The theory’s successes matter because they help ecologists understand what might be generating patterns in ecosystems. It’s a mystifying fact, for instance, that the majority of tree species in rainforests around the globe are rare. One would expect that the rare species would be outnumbered and ultimately displaced by common species, but instead the rare species persist. Most ecological models can’t mimic this situation. But it happens to be one of neutral theory’s most triumphant successes, implying that the persistence of rarity doesn’t require anything more complicated than randomness and the immigration of new species. [https://www.quantamagazine.org/20160311-a-timely-fix-for-a-grand-theory-of-nature/](https://www.quantamagazine.org/20160311-a-timely-fix-for-a-grand-theory-of-nature/)