MadSci Network: Zoology |
Hi Richard:
Modern evolutionary theory (and science in general) cannot answer "why" questions - that is more the realm of philosophers. Chickens, being domesticated animals, are also what might be termed an "evolutionary special case". Chickens have been domesticated for something like 4000 years (e.g. see here), and so in the recent evolutionary history of chickens, selection has been done by humans (as opposed to natural selection); this is known as artificial selection, or "breeding".
So chickens have been selected by human breeders for many many generations to regularly produce unfertilized eggs - that is not a great strategy for an animal living in the wild, but chickens of course do not live in the wild. Indeed, I would argue that chickens require the aid (care and feeding, protection from predators) provided by humans - that's why feral chickens are pretty rare. Because chickens are cared for by humans, the evolutionary consequences of laying lots of unfertilized eggs becomes irrelevant.
Hope that helps,
Rob Campbell, MAD Scientist
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