But multiple locally optimal strategies could be deduced from these assumptions. On the one hand, if a woman finds a man that stays, and has a child with him, the kid is likely to survive, and reproduce on his/her own, thus continuing the genetic line.
On the other hand, if she gets impregnated by a man who leaves, the chance of the baby reproducing are lower. However, if the father was very evolutionarily successful (great genes, exceptionally high mate value), even the low chance (5% for a male child that reproduces) can result in her genes being spread far and wide (assuming that the male child inherits his father's genes that make him very evolutionarily successful). Furthermore, the expected payoff of this strategy is further increased by the fact that (1) a woman can try this tactics multiple times in her life, and (2) she can cuckold a man that will stay with the child of the man that left.
The second strategy explains many this in our society, for example "why nice girls like bad boys", why "preselection" or "social proof" works for women, and why no sex before marriage was/is so strictly enforced in many societies.
On the other hand, if she gets impregnated by a man who leaves, the chance of the baby reproducing are lower. However, if the father was very evolutionarily successful (great genes, exceptionally high mate value), even the low chance (5% for a male child that reproduces) can result in her genes being spread far and wide (assuming that the male child inherits his father's genes that make him very evolutionarily successful). Furthermore, the expected payoff of this strategy is further increased by the fact that (1) a woman can try this tactics multiple times in her life, and (2) she can cuckold a man that will stay with the child of the man that left.
The second strategy explains many this in our society, for example "why nice girls like bad boys", why "preselection" or "social proof" works for women, and why no sex before marriage was/is so strictly enforced in many societies.