MYSTERIES OF THE ABYSS

The deep sea is Earth’s last unexplored domain. For the longest time, this enigmatic ecosystem has held within it answers to some of the most important questions in science. Now, a new wave of technologies are powering discoveries that will help us put together the story of Earth’s final frontier

- DR HELEN SCALES

1 DID LIFE BEGIN IN THE DEEP SEA?

Life on Earth began about four billion years ago. Where and how those simple cells first sparked into life remain tantalising mysteries, but evidence is stacking up that they could have first emerged in the deep ocean.

In 2017, palaeontologists identified microscopic tubes and filaments made of iron-rich haematite lodged within rocks formed between 3.77 and 4.28 billion years ago. The rocks are a rare fragment of primeval oceanic crust preserved on land (most of the seafloor gets dragged back into the Earth’s mantle, melted and recycled into new crust). The tiny formations have the characteristic shape of microbes that live today on deep-sea hydrothermal vents – the hot springs that form underwater at the edges of tectonic plates.

The fossil find lends support to a theory put forward in the 1990s by NASA chemist, Dr Michael Russell. His idea is that the templates for living cells were provided by tiny rocky pores inside the chimneys of hydrothermal vents. A specific set of circumstances would have been essential for this to happen, in particular the temperature can’t have been too high or the first signs of life would have been immediately scorched. Also, the fluids pouring through these vents would have needed to be alkaline to set up the conditions that generate energy in all living cells today.