A recent study led by the Australian National University (ANU) has argued that ancient giant mountain ranges as high as the Himalayas and stretching up to 8,000 kilometers across entire supercontinents may have played a crucial role in the emergence and evolution of life on Earth. According to the scientists, the erosion of these supermountains has provided essential nutrients to the oceans while boosting oxygen levels in the atmosphere – which are both necessary ingredients for life to emerge and thrive.
The researchers found that the largest of these supermountains only formed twice in our planet’s history – the first between 2,000 and 1,800 million years ago (called the “Nuna Supermountain”), and the second one between 650 and 500 million years ago (the “Transgondwanan Supermountain”). While the Nuna Supermountain corresponded to the emergence of eukaryotes (the ancestors of plants and animals), the Transgondwanan marked the appearance of large animals 575 million years ago and the Cambrian explosion 45 million years later, when an amazing diversity of animal species emerged and rapidly proliferated.
“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,” said study co-author Jochen Brocks, a professor of Earth Sciences at ANU.
According to Professor Brocks and his colleagues, when these supermountains eroded they most probably provided essential nutrients such as phosphorous or iron to the oceans, promoting new biological cycles and driving life on our planet to new levels of complexity. Furthermore, these supermountains may also have boosted oxygen levels in the atmosphere, which was necessary for complex forms of life 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,” explained study lead author Ziyi Zhu, a doctoral candidate at ANU. “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.”
Between these two major evolutionary events, there is no evidence of the formation of other supermountains. “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,” said study co-author Ian Campbell, an emeritus professor of Geochemistry and Geochronology at ANU.
“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.”
The study is published in the journal Earth and Planetary Science Letters.