When a child develops kidney failure or a rare bone disorder, the cause can seem painfully immediate. It may be a single broken gene, a sudden diagnosis, or a family searching for answers. However, some of those faults may trace back nearly two billion years, to a one-celled ancestor shared by every plant, animal, and fungus alive today. A University of Texas at Austin-led team has now reconstructed the most detailed map yet of the protein networks inside that ancestor, known as the last eukaryotic common ancestor, or LECA. In doing so, the researchers built a new way to hunt for disease genes in humans. They used some of the oldest molecular machinery in complex life as a guide. Their study, published in Cell Genomics, suggests that the deep history of life is not just a story about origins. It can also help explain why modern bodies fail. Rachael Cox, a former UT doctoral student who led the data analysis in the lab of senior author Edward Marcotte, said the approach proved unexpectedly powerful. “There …