I will try to address SOME of yann’s questions below. It takes some effort to understand the key concepts.
“Therefore, it is difficult to see how a human mind, even though it might be inhabited by greed or other mental impurities, could regress toward an animal life form post mortem.”
– The seeds for future lives are created during the lifetime. For example, if one kills another human, a kamma bija (seed) is created. That kammic energy can bring a “bad birth” in the future.
“Most of past life material i have read rarely if ever mention non human past lives.”
– Yes. Humans normally cannot recall past lives in other existence (bhava).
– Even that capability is there only for a few, and only as a child. As that child grows, such memories from past lives fade away.
“So human existence has a natural tendency to drag you toward fighting, hatred, accumulation of goods for survival, etc…”
– Not so if one comprehends Buddha Dhamma. Then one would stay away from such tendencies because one is aware of the bad consequences.
“Also if you are not born in a good environment, it is very difficult to develop intellect and understanding.”
“Most dying people are extremely tormented and unhappy. It seems absurd to me that they should be directed in a negative direction for a few understandable negative emotions.”
– Who is directing them? One is fully responsible for one’s destiny. If they had learned Dhamma, they would not be tormented.
“This passage is also hard for me to grasp.
Out of the 31 realms of existence (see, “The Grand Unified Theory of Dhamma“), the mind has much less capability in most other realms. Thus, it is very difficult to get rid of bad kamma seeds and cultivate good ones while in realms other than the human. Therefore, one should make the utmost effort to get rid of the bad seeds and to develop “good seeds” during this short life span of 100 years or so.”
– Think about the animal realm. Animals are like robots. They cannot learn Dhamma.
– Those in higher realms are CAPABLE of learning Dhamma. But they don’t have any incentive. They do not see much suffering around them.
“So human existence has a natural tendency to drag you toward fighting, hatred, accumulation of goods for survival, etc…. Even if you tend to be a moral person. Also if you are not born in a good environment, it is very difficult to develop intellect and understanding.”
– Yes. That is why relatively few people are interested in Buddha Dhamma. They do not take time to think about the “bigger picture” of the rebirth process among 31 realms. Of course, most people have not even heard about Buddha Dhamma.
“What would cause the end of this kammic potential?”
– One’s own thoughts with greed, anger, and ignorance (of the Buddha Dhamma).
Some of the essential concepts are discussed at, “Living Dhamma” and “Moral Living and Fundamentals” sections.