No mention of culture in the article, and apparently the Mechanical Turk population isn't actually that large[0], seems like this is likely to be a pretty WEIRD[1] result.

The WEIRD paper actually references evidence that altruistic behaviour is punished in some cultures (Figure 4), so to do a study of something similar without a good handle on the cultural background of the participants seems pretty trash.

The do have the nicest open science solution I've ever seen though, with very pretty Rweave (or some other notebook) renderings easily available: https://osf.io/xecdt/

[0]: https://www.sciencemag.org/news/2016/06/psychologists-grow-i... [1]: https://www2.psych.ubc.ca/~henrich/pdfs/WeirdPeople.pdf