People walked across a muddy layer of volcanic debris that dates to between around 19,100 and 5,760 years ago, the researchers report May 14 in Scientific Reports. Dating of a thin rock layer that partly overlaps footprint sediment narrows the age range for the footprints to between roughly 12,000 and 10,000 years ago, the team says. Engare Sero lies in the vicinity of two much older hominid footprint sites -- nearly 3.7-million-year-old Laetoli (SN: 12/16/16) in Tanzania and 1.5-million-year-old Ileret (SN: 4/16/12) in Kenya. At Engare Sero, Hatala's team analyzed foot impression sizes, distances between prints and which way prints...