The Seven Tribes have prospered since their liberation. Each year, they expand slowly outward as their population grows, a situation that has lead to the foundation of new settlements such as Griffentowne and Westholm. One factor in this growth is the fact that twin births are quite common among the tribals. Around one in ten pregnancies results in twins, usually fraternal. This can be traced back to the Z´bri selecting women likely to have multiple births to be breeders in their camps, and to the blessings of Eva the Mother.