How do animals progress through their spiritual evolution? What can be the cause of the degradation of human soul?

There are various kinds of animals in the natural world, and there are various phases or in manifestations of their souls. 

Some are primitive organisms, such as unicellular organisms, and some are highly-developed organisms, such as mammals. 

Animals have souls and are on the evolutionary path of spiritual practice over a long period of time, just as we are. 

Evolutionary process starting from simple organisms results in the emergence of more complex forms. The soul continues to be reincarnated in subsequent lives and eventually evolves into a more complex body of life during the spiritual evolutionary process.  

As for the animals, domestic animals and those that associate with people, such as pets, are spiritually advanced living creatures. 

Humans and dogs, cats have lived side by side for many years, and they are especially spiritually evolved animals. 

In fact, some of them plan to be reborn as human beings, and live with people in preparation for it. 

They deepen their learning even further by feeling the complex human feelings and having various experiences with people. Animals evolve by the influence of interacting with humans or human activities. 

Particularly, it is love from people that enables them to promote spiritual growth and development. Love is the one thing that determines evolutionary leap of their souls. 

Well-loved animals will be able to sense your love towards them, then they return their love that you are given. 

In this way, they are able to achieve substantial spiritual development by receiving love, and eventually some will be reincarnated into human beings. 

Love is the source of the spiritual development. 

Once animals learn about love and recognize this, it enables them to take an incredible leap of the soul. 

Contrarily, a human being is worse than any beast when he loses sight of the love. 

According to Buddhist thought, all living beings are reborn into a lower or a higher realm depending on their actions while still alive. Chikusho-do (world of animals) is the hell of beasts, it's the idea that  one of the  worlds where people go after their deaths 

Living a life without love and acting based on an animal instinct would result in bad effects. Their actions in this life impact where they are reincarnated into the next.  Those kinds of people would be born again in the animal realm. 

In other words, both humans and animals can evolve by learning to love, but degenerate by losing their love. 

Translated by UCO