Elk have antlers. Rams have horns. In the animal kingdom, males develop specialized weapons for competition when winning a fight is critical. Humans do too, according to new research from the University of Utah. Males' upper bodies are built for more powerful punches than females', says the study, published in the Journal of Experimental Biology, suggesting that fighting may have long been a part of our evolutionary history. For years, Carrier has been exploring the hypothesis that generations of interpersonal male-male aggression long in the past have shaped structures in human bodies to specialize for success in fighting. Past work has shown that the proportions of the hand aren't just for manual dexterity -- they also protect the hand when it's formed into a fist. Other studies looked at the strength of the bones of the face (as a likely target of a punch) and how our heels, planted on the ground, can confer additional upper body power.

Jeremy Morris, then a doctoral student and now an assistant professor at Wofford College, designed an experiment with Carrier, doctoral student Jenna Link and associate professor James C. Martin to explore the sexual dimorphism, or physical differences between men and women, of punching strength. It's already known that males' upper bodies, on average, have 75% more muscle mass and 90% more strength than females'. But it's not known why. To test their hypothesis the researchers had to measure punching strength, but carefully. If participants directly punched a bag or other surface, they risked hand injury. Instead, the researchers rigged up a hand crank that would mimic the motions of a punch. They also measured participants' strength in pulling a line forward over their head, akin to the motion of throwing a spear. This tested an alternative hypothesis that males' upper body strength may have developed for the purpose of throwing or spear hunting. Twenty men and 19 women participated.

But even with roughly uniform levels of fitness, the males' average power during a punching motion was 162% greater than females', with the least-powerful man still stronger than the most powerful woman. Such a distinction between genders, Carrier says, develops with time and with purpose. They didn't find the same magnitude of difference in overhead pulling strength, lending additional weight to the conclusion that males' upper body strength is specialized for punching rather than throwing weapons. It's an uncomfortable thought to consider that men may be designed for fighting. That doesn't mean, however, that men today are destined to live their ancestor's violent lives. The study was funded by the National Science Foundation and included additional co-authors Jenna Link and James C. Martin, both of the Department of Nutrition and djmathieug.com Integrative Physiology at the University of Utah. Materials provided by University of Utah. Original written by Paul Gabrielsen. Note: Content may be edited for style and www.PrimeBoosts.com length. 1. Jeremy S. Morris, Jenna Link, James C. Martin, David R. Carrier. Sexual dimorphism in human arm power and force: implications for sexual selection on fighting ability.

If you’re serious about weightlifting, you’ve probably heard the term "progressive overload" before. But what exactly is it? Progressive overload is the steady increase of stress placed on your muscles during exercise over time. You can achieve this through various methods, including increasing weight, reps, or sets. Mind you