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Australian pushback
New dating of ancient artifacts from Australia, including the oldest known polished ax heads, suggests that humans may have first set foot in the region 65,000 years ago, Maria Temming reported in “Humans’ arrival in Australia redated” (SN: 8/19/17, p. 10).
If the first Australians arrived by sea, they would have needed tools more advanced than primitive axes to get there, Stephen Wimbourne wrote online.
The first human colonists may have come by sea, says archaeologist Peter Hiscock. If they did, they probably came in bamboo boats, which wouldn’t have required axes or more advanced tools to make. In fact, axes at that time were hardly primitive. “In other parts of the world, [axes] were not invented until much later,” Hiscock says. Australia is home to a number of hardwood tree species, so the ax would’ve been a crucial, cutting-edge invention.
Over the exomoon
Data from the Kepler space telescope hint at the existence of an exomoon — a moon orbiting a planet orbiting a distant star, Lisa Grossman reported in “Possible exomoon spotted” (SN: 8/19/17, p. 15).
Online reader Robert Stenton wondered if the exomoon might instead be part of a double-planet system.
Researchers have yet to make additional observations of the object. At this point, it could be a moon or part of a planetary tango, Grossman says.
A double-planet system has yet to be discovered, although Pluto and Charon may be an example of a double system of dwarf planets. In a double-planet system, two planets orbit each other and a common center of gravity located outside of both planets. If the center of gravity is within one of the celestial bodies, though, then the other body would be considered a moon.
Correction
In the fascinating facts about tick biology presented in the Editor’s Note in the August 19 issue (SN: 8/19/17, p. 2), the amount of weight a tick can gain from a single blood meal was incorrect. Though ticks can consume more than 200 times their weight in blood, they salivate much of the water in the blood back into the host. Total weight gain is thus closer to 100 times the unfed weight. This is equivalent to an average U.S. man gaining nearly 20,000 pounds in a single meal.