What does developmental homology indicate about species?

Developmental homology refers to the similarities observed in the embryonic development of different species, despite the significant differences that may be present in the adult forms. This concept is crucial in understanding evolutionary relationships among species. When two species that appear quite different as adults share common traits during their developmental stages, it typically suggests a shared evolutionary ancestor.

This phenomenon can be seen in various examples across the animal kingdom, such as the embryonic stages of vertebrates like fish, birds, and mammals exhibiting similar structures, such as pharyngeal arches, which later differentiate into various adult features. Therefore, recognizing these developmental similarities provides strong evidence for evolutionary theory, indicating that species with different adult forms often retain a common developmental pathway that reflects their ancestry.

In contrast, other options would misrepresent the concept; for instance, stating that different adults share no similarities contradicts the very idea of evolutionary relationships, while suggesting that species are indistinguishable throughout their lives ignores the unique adaptations that arise as they mature. Additionally, claiming that embryonic development is unrelated to evolution overlooks the importance of developmental processes in tracing evolutionary lineage.