Evidently, men did not say hello and goodbye in antiquity as Basil Sydney and Stewart Granger are doing so below in 1953’s Salome, with a firm grip on one another’s forearms.
Whence the mutual clasping of radius and ulna? Various theories:
“I saw Dullin’s Julius Caesar, with Marchat playing Mark Antony — beautifully, I thought — and Jean Marais as a Gaul. In this play we learned the Roman handshake, which went up to the forearm, and it so impressed us that the entire lycee adopted it.” So writes Simone Signoret in Nostalgia Isn’t What It Used to Be (Harper & Row, 1978) p. 23. Note that Charles Dullin (1885-1949) was a notable French actor and director.
According to a 2015 post on Alison Morton’s blog:
One interesting speculation is that the forearm handshake was taught to the actors by painter Lawrence Alma-Tadema in a 1898 staging of Shakespeare’s Julius Caesar. During this time, Alma-Tadema was very active with theatre design and production. His meticulous archaeological research, including research into Roman architecture (which was so thorough that every building featured in his canvases could have been built using Roman tools and methods) led to his paintings being used as source material by Hollywood directors in their vision of the ancient world for films such as D. W. Griffith’s Intolerance (1916), Ben Hur (1926) and Cleopatra (1934). The designers of the Oscar-winning Roman epic Gladiator used the paintings of Alma-Tadema as a central source of inspiration.
I’d like to verify the Alma-Tadema theory sometime. Until then, all I can say is that the “manly man” forearm grip seems to be a thing of modern times. In antiquity, Romans shook hands more or less as we do today.
Update. The Alma-Tadema set design, by the way, from the Cadbury Research Library Flickr site.