ago. It was a revolution of ecosystems; it was the rise of algae."

For a long time the Earth was dominated by bacteria, small organism which lack complex structure. Algae are larger and more complex than bacteria but still single-celled. It appears that huge release of nutrients and cooler global temperatures created the perfect conditions for the rapid spread of algae and allowed them to replace bacteria. This process set the stage for a more complex life as we know it today.

Researchers have not been able to discover the fossils of algae. Instead they have found cholesterol molecules of algae which are similar to that of humans. 

"The Earth was frozen over for 50 million years. Huge glaciers ground entire mountain ranges to powder that released nutrients, and when the snow melted during an extreme global heating event rivers washed torrents of nutrients into the ocean,” said Dr. Brocks.

"These large and nutritious organisms at the base of the food web provided the burst of energy required for the evolution of complex ecosystems, where increasingly large and complex animals, including humans, could thrive on Earth.”

 

 

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Hira Bashir covers daily affairs around the world.

 

 

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