来自《耶鲁大学开放课程：心理学导论 第11集》

• 
  
  can he reproduce and copulate with the females.
  他才可以和雌狮们交配及繁衍后代
• 
  
  The females do their spontaneous abortions
  雌狮们自然的流产
• 
  
  because that's a reliable adaptive trick.
  因为这是一个很现实的适应技巧
• 
  
  These cubs are not going to survive once they are born
  这些小狮子们生下来也活不成
• 
  
  so the female's best strategy
  所以雌性的最佳选择
• 
  
  is to get rid of them and start anew.
  就是抛弃它们并重新开始
• 
  
  From a psychological point then,
  从心理学的角度来看
• 
  
  animals have evolved to be nice to their kin,
  动物们总是进化成对亲属友好的样子
• 
  
  particularly their children,
  尤其对它们的孩子
• 
  
  and particularly in birds and mammals.
  这点在鸟类和哺乳类动物中特别明显
• 
  
  Birds and mammals invest in quality
  鸟类和哺乳类(对后代)是有质量的投入
• 
  
  and not quantity,
  而非有数量的投入