Researchers at University College London developed a new way to measure how memes are made and spread. What they found won’t surprise anyone who’s peered into the darker parts of the internet in the last few years: The most toxic, yet most effectively spread, memes are first shared on two places, the subreddit r/the_donald and 4chan’s “politically incorrect” forum, called /pol/.

The researchers said they studied multiplatform meme ecosystems, with a focus on “fringe and potentially dangerous communities.”

“Considering the increasing relevance of digital information on world events, our study provides a building block for future cultural anthropology work, as well as for building systems to protect against the dissemination of harmful ideologies,” they added.

They’re not the first to think deeply and academically about the meme ecosystem, but the patterns they found also bolster what we already knew about memes: that based on sheer size and spread of these communities, you’re probably sharing images that were made to be distributed in toxic communities.

The researchers gathered a database of more than 100 million images from