I can find the first 4 precepts explicitly listed in the 8fold Path- but not the 5th precept regarding intoxicants. Am I missing it in there somewhere? I am wondering if it was a later addition to the tradition.
There is an interesting relationship between the first four precepts and the fifth precept.
For e.g. from the Kalama Sutta (quoted below), we can see that the fifth precept is not included. You can find a similar grouping of the first four precepts in the Sigalovada Sutta as the four vices. It also appears in this way in the Sankha Sutta.
But there's a reason for this. Consuming intoxicating substances is by itself not a vice or evil act (unlike killing, stealing, telling lies and sexual misconduct), but it can cause you to become heedless and violate the first four precepts.
In this sense, the fifth precept is only there to support the first four precepts (and the rest of the training).
From the Kalama Sutta:
“A greedy individual, overcome by greed, kills living creatures, steals, commits adultery, lies, and encourages others to do the same. Is that for their lasting harm and suffering?” “Yes, sir.”
“A hateful individual, overcome by hate, kills living creatures, steals, commits adultery, lies, and encourages others to do the same. Is that for their lasting harm and suffering?” “Yes, sir.”
“A deluded individual, overcome by delusion, kills living creatures, steals, commits adultery, lies, and encourages others to do the same. Is that for their lasting harm and suffering?” “Yes, sir.”
From the Sikkha-Dubbalya Sutta:
"Monks, these five are things that weaken the training. Which five? The taking of life, stealing, sexual misconduct, the telling of lies, and distilled & fermented beverages that are a cause for heedlessness. These five are things that weaken the training.
Please see this question for more info on heedfulness (appamāda).
AN4.201 lists these five:
And what is a better person?
It’s someone who doesn’t kill living creatures, steal, commit sexual misconduct, lie, or use alcoholic drinks that cause negligence.
And they encourage others to avoid these things.
This is called a better person.
This works for me. Does it work for you?
The Noble Eightfold path actually has 7 precepts (3 bodily + 4 verbal). In many suttas, the Buddha talk about the 7 precepts instead of the 5.
The 7 precepts are earlier because they are included in the Noble Eightfold Path. As the monastic sangha grew, new precepts were gradually added (including the 5th precept); most of the precepts were added after some issues had occurred and to prevent the same incidents from happening again.
Origin of 5th precept as I heard from Ven Dhammavuddho (abbot of Vihara Buddha Gotama): There was a monk who possessed psychic powers (means he attained at least the 4th Jhana). He had just tamed a Naga (snake spirit) and the villagers were very grateful. They wanted to make an offering and asked him what he wanted. He didn’t want anything but his fellow monks suggested he asked for alcoholic beverage. So, the monks drank the alcohol. His fellow monks were seasoned drinker; so they were not drunk. However, this monk became drunk. When they went back to see the Buddha, this monk had his feet pointing towards the Buddha (which he would not have done if he was sober). The Buddha asked the other monks whether this drunken monk could fight the Naga now. The answer is obvious; he couldn’t. From this incident, the Buddha added the precept to abstain from consuming intoxicants, which leads to heedlessness.