He may be talking about the last common ancestor (LUCA)which at last calculation was ~3500 years ago. IMS
Ah, right. What he may not realise is that LUCA's certainly cannot be sole ancestors. The genetic evidence indicates otherwise. There were numerous other people alive at the time who contributed to the modern gene-pool. It is just that the LUCA is the most recent person who contributed to the DNA of *everyone* alive today. The LUCA is in any case a retrospective coronation. When the LUCA was alive there was almost nothing whatever significant about that person that would have set them apart from their contemporaries. If a modern epidemic wiped out 99% of the human race, for example, than the LUCA's identity would almost certainly change to a more recent person. I am sure you know this, but it is worth pointing out for the lurkers.