The Tangled Bank Theory

Michael Ghiselin developed this idea further in 1974 and made some telling analogies with economic trends. As Ghiselin put it, "In a saturated economy, it pays to diversify." Ghiselin suggested that most creatures compete with their brothers and sisters, so if everybody is a little different from their brothers and sisters, then more can survive. The fact that your parents thrived doing one thing means that it will probably pay to do something else because the local habitat might well be full...