¹⁴Cooney, Gabriel. "The Passage Tomb Phenomenon in Ireland." Archaeology Ireland 11.3 (Supplement: Brú Na Bóinne) (1997): 7.
The author explains the elaboration of passage tombs as the phenomena spread from the west coast of Ireland to its east "as indicating a greater separation of what went on inside the tomb from the outside world. It would seem that over time the placement of bones and contact with the ancestors become more rarefied activities, the domain of elders and/or shamans who were recognised as being skilled in dealing with the spirit world."
Another possible explanation is offered by Alison Sheridan, who asserted that" the development of Irish passage tombs can best be understood in terms of the attempts of competing groups to outdo each other in the hallowing of the dead. In this particular case, then, the ideology of death appears to have been harnessed closely to the power politics of the living, and used as a medium for the assertion of status." (Sheridan, Alison. "Megaliths and Megalomania: An Account, and Interpretation, of the Development of Passage Tombs in Ireland." The Journal of Irish Archaeology 3 (1985/1986): 30.)