Indigenous Indo-Aryans

This is the summary of Kazanas' paper:

[quote]In this paper I argue that the Indo-Aryans (IA hereafter)are
indigenous from at least 4500 (all dates BCE except when otherwise
stated) and possibly 7000. In this effort are utilized the latest
archaeological finds and data from archaeoastronomy, anthropology
and palaeontology. I use in addition neglected cultural and
linguistic evidence. I find no evidence at all for an invasion. The
new term 'migration' is a misnomer since a migration could not have
produced the results found in that area. The Rigveda (RV) is neigher
post-Harappan nor contemporaneous with the Indus Valley Culture
(IVC) but much earlier, i.e. from, the 4th millennium (with minor
insignificant exceptions) and perhaps before.[unquote]

I request members to comment on the linguistic evidence for this
thesis of Kazanas. Is it possible that the Rigveda is earlier than
the 4th millennium?