Slave-Importing only ended when it became a 'biological crime' as well as an ethical crime

Millions around the world had profited, directly or indirectly, for centuries from the labour of 'imported' (aka kidnapped) slaves.

But suddenly, mid nineteenth century, they developed new (post Darwin) fears that age-old 'slave and master' miscegenation would lead inevitably to eugenic rot and race death.

Only then did the practise finally end.

For the minority who had always seen slavery as a (ethnical/moral) crime had never made much headway --- until the majority invented a new moral panic around the possibility of biological crimes 'against the race'....