While this is evidence of life, it is not a direct discovery of life. Further study will be needed to find out what organisms produced the graphite. But the discovery is hugely important by itself, as it pushes back when life on our planet began.
Discovering evidence of life early in Earth’s history is difficult, not least because rocks dating back this far are hard to find. The oldest rock on Earth is known as the Acasta Gneiss Complex, also in Canada and dating back 4.03 billion years. But as these rocks first originated in a deep magma chamber, and were then subjected to high pressures and temperatures, life isn't expected to be found within them.
This latest discovery is, therefore, pushing the limits of how far back into our planet’s history we can look. It doesn’t just have implications for life here, but life on other worlds too.
Mars and Venus in our Solar System were both thought to have hosted oceans at some point billions of years ago, with conditions not too dissimilar to Earth. If life was able to start on our planet around that time, could it have started elsewhere?
“The discovery of the biogenic graphite enables geochemical study of the biogenic materials themselves, and will provide insight into early life not only on Earth but also on other planets,” the team noted in their paper.