Read the excerpt from Chapter 2 of Wheels of Change . Dr. Benjamin Ward Richardson of Great Britain, a big fan of the wheel, nevertheless summarized its pitfalls in his 1895 article "What To Avoid in Cycling." Among those pitfalls were several dangers that resulted from "teaching the practice to subjects who are too young." Richardson believed serious riding should not be done by males or females until the skeleton was completely matured, which he said happened around age 21. What is the author’s most likely purpose in presenting Dr. Richardson’s research?