Heavens:
Characterised by- Pride; Complacency; Intoxication
'I've got everything that I want; there's nothing more I need."
The Heaven Realm is one of bliss and pleasure - there is little reason for the inhabitants of heaven to look beyond their comfortable and carefree existence to undertake religious training. Intoxicated by pleasure. they can ignore the harsher realities of life. However, when their good karma is exhausted, they are forced out of heaven to be reborn again - probably in less favourable circumstances.
The Heaven Realm shows that pleasure and bliss are transitory and so, although it looks to be a very desirable place to be, like the other realms it offers no lasting refuge. The Buddha in this Realm plays a musical instrument to rouse beings from their complacency.
Consider: Beautiful sights and sounds; Ideas of Heaven ... Foreign holidays etc.; Tennyson's 'Lotus Eaters'; We can be roused from our complacency by, for example, art - truths revealed through things of beauty i.e. Opera shows tragedy;


Asuras (Jealous Gods):
Characterised by.- Jealousy; Resentment; Ambition.
"I'll do anything to get what I want"
The Asuras are power seekers who try to get what they want by force. Their realm is divided from the Heavens by the "Wish-Fulfilling Tree" which has its roots in the Asura realm but bears its fruit in Heaven: the Asuras are trying to get the fruit by force by chopping the tree down. Because of their ambition and envy they spend their time in competition and warfare without a moments respite - which means that most will never seriously consider religious training.
The Realm of the Asuras points out the painful futility of competition and warring as a means of finding happiness - whatever is gained has to be constantly defended. The Buddha in this Realm holds a sword, the symbol of Wisdom, to show beings to seek understanding and insight rather than power.
Consider: Ruthless big business; Competing with others to have the best job, biggest car etc; Fortress mentality that needs to guard what it has gained; Circumstances can be Buddha - e.g. stock market crash;


Human Realm:
Characterised by:- Desire; Freedom of choice; Dissatisfaction.
"I don't want this, 1 want that".
In the Human Realm there is the constant attempt to maximise pleasure and minimise pain. But we find that no pleasure can be made permanent, and the unpleasant cannot always be avoided. We vacillate between the four pairs of opposites - gain & loss, fame & disgrace, praise & ridicule, elation & sorrow. This vacillation can lead to frustration which in turn may raise the question, "What is there that will truly satisfy?" It is this which motivates the religious quest. And so this realm is considered to be the best one for religious training. The Buddha in this Realm appears as a Monk to show beings the possibility of the religious path, the way of non-attachment.
Consider: Pursuit of the pleasurable, avoidance of the unpleasant; The ups and downs of our ordinary daily lives; No sooner is the desired thing gained than it begins to be scorned; The life of the monk;


Animal Realm:
Characterised by:- Ignorance; Domination of instinctual drives.
"I want food, sex. territory and sleep".
The Animal Realm is one of blind and passive surrender to basic instincts. These become our reasons for living. We are driven by our basic needs, and we strive to satisfy those needs without allowing ourselves to be distracted. This Realm is therefore characterised by willful ignorance of the true spiritual state of things: hence the Buddha in this Realm holds a Book to awaken awareness, thought and reason.
Consider: This is mine; my possessions; my pleasures are the most important thing; Wildlife programmes which show creatures killing and eating each other; We can be roused from this state by being aware of those who practise restraint;


Hungry Ghosts:
Characterised by - Greed; Insatiable cravings; Addictions.
"I want this, I need this, 1 have to have this".
This is the realm of intense craving. The Hungry Ghosts are shown with enormous stomachs and tiny necks - they want to cat, but cannot swallow; when they try to drink. the liquid turns to fire, intensifying their thirst. The torture of the hungry ghost is not so much the frustration of not being able to get what he wants. rather it is his clinging to those things he mistakenly thinks will bring satisfaction and relief. The Buddha in this Realm holds a Bowl from which the 'gifts of the gods' are distributed. This is to entice the hungry ghosts to desire for the Truth which is the only way that the deepest longings and hungers can be satisfied.
Consider: 'Gollum' from Lord of the Rings; The obssessive nature of Video Games; Addictions of various sorts; We can be helped in this Realm by our willingness to 'look up', to see beyond our obssessions.


Hel1 Realm:
Characterised by:- Rage; Torment; Despair
"I'm in pain, I'm suffering".
In Buddhism there is no judgement or punishment by an external deity. The pains and tortures experienced here are the consequences of habitually and willfully choosing to indulge greed, anger and delusion. Yama again appears in hell, holding up a mirror to show beings the results of their wrong actions. The Buddha in this Realm holds a flame to show that fire, as well as burning, can also purify.
Consider: Torture, starvation, physical pain; Being bullied; Concentration camps; Blind rage; We can be liberated from this realm by patience, acceptance and contrition;

Root Causes of Evil and Merit (Akusalamula-Kusalamula)
3.1 AKUSALAMLA (Root causes of evil) :
This implies whatever drives a person to do evil of all kinds. What has been seen as newspaper headlines nowadays reporting the acts of thefts, deceits murders, suicides and other evils stem from, according to Buddhism, the original causes within a person's mind called Kilesa (Defilements).
From the secular point of view, it is the critical or adverse situation in the people's life that are the culprits driving them to do those wrongs and evils. These imply, for instance, poverty, which is regarded as a cause of such crimes as stealing, robbing and other forms of violent acts. However, it is to be seen that quite a number of wealthy people there are who condescend to do the same evils. Such an accusation, therefore, serves only as a pretext, since there can be found many poor people have been diligently doing good, never resorting to such wrongful means.
According to Buddhism, the roots of evil are of three kinds viz.


3.1.1 LOBHA (Greed or Lustful Desires) -- For most people this is insatiable, with more desires growing as a result of more gratifications. What is worse, it drives a person to eye others' belongings with a greedy, possessive desire. This is both legally and morally wrong. For if such a desire is unchecked, the person is sure to resort to whatever means is available. Hence the acts of stealing, robbing, cheating, smuggling and other corrupted practices will be done.
This insatiable nature of Greed results in a person's constant self-inflicted suffering, which is unknown to poor people who know how to put a curb, or limit on their own desires. Of course, when a desire does not outrun one's capacity or overshoot one's status as far as the legal, economic and social norms are concerned, it can be productive of a degree of benefit both to oneself and to the society as a whole.


3.1.2 DOSA (Anger Irritation, Anger, or Hatred etc.) ---This Defilement has its roots in the feeling of irritation in the first place. Thereafter it develops, in varying degrees of intensity, into what can be called impatience, annoyance, resentment, anger, hatred, fury and revenge, to be followed by the desire to insult and to use violent means such as to kill or destroy by whatever means is possible.
Inflamed by Dosa, a person is irresistibly urged to resort to strong words and violent acts, the former to be expressed in insulting or sarcastic remarks and false accusations whereas the latter in violent and destructive deeds such as an assault, murder or arson. These are instances of the destructive effects of Dosa acting on the mind, inflamed by it.


3.1.3 MOHA (Delusion)--This includes various other shades of meaning connoted by Delusion such as bewilderment, ignorance, not knowing what is good from what is evil anti what is right from what is wrong. A person overwhelmed by this Defilement is like a blind man who has to grope about in the dark, being often led astray by his own hesitation, distraction and eventual wrong ideas, leading him to absent-mindedness and heedlessness or over-confidence., all of which drag him to wrongful thoughts and acts.

3.2 KUSALAMLA (In contrast of AKUSALAMLA) :
There are three kinds of producing right attitudes of mind and right actions as a result, as follows :


3.2.1 ALOBHA (Non-greed): ---This is to be without lustful or greedy desired. It implies the ability to feel content, to 'have enough'. Such a person is not tortured by an insatiable desire, having this Defilement reduced or removed thereby. Without eyeing other persons' belongings, an aspirant is not driven to commit an illegal or immoral act. This really is a kind of bliss.

3.2.2 ADOSA (i.e. to be without Dosa) : A mind not under the influence of this Defilement is cool, calm and clear. Always refreshes, it does not feel hurt and as a result does not cherish a desire to retaliate by insulting words or revengeful act, be it upon anybody's belongings or person.

3.2.3 AMOHA (Non-delusion) : This is opposite to Delusion or Bewilderment. It refers to the mind illuminated by the light of discriminating wisdom, the ability to distinguish what is right from what is wrong, what is good from what is evil, and what is beneficial from what is baneful. A mind unclouded by the various shades of Defilements is not troubled by doubt, hesitation, distraction or heedlessness. It is blessed with right attitudes, which, as a matter of coarse, is conductive to the benefit, progress and prosperity of one's self and society, including the country as a whole.

Cool, I got one of these portraits at home. I believe in the Theravada tradition, the asuras are considered lower than the human realm based on what i learnt:
http://www.basicbuddhism.org/index.cfm?GPID=52
The reason why the Tibetans place the asuras above the humans is because the Tibetan masters subdued the asuras in that region and turned them into Dharma protectors.

yes i agree too.