The introduction of Christianity resulted to the banning of traditional birth control, which had the consequence of a 50% increase of the population: 1,200 in 1920 to 1,800 in 1950. The increase in population resulted in migration to other places in the Solomon Islands, including in the settlement of Nukukaisi in Makira. On Tikopia in 1964, explorers found artefacts from the shipwreck of the expedition of Jean-François de Galaup, comte de Lapérouse. Cyclone Zoe in December 2002 devastated the vegetation and human settlements in Tikopia. Despite the extensive damage, no deaths were reported, as the islanders followed their traditions and sheltered in the caves in the higher ground. The narrow bank that separated the freshwater lagoon from the sea was breached by the storm, resulting in the continuing contamination of the lagoon and the threatened death of the sago palms on which the islanders depend for survival. A remarkable international effort by "friends of" the island, including many yacht crews who had had contact with Tikopia over the decades, culminated in the construction in 2006 of a gabion dam to seal the breach. Jared Diamond's book "Collapse" describes Tikopia as a success case in matching the challenges of sustainability, contrasting it with Easter Island. In 2009 a double canoe closely following the original design of the traditional Tikopia canoes was donated to the island, as well as to Tikopia's sister island Anuta, in order to give the islands their own independent sea transport. This canoe called 'Lapita Tikopia' and its sistership 'Lapita Anuta' were built in the Philippines in 2008 and sailed to Tikopia and Anuta in a 5 months voyage following the ancient migration route of the Lapita people into the Pacific. This voyage was called the 'Lapita Voyage', with more information about the voyage here. Its original concept (by Hanneke Boon of James Wharram Designs) to donate such a canoe was first published in 2005 in a project called 'A Voyaging Canoe for Tikopia' in order to raise money for the building of the canoes. The project was filmed and is available as DVD. In 2013 a Norwegian mother and father brought their two children and a nephew to Tikopia and lived there for 6 months. A film crew went along and a 13 episode children's series was made of the family experiences and stay, primarily focusing on the experiences of the young daughter of the Norwegian family, Ivi, with the local children, local school the local chief Tafua and his family, etc.