AdvertisementTrilobites A Population of Billions May Have Contributed to This Bird’s Extinction Image Passenger pigeons were once so plentiful in North America that flocks blotted out the sun. Credit Bailey Library and Archives, Denver Museum of Nature & ScienceNorth America was once a utopia for passenger pigeons. Analyzing the DNA of preserved birds, the researchers found evidence that natural selection was extremely efficient in passenger pigeons. This caused a loss in overall genetic diversity, which meant less raw material for adapting to human-induced change. Her team inferred that passenger pigeons had a huge, stable population for at least 20,000 years before extinction.

Source: New York Times November 16, 2017 19:30 UTC