In an hour, a science programme starts on Radio 4 dedicated entirely to The Sound of Life (9pm). From the first episode programme notes,
The programme uncovers the accidental sounds made by the first life-forms in the oceans which later evolved onto land. Bacteria, which can still be found in the Antarctic Ocean today, made the first sounds of life on planet Earth. They produced bubbles of oxygen, which made sounds as they passed through the water. They also formed dense, soggy mats which sloshed against the shores, creating the first sound of life for three billion years. The trailer I heard just now was a heavy humming. Awesome. Listen!