George Sodini made no secret of his hatred of women.

The systems analyst who allegedly opened fire, killing three women and injuring nine others before turning the gun on himself at a gym outside Pittsburgh, detailed the reasons in his chilling blog.

From his hatred of his mother, whom he refers to as "vicious" and "vindictive," to his despair over his inability to attract women, Mr. Sodini fits the mold of a classic misogynist. "I actually look good. I dress good, am clean-shaven, bathe, touch of cologne – yet 30 million women rejected me ...." he writes.

Misogyny has been around since almost as long as men and women have. The first poem written in Greek that still exists is called "Woman." Its author is anonymous, and it amounts to a harangue against the female sex.

While the gender-equality movement has made strides in the past century when it comes to some of the more blatant forms of societal misogyny, such as banning women from academic and professional settings, misogyny persists in American and other cultures around the world, according to historians.

"This killer fits into a long pattern of males who harbor hatred towards all women, the image of 'woman,' and towards individual real women, and who take out their frustration on a female scapegoat," says David Gilmore, an anthropology professor at Stony Brook University in New York and author of "Misogyny: the Male Malady."

Professor Gilmore cites two main reasons for the existence of misogyny. One is that women are still, by and large, the primary caretakers of children. As such, they are responsible for both gratification and, in some cases, great frustration. In his blog, Sodini refers to his mother as "the Boss above all other Bosses."

"She actually thinks she's normal," he wrote. "Her way and only her way with no flexibility toward everyone in the household. A power and control thing."

Another primary cause of misogyny has to do with a lack of recognition from women or a series of rejections by them. "For the man, a lot is tied up with his sexual/romantic success because that's a measure of him as a man," says Gilmore. "It's an insult to your manhood, as well as your sense of self ... to meet with rejections."

Sodini made a point on his Web page of saying his status was "Never married," and he complained about his lack of a love life.

That some men feel they're failures as males can bring about the "presence of intense rage, social disconnection and despair, anxiety, and acute humiliation about who one is," according to Neil Websdale, a professor of criminal justice at Northern Arizona University in Flagstaff. The sense of failure and powerlessness can spark a desire to exert power and control, which can manifest itself, as in Sodini's case, "in a misguided and heinous manner," he says.

The Pittsburgh Post-Gazette quoted Allegheny County Police Superintendent Charles Moffatt as saying, "He had a lot of hatred for women," adding, "He was hellbent on committing this act, and nothing was going to stop him."

Follow us on Twitter.