Before revision: Males vs. females Given the demands of fetal loading during pregnancy and the importance of producing offspring to the fitness of human beings, one can imagine that natural selection has had a role in selecting a unique anatomy for the lumbar region in females.
After revision: Evolutionary implications Given the demands of fetal loading during pregnancy and the importance of producing offspring to the fitness of human beings, natural selection may have had a role in selecting a unique anatomy for the lumbar region in females.