My only assumption for this argument is that human society was matriarchal in the begninning. I've already discussed about three migrations that left their mark on Indian population and how closely related were Dravidians and Indo-Aryans. For the sake of clarity and based on the earlier discussions, I'll be using the terminologies R1A Dravidians(Indo-Aryans), H-Dravidians, L-Dravidians, J-Dravidians and R-Dravidians.
Somewhere in North-West of Indian Subcontinent:
Few male cousins made a plan that would change the course of human history(exact period is unknown). Till then any human migration(or invasion) was undertaken by both men and women. As a result society remained matriarchical with mothers controlling the social and religious order. However, this migration of few closely related cousins(now we know as R1A-Dravidians) would change all that. First time in the history, a Homo-Sapien community left Indian subcontinent(the third homeland of Dravidians after Africa and Middle-East) without any females and moved to South-East Europe.
Now they are the masters of the society:
In the Kurgan lands these R1A-Dravidians took up the girls of Pre-Indo-European population. In the confusion of cultural conflicts, these R1A-Dravidian males ended up performing the religious duties. Now they were the one dictating terms for the social conducts. The taste of power in the community also motivated them to invent new gods in their mould.
The new patriarchical world order:
When the society was matriarchal the only driving reason behind any migration or invasion was lack of food. However, the male order changed all that. Now there were more migrations and invasions that is driven out of want for more land and more women. The greed was born. The new male order multiplied quickly. The societies under its attack either also became patriarchical or became extinct.
Elsewhere in the blogosphere:
NuSapiens feels transition from matriarchy to patriarchy was brought about by climate change. But I will stick to my position that it was due to few only male R1A-Dravidian migration to Europe from the sub-continent.