*/ In the June 8 SN: Measles roars back, collapsars spin gold, a new kind of dementia, the Southern Ocean’s secrets, Denisovans lived on top of the world, and more. TOOL TIME  Researchers study sediments in Ethiopia where sharp-edged stone tools dating to around 2.6 million years ago were found. Rocks placed over excavated areas protected fragile sediment. Discoveries in East Africa of what may be the oldest expertly sharpened stone implements suggest that early members of the human genus, Homo, invented these tools by around 2.6 million years ago, researchers say. But their conclusions are controversial. New finds at a site in Ethiopia called Ledi-Geraru fit a scenario in which various early Homo groups devised ways to sharpen handheld stones, assert archaeologist David Braun of George Washington University in Washington, D.C., and his colleagues. Ledi-Geraru artifacts date to between 2.58 million and 2.61 million years ago, the team reports online June 3 in the Proceedings of the National Academy of Sciences. Another team previously had unearthed sharpened stones that were 2.55 million to 2.58 million years old at Gona, a nearby Ethiopian site (SN: 4/17/04, p. 254). Un...