CANBERRA, Australia — There’s an old saying that “you can’t get blood from a stone” — but a new study reveals that the rise and fall of gigantic mountains in Earth’s past may be the reason there’s life on our planet today. Researchers from The Australian National University (ANU) say they’ve found a connection between the formation of “supermountains” and two crucial periods in the evolution of life on Earth.
The study finds these mountain ranges were likely as tall as the Himalayas and stretched for nearly 5,000 miles across the planet’s ancient supercontinents. Study authors were able to find evidence of these enormous landmarks through traces of zircon with low lutetium content. This combination of a mineral and rare earth element only exists in the “roots” of large mountains, where they formed under extreme pressure in the planet’s surface.
Scientists find 2 links between evolution and mountains
The ANU analysis revealed that most of the world’s supermountains formed during two periods in history. The first was 1.8 to two billion years ago. The next took place between 500 and 650 million years ago. What makes this interesting is that both of these periods in Earth’s past also mark times where life took a major step forward in the evolutionary process!
“There’s nothing like these two supermountains today. It’s not just their height – if you can imagine the 2,400 km long Himalayas repeated three or four times you get an idea of the scale,” says lead author and ANU PhD candidate Ziyi Zhu in a university release.
“We call the first example the Nuna Supermountain. It coincides with the likely appearance of eukaryotes, organisms that later gave rise to plants and animals,” Zhu explains.
“The second, known as the Transgondwanan Supermountain, coincides with the appearance of the first large animals 575 million years ago and the Cambrian explosion 45 million years later, when most animal groups appeared in the fossil record.”
“What’s stunning is the entire record of mountain building through time is so clear. It shows these two huge spikes: one is linked to the emergence of animals and the other to the emergence of complex big cells,” adds co-author Professor Jochen Brocks.
So, how does a mountain provide the spark of life?
Researchers say that when these enormous mountains eroded over time, they “seeded” the world with essential nutrients like phosphorous and iron. In the oceans, this supercharged biological cycles during Earth’s early years and drove evolution to create more complex creatures.
Additionally, the team believes supermountains likely increased oxygen levels in the atmosphere — which complex lifeforms need to breathe.
“The early Earth’s atmosphere contained almost no oxygen. Atmospheric oxygen levels are thought to have increased in a series of steps, two of which coincide with the supermountains,” Zhu says. “The increase in atmospheric oxygen associated with the erosion of the Transgondwanan Supermountain is the largest in Earth’s history and was an essential prerequisite for the appearance of animals.”
What makes the team’s case even more compelling is the fact that scientists can’t find another time in history between these two events where supermountains formed.
“The time interval between 1,800 and 800 million years ago is known as the Boring Billion, because there was little or no advance in evolution,” notes co-author Professor Ian Campbell. “The slowing of evolution is attributed to the absence of supermountains during that period, reducing the supply of nutrients to the oceans.”
“This study gives us markers, so we can better understand the evolution of early, complex life,” Prof. Campbell concludes.
The study is published in the journal Earth and Planetary Science Letters.