The handshake is a political performance. On the one hand, it can signify two powers coming together for cooperation. Adversaries can be unmade. Alliances can be forged.

On the other hand, dominance can be asserted. The number of seconds two people embrace, whose hand lingers, and who grips harder serve as pieces of evidence. Is this photo op all that it seems?

A number of historic handshakes happened in 2015. The Pope met with Fidel Castro. The highest ranking officials of China and Taiwan shared the same stage for the first time in more than 60 years. U.S. President Barack Obama became the first sitting head of state to visit Kenya, his father’s homeland. The culmination of years of negotiations with Iran was solidified with a grasp between U.S. Secretary of State John Kerry and Iranian Foreign Minister Javad Zarif.