1 If you're under 16, it can helpful to bring along a parent or guardian for the initial interview with the people seeking babysitting. 2  This reassures the other parents that your own parents are invested in your success and that you mean business, and it also protects you.
Evolutionary biology. Fitness (often denoted w {\displaystyle w} or Ï in population genetics models) is the quantitative representation of natural and sexual selection within evolutionary biology. It can be defined either with respect to a genotype or to a phenotype in a given environment.
In the narrow sense, the term refers to biological ageing of human beings, animals and other organisms. In the broader sense, ageing can refer to single cells within an organism (cellular senescence) or to the population of a species (population ageing). In humans, ageing represents the accumulation of changes in a human being over time, encompassing physical, psychological, and social change. Reaction time, for example, may slow with age, while knowledge of world events and wisdom may expand.