Emerging from the horrors of World War II that fundamentally transformed his view of the world and humanity's place in it, the nature of human beings strikes at the heart of Golding's characterizations. Golding stated that the novel is an exploration into the nature of man through the characters presented:
[The book is] an attempt to trace the defects of society back to the defects of human nature. The moral is that the shape of society must depend on the ethical nature of the individual and not on any political system however apparently logical or respectable.
The "ethical nature of the individual" relates to the very nature of humanity presented in the novel. The characters represent this exploration.
In each of the characters, some definable aspect regarding the nature of humanity is revealed. For example, in Ralph exists the nature of humanity that strives for order and consensus. Ralph embodies this in his belief of the conch, the liberal minded approach that being saved off of the island is the most important element of the group, as well as possessing the basic element that human impulses can be geared towards the general good. This is seen at different points in the text. For example, Ralph is the one says that "If a ship comes near the island they may not notice us" and explores problem solving options such as whether there are other people on the island. It is Ralph who represents the aspirations and fundamental failure of political leadership. The nature of humanity that is revealed at the end as he weeps for the loss of innocence is reflective of this condition of being in the world.
Piggy embodies the nature of humanity that uses rationalism to solve problems. Piggy's glasses as being the source of fire is one such example of this. At the same time, Piggy echoes a world view that preaches rationalism in its approach to the nature of being in the world: "Which is better—to have rules and agree, or to hunt and kill? ... law and rescue, or hunting and breaking things up?" Piggy's assertion that life is "scientific" and faith in logic are elements that he believes is natural to the state of humanity, elements that should be revered by others. It becomes sadly apparent that it is not, as Piggy becomes victimized by the same rationality used for evil in how he dies.
Golding asserts that the nature of humanity contains a malevolent side to it. Characters like Jack and Roger embody this darker aspect of being. When social structures and political structures are stripped away, both characters reveal how the desire for power and a particular cruelty exist in the heart of the individual. Once Jack learns how to control "the enormity of the knife descending and cutting into living flesh; because of the unbearable blood," he revels in the power it contains. Roger is savagely cruel in how he embraces the “delirious abandonment” that comes with an absence of structure. In both of these characters, the human nature that embraces violence and cruelty is evident. Golding is lucid in suggesting that individuals possess this ethical predisposition towards hurt and targeting, something that must be confronted before it is to get any better.
Finally, Golding uses characters like Simon to represent the transformative nature of humanity that might not be appreciated in the Status Quo. Simon is fundamentally different than the other boys. He represents the non- conformist aspect of human beings that sense something might be amiss with the power of the group. It is Simon who gains insight into what is happening to the boys. Simon understands the perfect sense of tranquility that the island possesses before the boys enter and recognizes that the "beast" is actually within them. It is for this reason that Simon dies as he is mistaken as the beast. Everyone participates in this as they "ripped and tore at the beast." Simon's death embodies how the nature of humanity possesses capacity for transformation, but is often silenced by the inertia of the world that gives birth to it. Simon's death is a sad reminder of how the nature of humanity might not always revere all voices, but rather silence those that it finds dissonant.
In order to draw parallels with the savagery to which Jack and the hunters of Lord of the Flies degenerate, one must report on some rather unpleasant truths. A 1966 documentary made by Italian journalists about the end of the European colonial era in Africa entitled Africa Addio ["Farewell Africa" in Italian] draws rather brutal, but likely parallels to the desecration of the sow by Roger in Chapter 8, the murderous scene of Simon's attack, the hurling of the pink granite boulder upon Piggy by Roger in Chapter 11--
High overhead, Roger, with a sense of delirious abandonment, leaned all his weight on the lever....
The rock struck Piggy a glancing blow...the conch exploded into a thousand white fragments and ceased to exist (symbol of civilization gone--the British government removed)....Piggy fell forty feet...His head opened and stuff came out and turned red--
and the burning and destruction of the island by the hunters in their efforts to flush out Ralph.
For the purposes of comparison, a second film, shortened from the original documentary released in the United States under the title of Africa Blood and Guts, and in the United Kingdom under the title Farewell Africa is a better choice. Nevertheless, there are some disturbing scenes. One scene which can be used to parallel actions of the hunters in Golding's novel is that of the attacks that were made upon the Afrikaners who remained after the British rulers left. With the ensuing anarchy that arose in the absence of a solid transitional government (much like the boys without any adult supervision--the "liberation into savagery" in Ch.11), some of those farmers descended from Dutch settlers who remained in Africa suffered deadly and brutal attacks upon their persons and their families, as well as having their homes destroyed or burned. Also, as a parallel the desecration of the sow by Roger, the dairy cows which belonged to the Afrikaner farmers had the ligaments of their back legs severed so that they could not walk; consequently, their udders filled so full of milk, they suffered excruciating deaths.
The following is a passage from Arthur Schopenhauer's essay "On Ethics," which you can probably find in your library. Schopenhauer was notorious as a pessimistic philosopher, but his references to slavery which still existed in the American South might be the kind of specific example you are looking for. The recent movie Twelve Years a Slave gives a good picture of man's inhumanity to man. Victor Hugo's description of the lives of galley slaves in Les Miserables comes to mind, as does Captain Bligh's behavior in Mutiny on the Bounty by Nordhoff and Hall. Then of course much has been written about the concentration camps in Germany and Poland during World War II. Check out Night by Elie Wiesel, which has a lot of coverage by eNotes.
Here is Schopenhauer:
In spite of all this, however, the difference between men remains immeasurably great, and many a man would be shocked if he were to see another as he himself is. O for an Asmodeus of morality who for his minion rendered transparent not merely roofs and walls, but also the veil of dissimulation, falseness, hypocrisy, grimace, lying, and deception that is spread over everything, and who enabled him to see how little genuine honesty is to be found in the world and how often injustice and dishonesty sit at the helm, secretly and in the innermost recess, behind all the virtuous outworks, even where we least suspect them. Hence we see the four-footed friendships of so many men of a better nature; for how could we recover from the endless dissimulation, duplicity, perfidy, and treachery of men if it were not for the dogs into whose open and honest eyes we can look without distrust? Our civilized world, then, is only a great masquerade; here we meet knights, parsons, soldiers, doctors, barristers, priests, philosophers, and the rest. But they are not what they represent themselves to be; they are mere masks beneath which as a rule moneymakers are hidden. One man dons the mask of the law which he has borrowed for the purpose from his barrister, merely in order to be able to come to blows with another. Again, for the same purpose, a second chooses the mask of public welfare and patriotism; a third that of religion or religious reform. Many have already donned for all kinds of purposes the mask of philosophy, philanthropy, and so on. Women have less choice; in most cases, they make use of the mask of maidenly reserve, bashfulness, domesticity, and modesty. Then there are universal masks without any special characteristic, the dominoes, as it were, which are, therefore, met everywhere; we see them in strict integrity, probity, politeness, sincere interest, and grinning friendliness. In most cases, as I have said, manufacturers, tradespeople, and speculators are concealed beneath all these masks. In this respect, merchants constitute the only honest class, for they alone pass themselves off for what they are; and so they go about unmasked and therefore stand low in rank. It is very important for us to learn early in youth that we are living in a masquerade, otherwise we shall be unable to grasp and get at many things but shall stand before them quite puzzled; and indeed those will stand longest who ex meliore luto finxit praecordia Titan. ('Whose heart was fashioned by Titan out of better clay,' Juvenal, Satires, XIII, 183). Such are the favour found by baseness and meanness, the neglect suffered by merit, even by the rarest and greatest, at the hands of men of its branch, the odium incurred by truth and great abilities, the ignorance of scholars in their own branch. Almost invariably, the genuine article is rejected and the merely spurious sought. And so young men should be taught that in this masquerade the apples are of wax, the flowers of silk, the fish of cardboard, and that everything is a plaything and a jest. They should be told that, of two men who are so seriously discussing something, one is giving nothing but spurious articles, while the other is paying for them in counters.
But more serious considerations are to be made and worse things reported. At bottom, man is a hideous wild beast. We know him only as bridled and tamed, a state that is called civilization; and so we are shocked by the occasional outbursts of his nature. But when and where the padlock and chain of law and order are once removed and anarchy occurs, he then shows himself to be what he is. Meanwhile, whoever would like without such occasions to be enlightened on this point can convince himself from hundreds of ancient and modern accounts that man is inferior to no tiger or hyena in cruelty and pitilessness. An important instance from modern times is furnished by the answer which the British Anti-slavery Society received to their question in 1840 from the North American Anti-slavery Society in respect of the treatment of slaves in the slave-holding states of the North American Union: Slavery and the internal slave-trade in the United States of North America, being replies to questions transmitted by the British Anti-slavery Society to the American Anti-slavery Society. London, 1841, 280 pp., price 4s. in cloth. This book constitutes one of the gravest indictments against human nature. None will lay it aside without horror and few without tears. For whatever its reader may have heard, imagined, or dreamt about the unhappy state of the slaves or even human harshness and cruelty in general, will seem to him of no account when he reads how those devils in human form, those bigoted, church-going, strict sabbath-observing scoundrels, especially the Anglican parsons among them, treat their innocent black brothers who through violence and injustice have fallen into their devil’s claws. This book, which consists of dry but authentic and substantiated accounts, inflames to such a degree all human feeling that, with it in our hands, we could preach a crusade for the subjugation and punishment of the slave-holding states of North America. For they are a disgrace to the whole of humanity. Schopenhauer, "On Ethics"