Often you can come up with better explanation by taking a wider view. For example, I’ve heard people suggest that Europeans have lower IQs than Ashkenazi Jews because of priestly celibacy.
But a broader perspective suggests that is not key: lots of populations that never had anything like priestly celibacy score lower and accomplish less than Western Europeans. Western Europeans aren’t anomalously dumb – Ashkenazi Jews are anomalously smart. Look for an explanation based on their genetics and history, not someone else’s .
In the same way, when looking at the wave of extinctions in North America about 12,000 years ago, the story becomes clearer if you consider the extinctions in South America ( a bit later), in the Caribbean islands ( thousands of years later), in Australia ( about 46,000 years ago) , on Madagascar and New Zealand, on various oceanic islands ( flightless birds disappear in Oceania and the Azores): the common factor is the arrival of modern humans.
Similarly, when considering the origin of cognitive differences between racial groups in the US, a wider perspective is helpful. Probably low scores in Zimbabwe are not caused by structural racism or implicit bias. You might want to blame Mugabe – but scores are similarly low throughout sub-Saharan Africa.