Surprise find in NC could force evolution rethink

ogist Stefan Bengtson from the Swedish Museum of Natural History, the significance of the microfossils became clear.

Up until now, previous geological evidence for fungi only extended as far back as 385 million years ago, but the Ongeluk discovery suggests that life has inhabited submarine volcanics for more than 2.4 billion years.

The researchers, however, aren’t claiming that what they’ve found is definitely evidence of ancient fungi – although signs are positive, as the appearance of tangled filaments is highly similar to other fungal fossil discoveries.

“This is why we call the fossils ‘fungus-like’ rather than ‘fungal’. We have been careful to point out that the filaments we see are very simple,” Bengtson was quoted as saying.

“(But the fossils) are practically indistinguishable in habitus and habitat from the proven fungi in the much younger fossil record. We were quite excited that the fossils were so fungus-like.”

If subsequent research can verify that the discovery was left by a type of ancient fungus, it would also be the earliest fossil evidence of eukaryotes – the biological kingdom of organisms that also contains fungi, in addition to animals and plants.

But the biggest implications of the research could be that it suggests fungi may have evolved under the sea, rather than on land as previously thought.

The dating of the ancient basalt to 2.4 billion years ago means the organisms existed before what’s called the Great Oxygenation Event – which possibly occurred 2.3 billion years ago, dispersing dioxygen (O2) into the atmosphere.

By pre-dating this event, it means the life-forms evolved to survive deep under the sea, without access to either light or oxygen.

The team suggests the fungus-like organism may have existed in symbiosis with other microbes, somehow using chemically stored energy to stay alive.

“This would have tremendous implications for the lifestyle of the early ancestors of eukaryotes and fungi,” Rasmussen said.

In addition, the research shows that scientists stand to learn a lot from studying the deep biosphere – the hidden terrain of the ocean floor and the ecosystems underneath it.

“The deep biosphere (where the fossils were found) represents a significant portion of the Earth, but we know very little about its biology and even less about its evolutionary history,” Bengtson added

In light of these findings, now could be the time to address that lack of knowledge, by digging a little deeper.

Nicola McLoughlin from Rhodes University said in a commentary on the paper, that the newly-discovered fossils raised the question of whether “we have been looking in the wrong place for the earliest eukaryotes and fossil fungi in particular”.

“Independent of whether these fossils are definitely fungal or not, these findings pose provoking questions about the antiquity of eukaryotes during an interval of time known as the Great Oxidation Event of Earth’s atmosphere approximately 2.4 to 2.2 billion years ago.”