The study of evolution is a constantly unfolding story, and new discoveries are being made all the time that change our understanding of how life on Earth has developed. One fascinating area of research is the study of the origins of fungi, one of the most diverse groups of organisms on the planet.
The last universal common ancestor (LUCA) of all living organisms is thought to have existed around 4.2 billion years ago, in the Hadean period. This was a time when Earth was still in its early stages, with dry land consisting of bare rock and the seas as the primary breeding ground for new forms of life. Deep volcanic vents spewing out sulfur and phosphorus provided a hot, nutrient-rich environment for the beginnings of life.
In the fossil record, scientists have found evidence of proto-fungi dating back 2 billion years ago. These fossilized filament-like structures, found in the Onquilloche formation off the coast of South Africa, are thought by some to be an example of early mycelium, the part of the fungal organism that lives within soil or trees. However, due to a lack of organic evidence, this is still a speculative idea.
Around 1 billion years ago, more concrete evidence of early fungi starts to appear in the fossil record. Microscopic fossils found in Arctic shales along the Canadian coastline appear to show strands of mycelium, or bundles of hyphae, which are the building blocks of fungi. These fossils also appear to show a structure that looks like a spore sack, which is considered to be the oldest confirmed fungal relic known to date.
The importance of this discovery lies in the fact that 1 billion years ago, life on land did not yet exist. The only form of plant life that existed at this time were marine algae, which lived in the oceans. Scientists believe that these early waterborne fungi likely formed a symbiotic relationship with marine algae, which could produce carbohydrates through photosynthesis. This partnership would have allowed fungi to thrive and eventually make their way onto land, where they would play a crucial role in the development of soil and the growth of plants.
The study of the origins of fungi is still a relatively new field, but the discovery of these ancient fossils is providing valuable insights into the early evolution of life on Earth. The story of how fungi came to be is still being written, but the evidence we have so far tells a fascinating tale of survival and adaptation in the face of a constantly changing environment.