Your sense of smell may fluctuate in sensitivity over the course of 24 hours, in tune with our circadian clocks, with your nose best able to do its job during the hours before you go to sleep, according to a study in the journal Chemical Senses. For the experiment, 37 adolescents ranging in age from 12 to 15 came into a lab for a very long sleepover party. For nine days, they followed a strict schedule to allow researchers to focus on the circadian clock, which helps control wake and sleep, but also influences other processes in the body, including metabolism. The results showed that the children's noses were most sensitive tended to correspond to the evening, with an average peak of 9 p.m. Smell was at its lowest ebb, intriguingly, from about 2 a.m. to 10 a.m. More research is needed to see if the findings apply to adults.

Male mammoths fell victim to natural traps

Swallowed by a sinkhole. Washed away by a mudflow. Drowned after falling through thin ice. These are the fates that many unlucky mammoths suffered in Siberia thousands of years ago. Their well-preserved fossils have provided paleobiologists with insight into their prehistoric lives. Now, after performing a genetic analysis on the remains from the furry victims of natural traps, a team of scientists made a striking discovery: Most were male. In a study published in the journal Current Biology, researchers analyzed DNA from nearly 100 mammoth bones, teeth and tusks, and found that about two-thirds came from males. They speculate the reason for the skewed sex-ratio may have to do with the risky behavior that young males take after leaving the protection of their mothers to live on their own.

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