Population density shows how cramped or spread out inhabitants are. Cities with high population densities can be considered overpopulated, but the extent to which this is the case depends on factors like quality of housing and infrastructure and access to resources. Source: Wikipedia, 2017.
Livor mortis on the posterior aspects of the body is caused by settling of the blood because of gravity when the body is in a supine position. As the postmortem interval lengthens, Tardieu spots develop in areas of lividity, such as this individual's shoulder area, as decomposing capillaries rupture.
This stiffening is called rigor mortis. Depending on temperature and other conditions, rigor mortis lasts approximately 72 hours. The phenomenon is caused by the skeletal muscles partially contracting. The muscles are unable to relax, so the joints become fixed in place.