Sociobiology is a branch of science that holds that all behavior is ultimately determined by genetics, and subject to the same laws of survival via natural selection as physical attributes. Genes determining behavior favorable to survival will be selected, while those governing deleterious behavior will eventually drop from the gene pool. Individual genes increase their chance for survival through a sometimes bewildering pattern of kin selection and survival advantage for the species at the expense of particular individuals. Genetically determined or not, social behavior and evolution adheres to those same laws of selection often favoring group selection over individual survival. Intricate social patterns have evolve that incorporate all of life into a coherent whole, imbued with a unity and spirituality, in harmony with nature and the environment.
Every behavior fills a social niche, just as every creature fills an environmental niche.
Ramifications of the loss of a behavioral practice can be as drastic and unpredictable to a culture as the loss of a species is to the environment. Female infanticide, constant bickering and intravillage village may appear aberrant and be horrifying to our culture, but may be necessary for the survival of the group. Curtail those behaviors because of our own sensibilities could easily upset a social balance that has evolved through a thousand generations and result in the loss of identity and sense of belonging that seems to be the bane of modernity. From a western perspective, because the Yanomami don't hold individual life with the same importance as western culture doesn't mean that they don't hold life sacred. In their belief everything has a spirit.