They are one of the most populous tribes in the highlands, and are found spread out through the highlands. The Dani are one of the most well-known ethnic groups in Papua, due to the relatively numerous tourists who visit the Baliem Valley area where they predominate. "Ndani" is the name given to the Baliem Valley people by the Moni people, and, while they don't call themselves Dani, they have been known as such since the 1926 Smithsonian Institution-Dutch Colonial Government expedition to New Guinea under Matthew Stirling who visited the Moni.
Linguists identify at least four sub-groupings of Dani languages:
- Lower-Grand Valley Dani (20,000 speakers)
- Mid-Grand Valley Dani (50,000 speakers)
- Upper-Grand Valley Dani (20,000 speakers)
- and the Lani or Western Dani (180,000 speakers)
The Dani languages differentiate only two basic colours, mili for cool/dark shades such as blue, green, and black, and mola for warm/light colours such as red, yellow, and white. This trait makes it an interesting field of research for language psychologists, e.g. Eleanor Rosch, eager to know whether there is a link between way of thought and language.
First contact 
A small fringe group of the Dani, living south of Puncak Trikora and presenting themselves as the Pesegem and the Horip tribes, were met on October 29, 1909, by the Second South New Guinea Expedition led by Hendrikus Albertus Lorentz, who stayed several nights in their village. First contact with the populous Western Dani was made in October 1920 during the Central New Guinea Expedition, which group of explorers stayed for six weeks with them at their farms in the upper Swart River Valley (now Toli Valley). The Grand Valley Dani were only sighted in the summer of 1938 from an airplane by Richard Archbold.
Sweet potatoes are important in their local culture, being the most important tool used in bartering, especially in dowries. Likewise pigs feasts are extremely important to celebrate events communally; the success of a feast, and that of a village big man (man of influence) or organiser, is often gauged by the number of pigs slaughtered.
The Dani use an earth oven method of cooking pig and their staple crops such as sweet potato, banana, and cassava. They heat some stones in a fire until they are extremely hot, then wrap cuts of meat and pieces of sweet potato or banana inside banana leaves. The food package is then lowered into a pit which has been lined with some of the hot stones described above, the remaining hot stones are then placed on top, and the pit is covered in grass and a cover to keep steam in. After a couple of hours the pit is opened and the food removed and eaten. Pigs are too valuable to be served regularly, and are reserved for special occasions only.
Ritual small-scale warfare between rival villages is integral to traditional Dani culture, with much time spent preparing weapons, engaging in both mock and real battle, and treating any resulting injuries. Typically the emphasis in battle is to insult the enemy and wound or kill token victims, as opposed to capturing territory or property or vanquishing the enemy village. The Dani practiced cannibalism well into the 20th century, as documented by missionaries who were invited to witness tribe members dismembering the body of an enemy slain in battle the day before as the fallen warrior's kin watched from a nearby hilltop.
Changes in the Dani way of life over the past century are tied to the encroachment of modernity and globalization, despite tourist brochures describing trekking in the highlands with people from the 'stone age'. Observers have noted that pro-independence and anti-Indonesian sentiment tends to run higher in highland areas than for other areas of Papua. There are cases of abuses where Dani and other Papuans have been shot and/or imprisoned trying to raise the flag of West Papua, the Morning Star.
Ethnographic studies 
In 1961, as a member of the Harvard-Peabody study, filmmaker Robert Gardner began recording the Dani of the Baliem River Valley. In 1965, he created the film Dead Birds from this experience. Gardner emphasizes the themes of death and people-as-birds in Dani culture. "Dead birds" or "dead men" are terms the Dani use for the weapons and ornaments taken from the enemy during battle (wim). These trophies are displayed during the two day dance of victory (edai) after an enemy is killed.
Michael Rockefeller, son of former Vice-President of the United States Nelson Rockefeller, was a member of the Harvard-Peabody study and involved in the production of Dead Birds. While conducting further research on the Asmat people elsewhere in New Guinea, Michael Rockefeller disappeared. His body was never found.
Further reading 
- Gardner, Robert. (1968). Gardens of War: Life and Death in the New Guinea Stone Age. New York: Random House.
- Heider, Karl G. (1970). The Dugum Dani: A Papuan Culture in the Highlands of West New Guinea. Aldine Publishing.
- Heider, Karl G. (1996). Grand Valley Dani: Peaceful Warriors (Case Studies in Cultural Anthropology). Wadsworth Publishing (3rd ed.).
- Matthiessen, Peter. (1962). Under the Mountain Wall: A Chronicle of Two Seasons in Stone Age New Guinea. Viking Press. ISBN 978-0-14-025270-5
- Monbiot, George. (1989). Poisoned Arrows: An Investigative Journey Through Indonesia. Abacus ISBN 0-7181-3153-3
- Zuckoff, Mitchell. (2011). Lost in Shangri-La: A True Story of Survival, Adventure, and the Most Incredible Rescue Mission of World War II. Harper ISBN 978-0-06-198834-9
- Extensive English language library, some material written by Lani (highland) tribespeople
- SIL Ethnologue on Papua, Indonesia
- Expeditions to West Papua
- Jennifer Bensley, 1994 The Dani church of Irian Jaya and the challenges it is facing today, Chapter 1, p.17-18
- "Here Be Cannibals: Recent cannibalism in New Guinea"
- "Warning shots in Indonesia's Papua, one dead"
- "Oppression still rife in West Papua"