Human Sacrifice and Aliens

I was reading an article about human sacrifices in the history of mankind, and suddenly it dawned on me that this practice could have been initiated by aliens on the poor helpless people in those dark ages. Think of these points :

1. why would anyone kill one of his own kind for whatever reasons, other than that there is no other choice?
2. why were human sacrifices almost always a young woman? why not an old man, old woman, or even a young man?
3. the altars used by these ancient people were always high, and often on a mountain - this suits the aliens' spacecraft coming from the sky; it also makes it easy for them to locate the altar;
4. why were sacrifices done on a regularly basis?
5. very often, the reason recorded for these sacrifices was 'to appease the gods'.
6. some sacrifices were also burnt; why?

Today, we do not see such practices any more, and there is no need to appease these gods. Why? I suspect that the aliens involved could have located these isolated tribes and used technology to frighten them into believing that they were god/s and then forced them to worship and obey them (sounds just like what happened in the Bible, right?).

It could most likely be that the aliens wanted something from a young, healthy body for their genetics or other experimentation. Maybe they could not procreate on their own anymore and needed something from us. Or maybe they wanted to taste human meat (then that explains the burnt sacrifice)? Even the Bible talks about human sacrifices, with the Bible-god asking Abraham to sacrifice his own son.

Alien Abductions

Today we have stories of abductions of humans by aliens. Could it be that the aliens cannot use the same method of human sacrifice so they use force to get what they want to from us?