The Argentinian monkeys studied are in the same nocturnal genus, Aotus , as the Panamanian owl monkey pictured Researchers led by a University of Pennsylvania scientist have discovered that moonlight increases the nocturnal activity of owl monkeys in South America. The researchers say this is the first long-term study showing that heat and light can affect the nocturnality of primates in the wild. Azara's owl monkeys were known to have regular activity patterns that included both nocturnal and diurnal (daytime) activity. These patterns changed more frequently than a few times per year along with seasonal phenomena. The study showed the monkeys' nocturnal activity increased in warmer months and peaked on full moon nights — but decreased during full lunar eclipses on full moon nights, which occurred three times during the study. Lead investigator and assistant professor in U.Penn.'s Department of Anthropology Eduardo Fernández-Duque explained that many animals change their activity levels with changes in environmental conditions. These changes are called "masking" in chronobiology . But the species of owl monkeys is distinguishable by its increased activity during nights with better moon light. Team member Horacio de la Iglesia, of the Department of Biology at the University of Washington , pointed out that the changes of activity, though seasonal, aren't a built-in biological clock. He was sure that they wouldn't happen in absence of the Moon. He stated, "If there was a biological clock that they were depending on to regulate this activity, you could expect the activity to continue even in the absence of lunar light. The lunar day has not been a stable force as much as the solar day to evolutionarily select for a clock. We still have to prove it in the lab, but the evidence in this paper points to a lack of a lunar biological clock."
The Argentinian monkeys studied are in the same nocturnal genus, , as the Panamanian owl monkey pictured Researchers led by a scientist have discovered that moonlight increases the nocturnal activity of owl monkeys in South America. The researchers say this is the first long-term study showing that heat and light can affect the nocturnality of primates in the wild. were known to have regular activity patterns that included both nocturnal and diurnal (daytime) activity. These patterns changed more frequently than a few times per year along with seasonal phenomena. The study showed the monkeys' nocturnal activity increased in warmer months and peaked on full moon nights — but decreased during full lunar eclipses on full moon nights, which occurred three times during the study. Lead investigator and assistant professor in U.Penn.'s Department of Anthropology Eduardo Fernández-Duque explained that many animals change their activity levels with changes in environmental conditions. These changes are called "masking" in . But the species of owl monkeys is distinguishable by its increased activity during nights with better moon light. Team member Horacio de la Iglesia, of the Department of Biology at the , pointed out that the changes of activity, though seasonal, aren't a built-in biological clock. He was sure that they wouldn't happen in absence of the Moon. He stated, "If there was a biological clock that they were depending on to regulate this activity, you could expect the activity to continue even in the absence of lunar light. The lunar day has not been a stable force as much as the solar day to evolutionarily select for a clock. We still have to prove it in the lab, but the evidence in this paper points to a lack of a lunar biological clock."
D
Aotus
D
University of Pennsylvania
D
Azara's owl monkeys
D
chronobiology
D
University of Washington