The first life forms on Earth might have come from Saudi Arabia, scientists find new proof

Despite its barren and unforgiving environment, Saudi Arabia has emerged as a blazing beacon of infrastructural development. Remarkably enough, this story of resilience extends far into the past, as the region may also be where the first bits of life on Earth originated.
Earliest forms of life
Scientists have unearthed living stromatolites — ancient geological structures made from algae — on Sheybarah Island, nestled on the northeastern shelf of the Red Sea in Saudi Arabia. These ancient life forms, dating back 3.48 billion years, were previously thought to thrive only in select modern environments like Shark Bay, Australia, and the Exuma Islands in the Bahamas.

The reason this is such a crucial discovery is because Stromatolites are the earliest geological indicators of life on Earth. Further, these biotic structures were instrumental in the Great Oxygenation Event over two billion years ago, introducing oxygen into the atmosphere and transforming the planet's habitability.

The oxygenation event initially wiped out many of their competitors, allowing stromatolites to dominate the biosphere during the Archean eon, when life had just begun to bud. However, as life forms adapted to the oxygen-rich atmosphere, stromatolites began to decline, only reappearing in the geological record after mass extinctions or in extreme environments.

"The bacteria are always around, but they don't usually get the chance to make stromatolites," explains study author Volker Vahrenkamp. "They are largely outcompeted by corals."
An accidental discovery
The Sheybarah Island’s several hundred stromatolites formations were accidentally found when the researchers were studying tepee structures — massive salt crust domes visible from space. Some stromatolites were well-developed and textbook-perfect, while others were more sheet-like with low relief. This diversity intrigued the researchers, hinting that they may be at different stages of development.

The island's harsh environment — characterised by extreme temperature swings, alternating wet and dry conditions, and nutrient-poor waters — mirrors the conditions of the Bahamas, suggesting that similar stromatolite fields might exist elsewhere on the Al Wajh carbonate platform. However, the small size of stromatolites, about 15 cm across, makes them challenging to detect without close inspection.

Understanding stromatolite growth rates remains a significant scientific challenge because dating these structures is complicated by the presence of two indistinguishable carbonate components: the newly microbe-precipitated material and environmental carbonate sand. To overcome this, Vahrenkamp's team conducts monthly monitoring, documenting any visual changes. Future plans include experimental attempts to cultivate stromatolites in aquarium settings, aiming to unlock the secrets of their growth and development.

The rediscovery of stromatolites on Sheybarah Island not only provides a unique glimpse into Earth’s ancient history but also offers potential insights into the search for extraterrestrial life, particularly on Mars. By studying stromatolites, which thrived before Earth had an oxygenated atmosphere, scientists can develop models to recognise potential signs of life on other planets.

The findings of this research have been published in Geology and can be accessed here.