Most of us have experienced this: you reach out to shake someone's hand and then cringe when you find yourself holding a limp fish. There may be an evolutionary basis to this reaction, especially when the weak handshaker is male.
In the November issue of _Evolution and Human Behavior_, researchers from the University of Albany reported that a firm handshake correlates with health and vitality among men and women.
Gordon Gallup, a professor of psychology at UAlbany, and a team of scientists measured handgrip strength (HGS) among college-aged males and females to see if a relationship existed between HGS and illness and mortality. HGS, an inherited trait, has been used to track childhood development, assess adult post-operative recovery and observe the effects of aging.
My interest in HGS was completely independent of those [older] studies,"" Gallup said. His interest stemmed from a 2002 study where he discovered that ovulating women tended to have stronger handgrip strength than non-ovulating women. ""This suggests that there may be an embedded mechanism that enables females to minimize the chance of conception as a consequence of rape,"" he said. He then wondered if there were connections between HGS and other features in men.
In the current study, Gallup's team concluded that high HGS scores in men not only predict high testosterone levels, but greater attractiveness, a strong body build, an active sexual history and a predisposition to bullying. HGS also predicted sexual aggression, promiscuity and the age when males first had sex. Among females high HGS scores were a strong indicator of health and fitness, but had no relationship to body type or sexual behavior.
But why does high HGS mean high testosterone, attractiveness and body mass among males?
Gallup theorizes that before we became bipedal, we swung from trees, racing through the forest canopy branch by branch. We had to get through traffic without falling, and males and females were equally required to have this set of acrobatic skills.
According to Gallup, this evolutionary trait can be seen today in modern infants. He said, ""A premature infant can hang onto a rope with his hands and feet,"" harkening back to an earlier phase in evolution when we not only needed to navigate through the forest, but when infants grasped onto their mother's hair while she got around. In full-term infants, this is less prominent than in pre-term, suggesting the trait gets ""sorted out"" as term approaches. After birth, ""this grasping ability diminishes substantially within three to six months,"" Gallup said.
Once we became upright, labor was divided, with males being required to compete in a tough world for resources like food and real estate, hew and wield tools, and literally haul home the bacon. For these tasks, they still needed both strong hands and body.
In the modern man, the handshake has become a quick communicator of physical status. What about the American fist bump, the chest bump and the high five? ""Those greetings are not universal across cultures, but a working hypothesis could be that they are modern variations of the handshake,"" Gallup said.
For baseball players, handgrip strength is the name of the game. Take 27-year-old New York Yankees slugger Shelley ""Slam"" Duncan. In his Yankees debut, he hit five homeruns in his first four games, a testament to an assuredly high HGS. But his enthusiastic and hard-hitting celebratory chest bumps and high-fives typically sent his teammates and manager running for cover.
In the July issue of Major League Baseball's _Yankee News_, teammate Andy Philips recalls after offering his hand for a high-five: ""It was an awesome experience until [Duncan] slapped me in the hand and nearly knocked me down.""
So, should women now include firm handshakes into their already complex algorithms for determining suitable mates?
Gallup cautions against it, stating that his 2002 study on female HGS and self-preservation suggests that a man could inadvertently send an aggressive ""assault"" signal with an over-firm handshake, especially if the woman is ovulating. As a form of communication, the firm handshake seems to be ""confined to male-male greeting behaviors.
