They basically did not age at all. Look at it this way, @elfquestfanAZ: You enter a time machine and make a jump of 10,000 years into the future. This does not take time at all. No aging. Then you spend a day there ... ... while your tribemates and kin stay back and need to live on (or sleep) for 10,000 years. They need about a day or two to discover the Palace who has fallen back in time (in fact Picky did) and get there. Thus the immortals aged 10,000 years and the Wolfriders about 500 years (rest of the time they spent in wrapstuff).