Search Here

Scientists have discovered that bird eggs are fertilized by more than one male, upending decades of long held scientific thought.

Polyspermy, which is when more than one sperm fertilizes an egg, is quite rare, but also quite critical to birds, even if researchers aren't exactly sure why, The New York Times reports. The study with the findings was published in Proceedings of the Royal Society B.

The discovery was made after researchers inseminated eggs from chickens and zebra finches with different numbers of sperm. The eggs that had lower numbers of sperm penetrate them also had lower survival rates.

With the zebra finches, the scientists used anywhere from one to 15 sperm, while in nature zebra finch eggs are typically fertilized with anywhere from 10 to hundreds of eggs.

The chickens were inseminated with 10,000 sperm, which is low for the species, while other chickens were given as much as 10 million sperm.

The researchers theorize that the extra sperm may be necessary to help along cell development and activity.