Thus, altruism is costly to self, but is a beneÃt to others. In other words, the cost of altruism is described exclusively. in terms of changes in Ãtness for a focal individual and the. beneÃt of altruism is described exclusively in terms of the. changes in Ãtness of the complement of the focal individual.
Petechiae on the face and conjunctiva (eyes) can be a sign of a death by asphyxiation, particularly when involving reduced venous return from the head (such as in strangulation). Petechiae are thought to result from an increase of pressure in the veins of the head and hypoxic damage to endothelia of blood vessels.
Petechiae tend to occur whenever there is a combination of increased backpressure in the capillaries and deficient blood oxygen (hypoxia). Such a combination occurs during manual (bare hands) strangulation. Neck compression impedes venous return to the heart from the face and head. Airway compromise causes hypoxia. The combination of these events causes ocular capillaries to rupture, forming petechiae. When hypoxia and pressure is extreme, the petechiae become numerous and large, and merge together to form so called confluent petechiae and hemorrhages. Ocular petechiae are seen in other forms of asphyxia as well. Asphyxia is the condition of insufficient supply of oxygen to the tissues.