Here is the link to the original study:

http://www.cell.com/current-biology/fulltext/S0960-9822(17)31466-5

Here is the link to a BBC news blurb:

http://www.bbc.com/news/science-environment-42352256

Here is a link to a Huffington Post news blurb:

https://www.huffingtonpost.com/entry/dna-from-cincinnati-zoos-ipuh-provides-evidence_us_5a343df7e4b0e7f1200cfae1