I recently communicated with Dr Schmidt (he heads up the Gobekli Tepe excavation) on this topic of Dakhmas. Here is the email --
Dear Dr. Schmidt,
> I have followed with great enthusiasm your excavations in Turkey. It has
> potentially changed my entire conception of the Neolithic Revolution. I
> recently came across a verse in the Zoroastrian text of Zend Avesta
> that you
> may find interesting. It could help explain the cultural purpose of the
> Gobekli Tepe structures:
> “With regard to Dakhmas, see Introd. V, 10. 'Nor is the Earth happy at
> place whereon stands a Dakhma with corpses upon it; for that patch of
> will never be clean again fill the day of p. 25 resurrection' (Gr.
> Rav. 435,
> 437). Although the erection of Dakhmas is enjoined by the law, yet the
> in itself is as unclean as any spot on the earth can be, since it is
> in contact with the dead (cf. Farg. VII, 55). The impurity which would
> otherwise be scattered over the whole world, is thus brought together
> to one
> and the same spot. Yet even that spot, in spite of the Ravaet, is not
> to lie
> defiled for ever, as every fifty years the Dakhmas ought to be pulled
> so that their sites may be restored to their natural purity (V. i.
> Farg. VII,
> 49 seq. and this Farg. § 13).”
> I found this compellingly similar to what you have found at Gobekli Tepe.
> Good luck to you. Have a nice day.
Dr Schmidt responded --
"Dear Mr. Sims
thank you for your interesting reference, yes, the hypothesis, that the
Göbekli Tepe enclosures had been neolithic Dakhmas seems highly probable"
This is interesting, since there is no reference to Dakhmas in the NatGeo special. But it would seem Schmidt agrees with the Dakhmas theory.