Last week, the Cubs made a rare visit to Fenway Park to face the Red Sox in a Major League Baseball inter-league series. Things got a little nasty when Sox pitcher Alfredo Aceves put a fastball into the face of the Cubs’ Marlon Byrd, causing multiple fractures. As is “tradition” in baseball, the Red Sox batters knew the score would be settled in the following game. After just missing Jed Lowrie with an inside pitch in the eighth inning, Cub pitcher Kerry Wood made sure he connected with his target and plunked Lowrie in the behind on the very next pitch.

"After he missed the first one, I figured there's a good chance [I'd get hit]," Lowrie told"I'm [ticked] off. I just got hit with a 97-mph fastball," he said. "I mean, I understand the situation, but I'm [ticked] off."

This type of diamond justice will only get worse as we get into the hot summer months of the season, according to researchers at Duke University. Richard Larrick, a management professor at the Fuqua School of Business studied 57,293 Major League Baseball games from 1952 through 2009, including 4.5 million at bats. He looked at the relationship between batters hit by a pitch and the air temperature during the game. If a pitcher’s teammate gets plugged, whether it be intentional or not, he is much more likely to retaliate if the temperature is 90F or above.

However, if no one has been hit yet, the heat is not any more likely to cause the first knockdown.

"We found that heat does not lead to more aggression in general," said Larrick. "Instead, heat affects a specific form of aggression. It increases retribution."They used baseball as a test environment as most other variables can be controlled. "There are decades of research showing heat leads to aggression, like finding more violent crime in the summer," he said. "But in crime statistics, it's hard to really determine if it's heat or other things. One of the nice things about studying baseball is that we're able to control for factors besides heat."

Just boys being boys, right? That would seem to be the male stereotype according to another “let’s use baseball to test something” study. A group of researchers led by Kerri Johnson, an assistant professor of communication studies and psychology at UCLA, wanted to see if certain emotions are unfairly connected to gender in our perceptions. By using the same type of video motion capture technology used to model athletes in sports video games, they captured the baseball throwing motion of 30 different male and female actors.

They were asked to throw pitches with different emotions, like sadness and anger. By using the motion capture camera, only the bio-mechanical actions of the actors were captured, not their facial expressions or gender.

Next, Johnson asked 93 college student volunteers to watch these randomly ordered videos of the pitchers and try to identify the emotion and the gender of each thrower. Thirty percent of the time, they correctly identified a “sad” throw while an “angry” throw was chosen 70 percent correctly.

However, even though each volunteer was shown an equal number of sad and angry throws from each gender pitcher, the sad throws were identified as being female 60 percent of the time while 70 percent of the angry throws were associated with a male pitcher.

"It's OK -- even expected -- for men to express anger," Johnson said. "But when women have a negative emotion, they're expected to express their displeasure with sadness. Similarly, women are allowed to cry, whereas men face all kinds of stigma if they do so. Here, we found that these stereotypes impact very basic judgments of others as well, such as whether a person is a man or woman."

So, we’ll just go with that gender bias and assume that when Kerry Wood was coming inside on Jed Lowrie, it was most likely out of anger, not sadness.