Life on Earth developed the way it did because of how environment impacted the course of evolution. A team of scientists led by the University of Tasmania revealed how Earth crust participated in the evolution of life. Scientists analysed how minerals from Earth‘s crust made their way into the ocean where they played a crucial role in the evolution of life.
Some minerals, also known as trace elements, are crucial for life. It is actually how we look for life in other planets too – mineral composition can determine whether the planet is suitable for life. Scientists analysed the make-up of the Earth’s crust going back three billion years and found that different types of rocks contain different levels of nutrient elements necessary for life. Scientists found that mafic rocks contain more nutrient elements, such as iron, phosphorus, nickel, cobalt, selenium, molybdenum, copper, zinc and manganese, than felsic rocks. When mafic rocks (for example, basalt and dolerite) dominate in Earth’s crust, these minerals flow into the ocean.
Basalt lavas billions of years ago made sure that oceans are full of important life-supporting minerals. However, oceans were also filled with arsenic, mercury and antimony, which limited evolution of life for time being. When the levels of these toxic minerals declined, between 2.2 and 1.8 billion years ago evolution could pick up some speed. At this time large basalt lava eruptions supplied a lot of nutrient for the ocean and caused levels of oxygen in the atmosphere to increase. However, after that, granites started dominating, which caused a bit of a nutrient crisis. Single cell organisms struggled, but that pressure caused multi-cell organisms to appear.
The last 500 million years saw huge fluctuations in nutrient elements in the ocean, because the composition of Earth’s crust was always changing. That is visible in the evolution course as well – sometimes we can see rapid adaptation to new conditions and sometimes mass extinctions. This research revealed how Earth itself played a crucial role in evolution of life. Nutrient elements provided by the Earth’s crust during eruptions and tectonic movement were key in determining course of evolution.
Scientists made these findings using new technology, which deploys laser analysis of Rare Earth Elements in shale samples collected from all over the world. Raw data then was analysed using statistical methods. It is very interesting to see that Earth was not just a place where evolution evolved. It was actually an active actor.
Source: University of Tasmania