Episode 5 : Deep Time

The deep sea is one of our last frontiers. For most of human history, it was a vast, dark, and unknown realm that invoked awe and terror. Now, one thing we do know is that it is critically important and central to the future of life on this planet.

In The Dark Frontier, marine microbiologist and deep-sea explorer Jeffrey Marlow reveals how life can thrive in even the most remote, unforgiving landscapes. Professor Marlow’s research focuses on understanding the microbes that inhabit the rocks and sediments of the seafloor.

In his lab in Boston, he works with a team of scientists to discover how these communities of microbes perform feats of metabolic ingenuity that shape the global carbon cycle and push the boundaries of life’s limits in extreme environments.

In this final episode, Jeffrey reveals how time slows down in the deep ocean. Microbes on the ocean floor slow their metabolism so they hover on the edge of extinction, entering a liminal state between life and death:
“But whenever an edible carbon molecule somehow got through the sediment – maybe every few thousand years – a microbe would pounce. The detection of microbes that could plausibly be one hundred million years old emphasised, to me, how sharply the deep sea diverges from our ingrained understanding of the natural world. Entire civilizations have come and gone while these bacteria beneath the sea napped.”

Reader: Adam Sims
Abridged and produced by Elizabeth Burke
Executive producer: Sara Davies
Sound design: Jon Calver
A Loftus Media production for BBC Radio 4