Being the only child is a unique position in a family. Without any siblings to compete with, the only child monopolizes his parents' attention and resources, not just for a short period of time like a firstborn, but forever.
Like gravity and plate tectonics, evolution is a scientific theory. In science, a theory is the most logical explanation for how a natural phenomenon works. It is well tested and supported by abundant evidence. It means quite the opposite from our informal use of the word theory, which implies an untested opinion or guess. As a scientific theory, evolution enables scientists to make predictions and drives investigations that lead to new kinds of observable evidence.
Evolution as a scientific theory. In non-scientific contexts, âtheoryâ usually means something like a guess (e.g., I have a theory aboutâ¦). But in its scientific sense, a theory is a tested and well-confirmed explanation for a set of observations. The observations explained by the theory of evolution come primarily from the fossil record, comparative morphology, biogeography, and now most importantly, genetics.