The researchers visited a number of sites in northern Labrador, including Big Island, where they collected some of the oldest rocks on Earth at 3.95 billion years old.
Researchers report that Graphite, a form of pure carbon found in the 3.95-billion-year-old rocks shows the geochemical signature of having come from the decomposition of living organisms.That's at least 150 million years older than the oldest graphite from living organisms previously found in 3.7 billion to 3.8 billion-year-old rocks in Greenland and northern Quebec.
Some of the signatures in the Labrador rocks suggests that the organisms that left them were autotrophic — that is, they could produce their own food from chemicals in their environment, as algae and some kinds of bacteria do