Stromatolites & You


We humans are part of a very tiny slice of history, whereas in Western Australia we can have a glimpse at a big slice of history. It is humbling, and at the same time inspiring. As good science journalism should be. We are not too proud to admit that these had completely escaped our attention until just now:

The natural wonder that holds the key to the origins of life – and warns of its destruction

Stromatolite-building bacteria once ruled the Earth, then changed its climate so much they nearly became extinct. Michael Slezak visits the world’s largest surviving colony in Hamelin pool, Western Australia

Just shy of the westernmost tip of the Australian continent lies a pool that provides an unparalleled window into the origins of life on Earth. In its warm, briny waters a biological process takes place that began just as the continents were starting to form.

It is this very process that made the abundance of life on the planet possible and studying it today promises insights into how life began as well as what the Earth was like 3.7bn years ago.

It is also a cautionary tale about an organism that dominated the Earth and transformed its atmosphere – then found itself unable to live with the result.

Hamelin pool contains the world’s largest collection of active stromatolites – stony mounds of sand and calcium carbonate stuck together with a kind of biological glue, which emerge from the water as the tide goes out.

The bacteria that build these stony mounds transformed the planet from a scorching ball of carbon dioxide into the temperate, oxygen-rich world we enjoy today. The mounds they built around the world reveal that they began the process at least 3.7bn years ago. By about 1.25bn years ago, the bacteria that formed them were the world’s dominant lifeform.


Stromatolites at Hamelin pool, which emerge from the water as the tide goes out. Photograph: Michael Slezak for the Guardian

These cyanobacteria belong to the family known as blue-green algae – a misnomer since they are not an algae at all. They were among the first organisms to collect their energy from the sun using photosynthesis – breathing in carbon dioxide and breathing out oxygen.

According to current scientific theories, these bacteria – or their ancestors – then donated the genes that let them photosynthesise to other organisms (in a process known as “lateral gene transfer”). Those other organisms then evolved into the plants we see on land and the seafloor.

In doing so, the stromatolite-forming bacteria sowed the seeds of their own destruction. Though they thrived in hellish environments like those on early Earth, they were unsuited to the paradise they created and disappeared. In a process that is hard not to compare with what humans are doing now; they changed the climate so dramatically they were no longer able to survive…

Watch the video and read the article here.

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