Final answer:
Sheldon's concept indicated that each body characteristic reflects an overemphasis on one of the embryo's layers, which aligns with embryological research showing that both genes and environment play crucial roles in development. This idea is foundational to the study of epigenetics, which looks at how environmental factors can influence gene expression and thus affect the phenotype of an organism.
Step-by-step explanation:
According to Sheldon, each body characteristic reflects an overemphasis on one of the layers of the embryo. This concept is part of a wider discussion on the influence of embryological development. In embryology, including the work of Conrad Waddington, it has been demonstrated that both the physical and chemical environment and genetic factors influence embryonic development. For instance, Waddington's concept of epigenetics underlines the role of the environment and genes in the development of the phenotype, indicating the interaction between the two in determining the traits of an organism. Experiments by Waddington and others suggest that the physical and chemical conditions surrounding the embryo can significantly affect its development, a notion mirrored in the works of embryologists such as Hans Speemann, who won the Nobel Prize for his discoveries on embryonic organizers.
Epigenetics is a fundamental aspect of development, describing how environmental factors can alter gene expression and therefore influence the phenotype. This is a dynamic process where external factors, such as exposure to smoking or experiencing trauma, can lead to heritable changes that may span generations, illustrating evolution in real time. The idea is that while genetics provide a foundation, the environment plays a key role in shaping how an organism develops and functions.