Posts Tagged ‘South America’

By Traci Watson, National Geographic

Don’t blame the lure of a glowing smartphone for keeping you up too late. Even people without modern technology don’t sleep the night away, new research says.

Members of three hunter-gatherer societies who lack electricity—and thus evenings filled with Facebook, Candy Crush, and 200 TV channels—get an average of only 6.4 hours of shut-eye a night, scientists have found. That’s no more than many humans who lead a harried industrial lifestyle, and less than the seven to nine hours recommended for most adults by the National Sleep Foundation.

People from these groups—two in Africa, one in South America—tend to nod off long after sundown and wake before dawn, contrary to the romantic vision of life without electric lights and electronic gadgets, the researchers report in Thursday’s Current Biology.

“Seeing the same pattern in three groups separated by thousands of miles on two continents (makes) it pretty clear that this is the natural pattern,” says study leader and sleep researcher Jerome Siegel of the University of California, Los Angeles. “Maybe people should be a little bit more relaxed about sleeping. If you sleep seven hours a night, that’s close to what our ancestors were sleeping.”

Previous research has linked lack of sleep to ills ranging from poor judgment to obesity to heart disease. The rise of mesmerizing electronic devices small enough to carry into bed has only heightened worries about a modern-day epidemic of bad sleep. One recent study found that after bedtime sessions with an eBook reader, test subjects took longer to fall asleep and were groggier in the morning than when they’d curled up with an old-fashioned paper book.

Many scientists argue that artificial lighting curtailed our rest, leading to sleep deficits. But Siegel questioned that storyline. He was studying the sleep of wild lions when he got the inspiration to monitor the sleep of pre-industrial people, whose habits might provide insight into the slumber of early humans.

Siegel and his colleagues recruited members of Bolivia’s Tsimane, who hunt and grow crops in the Amazonian basin, and hunter-gatherers from the Hadza society of Tanzania and the San people in Namibia. These are among the few remaining societies without electricity, artificial lighting, and climate control. At night, they build small fires and retire to simple houses built of materials such as grass and branches.

The researchers asked members of each group to wear wristwatch-like devices that record light levels and the smallest twitch and jerk. Many Tsimane thought the request comical, but almost all wanted to participate, says study co-author Gandhi Yetish of the University of New Mexico. People in the study fell asleep an average of just under three and a half hours after sunset, sleep records showed, and mostly awakened an average of an hour before sunrise.

The notable slugabeds are the San, who in the summer get up an hour after sunrise. The researchers noticed that at both the San and Tsimane research sites, summer nights during the study period lasted 11 hours, but mornings were chillier in the San village. That fits with other data showing the three groups tend to nod off when the night grows cold and rouse when temperature bottoms out before dawn.

Our time to wake and our time to sleep, Siegel says, seem to be dictated in part by natural temperature and light levels—and modern humans are divorced from both. He suggests some insomniacs might benefit from re-creating our ancient exposure to warmth and cold.

http://news.nationalgeographic.com/2015/10/20151015-paleo-sleep-time-hadza-san-tsimane-science/

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When zoologist Ivan Sazima went for a walk in the park in southeastern Brazil on a warm September day in 2013, he was hoping to find noteworthy animal behavior to study.

But he did not expect to witness lizard necrophilia. Right in front of him, he saw a male reptile trying to court and mate with a dead female of the same species, Salvator merianae, commonly known as the black-and-white tegu.

“I felt a sense of wonder, because I did not observe this behavior in lizards before, only in frogs,” said Sazima, of the Zoology Museum of the University of Campinas in São Paulo.

Necrophilia occurs in other lizard species, but it’s the first documented instance in black-and-white tegus, one of the most common lizards in South America.

Sazima watched the male lizard flick his tongue at the deceased female—a common courtship behavior—and try to mate with her for about five minutes. Then a group of geese showed up, causing the confused suitor to flee.

The scientist returned to the same spot the next afternoon. By that time, the corpse was bloated and had begun to rot and smell.

But even the stench did not discourage another male black-and-white tegu from attempting to have sex with the dead body—this time for nearly an hour.

During this time, the new male embraced the dead female and bit her head, another courtship behavior. He rested on her body from time to time, taking breaks from the exhausting sexual activity, before finally flicking his tongue on the corpse and leaving, according to the study, published in January in the journal Herpetology Notes.

Sazima’s encounter adds to several reported instances of necrophilia in the animal world.

Henrique Caldeira Costa of the Federal University of Minas Gerais, in Belo Horizonte, Brazil, reported necrophilia in male green ameiva lizards in Brazil in 2010. The female had likely been hit by a vehicle on the road, he wrote in the journal Herpetology Notes.

In another incident, Kamelia Algiers, a biologist at Ventura College in California, described a necrophiliac long-nosed leopard lizard in Nevada, in the western United States.

The animal attempted to copulate with a roadkill female, whose “intestines were sticking out, and there were ants crawling all over it,” said Algiers, who described the event in 2005 in Herpetological Review.

What’s more, mating with the dead isn’t restricted to reptiles and amphibians: Ducks, penguins, sea lions, pigeons, and even ground squirrels have also been caught in the grisly act.

Why Mate With the Dead?

So, what exactly draws some male lizards to female corpses? Despite many scientific observations, “necrophilia in lizards is still poorly understood,” said Costa, who wasn’t involved in the new tegu research.

But as for those amorous black-and-white tegus, the Zoology Museum’s Sazima has a theory: The males may have been simply fooled into thinking the female was alive.

For one, the dead female lizard was still warm: Though dead, her body temperature was probably close to that of the ambient air. And her pheromones, likely still detectable on her body after death, may have allured the male admirers.

Federal University’s Costa agrees this is a valid theory, and suspects that the female’s high body temperature and pheromones might have explained the lizard necrophiliac he described in 2010.

Interestingly, necrophilia seems to be beneficial for at least one species: a small frog in Amazonian Brazil called Rhinella proboscidea.

A 2013 study showed that R. proboscidea males can extract eggs from dead sexual partners and fertilize them, a process called “functional necrophilia.”

http://news.nationalgeographic.com/news/2015/02/150227-necrophilia-lizards-animals-mating-sex-science-brazil/?google_editors_picks=true

Thanks to Da Brayn for bringing this to the attention of the It’s Interesting community.