The complicated relationships of alien to man can be examined on a number of different levels. When we explore human/alien symbiosis, we should understand the basic dynamics of such relationships.
In a nutshell, symbiosis describes the intimate relationship of two dissimilar organisms living in close association to one another. When discussing human/alien symbiosis, I am not describing the cultural intimacies associated with the “prawns” and humans from District 9, nor the sporting relationships of the Predator and his human prey, for these types of relationships are relatively casual without any significant form of biological commerce.
Specifically, I wish to explore many manifestations of alien/human parasitism: a relationship in which a parasite (alien) benefits from this intimacy, while the host (human) is harmed. Other forms of symbiosis such as mutualism(1) and commensalism(2) do not apply here.
HUMAN HOST AND ARTHROPOD PARASITE
Animal/arthropod relationships are exceedingly common. Lice, mites, and fleas are common infesters of humankind. Itchy, embarrassing annoyances at best, and carriers of deadly disease at worst, these critters have sucked human blood, drunk human sebum (skin oil), eaten skin flakes, and burrowed into our skin for thousands of years.
Lice are not aliens, but they are blood-sucking, sebum-drinking parasites.
Most direct harm caused to human hosts by these relationships is minor. However lice and fleas can also be vectors for disease, transmitting microbes responsible for bubonic plague and other nasty illnesses.
The Alien relies on a host of any variety of life forms, during an incubatory phase in its life cycle. An Alien larval organism emerges from its egg, possessed of four pairs of legs. These legs enable the organism to spring at the “face” of a host be it dog, human, or predator.
This larval stage creature, according to the wiki literature, implants what has been referred to as an “embryo” in the chest of the host. Implantation may be through esophageal or tracheal penetration, but no definitive data has been collected as yet on this subject.
Alien incubation has been seen in both the thoracic and abdominal cavities(3). Most symptoms of Alien infestation are symptoms of cardiopulmonary distress, as opposed to digestive disorders, or abdominal complaints. However, it is important to remember that gastrointestinal conditions like heartburn and acid reflux can cause sternal and epigastric pain that mimic angina(4).
Nestled within the mediastinum of the chest, between the lungs and the heart, the Alien develops into a nymph that is called a “chestbuster” in wiki speak(5). While ensconced in its host, the human is relatively unharmed. However, when the nymph is ready to re-emerge from its encasement, it punches out of the chest wall, like a baby chick on a cocktail of speed, meth, and steroids. During this process, the nymph destroys the sternum, ribs, adjacent musculature and all associated vascular structures.
Additionally, the vigorous physical activity necessary for breaking through the thorax, will also likely cause lacerations to the lungs, pericardium, and heart. This process usually kills the host organism (providing) they possess a heart and lungs in the thoracic cavity. For this reason, a Vulcan may survive Alien parasitic infestation of the chest, but not of the abdomen.
Signs and symptoms of alien infestation include: short term memory loss with vague associations of anxiety and terror, palpitations, dyspnea (shortness of breath), and angina.
Endstage signs and symptoms include: excruciating chest pain, collapsed lung, sternal and rib compound fracture, hemorrhage, bleeding, muscle tear, unconsciousness, and death.
Currently there is no known treatment for alien infestation.
1. Mutualism is a relationship in which both organisms benefit from their relationship. The relationship between human beings and the beneficial bacteria living in their guts is considered a mutualistic relationship.
2. Commensal relationships neither benefits nor harms the host supporting an organism. Eyelash mites living (you guessed it!) on your lids and lashes are often used as an example of this form of relationship.
3. Different movies, and scenes within the same Alien movie, will show Aliens emerging from the chest, and/or the abdomen. The films are not clear.
4. Angina is chest pain, usually signifying that the coronary arteries are not supplying the heart with enough blood.
5. I'm assuming a more formal, scientific name would be "chestbuster" in Latin or Greek.