- Firstly, we are looking at the fairly recent domestication of the species; in the wild it is likely that roosters would be naturally part of the flock and all eggs produced would be fertilized. In the domestic situation roosters are often not present but the evolution of the hen has not (as yet anyway) been modified!
If we look at egg production in any species we will notice that eggs are usually released and developed in a cyclic manner (we humans are no different). If you see this cyclic process as being wasteful at times then the label will fit for most animals, not just the humble hen!
Finally, you could suggest that it is a downside to the evolution of the egg shell! Animals that produce soft shelled eggs usually have a requirement for water in the reproductive process. In fact, for many of these species the eggs are fertilized outside the female body. Although the addition of an egg shell removed the dependence on water for reproduction, it also removed the possibility of fertilisation once the egg is laid!
So there you have it, these are some of my thoughts on the subject. I am not suggesting that any of these points are backed up with scientific findings…. the are just the random thoughts of this simple scientist! Maybe you have your own theories to add?