I think some of the above posters are looking at it in the wrong way. Instead of rationalizing why the Africans are losing, we should be asking why non-Africans sucked so much in the 90s and early 2000s or why they’ve improved so much since.
Look through old championship 5k results and you’ll see what I mean. In 2003, all the non-Africans were left in the dust before the last 800m burn up, and the top non-African finisher was Juan Carlos de la Ossa in 13:21–over 28 seconds behind Kipchoge! The American in the final, Jorge Torres, placed last in 13:43. He had a 13:20 lifetime best with 3:41 1500 speed—he wouldn’t even come close to making a U.S. team these days. 1999 is another good one: the top 8 finishers were African-born and the remaining 6 finishers were non-African. Americans Bob Kennedy and Adam Goucher ran 13:23 and 13:39 respectively, in a race won in 12:58…
Bob Kennedy and Craig Mottram at their peaks were seen as total anomalies, far separated from their countrymen and the only non-Africans running sub-13 for 5k. Now there are a dozen non-Africans of a similar caliber + a Jakob Ingebrigtsen who’s on another level entirely. There are still plenty of Africans running fast 5ks, the difference is non-Africans are running much faster.
As for the 1500, would you believe that throughout the entire decade of the 90s only 7 men broke 3:30?—6 of whom were African, 1 of whom was Fermin Cacho. Whereas in 2023 alone 5 men not of African heritage have broken 3:30, plus a slew of guys in the 3:30-3:32 range.