Animals and humans in Science vs. Buddhism About the doctrine of the 31 realms of existence. I have a few questions, because science, especially the theory of evolution, makes a good argument for categorizing humans as animals.


Is this list of 31 realms static or can single realms vanish? Because due to science we know that this earth won't last forever. This would mean, that there are no animals or humans anymore, unless a similar species lives on another planet somewhere in this universe (which is very, very, very unlikely if you consider the set of condition it took of several billion years to evolve humans).
The theory of evolution proofs, that humans have evolved from animals and just use different techniques for surviving as every other species as well. So knowing that there was a time of transition, where there only existed primordial human beings, how could you at that time say if it was a human or an animal? How can you cross that line between one species (humans) and every other one? Because it is sure, that in the next few 100.000 years humans will have evolved to a totally different species according to the conditions in the environment.      


So how should you understand this classification of beings. Is it just a provisional and time-dependent concept? Or is it only related to the degree of suffering, which predominate each realm?

I know on this topic are already many questions. But none of these related to this particular question. So please don't tag as duplicate.
Some Buddhists regard the realms of existence as psychological states of people. For example, if you are moral &amp; humane, you have a 'human' existence. If you act impulsively, without self-control, without reasoned reflection, &amp; particularly without moral conscience &amp; with violence, your state of mind is like an 'animal'.

The following quotes from the scriptures support this view. Particularly, the quote at the bottom states an 'animal', by realising the Four Noble Truths, can be reborn as 'human', such as occurred to Angulimala  (the former mass murderer who became a fully enlightened monk), as shown in the video link at the bottom.  


  Monks, these two bright qualities guard the world. Which two?
  Conscience &amp; concern. If these two bright qualities did not guard the
  world, there would be no recognition of 'mother' here, no recognition
  of 'mother's sister,' 'uncle's wife,' 'teacher's wife,' or 'wife of
  those who deserve respect.' The world would be immersed in
  promiscuity, like rams with goats, roosters with pigs or dogs with
  jackals. But because these two bright qualities guard the world, there
  is recognition of 'mother,' 'mother's sister,' 'uncle's wife,'
  'teacher's wife,' &amp; 'wife of those who deserve respect.'" 
  
  http://www.accesstoinsight.org/tipitaka/an/an02/an02.009.than.html


~~~~


  I have heard that on one occasion the Blessed One was staying in
  Savatthi at Jeta's Grove, Anathapindika's monastery. Now at that time
  a large number of monks, after the meal, on returning from their alms
  round, had gathered at the meeting hall and were engaged in many kinds
  of bestial topics (tiracchānakathaṃ) of conversation: conversation
  about kings, robbers, &amp; ministers of state; armies, alarms, &amp; battles;
  food &amp; drink; clothing, furniture, garlands, &amp; scents; relatives;
  vehicles; villages, towns, cities, the countryside; women &amp; heroes;
  the gossip of the street &amp; the well; tales of the dead; tales of
  diversity, the creation of the world &amp; of the sea; talk of whether
  things exist or not.
  
  http://www.accesstoinsight.org/tipitaka/an/an10/an10.069.than.html


~~~~


  Few are the beings who, on passing away from the animal realm, are
  reborn among human beings or gods. But far more numerous are reborn is
  hell. For what reason? They have not seen the Four Noble Truths. 
  
  SN 56.123 (no link)


Video link: https://www.youtube.com/watch?v=i49oX1Shxf4