Final answer:
The primary reason for the average height increase of college students in the 20th century is improvements in nutrition and healthcare, not changes in genetics or the popularity of sports and exercise.
Step-by-step explanation:
The average height of college students increased throughout the 20th century mainly due to improved nutrition and healthcare. Factors such as exercise or engagement in competitive sports had a lesser impact in comparison.
Throughout the 20th century, the average height of individuals in industrialized countries has risen. This is attributed to enhanced living standards, including better nutrition, healthcare, and changes in human capital. As countries improved their infrastructure and technology, populations had better access to quality food and medical services, significantly impacting physical development. This uplift in human capital is not solely due to advances in physical fitness or sports participation; it is also connected to the overall betterment of living conditions.
While genetic factors do play a crucial role in determining height, the vast improvements in nutrition have allowed individuals to reach and often surpass their genetic potential for growth. Exercise routines and sports may contribute to overall health, but they are not the primary drivers for the observed increase in stature. Increased education levels, represented by the growth in high school and college degree attainment, reflect a deeper commitment to overall human development, which includes the physical aspect of growth, driven by societal investments in health and well-being.