HALVING IS HARD. “The behavior of chromosomes in meiosis is much more complex than in mitosis. Additional demands such as chiasmata formation, mono-orientation of sister kinetochores, protection of centromeric cohesion, and prevention of DNA replication between the two divisions are imposed upon the chromosome segregation machinery.”
http://www.sciencedirect.com/science/article/pii/S0092867403000837