It is also possible that the plant floated across the ocean after being discarded from the cargo of a boat. Phylogenetic analysis supports the hypothesis of at least two separate introductions of sweet potatoes from South America into Polynesia, including one before and one after European contact. Dutch linguists and specialists in Amerindian languages Willem Adelaar and Pieter Muysken have suggested that the word for sweet potato is shared by Polynesian languages and languages of South America. Proto-Polynesian *"kumala" (compare Easter Island "kumara", Hawaiian "uala", Māori "kumāra"; apparent cognates outside Eastern Polynesian may be borrowed from Eastern Polynesian languages, calling Proto-Polynesian status and age into question) may be connected with Quechua and Aymara "k'umar ~ k'umara". According to Adelaar and Muysken, the similarity in the word for sweet potato "constitutes near proof of incidental contact between inhabitants of the Andean region and the South Pacific." The authors argue that the presence of the word for sweet potato suggests sporadic contact between Polynesia and South America, but no migrations. A team of academics headed by the University of York's Mummy Research Group and BioArch, while examining a Peruvian mummy at the Bolton Museum, found that it had been embalmed using a tree resin. Before this it was thought that Peruvian mummies were naturally preserved. The resin, found to be that of an "Araucaria" conifer related to the monkey puzzle tree, was from a variety found only in Oceania and probably New Guinea. "Radiocarbon dating of both the resin and body by the University of Oxford's radiocarbon laboratory confirmed they were essentially contemporary, and date to around CE 1200." Researchers including Kathryn Klar and Terry Jones have proposed a theory of contact between Hawaiians and the Chumash people of Southern California between 400 and 800 CE. The sewn-plank canoes crafted by the Chumash and neighboring Tongva are unique among the indigenous peoples of North America, but similar in design to larger canoes used by Polynesians for deep-sea voyages. "Tomolo'o", the Chumash word for such a craft, may derive from "kumula'au", the Hawaiian term for the logs from which shipwrights carve planks to be sewn into canoes. The analogous Tongva term, "tii'at", is unrelated.