The adult T. solium lays its eggs into human feces. When either the eggs or gravid (pregnant) proglottid segments inside the feces are consumed by a pig (or a human in the case of autoinfection), T. solium has reached its intermediate host. Here the Pork Tapeworm eggs will hatch within the pig's intestinal tract and migrate to its muscle tissue where it will develop into its larval stage, called cysticerci. When the pig is killed, processed, and eventually eaten by humans, the infected muscle tissue can further develop in the intestines of said humans (generally only when the meat is under-cooked). The T. solium use their scolex suckers to physically attach themselves to the walls of the intestines, where they can begin to significantly grow in length. After the Pork Tapeworm has developed into a fully grown adult, it will then lay eggs in the person's excrement, starting the process over again. 
The distribution of T. solium is very common in urbanized communities where livestock are in close and frequent contact with humans. This is especially so in third world countries where there are few, if any cooking regulations, and under-cooked or unsanitary pork is a commonality. The knowledge of disease causing tapeworms in pigs dates back to Ancient Egypt and is considered the major reason why consumption of pigs are against Jewish and Islamic dietary laws.  The effects it has on humans can be fatal, and the prescription medication used to treat it can be costly. The effects of Pork Tapeworm and other parasites like it are a major reason why pork production is so closely scrutinized in the United States.
T. solium exemplifies fecal-oral transmission. In fecal-oral transmission, eggs of the parasite are laid in the fecal matter of the primary host, where they are then consumed by an intermediary host. Because of humans close contact with livestock throughout history, parasitic tapeworms like T. solium adapted long ago to develop a life cycle that utilized fecal-oral transmission and allowed for a high level of reproductive success. 
 "Taenia solium (Pork Tapeworm)" Standford. http://www.stanford.edu/class/humbio103/ParaSites2001/taeniasis/solium2.html
 "Taeniasis" Laboratory Identification of Parasites of Public Health Concern. http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Taeniasis_il.htm
 "Cysticercosis" Center For Disease Control and Prevention. http://www.cdc.gov/parasites/cysticercosis/index.html
 "Ancient Hebrew Medicine" Health Guidance. http://www.healthguidance.org/entry/6309/1/Ancient-Hebrew-Medicine.html
 "Zoonoses and Veterinary Public Health" World Health Organization. http://www.who.int/zoonoses/diseases/taeniasis/en/index.html