But in case a gallstone obstructs the bile duct, certain problems may occur. The common symptoms of gallstones include: Sudden onset of pain that may just as suddenly increase in severity. The pain is mainly felt in the right side of the abdomen.
Affiliative behavior can be defined as any prosocial behavior that brings two or more individuals into close proximity. The formation of social units, such as mating pairs, family units, colonies, or even societies is critical for the survival of most species, including humans.
Facultative means optional or discretionary (antonym obligate), used mainly in biology in phrases such as: 1  Facultative anaerobe, an organism that can use oxygen but also has anaerobic methods of energy production. It can survive in either environment. Facultative biped, an animal that is capable of walking or running on two legs as well as walking or running on four limbs or more, as appropriate.