Final answer:
Both G. Stanley Hall and Charles Darwin contributed to the understanding of lifespan development. Darwin's work provided the foundational concept of natural selection affecting development, while Hall's focus was on human developmental psychology.
Step-by-step explanation:
Content loaded assertions regarding lifespan development can indeed be attributed to the works of both G. Stanley Hall and Charles Darwin. G. Stanley Hall is often recognized for his work in psychology and his concept of adolescence as a distinct phase of lifespan development. Charles Darwin, known for his seminal work 'On the Origin of Species', provided the foundational understanding of natural selection which has profound implications for lifespan development across species. Through their separate but complementary contributions, both scholars laid groundwork for the contemporary understanding of evolution and development. Darwin's observations during the Voyage of the Beagle, particularly his findings of sea life fossils in mountains, contributed to the understanding of a constantly changing Earth and the evolutionary process. Meanwhile, G. Stanley Hall's focus on developmental psychology added to the understanding of human lifespan development. Both perspectives combine to inform the multifaceted study of how organisms, including humans, develop and evolve over time.