Question

27. The average height of humans in industrialized nations has increased steadily for the past 100 years. This trait clearly changed over time. Most physicians and human geneticists hypothesize that the change is due to better nutrition and a reduced incidence of disease. Has human height evolved?

A. Yes, because average height has changed over time
B. No, because changes in height due to nutrition and reduced incidence of disease are not heritable
C. Yes, because height is a heritable trait
D. No, because height is not a heritable trait

Answer 1

Human height has increased in industrialized nations due to environmental factors like better nutrition and reduced disease, not genetic changes. Thus, these improvements, while significant, do not represent biological evolution of height.

Step-by-step explanation:

The question about whether human height has evolved due to the increase in average height over time raises the issue of whether the observed changes are heritable. While it is true that human height has changed, the changes attributed to better nutrition and reduced incidence of disease are not, in themselves, genetic alterations passed down through generations. Hence, these improvements in overall height statistics due to environmental factors do not constitute biological evolution in the strict sense.

While height is indeed a heritable trait, the specific changes observed in the past 100 years in industrialized nations are largely environmental adaptations rather than genetic changes. Adaptations that are not genetic do not affect the gene pool and therefore do not constitute evolution. Therefore, the correct answer to the question is B - No, because changes in height due to nutrition and reduced incidence of disease are not heritable.