<Tr> <Th> Stages </Th> </Tr> <Tr> <Td> <Ul> <Li> Human embryogenesis </Li> <Li> Fetus </Li> <Li> Infant </Li> <Li> Toddler </Li> <Li> Early childhood </Li> <Li> Child </Li> <Li> Preadolescence </Li> <Li> Adolescence </Li> <Li> Adult </Li> <Li> Middle age </Li> <Li> Old age </Li> </Ul> </Td> </Tr> <Ul> <Li> Human embryogenesis </Li> <Li> Fetus </Li> <Li> Infant </Li> <Li> Toddler </Li> <Li> Early childhood </Li> <Li> Child </Li> <Li> Preadolescence </Li> <Li> Adolescence </Li> <Li> Adult </Li> <Li> Middle age </Li> <Li> Old age </Li> </Ul> <Tr> <Th> Biological milestones </Th> </Tr>

Who helped to make adolescence a separate developmental stage