Mystery Of How Early Animals Survived Ice Age

In a recent study which got published in the Proceedings of the National Academy of Sciences, researchers had studied that iron-rich rocks has left behind by glacial deposits in Australia, Namibia, and California for getting a window into the environmental conditions during the period of ice age. Using geological maps and clues from the locals, they have hiked to rock outcrops, navigating challenging trails to track down the rock formations.

By examining the strong chemistry of the iron formations in these rocks, the researchers were further able to estimate the amount of oxygen in the oceans around 700 million years long ago and will better understand the effects this would have had on all the oxygen-dependent marine life, which includes the earliest animals like simple sponges.

Maxwell Lechte, a postdoctoral researcher in the Department of Earth and Planetary Sciences under the supervision of Galen Halverson at McGill University said that the evidence suggests that although there are much of the oceans during the deep freeze would have been uninhabitable due to lack of oxygen, in areas where the grounded ice sheet has begun to float there was a critical supply of oxygenated meltwater. This trend can be easily explained by what we call a 'glacial oxygen pump'; air bubbles has trapped in the glacial ice and are released into the water as it melts, enriching it with oxygen.

Around 700 million years ago, the Earth has experienced the most severe ice age of its history that threatens the survival of much of the planet's life. Previous research has furthermore suggested that oxygen-dependent life may have been restricted to melt water puddles on the surface of the ice, but this study provides us new evidences of oxygenated marine environments.

Lechte, who is also the study's lead author said that the fact that the global freeze has occurred before the evolution of complex animals suggests a link between Snowball Earth and the animal evolution. These harsh conditions could have also stimulated their diversification into more complex forms.

Lechte also has pointed out that while the findings focus on the availability of oxygen, primitive eukaryotes would have needed food to survive the harsh conditions of the ice age. 

By: Prerana Sharma

Content: https://www.sciencedaily.com/releases/2019/12/191202190423.htm