Ancient ‘supermountains’ fast-tracked evolution of life – study
Giant mountain ranges rivaling the Himalayas in height and stretching across entire ‘supercontinents’ provided crucial boosts for the evolution of early life on the planet, Australian geologists revealed on Friday. Nutrients leached from those ‘supermountains’ through erosion spurred the development of animals and complex cell organisms, the scientists claimed in a new study.
Its findings, published recently in the Earth and Planetary Science Letters journal, indicated that “two huge [evolutionary] spikes” at some of the most important points in the planet’s biological history were linked to these massive ranges. Researchers from the Australian National University (ANU) found that such mountains, which have long since disappeared, were only formed twice.
The first range, called the Nuna Supermountain, was formed between 2,000 and 1,800 million years ago and “coincided with the likely appearance of eukaryotes,” which are the early organisms that later gave rise to plants and animals.
The second range, named the Transgondwanan Supermountain, rose between 650 and 500 million years ago – coinciding with the arrival of the first large animals some 575 million years ago. It is also linked to the Cambrian explosion 45 million years later, when most major animal groups began appearing.
“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,” the lead author, ANU PhD candidate Ziyi Zhu, said.
As these mountains gradually eroded, vital nutrients like phosphorous and iron were drained into the early oceans, where they triggered increasingly complex biological cycles. At the same time, the erosion process may also have helped raise atmospheric oxygen from nearly non-existent levels, thereby allowing the developing life-forms to breathe.
The researchers found no evidence to suggest other supermountains formed at any time between these two milestone events, which adds to their significance. To confirm this, they tracked the ranges’ formation by examining traces of zircon with low lutetium content – a unique mix of mineral and rare earth element that is only formed under intense pressure at the roots of high mountains.
The time interval between 1,800 and 800 million years ago is called the ‘Boring Billion’, because there were almost no evolutionary advances during this period, co-author Ian Campbell said. He added that this pointed to a decreased supply of nutrients to the oceans due to the lack of supermountains.
