Robert Langs distinguishes three types of<unk> : Predatory<unk>  Predatory<unk>  arises from the fear of being harmed. It is the oldest and most basic form of<unk> , with origins in the first unicellular organisms' set of adaptive resources. Unicellular organisms have receptors that have evolved to react to external dangers, along with self-protective, responsive mechanisms made to increase the likelihood of survival in the face of chemical and physical forms of attack or danger. In humans, predatory<unk>  is evoked by a variety of dangerous situations that put one at risk or threaten one's survival. Predatory<unk>  mobilizes an individual's adaptive resources and leads to a fight-or-flight response, consisting of active efforts to combat the danger or attempts to escape the threatening situation. Predation or predator Predation or predator<unk>  is a form that arises when an individual harms another, physically and/or mentally. This form of<unk>  is often accompanied by unconscious guilt. This guilt, in turn, motivates and encourages a variety of self-made decisions and actions by the perpetrator of harm to others. Existential Existential<unk>  stems from the basic knowledge that human life must end. Existential<unk>  is known to be the most powerful form of<unk> . It is said that language has created the basis for existential<unk>  through communicative and behavioral changes. Other factors include an awareness of the distinction between self and others, a full sense of personal identity, and the ability to anticipate the future. The existential psychiatrist Irvin Yalom asserts that humans are prone to<unk>  because "our existence is forever shadowed by the knowledge that we will grow, blossom, and inevitably, diminish and die." Human beings are the only living things that are truly aware of their own mortality and spend time pondering the meaning of life and<unk> . Awareness of human mortality arose some 150,000 years ago. In that extremely short span of evolutionary time, humans have fashioned a single basic mechanism through which they deal with the existential<unk> es this awareness has evoked: denial. Denial is effected through a wide range of mental mechanisms and physical actions, many of which go unrecognized. While denial can be adaptive in limited use, excessive use is more common and is emotionally costly. Denial is the root of such diverse actions as breaking rules, violating frames and boundaries, manic celebrations, directing violence against others, attempting to gain extraordinary wealth and power, and more. These pursuits are often activated by a<unk> -related trauma, and while they may lead to constructive actions, more often than not they lead to actions that are damaging to self and others.
Death anxiety
Self-hatred
Body image disturbance
Somatic experiencing
Tolerated illness
Distress 
Happy life expectancy
Unipolar emotions