Their only documented predators—apart from humans—include snakes, changeable hawk-eagles and orangutans, although cats, civets and sun bears are suspected.
Little is known about their social structure, but they are known to communicate by scent marking. Slow lorises reproduce slowly, and the infants are initially parked on branches or carried by either parent.
Due in part to the large eyes that are an adaptation to their nocturnal lifestyle, they have also been popularized as 'cute' pets in viral videos on You Tube.
Slow lorises have their teeth cut or pulled out for the pet trade.
They are thought to have reached the islands of Sundaland when the Sunda Shelf was exposed at times of low sea level, creating a land bridge between the mainland and islands off the coast of Southeast Asia.
The earliest known mention of a slow loris in scientific literature is from 1770, when Dutchman Arnout Vosmaer (1720–1799) described a specimen of what we know today as N.
They are less closely related to the remaining lorisoids (the various types of galago), and more distantly to the lemurs of Madagascar.
Their next closest relatives are the African lorisids, the pottos, false pottos, and angwantibos.
The group's closest relatives are the slender lorises of southern India and Sri Lanka.
The three newest species are yet to be evaluated, but they arise from (and further reduce the ranks of) what was thought to be a single "vulnerable" species.
All four of these are expected to be listed with at least the same, if not a higher-risk, conservation status.