The slow loris’ huge eyes and soft fur make it incredibly cute and appealing to humans, but these features also cause people to think the slow loris makes a tempting pet.  The exotic pet trade in slow lorises is now one of the biggest reasons behind their decline.  The little primates are popular pets in Indonesia, and are frequently smuggled out to Japan, Saudi Arabia, Taiwan, Russia, and even as far as the US to be purchased by unwitting owners.  Many of these “pet” slow lorises have their teeth clipped or pulled in order to neutralise their toxic bites, which risks infection and death for the animal.  It is also difficult for the average person to replicate the loris’ complex diet, meaning that these “pet” lorises are often malnourished and/or obese.  They are also very prone to stress and shock, as well as sensitive to light.  And finally, as slow lorises do not breed well in captivity, almost all of the animals purchased as pets have been taken from the wild.  As many as 95% of these hapless animals will die of infection or improper care.

It should also be noticed that many “cute” behaviours displayed by “pet” slow lorises are actually misinterpretations by humans; the popular video of the slow loris raising its arms to be tickled, for example, most likely is actually a frightened loris displaying its venom glands as a form of defense, not a pet enjoying human attention.


There are a number of subspecies of the red slender loris, and probably the most elusive of them in the Horton Plains slender loris, found only in the highlands of Sri Lanka.  This subspecies, adapted to a mountainous habitat where temperatures could drop below freezing, had shorter, stockier limbs and thicker fur than other slender lorises, making it much more closely resemble a slow loris.  Since 1937, this subspecies had only been sighted four times, and since the mid-1940s it was believed to be extinct.  In 2002, however, the subspecies was spotted again in Horton Plains National Park, and in 2009 a team from the Zoological Society of London managed to capture one of the animals, photographing, measuring, and taking samples from it before releasing it back into the wild.  It’s believed there may be as few as 100 Horton Plains slender lorises left in the wild, making it one of the world’s rarest primates.


Slow lorises are the world’s only venomous primate.  The venom is secreted from a gland in the loris’ elbow which the loris licks, mixing the secretion with their saliva.  The loris can then inflict painful, toxic bites, and will also lick the fur of their infants before leaving them, covering their bodies with the toxin to deter predators.  Wildlife biologists have said that the bite of the slow loris is among the most painful in the world, pain which is exacerbated by the fact that the loris will bite down and refuse to let go in an effort to inject as much venom as possible into the wound.  Some victims have found that the only way to make the loris let go is to submerge it in water.  

There is some speculation that, rather than being truly toxic, the venom of the slow loris actually induces a severe allergic reaction in humans.  The only recorded human death due to slow loris bite occurred due to anaphylactic shock.

Evidence of a chimpanzee-sized ancestor of humans but a gibbon-sized ancestor of apes
Body mass directly affects how an animal relates to its environment and has a wide range of biological implications. However, little is known about the mass of the last common ancestor (LCA) of humans and chimpanzees, hominids (great apes and humans), or hominoids (all apes and humans), which is needed to evaluate numerous paleobiological hypotheses at and prior to the root of our lineage. Here we use phylogenetic comparative methods and data from primates including humans, fossil hominins, and a wide sample of fossil primates including Miocene apes from Africa, Europe, and Asia to test alternative hypotheses of body mass evolution. Our results suggest, contrary to previous suggestions, that the LCA of all hominoids lived in an environment that favored a gibbon-like size, but a series of selective regime shifts, possibly due to resource availability, led to a decrease and then increase in body mass in early hominins from a chimpanzee-sized LCA. The pattern of body size evolution in hominids can provide insight into historical human ecology. Here, Grabowski and Jungers use comparative phylogenetic analysis to reconstruct the likely size of the ancestor of humans and chimpanzees and the evolutionary history of selection on body size in primates.

Unlike the slow loris, the red slender loris is extremely social.  They live in small, female-dominated groups that spend their days sleeping, play-wrestling, and grooming each other.  During the night, the adults will hunt for food alone, leaving the young waiting at the home nest.  This practice is known as “infant parking”.

Slow lorises may look like big-eyed Ewoks, but their cute countenance has made these primates a target of the illegal wildlife trade. Join Mary Blair, primatologist and Director of Biodiversity Informatics Research at the Center for Biodiversity and Conservation, as she discusses how research on these endangered animals can contribute to a better understanding of wildlife trafficking, including the risk of zoonotic disease spread.

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