O Tannenbaum the faithless maiden of the folk song. This was changed to ' (green) at some point in the 20th century, after the song had come to be associated with Christmas. The tune is an old folk tune attested in the 16th century. It is also known as the tune of "" and of "". Below is the tune with the original German lyrics of the first verse: <score vorbis="1"> » </score> The tune has also been used (as a contrafactum) to carry other texts on many occasions. Some notable uses include: O Tannenbaum "" (; "O fir tree", English: "O
Emmanuel David Tannenbaum subsequently devoted his research to studying various problems in evolutionary dynamics using quasispecies models. His seminal work centered on the key question of the evolutionary advantages of sexual reproduction. Tannenbaum demonstrated a strong selective advantage for sexual reproduction with fewer and much less restrictive assumptions than previously considered. Closely related to this line of reasoning, was the original work by Tannenbaum and James Sherley on the immortal strand hypothesis. Tannenbaum also proposed a pioneering theory of why higher organisms need sleep. Towards the end of his life, he proposed a new approach to anti-stealth technology based on the theory of