Final answer:
Body shape is the least highly canalized trait in most human beings, as it is influenced by a variety of environmental and genetic factors, leading to a higher degree of variation.
Step-by-step explanation:
The trait among eye color, body shape, motor development, and cranium size that would be the LEAST highly canalized in most human beings is body shape. Canalization refers to the degree to which a trait is buffered against environmental or genetic variation, resulting in a consistent phenotype despite these potential influences. Eye color, motor development, and cranium size are generally well canalized; they follow a predictable pattern and are less influenced by environmental factors than body shape. Body shape, on the other hand, is influenced by a variety of environmental factors, such as diet and exercise, as well as genetic factors. Therefore, body shape shows a higher degree of variation across individuals and populations, illustrating a lower degree of canalization.