Simply because evolution has favored aggressive behavior in the males of any species. Males are the most expendable members of any society, as loosing a few has no impact on the number of offspring tha can be made. As a result males are the ones that became responsible for dangerous tasks; hunting, fighting, etc. Combine this with the male reproductive strategy (reproduce often and with as many partners as possible. This is why many animals have males fight over mates) and you get an evolutionary pressure for competitive, aggressive behavior.

Females on the other hand had a selective pressure to avoid such conflicts and dangers. If thr females of a group start dying, the number of potential offspring is reduced. Because they were more valuable to a tribe, they would not take place in dangerous tasks and would instead handle other tasks; gathering, child care, etc. Evolution favored females that avoided conflict.

This is also why gender roles are so hard to combat in the modern world. The underlying attitudes are biologically ingrained. With modern technology, these primitive functions are no longer needed, but evolution will take many generations to catch up.

biology

Women are not often on positions of power that enable them to commit such atrocities, and those that are have to be exceptional to overcome our unfortunately barbaric prejudice against female leaders.

The cause of all of this is that men tend to be more aggressive because we are still animals with the same instincts that allowed our ancestors to survive. When there are power vacuums (like the ones that have been created in the middle East), those instincts kick in, and it usually means that the most extreme and aggressive factions rise to power.

Unfortunately, those instincts don't fade just because we sit in a fancy seat, and the lions that came to rule the wild act the same way to conquer the cities, with disastrous consequences.

That's my explanation of why these things keep happening. I hope it's something that we can eventually overcome. It will be the end of us if we can't.

Oh, and speaking of the non-violent tendencies of women, I wonder if you have seen this scene from The Life of Bryan (most likely you have).

Men tend to support what they consider "masculine" in other men (strength, decisiveness, obnoxious behavior, independence, etc.) while condemning what they consider "feminine" behavior (tenderness, displays of emotion, affection, etc.) I think this can be particularly damaging to men who are constantly reinforced to conform to certain "masculine" standards to the point where they are discouraged from hugging, touching, crying, talking about their feelings, and other such "feminine" behaviors. Men are uncomfortable with (for lack of better words) their feminine side. They're especially uncomfortable of revealing any "feminine" behavior towards other men. I think such supression of "feminine" behaviors (especially lasting over many generations) has a lot to do with why men tend to be more violent. I think that embracing and practicing "feminine" behaviors would do much to pacify such violent tendencies.

I could be wrong, but that's what I think.

Why do men do all the dirty work? That's the question I'm hearing. You're focussing on the negative aspects and that's reasonable and valid. It's a genuine consern that needs remedy.
But this fire that scalds, burns and ruins can also warm, weld and cauterize. The same energy that can entice a man to enslave and kill could also lead him to explore, build and suffer long hours on the back of a garbage truck. It's a matter of ideology really. A tool of destruction or an implement of freedom, he has to be aware of this choice and the responsibilies that go with it.

"...why it is that the male gender is the one that commits by far the most atrocities?" An excellent question--perhaps it's testosterone?

In all seriousness, while I am not a psychologist, sociologist or biologist, it seems to me that we need to ask the following question: to what degree does a society or community play a role in amplifying, ignoring or attenuating aggression, which appears strongest in those of us with Y chromosomes?

My initial response is that males commit atrocities more often because they are more frequently in positions of power that position them to do so. Frequency imbalance might be related to power imbalance.

Tetosterone!

I'm not sure we could isolate one single primary variable most directly responsible. There are lots of valid points here: testosterone makes men more aggressive, men have been in an overwhelming position of authority in most of the world, religion or beliefs determine actions...

My point is, this is all speculative.

No issue with saying men commit the majority of crimes/issues in the world. Just be careful what conclusions you draw or what generalizations you make about men.

Interesting that on this site no one mentioned the affect that religion plays in this. Take all of the other indicators that were mentioned and then add in religion as an ignitor. Boom! Wars, concentration camps, etc.

It seems to me that most of the comments have pointed to biology or chemistry as being the culprit. If it is those things then why don't all men behave that way?
I used to think the reason for hate between groups came from a "not of my tribe" reasoning left over from the hunter/gatherer period. Then I thought if that were the case why didn't everyone act that way? We don't. Thus ended the 'not of my tribe" hypothesis.
I think it may lie in chemistry combined with life experiences and the individual's wiring of their brain.
I'm not an expert or an educated student of human behavior (I've had a few classes in pursuit of a Social Work degree), I try to compare behaviors based on experiences. Such as: I have 5 brothers and none of us act the same nor share very many interests. I worked with an older brother and had co-workers ask me if we were really biologically related, was he my really my cousin? He's a dick, I'm not. Yet we grew up in the same household, matching experiences etc. Why are we so different? Is it truely the 'person in enviroment' explanation or a combination of experience, wiring, societial expectations, personal growth, biology, chemistry? Nature vs nurture?
I wonder if we will ever truely know the answer.

Thee answer lies surely in the history of evolution of our species. Will the evolutionary [unthinking] machine ever get us a second chance to evolve into a more equal society? - that is now that we are just deciding to do more about the inequality of the sexes?. Well if it could it would take a very long time so you would probably want a more sociological approach as opposed to a fast track evolution. I think it could be done. Men would have to tone down their testosterone. Women would have to just keep on achieving more and more by way of gender supremacy in hitherto male roles. But please give up when you have supremacy and don't take out any revenge.

Good question!! It is pretty much indesputable that men ae more violent than women. More over, most crime, violent and otherwise, is committed by males between the onset of puberty and 30 or so. This suggests that hormonal changes have something to do with male violence. Of course some cultures are less tolerant of violence than others and define the limits of masculinity differently. ( for what it is worth I am a 70 yr old male with degrees in Sociology & Anthropology)

It's all part of the evolution of the human species with one goal: perpetuation of the species, and it worked out that the male became the driving force, while the female, by the nature of having the womb, became the nurturer. However, we are not cavemen anymore. We have gained a level of development that allows the brighter among us to understand we are socially evolved enough that we no longer have to club our women and drag them around by the hair. Unfortunately, there are many who are not so "evolved" as others. It's still in our DNA, and we must continue to seek and understand what is the best way to participate in a modern community.

Testosterone is the simple answer, in my opinion, but obviously socirty and the socialization of males and females plays a part as well. I'm tinking mainly of here in the U.S. as I have no real, meaningful, knowledge of other cultures. Boys and gurls here have been driven into very narrow gender stereotypes, more so in the past than now. The obsession with religion plays a big part in this (again, just my opinion). Girls have always been given much more latitude in their concept of self than boys, probably because they were considered inferior to males, with a very constrained role to play, motherhood and subservience to men. Boys, on the other hand, while also having a limited role as provider, protector, and, most importantly, RULER, were often forced into a gender stereotype of hyper-masculinity, as any traits associated with the "weaker" sex had to be squashed immediately. So, FEAR, on the part of society (and religion), and later the boys, as they grew and developed, became the motivating factor for the sublimation of cultural values. And THAT process, in any culture, ensured that very few would stray from the desired social behavior. But, obviously, a few did, and today MANY do, which is a good thing. Gender diversity, like racial or ethnic diversity is a very good thing for society, but that cultural FEAR remains, mostly in men and in RELIGION, and it is very powerful! Especially when combined with the thought of losing their dominant position in socirty. And this easily translates into violence and death and a tighter grip on power, as we are witness to today. Sorry if I am rambling. Just wanted to put my 2 cents in. Sociology and culture are important areas of study, if you really want to understand what is going on around you.

"If you want a picture of the future, imagine a boot stamping on a human face--forever." -- George Orwell, "1984"

Biology to start with. Sheer physical power undoubtedly had a lot to do with it as it dictated early social systems.
Then socialisation. Two thousand years of Abrahamic subjugation of women won't be shrugged off in a mere few decades.
This has put men almost exclusively in the positions of power. The women who've got to the top have then started atrocities too. Check out Thatcher's record. Not just the Falklands war, but the poll tax, and her ongoing war on the poor. Neither Queens Mary or Elizabeth 1 were paragons of peace and forgiveness.
At least part of it comes down to men having more opportunity to produce atrocities as a consequence of how our societies have been/are structured.
I've no doubt that Clinton. H. would not have hesitated to start a war if she thought it neccessary.

Why limit to what is happening in Syria only. Why is every one blind folded about what is happening in Yemen?

Because women are by nature far more advanced emotionally than men. The poet Rilke ends the third elegy this way: Oh gently, gently,
let him see you performing, with love, some confident daily
task,-
lead him out close to the garden, give him what outweighs
the heaviest night . . . . . . Restrain him . . . . . .

I excerpted the following from an NPR feature titled “Can Genes And Brain Abnormalities Create Killers?” In Talk of The Nation.
Three elements seem to be at play when it comes to serial killers:

1. On brain scans, it looks like the orbital frontal cortex of a serial killer, which is right above the eyes, is a little bit less active, or a lot less active, than the amygdale, when they're processing information. The orbital frontal cortex is involved with moral decision-making and ethical behavior, and it puts a brake on the amygdale, which is involved with fear, and anger, and violence, and appetites. So if the orbital cortex, the moral decision-making area of the brain, is not doing its job, then the person is more likely to be violent.
2. There are certain genes that have been found to be related to violence, and one in particular is the MAOA gene, also called the warrior gene because it regulates the serotonin system in the brain, which affects moods. With a particular variant of this gene, the person is going to be predisposed toward violence. So, serial killers have both a different brain function and a different genetic makeup.
3. The person needs to have been abused as a child; needs to have experienced violence as a child.
   So it is a matter of nature and nurture. Not everything is determined by genes and brain function. It could be that having a good childhood is the reason why most people are not behind bars. A genetic disposition is not fate. We can be taught how to control these passions.
   There is probably a lot that is not known yet. Not all the population has been scanned, and most likely that will never happen. But what is theorized is that there are a lot of people out there with brains like this, people with psychopathic or sociopathic tendencies, who are not acting on those tendencies, who are making the right decisions, and it is not exactly known why. That field of science is still young, but so far it looks like upbringing could be a brake on bad behavior.

Men are more agressive. Male animals normally provide and defend, females nurture,
Man has evolved from animals in tah we have civilisations and tools technology and such. But look at the timeline, that is all so recent. We have not evolved from our earlier instincts. We still seek to obtain and hoard and wipe out any seen as rivals.
I don't blame males, I blame the species.

I agree with the reply of sueincoombs. Yes we should realize that humans are just another animal, created by evolution, a very successful one, that’s clear enough I guess. An animal that needs to breed and spreading there genes as wide as it can, a drive fired by hormones. As the female in general, can only reproduce one child in a period of, let’s say, one year, the male is not limited like that, he can spread his genes all year through. Fired by testosterone is also aggression needed for the fight of dominance. The dominant, just as in the rest of the majority of the animal kingdom, can therefor spread his genes the most, creating the strongest race.
This drive fires also suppression instincts. In a war-zone, the human in the animal is suppressed systematically by the military system. Preferably leaving only the aggressor fighting for his life. This suppression of their human instincts leads to basic animal behavior. So rape of the females of the enemy (but also of colleague female fighters) is just around the corner, just like murder of civilians, looting, etc., etc.
Personally, in general, I don’t think women are to blame, although they also are subject to basic animal behavior, so they might support the male in certain situations. Sure they are capable of murder and violence, but that’s a different story.
Well, this matter is actually so complicated that these few words about this animalistic behavior, is only a tip of the iceberg. As you said. Food for sociologists and psychologists.

Chemistry, the high levels of testerone naturally found in men from puberty on pushes them to performance activities, athletics, hunting, etc. With this natural push and an enviroment that still teaches , granted much more subtlely than before, male dominence, if they have the slightest mental breakdown we see violence. If you look at the world of wild animals, it is usually the males who fight for dominance, defend their harems, etc. Brain chemistry gone awry via social conditioning. You have met women who have that aggressive behavior and my guess would be her hormone levels are off, brain chemistry is the basis of mental illness in all forms.

Women in Germany during WWII worked as concentration camp guards and were guilty of just as many attrocities than the men. I was a sociology major Testastarone probably is the culprit.

I think it's a combination of testosterone and socialization. We raise our kids differently depending on gender, but also there is a difference in drives. Young boys and trans boys at play are different then their opposite. There might be small crossover, but boys like guns and if you take them away, sticks become guns. In our day and age, the status quo is tipping, and men are loosing dominance. Power is an essential part of maleness. Men would rather be respected than loved. This causes serious upheaval in the ego of men and the fight response if triggered. This is, I believe, the cause of school.shootings, wars, and the rise in hate crimes world wide. I could go on, but I'm typing on a phone and my old fingers are tired. Lol