Boston scientists released a ... report yesterday that challenges the timeline of human evolution ... suggests ... human ancestors bred with chimpanzee ancestors long after they had initially separated into two species. The researchers, working at the Cambridge-based Broad Institute of Harvard and MIT ... estimate ... the first human ancestors split from the chimpanzees. ... at least 1 million years later than paleontologists had believed, based on fossils of early, humanlike creatures. The lead scientist said that this jarring conflict with the fossil record, combined with ... other strange genetic patterns the team uncovered, led him to a startling...