Ele começou a envelhecer porque ele é velho.
Lógica circular, eu sei.
Falando mais sobre as cicatrizes, o diretor James Mangold explicou em uma entrevista , mas se relaciona com o envelhecimento dele também:
“One of the things we all thought about as we worked on this film is, well, we don’t want to rebuild everything. We want to have some questions. In order to make a different Logan, and a different tone of a Wolverine movie, we felt like we couldn’t hold on to every tradition established in all the movies religiously, or we’d be trapped by the decisions made before us. So we questioned whether Logan’s healing factor causes him to heal without even a scar. We imagined that it may have when he was younger, but with age, he’s getting older and ailing. Perhaps his healing factor no longer produces baby-soft skin. So we imagined he heals quickly, still, but it leaves a scar. The simple idea was that his body would start to get a little more ravaged with a kind of tattooing of past battles, lacerations that remain of previous conflicts.”
Como Logan ficou mais velho, seu fator de cura diminuiu, fazendo com que ele envelhecesse e suas feridas se curassem mais devagar, resultando em cicatrizes.
Pode-se notar que a Transigen também está fazendo algo que afeta o suprimento de água do público em geral - não está claro, mas é possível que eles adicionaram algo à água que afetou / envenenou a população mutante.