What exactly does the term intelligence mean? Intelligence is defined as the ability to acquire and apply knowledge and skills. Does birth order affect intelligence? According to researchers, there is some evidence that birth order does indeed affect intelligence; however, critics remain skeptical of this and claim that the evidence is inconclusive and biased (Carey, 2007). The relationship between birth order and intelligence is the subject of ongoing scientific debate dating back to the late 1800s. Francis Galton, an English scientist, published a book in 1874 chronicling the lives of 180 men important in the field of science. Galton collected birth order data from 99 subjects and reported that 48% were "eldest or only sons." Galton eliminated women from his studies because, theoretically, the subject could be a firstborn and fifth child if all of his older siblings were female. Studies of 314 prominent figures were carried out to support Galton's theory; these studies confirmed that 46% of them were eldest children and that they were among the Nobel Prize winners...