City experts discover evidence of evolution
A TEAM of Sheffield scientists has found fossils on the edge of a remote Scottish loch of some of the first life forms to make the pivotal jump from the oceans to land.
Rocks around Loch Torridon on Scotland’s west coast contain the preserved remains of organisms that once lived at the bottom of lakes a billion years ago.
They mark a key moment in evolution when simple bacteria started to become more complex collections of cells, capable of photosynthesis and sexual reproduction.
The Sheffield University experts have been working with scientists from Oxford University and Boston College.
Unlike their bacterial ancestors, the cells had specialised structures including a nucleus, as well as machinery vital for photosynthesis.
They also reproduced sexually, which helped to speed up evolution.
Experts believe the organisms ultimately gave rise to green algae and land plants.
Dr Charles Wellman, from The University of Sheffield, said: “It is generally considered life originated in the ocean and that the important developments in the early evolution of life took place in the marine environment.
“During this time the continents are often considered to have been essentially barren of life. We have discovered evidence for complex life on land from one billion-year-old deposits from Scotland.
“This suggests life on land at this time was more abundant and complex than anticipated.
“It also opens the intriguing possibility that some of the major events in the early history of life may have taken place on land and not entirely within the marine realm.”
Around 500 million years after the appearance of the life forms, the land surface began to be colonised by simple vegetation such as lichens, mosses and liverworts, said the scientists.
At about the same time the first simple animal organisms began to migrate out of the sea.
They were followed by the emergence of fish, reptiles, mammals, ferns, conifers and flowering plants.