Original sentence: Although research on attachment behaviours continued after Bowlby's death in 1990, there was a period when attachment theory was considered to have run its course.Related later research looked at cross-cultural differences in attachment, and concluded that there should be re-evaluation of the assumption  that attachment is expressed identically in all humans.Some authors argued that attachment should not be seen as a trait (lasting characteristic of the individual), but instead should be regarded as an organising principle with varying behaviours resulting from contextual factors
Edited sentence: Following the argument made in the 1970s that attachment should not be seen as a trait (lasting characteristic of the individual), but instead should be regarded as an organising principle with varying behaviours resulting from contextual factors, later research looked at cross-cultural differences in attachment, and concluded that there should be re-evaluation of the assumption  that attachment is expressed identically in all humans