That point about the sarsens and antlers representing the "ancestors " is purely 21st C speculation and isn't even based on folklore .
I think I may have missed the bit about antlers representing the ancestors but the small sarsen boulders found within Silbury may be a different matter. It is true that a connection between the boulders at Silbury and the ancestors may be 21st (and 20th) century speculation but so too is much of the speculation found on these pages - speculation which has subsequently been accepted by the academic community.It's good to see this topic now opening up on TMA and, while not wishing to detract from that, an interesting parallel discussion will also be found here - http://www.eternalidol.com/?p=6179