An Evolutionary Tree Including Four Proposed Episodes of Gene Flow (image) University of Utah Share Print E-Mail Caption An evolutionary tree including four proposed episodes of gene flow. The previously unknown event 744,372 years ago (orange) suggests interbreeding occurred between super-archaics and Neanderthal-Denisovan ancestors in Eurasia. Credit Adapted from Alan Rogers Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.