I don't really know and I approach the issue with some trepidation. This is Larry Summers territory. But the hallmark of an honest mind is to deal with the evidence you have rather than the evidence you wish you had. Virtually all parents, teachers and librarians with whom I speak acknowledge that there are different patterns of reading behavior between the genders. It is taken for granted that there is certainly a large overlap between the two, but at the margins there are differences. In order to make the essay flow a little more smoothly, let me seek your indulgence before I go much further, and ask that from this point forwards, whenever you read an unequivocal gender-related statement, you simply insert the missing modifiers, "on average", "with some exceptions", "not necessarily true for all", etc. so that it is salt and peppered to your taste.
I suggest that there are probably several elements that constitute an engaging adventure story for boys. I omit the elements that are common to all good writing. The following is my exercise in recovered memory from my ten to fifteen year old self.
• Action - preferably unrelentingly sequential action. Chaotic action is also acceptable.
• Moral clarity - There have to be good guys and bad guys. It is fine for a good guy to mistakenly appear bad or even be not particularly engaging but at the end of the day, he (usually he but certainly can be she), has to be morally good. Flaws in character, especially where they lead to humor/farce, are fine as well, but don't waste my boy time humanizing the bad guy. Nuance might as well be a four letter word.
• Reportorial - Just the facts please. Tell me what happened in what order. When using dialogue, only report the necessary minimum. When discussing what caused something, stick to the provable and stay away from speculation. Might have, could have, wished, felt, perceived, motivation - all are danger signs of plot material that is going to slow down the action.
• Dialogue - Concrete, statement of the obvious and not more than fifty percent of the story please.
• Audience - The protagonist with whom the boy is identifying has to have some audience to either respect his actions (other boys or a group) and/or admire him (usually a reasonably uni-dimensional female).
• Exoticism - If you are thinking about setting the story in some quotidian environment, think again. The setting doesn't have to be fantastic, but it does need to be out of the ordinary. Even if the story is in the here-and-now and the familiar, there has to be something exceptional that propels it away from ordinary.
• Humor - A nice occasional counterpoint. Use all its varieties - Basic, Slapstick, Puns, and Farce. More exotic forms such as wit can be indulged in moderation.
• Suffering - Nice to have, particularly when it is brought upon the protagonist through no fault of their own and allows them to be noble. Don't forget to make it worthwhile in the end, though. Suffering to no avail is a mug's game.
• Emotions - Less is more. Emotions are not the meat of the story, the action is. Emotional content can spice up the story a bit, but needs to be kept in moderation. I care about what happened, what the characters did; not so much about what they felt.
• Violence - Well, yes, but with some boundaries. Blowing things up - just fine. Injuring or killing people - acceptable within the context of the plot if that is what is required. Graphic is generally good except where it is clearly gratuitous. Cruelty is generally frowned upon except where it is the precursor for the perpetrator of that cruelty to then be hoisted on his own petard.
• And finally, Consequences - Clean outcomes not suppurating outcomes. Moral clarity, not ambiguity. Bad things, even really bad things, can happen to the protagonist: they can be injured, die, etc., but don't leave them hanging. Just say "No!" to ambiguity. Fine to have Flash Gordon endings where it appears to end one way, but you leave a backdoor for them to pop up again in a sequel. We like to be tricked now and again. But the hero needs to be a hero, the villain a villain and each needs to reap their just desserts.
Do any of these elements show up in fine literature? Absolutely! Is the mix of these elements that characterizes traditional boys' adventures the same mix that characterizes fine literature? Usually not. But is that OK? - I think so.
The aspersions I hear cast upon quintessential boys' adventures stories are that they are too violent, too shallow, and too prone to stereotyping. I think that they are probably gloriously guilty of each of these charges, but not in the way expected.
Let's tackle the issues one by one.
Assertion: Boys adventures are needlessly and pointlessly violent. I am inclined to accept that charge with a couple of modifications. Fast moving vehicles, explosions, and even physical conflict are, I think, certainly are mainstays of most boys' adventure books that you might pick out at random, but within certain prescribed bounds of acceptability. I would argue that the issue is not violence per se, but explicitness and cruelty. Here, the argument gets more refined.
There is an old English adage which encapsulates one of the core differences in male and female reading (or maybe parent/child reading).
Meek Michael thought it wrong to fight.
Bully Bill, who killed him, thought it right.
When push comes to shove (and how revealing is that phrase?) I think boys are substantially willing to accept and act on the inherent conflict framed in that adage. They may try and talk their way out of a situation, but they accept that there are instances where you are confronted by an implacable opponent not willing to engage in discussion. In those instances you have to act and that predisposition to act (and act violently if that is what is called for) shows up in the stories they like to read. Meanwhile, as parents, we are constantly trying to modify and constrain violent behavior rather than encourage it.
Therefore, we are faced with a choice, a potentially unpleasant one, but a choice none-the-less. If our boys aren't interested in the stories we want them to like but are interested in stories we don't like, then are we willing to let them read that of which we disapprove in order for them to enjoy reading or do we accept their not reading at all because they choose not to read that which we wish them to read?
I come down in the camp of letting them read what they will as long as they read and as long as you know what they are reading in order to shape their understanding of issues. Bemoaning that boys aren't reading is just a symptom of bemoaning a reality we don't want to confront. It is not that boys don't read, the issue is that they don't always read what we want them to read.
If we accept that stories that appeal to boys often (but not always) have a higher violence index, there are still a couple of other issues buried in that violence. One is its explicitness. It is a fine line between explicit and gratuitous and I think adults draw that line at a different point than do children. I am not sure that the explicitness is necessarily a gender issue, though it might be. My youngest boy hews pretty closely to a classic active boy: he likes guns, things that explode, toy soldiers, sports, hiking around the great outdoors, physical rough-and-tumble, etc. His reading, to his mother's distress, tends to mirror these proclivities. One example from among many in the past year stands out. In one story, The Book of the Lion, (set in the middle-ages) within the first twenty pages, the blacksmith to whom the protagonist is apprenticed, has been seized for counterfeiting gold coins, and in punishment, had his left hand lopped off. But this is not an event alluded to off-stage. It is front and center and graphic and alluded to repeatedly. My son was totally gripped.
To Sally's distress, he has also wanted to discuss that scene with her, and not just once but several times. She finds the scene stomach-churning. But his questions are not prurient, they are almost of an engineering quality. Do you use a sword or an axe to cut off the hand? Why the left hand and not the right? Why don't you bleed to death? How does cauterizing the stump work? Why does the hand wiggle after being chopped off? OK - I'll stop; but you get the picture. As distressing as she found these discussions, at the same time there were a couple of very positive outcomes. He now has some additional factual knowledge about how the body accommodates trauma, knowledge which might be useful some day. And more than that, his questions led to a discussion of why we don't go around lopping off hands today (and which cultures still do and why), why that was done in the middle-ages, how life was back then, etc. This is more than a silver lining in a cloud. These were good conversations. So, is violence that is explicit bad? Not necessarily.
As an aside, it is fun to see how families generate their own internal language. The Book of the Lion, has become in our family, the verbal short-hand (couldn't resist) for how one story can affect two readers so differently.
The second issue is cruelty. Here, I think there is an interesting twist in boys' adventures that sometimes in our rush to condemn, we overlook. In most of the classical boys' adventure stories that have some element of violence to them, it is usually not gratuitous (i.e. it is there for a reason in the context of moving the story along), and it follows some predictable pattern. The protagonist does not usually resort to violence lightly. When violence is engaged in, it usually of an almost Old Testament context - Alright boys, time to go out and smite the wicked. When there is cruelty mixed in with the violence, it is almost always explicitly condemned and is often the justification for whatever come-uppance is visited upon the perpetrator.
I would argue that yes, boys' adventures stories probably have a higher violence index than most genres, that this violence fits into a child's world view (or a boy's world view) better than it does to a parent's, and that within the classical boys' adventures stories it is usually presented in fairly constructive ways (condemning cruelty, making it clear that violent action is a last not a first resort, etc.).
Now what about the other two charges - Too Shallow and Stereotyping.
Assertion: Classic boys' adventure stories are too shallow and lack nuance, emotional context and depth. Well yes, and not a bad thing either. The flip side of these coins is that boys adventure stories might alternatively be characterized as having moral clarity, straightforward narrative structure (how do I communicate the most with the least), and encourage analytic thinking (if X then Y).
Assertion: Classic boys' adventure stories indulge in stereotyping to an unacceptable degree. What is stereotyping but a short-hand for communicating something? I would argue that there is unintentional stereotyping in boys' adventures stories but that that is simply a by-product of a spare story-telling style and structure. And when you return to some of the more often condemned stories, you often find that it takes an almost willful misreading to sustain the charge of negative stereotyping. A classic example might be Rudyard Kipling, arch-imperialist, purveyor of stereotypes extraordinaire. But look at what he is actually saying in his poem Fuzzy-Wuzzy (Soudan Expeditionary Force). Yes his terminology is irredeemably imperial, yes his vernacular has an implicit derogatory sound to it but what is he actually saying? I respect you as the greatest warriors we ever fought and we only won because we had advantages you didn't.
So, below are a series of boys adventures stories which tend to appeal much more to boys than to girls and which usually have many of the above mentioned traits. I omit, and it is a terrifically long list, those adventure stories which appeal to both sexes (The Chronicles of Narnia, Hatchet, etc.)
P.S. - Sally was just asking me, apropos something she is doing with her Cubs Scouts, whether I ever did secret codes as a boy. Oh my goodness yes. Which reminds me of one other attribute that should probably be added to a solid boys' adventure story - It should include some new skill: codes, signaling, how to light a fire with sticks, how to make a bow, etc. In the movie Napoleon Dynamite there is a great exchange between Napoleon Dynamite and his buddy Pedro, that captures a boy's fascination with skills.
Napoleon Dynamite: Well, nobody's going to go out with me!
Pedro: Have you asked anybody yet?
Napoleon Dynamite: No, but who would? I don't even have any good skills.
Pedro: What do you mean?
Napoleon Dynamite: You know, like nunchuku skills, bow hunting skills, computer hacking skills... Girls only want boyfriends who have great skills.
Crispin: the Cross of Lead by Avi
High Citadel by Desmond Bagley
The Vivero Letter by Desmond Bagley
Adrift by Steve Callahan
King Solomon's Mines by H. Rider Haggard
Seven Years in Tibet by Heinrich Harrer
The Dark Frigate by Charles Boardman Hawes
Captains Courageous by Rudyard Kipling
Endurance by Alfred Lansing
The Call of the Wild by Jack London
The Great Escape by Paul Brickhill
Sharpe's Tiger by Bernard Cornwell
Wind, Sand and Stars by Antoine de Saint Exupery
The Adventures of Sherlock Holmes by Sir Arthur Conan Doyle
Lord of the Flies by William Golding
Kon-Tiki by Thor Heyerdahl