The study suggests morality would be a steadily declining slope throughout this time rather than a periodic wave if it were true. This is not so. It merely swings over shorter periods of generations.
We have gone through times of slavery, racism, imperialism, war, reclamation and so on. All of these things cause moral reflection and transformation.
Just last week some so-called philosopher suggested the best way to communicate with aliens would be to start killing them, and many HN commentators agreed, despite this pundit not really know where things should go after that. It’s like C Columbus all over again. I’m pretty sure the world reeled for some generations from that one (Montaigne).
I think those conducting this research are poor students of actual history.
Objective morality: it is immoral and wrong to harm the innocent. Ever.
Everything else (sex, drugs, concern for each other, regard for our differences, etc.) has a realm of “subjective relativism“. These can be difficult to plot.
Harming the inculpable for personal, political, or convenience in any form at any time is absolutely wrong and this attitude changes periodically throughout time.
As a student of history I can say twelve million data points scattered over several millennia does not give a grounded scale where lives of generations vacillate in merely decades.
Shall I start with Gilgamesh? Things could only improve. Hammurabi? They did improve. Cyrus the great? His fore-bearers ethnic cleansed and salted the earth so nothing could grow for f-sake. He was a civilizing force.
Europe? Reformation? Christians burned each other alive.
America? We’re now back to being more racially charged than we were 30 years ago (which was objectively better than 50 years before that.
Obviously times do change, we are rising and falling and we must be vigilant for this happens within our lifetimes.