As September draws to a close, let’s look back on some of the research that caught the media’s attention, published this month in PLOS ONE: orangutans communicated their travel plans, mice permanently lost their fear of cats, and hibernating lemurs taught us about sleep.
While orangutans aren’t yet hiring travel agents, researchers recently published findings on these great apes, who apparently love to chat about travel plans. Male Sumatran orangutans develop flanges, large cheek pads, thought to assist in the vocalization of ‘long calls.’ Dominant males produce these calls in a specific direction, for anywhere from eighty seconds to four minutes.
Researchers tracked the movement of the dominant males and fellow orangutans in their arboreal territory after each call and found that the flanged male will travel in the direction of his howl until he produces a new long call along a different route. Local females also use the direction of the long call to stay within range of their dominant male, traveling the same course. To find out more, check out the following articles in Scientific American, The New York Times, and the San Francisco Chronicle.
The relationship between mice and cats has taken a surprising turn. Prior research revealed that mice infected with the parasite Toxoplasma gondii lost their fear of cats. This month, the tale continues with a new study published in PLOS ONE. Researchers exposed three types of mice to cat urine: mice never infected with T. gondii, mice currently infected, and mice cleared of the parasite. The cleared mice exhibited no anxiety over the potential threat of a nearby cat.
The researchers suggest that the loss of fear in the mice becomes hardwired and that some parasitic infections may leave a lasting impact. Learn more about this study by visiting Nature, BBC News, and the Smithsonian.
Researchers studied captive and wild fat-tailed dwarf lemurs, and found that they sleep differently during hibernation than other hibernating mammals. For instance, ground squirrels experience non-REM sleep during moderate temperatures, whereas fat-tailed dwarf lemurs experience mostly REM sleep.
While we don’t know much about why humans and animals sleep, we suspect that temperature and metabolic rate are affected. Now, hibernation isn’t exactly sleep; instead, hibernation is when the body dramatically reduces temperature and metabolic rate to conserve energy. Since both hibernation and sleep relate to the regulation of body temperature and metabolic rate, hibernation research on this little primate could teach us about human sleep, and maybe one day, human hibernation.
Ingram WM, Goodrich LM, Robey EA, Eisen MB (2013) Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine, Even after Extensive Parasite Clearance. PLoS ONE 8(9): e75246. doi:10.1371/journal.pone.0075246
Krystal AD, Schopler B, Kobbe S, Williams C, Rakatondrainibe H, et al. (2013) The Relationship of Sleep with Temperature and Metabolic Rate in a Hibernating Primate. PLoS ONE 8(9): e69914. doi:10.1371/journal.pone.0069914
van Schaik CP, Damerius L, Isler K (2013) Wild Orangutan Males Plan and Communicate Their Travel Direction One Day in Advance. PLoS ONE 8(9): e74896. doi:10.1371/journal.pone.0074896
Keywords: orangutan, Sumatra, flanges, long call, hibernation, sleep, fat-tailed dwarf lemur, REM, non-REM, Toxoplasma gondii, mice, fear, parasite, metabolic rate, temperature, hypothermia, homeostasis, Cheirogaleus medius, Madagascar, Pongo abelii, great apes.