Five Precepts - did Buddha really preach them? The five precepts are (from wikipedia)


I undertake the training rule to abstain from killing.  
I undertake the training rule to abstain from taking what is not given.     
I undertake the training rule to avoid sensual misconduct.  
I undertake the training rule to abstain from false speech.
I undertake the training rule to abstain from fermented drink that causes heedlessness.


I am very new to Buddhism, but from what I'm understanding right now, Buddha's teachings are very simple.
The first 4 rules make sense. They are all forms of practicing detachment.

But the 5th... it's too human. Too specific. I just don't see Buddha teaching it to his disciples.

It's the same as with Ānantarika-karma, where the last crime is creating a schism in the sangha (the community of Buddhist monks and nuns). It's too specific and so Buddhist oriented. Once again, I just don't see Buddha teaching it.

The question is, did Buddha teach the five precepts?
The five precepts are mentioned in Dhammika sutta. The main reason for teaching the fifth precept is said to be that intoxication easily instigates people to break other precepts by concealing the seriousness. 


  "Now I will tell you the layman's duty. Following it a lay-disciple
  would be virtuous; for it is not possible for one occupied with the
  household life to realize the complete bhikkhu practice (dhamma).
  
  "He should not kill a living being, nor cause it to be killed, nor
  should he incite another to kill. Do not injure any being, either
  strong or weak, in the world.
  
  "A disciple should avoid taking anything from anywhere knowing it (to
  belong to another). He should not steal nor incite another to steal.
  He should completely avoid theft.
  
  "A wise man should avoid unchastity as (he would avoid falling into) a
  pit of glowing charcoal. If unable to lead a celibate life, he should
  not go to another's wife.
  
  "Having entered a royal court or a company of people he should not
  speak lies. He should not speak lies (himself) nor incite others to do
  so. He should completely avoid falsehood.
  
  "A layman who has chosen to practice this Dhamma should not indulge in
  the drinking of intoxicants. He should not drink them nor encourage
  others to do so; realizing that it leads to madness. Through
  intoxication foolish people perform evil deeds and cause other
  heedless people to do likewise. He should avoid intoxication, this
  occasion for demerit, which stupefies the mind, and is the pleasure of
  foolish people.
  http://www.accesstoinsight.org/tipitaka/kn/snp/snp.2.14.irel.html


As for creating a schism in the sangha, my understanding is that this is not applicable for laypeople. Only monks are capable of causing a split. But a layperson can be a cause indirectly which isn't a severe offense.