This comment has been deleted by ni
researchers discovered that the animals strongly objected if they perceived others were being rewarded more than themselves for the same task. Some even sulked or refused to take part any further.
Though if you think about it, spite doesn't work without the expectation of fairness.
The "roots of morality" they mention seem to be things I read about over a decade ago, in books that were old at the time. The article doesn't really go into the experiments though.Chill out, snowflake.
If you're interested, I can take five minutes to dig up the paper to snag the reference.
This comment has been deleted by jxg