...because of his already established reputation as a Hollywood strong man (e.g. his role as the Mighty Man of Valor in the 1916 DW Griffith classic "Intolerance").

Also, the image of Tarzan in 1918 was not that of a lithe gymnast like Christopher Lambert in "Greystoke", but of a man powerful enough to wrestle lions. Strength equalled bulk.

There's an interesting piece of trivia attached to that movie and Uganda (that's in East Africa) where I'm now based. There's a popular myth around here that the 1918 version of "Tarzan of the Apes" was filmed on the northern shores of Lake Victoria. In fact it was shot, I believe, in Louisiana.

• Young men from the New Orleans Athletic Club played the ape parts.
• In one scene a lion is supposed to crawl through the window of Tarzan's cabin to devour Jane. Tarzan grabs him and pulls him out. Rumor has it that the old and drugged lion turned on Elmo Lincoln who stabbed and killed him. "I stepped on him to beat my chest. As my foot pressed down on him, the remaining air in his lungs escaped with a loud whoosh. I was already shaken and you should have seen me jump!" The lion wound up as a lobby display when the picture opened on Broadway. However, Enid Markey and others from the cast have disputed this version of events, saying that the lion was actually killed off screen. Contrary to popular opinion, the death of the lion is not actually shown on screen. It is already dead when Elmo stabs at it, barely puncturing its skin.
• Production began with Stellan Windrow playing Tarzan. After five weeks of shooting, Windrow quit to enlist in the First World War. Footage of him swinging from vines remains in the final film.