CRISPR Origins Traced Back to LUCA

The researchers compared the genomes of 700 modern microbes, using sophisticated genomic analysis tools to identify shared features that arose first. They constructed a phylogenetic tree using 57 marker genes from 350 bacteria and 350 archaea species, tracking gene duplications and mutations to estimate LUCA's timeline and ecological interactions.

LUCA was until recently thought to have lived approximately 3.5-3.8 billion years ago. Still, the new study suggests that it emerged far earlier, namely 4.2 billion years ago and just a few hundred million years after the planet formed.

"How evolution proceeded from the origin of life to early communities at the time of LUCA remains an open question, but the inferred age of LUCA compared with the origin of the Earth and Moon suggests that the process required a surprisingly short interval of geologic time," the authors conclude in their paper.

This comprehensive study not only pinpoints the early existence of the CRISPR-Cas system. It also suggests that LUCA possessed a relatively complex genome, indicating that it was a cellular organism with sophisticated metabolic and genetic systems similar to modern prokaryotes. The study also provides insights into LUCA's lifestyle, which included a diet of hydrogen gas and carbon dioxide.

The research was led by Edmund Moody and Philip Donoghue from the University of Bristol, with contributions from various international collaborators. It was published in Nature Ecology & Evolution on July 12.