The Katsuragi Expedition Team undertook a mysterious procedure on September 13, 2000, which one scientist referred to as "the contact experiment with the donor". This "contact" was apparently physical, and somehow resulted in DNA "diving" into Adam and "physically fusing" (to use their own cryptic phrasing). It has been forwarded as the direct impetus for Second Impact. It is also very strongly intimated (in the manga, essentially stated) that Tabris was born from this joining of Lilin genes and Adam's body. The identity of the donor is unknown.