Molecular clock
The "Mostly Male Theory" has a more genetic basis. Proponents of this theory point out that the gymnosperms have two very similar copies of the gene "LFY" while angiosperms only have one. Molecular clock analysis has shown that the other "LFY" paralog was lost in angiosperms around the same time as flower fossils become abundant, suggesting that this event might have led to floral evolution. According to this theory, loss of one of the "LFY" paralog led to flowers that were more male, with the ovules being expressed ectopically. These ovules initially performed the function of attracting pollinators, but sometime later, may have been integrated into the core flower.