Strepsirrhini primates are defined by a moist, hairless rhinarium that connects directly to the mouth via a philtrum. This anatomical feature serves as a tactile interface for detecting pheromones and fluid-based chemicals. This biological trait distinguishes them from all other primates and forms the foundation of their sensory world.
The last of the extinct adapiforms vanished at the end of the Miocene approximately 7 million years ago. These primates thrived across Europe, North America, and Asia during the Eocene epoch between 56 and 34 million years ago. They disappeared from most of the Northern Hemisphere as the climate began to cool and dry.
Genetic analysis suggests that the ancestors of these primates rafted from Africa to the island between 47 and 54 million years ago. They arrived in a world devoid of competing simians and underwent a rapid radiation to fill ecological niches. This isolation allowed for the development of traits such as the specialized toothcomb found in most lemuriforms.
Nocturnal Strepsirrhini possess a reflective layer called the tapetum lucidum composed of riboflavin crystals to improve vision in low light conditions. They also have large, independently movable ears that can swivel to catch the faintest sounds. Sensitive tactile hairs help them navigate their arboreal environment alongside these visual and auditory adaptations.
Populations are declining due to habitat destruction, hunting, and the exotic pet trade. In Madagascar, lemurs are the most endangered mammals on Earth following a political crisis in 2009 and illegal logging. In Southeast Asia, slow lorises face similar threats from the exotic pet trade and the demand for traditional medicine.