But what Dr Turner has done is logically equivalent to the step taken by, for example, one particular chimpanzee retrovirus when it leapt to humans and evolved into what is now known as HIV.

• 人类感染了非洲黑猩猩身上的一种特殊的反转录病毒，这种病毒就会发展成现在人所共知的HIV病毒。