Jharkhand rock holds oldest directly dated traces of life

A 3.5-billion-year-old rock from the Singhbhum Craton in Jharkhand carries the oldest directly dated chemical signatures of microbial life, scientists reported. The study, published in the Proceedings of the National Academy of Sciences, involved researchers from the Geological Survey of India, the University of California Los Angeles, and other institutions. The team dated zircon crystals in a black-and-white banded chert to 3.497 billion years.

The Deccan Herald reports that the rock's carbonaceous matter showed a biological origin involving sophisticated metabolism. The Hindu notes that the carbon isotope balance matched material captured by living cells, and the structure indicated degraded organic matter rather than contamination. The authors told The Hindu the evidence is "compelling" but rests on chemistry and geological context, not fossils.

Earth formed about 4.54 billion years ago, so life appears to have emerged within a billion years of the planet's birth. The scientists say the findings suggest key biological processes were active by 3.5 billion years ago and that similar ancient cherts may hold more records of early life.