What is the theme in The Valley of Horses: A Novel by Jean M. Auel?

Brotherly Love is another theme in the book. Jondalar is content in his life. Jondalar is not in love, but has a spirited woman he might mate. However, when Jondalar's brother, Thonolan, announces he wants to go on a Journey, Jondalar immediately jumps at the chance to go along. Thonolan often questions Jondalar's motives, accusing him of running away from the spirited woman who is determined to force him to settle down. Jondalar denies it but admits to himself that perhaps he is running from a loveless mating.