Interbreeding with Neanderthals was likely a mixed bag for our ancestors. Our recent feature story “How Neanderthal DNA Helps Humanity” detailed how Neanderthals (and Denisovans) supplied early humans with genetic variants that helped them adapt to new environments. But our ancient cousins also gave us some genetic duds. According to the new findings, published in Genetics this month, Neanderthal genomes were rife with harmful DNA that significantly reduced the species’ fitness. The researchers conclude that Neanderthals were roughly 40 percent less fit than modern humans, meaning they were less likely to produce offspring.
https://www.quantamagazine.org/20160614-the-downside-to-neanderthal-dna/
