One of the foremost lemur research facilities is the Duke Lemur Center (DLC) in Durham, North Carolina.

Large parts of Madagascar, which are now devoid of forests and lemurs, once hosted diverse primate communities that included more than 20 lemur species covering the full range of lemur sizes.

The eyes of the ring tailed lemur contain one cone to five rods.

Research facilities like the Duke Lemur Center have provided research opportunities under more controlled settings.

Most of the approximately 100 species and subspecies of lemur are either threatened or endangered.

A village or region may believe that a certain type of lemur may be the ancestor of the clan.

Lemur taxonomy is controversial, and not all experts agree, particularly with the recent increase in the number of recognized species.

In the decades that followed, huge strides have been made in lemur studies and many new species have been discovered.

The ring tailed lemur has different calls and reactions to different classes of predators, such as predatory birds, mammals, or snakes.

During the 19th century, there was an explosion of new lemur descriptions and names, which later took decades to sort out.

Many are likely to be considered threatened since the new lemur species that have been described recently are typically confined to small regions.

This can leave lemur populations without fruit or leaves until the following spring, requiring them to subsist on crisis foods, such as epiphytes.

Most lemur species are covered by this network of protected areas, and a few species can be found in multiple parks or reserves.

Although field observations trickled in from early explorers, modern studies of lemur ecology and behavior did not begin in earnest until the 1950s and 1960s.

Even though hunting has been a threat to lemur populations in the past, it has recently become a more serious threat as socioeconomic conditions deteriorate.

Now represented only by recent or subfossil remains, they were modern forms that were once part of the rich lemur diversity that has evolved in isolation.

This may also relate to the relatively high mortality rate among adult females and the higher proportion of adult males in some lemur populations both unusual traits among primates.

With the political crisis in 2009, illegal logging has proliferated and now threatens rainforests in the northeast, including its lemur inhabitants and the ecotourism that the local communities rely upon.

From these collections, as well as increasing observations of lemurs in their natural habitats, museum systematists including Albert Günther and John Edward Gray continued to contribute new names for new lemur species.

The Petters and Jolly spawned a new era of interest in lemur ecology and behavior and were shortly followed by anthropologists such as Alison Richard, Robert Sussman, Ian Tattersall, and many others.

Rafting has since been the most accepted explanation for the lemur colonization of Madagascar, but until recently this trip was thought to be very unlikely because strong ocean currents flow away from the island.

Today, the diversity and complexity of lemur communities increases with floral diversity and precipitation and is highest in the rainforests of the east coast, where precipitation and floral diversity are also at their highest.

Other facilities, such as the Lemur Conservation Foundation, located near Myakka City, Florida, have also hosted research projects, such as one that looked at lemurs' ability to preferentially select tools based on functional qualities.

As of 2005, the International Union for Conservation of Nature (IUCN) listed 16 of all lemur species as Critically Endangered, 23 as Endangered, 25 as Vulnerable, 28 as Data Deficient , and only 8 as Least Concern.

Today, there are nearly 100 species of lemurs, and most of those species have been discovered or promoted to full species status since the 1990s however, lemur taxonomic classification is controversial and depends on which species concept is used.

Tactile communication (touch) is mostly used by lemurs in the form of grooming, although the ring tailed lemur also clumps together to sleep (in an order determined by rank), reaches out and touches adjacent members, and cuffs other members.

The loudest lemur is the indri, whose calls can be heard up to 2 km (1.2 mi) or more and thus communicate more effectively the territorial boundaries over its 34 to 40 hectares (0.13 to 0.15 sq mi) home range.

Because of these threats and their declining numbers, the International Union for Conservation of Nature (IUCN) considers lemurs to be the world's most endangered mammals, noting that as of 2013 up to 90 of all lemur species face extinction within the next 20 to 25 years.