The abstract mostly seems to state &quot;increased intelligence is currently too difficult to measure, so we wouldn&#x27;t know.&quot;<p>Which is fair. But &quot;is a myth so far&quot; suggests disproof, not proof that it&#x27;s not currently true. As they repeatedly show, it would be very difficult for them to prove that, since they&#x27;d have to usefully measure delta in intelligence.