in 1965 he published the Material Culture of the Gilbert Islands. His field work produced 70 films of traditional practices and material culture. The Ethnological Museum of Berlin also holds photos and an extensive collection of audio tapes (including music-ethnological material) made by Koch. Social problems Drinking alcohol is part of the culture and consumption of toddy, a locally made fermented coconut juice, is widespread. Alcoholism is a common problem, especially on the main island of Tarawa. Domestic violence is also common. Dueling Kiribati has a history of contrived and ritualized duels. The armor was made of thickly woven sennit, a kind of coconut fiber. The duelists wore helmets made of blowfish remains. The helmets were resilient and, due to the structure of blowfish, covered with many points, which had the ability of damaging weapons. The weapons resembled broadswords with a serrated edge created with many shark teeth. The duels were performed mostly for the purpose of settling disputes and maintaining honor. The practicality of the duels is debatable. Due to the difficulty of moving in this armor, falling over and becoming unable to get back up was common enough that duel assistants were required. Kiribati traditional martial arts Kiribati has been known for its traditional martial arts which were kept within the secrets of several families for generations. The Kiribati arts of fighting as opposed to Asian martial arts are not often mentioned or even advertised to be known by the general public. Though, there may be some noticeable parallels in principle to that of Asian martial arts, they are merely really different. For instance, generally, there is no kicking as in Karate kicks or Kung Fu kicks, and speed is more important than power. A list of some of these traditional martial arts is as follows: Nabakai, Nakara, Ruabou, Tabiang, Taborara, Tebania, Temata-aua, Te Rawarawanimon, and Terotauea. The essence of Kiribati traditional martial arts is the magical power of the spirits of the ancestral warriors. All these martial arts skills share one thing in common. That is, they came from an ancestral spirit. "Nabakai" is a martial art from the island of Abaiang originated from the person named Nabakai. Nabakai was a member of the crab clan called "Tabukaokao". The three ancestral female spirits of this clan "Nei Tenaotarai", "Nei Temwanai" and "Nei Tereiatabuki" which usually believed to manifest themselves with a female crab came to him and