Humans

New World island roots
Prehistoric people who took sea voyages to an island 42 kilometers from California’s coast laid down offshore roots by eating some. Between about 11,500 and 3,000 years ago, residents of San Miguel Island ate carbohydrate-rich corms — energy-storage bulbs attached to certain plant roots. Soil samples from a cave occupied by early islanders contain corm fragments, report ethnoarchaeologist Seetha Reddy of Statistical Research Inc. in Woodland, Calif. and archaeologist Jon Erlandson of the University of Oregon in Eugene in an upcoming Journal of Archaeological Science. Corms and seafood provided a nutritious diet far from the mainland, the team proposes. —Bruce Bower

Rock, paper, copycat
Rock smashes scissors, scissors cuts paper and imitation trumps self-interest. People ape opponents’ gestures in the rock-paper-scissors game more often than expected by chance, at least if the opponent moves first by a fraction of a second, say psychologist Richard Cook of University College London and his colleagues. Imitation is a lousy game strategy, since it always produces draws, but the brain has evolved to prompt involuntary mimicking of social partners’ actions, the scientists propose online July 20 in the Proceedings of the Royal Society B. The imitation effect was strongest for the scissors gesture, which the researchers note is very different from the starting fist position. —Bruce Bower

Danger’s less scary together
Emotional security may hinge on nonverbal cues that someone else has our backs. Volunteers walking a cliffside path in a 3D virtual world concentrated better and reported less anxiety when accompanied by avatars of their real-life romantic partners that clapped, waved and looked toward them, versus digitized partners that looked away, say psychologist Heidi Kane of the University of California, Los Angeles and her colleagues. Participants stayed farther away from inattentive than from attentive virtual partners after cliff walks, the researchers report in an upcoming Journal of Experimental Social Psychology. Others’ emotional presence matters more than their physical presence, they conclude. —Bruce Bower