Eles determinaram que a vida de Oesh Rod encurtou a vida de Aes Sedai em contraste com os Kin, que viveram mais tempo e não pareciam "sem idade" da mesma maneira. From O Caminho das Adagas (ênfase minha):
She hoped that was the end of it. It should have been. But when Chilares left, Sareitha replaced her, and she too had a reason the Kinswomen were not to be trusted. Their ages. Even Kirstian claimed to be older than any living Aes Sedai, while Reanne was over a hundred years more than that and not even the oldest of the Kin. Her title of Eldest went to the oldest of them in Ebou Dar, and the rigid schedule they followed to avoid notice had a number of still older women off in other places. It was obviously impossible, Sareitha maintained.
Elayne did not shout; she very carefully did not shout. “We will learn the truth eventually,” she told Sareitha. She did not doubt the Kinswomen’s word, but there had to be a reason why the Kinswomen looked neither ageless nor anything near the ages they claimed. If she could only puzzle it out. Something told her it was obvious, but nothing leaped up said what. “Eventually,” she added firmly when the Brown opened her mouth again. “That will be enough, Sareitha.” Sareitha nodded uncertainly and fell back. Not ten minutes later, Sibella replaced her.
Não consegui encontrar o 'eureka!' momento, mas pelo Coração de Inverno , os Parentes são citados como prova de que o Juramento Rod encurva a vida (ênfase minha):
Egwene raised one hand as if to stop her, but her reply was calm and level. “There’s no need to think further, Elayne. The Three Oaths, sworn on the Oath Rod, are what make us Aes Sedai. I didn’t see that, at first, but I do, now. The very first day we have the Tower, I will swear the Three Oaths, on the Oath Rod.”
“That’s madness!” Nynaeve burst out, leaning forward in her chair. Surprisingly, still the same chair. And still the same dress. Very surprising. Her hands were fists resting on her lap. “You know what it does; the Kin are proof! How many Aes Sedai live past three hundred? Or reach it? And don’t tell me I shouldn’t talk about age. That’s a ridiculous custom, and you know it. Egwene, Reanne was called Eldest because she was the oldest Kinswoman in Ebou Dar. The oldest anywhere is a woman called Aloisia Nemosni, an oil merchant in Tear. Egwene, she’s nearly six . . . hundred . . . years . . . old! When the Hall hears that, I wager they’ll be ready to put the Oath Rod on a shelf.”