The issue focused on exploring genetic similarity among monkeys (Bailey et al., 1999), exploring similarities among apes (Masuda et al., 1997), examining chimpanzee physiology (Yang et al., 1997), examining phylogenetic trees (Walker et al., 1995), examining phylogenetic structures within phylogenetic trees (Bowyer et al., 1993), examining phylogenetic structures among apes (Allen et al., 1991), examining phylogenetic structures among primates (Cowden et al., 1988), examining phylogenetic structures among reptiles (Gilchrist