What specifically is in the Pentateuch that later writers could not have known?

Since the story of creation, and especially from creation in Genesis 1:1 until the sixth day; The only ones around were the three members of the Trinity; those revelations could only be divine.

Several other incidents such as Cain slaying Able did not have a lot of eye witnesses.

Several pastors I have encountered have felt that these things were probably told to Moses during is first 40 day visit with God on the mountain.

1. Could the Pentateuch have been written by ordinary scribes in the Iron Age

2. Are there actually specific details that could have only been known at one point in time

   1. Something people of the Bronze Age would have known was that the southern coastline was still occupied by Canaanites - the Philistines did not arrive until Iron I. This is something that ordinary scribes later in the Iron Age could not have known. There are quite a few mentions of the Philistines, such as in Genesis 21:34 (And Abraham sojourned in the Philistines' land many days.), demonstrating that Genesis, at least, could have been written by ordinary scribes in the Iron Age.

   2. If we are talking specifically about details that prove Bronze Age authorship, there is little likelihood that there were specific details that could only have only been known at an earlier point in time. Whenever we can verify information in the Pentateuch, we find that the information could as easily have been known in the Iron Age as in the Bronze Age. Conversely, Iron Age writers would have known that Philistines occupied the southern coastline and would have believed that always to have been the case.

^{To head off non-constructive debate in comments, bear in mind that whether these are convincing arguments is off-topic for the site. That sort of thing belongs in chat.}

If I'm not mistaken, you're referring to the medical knowledge implicit in some of the Mosaic law. The standard Apologetic argument goes that long before modern medical knowledge, God gave Laws relating to cleanliness and avoiding disease and other scientific knowledge that was well ahead of its time.

An example is found at bibleevidences.com

Sample:

Sanitary Practices

For centuries doctors denied the possibility that disease could be transmitted by invisible agents. However, in the late 19th century Louis Pasteur demonstrated in his Germ Theory of Disease that most infectious diseases were caused by microorganisms originating from outside the body. This new understanding of germs and their means of transmission led to improved sanitary standards that resulted in an enormous drop in the mortality rate. Yet these core principles of sanitation were being practiced by the Israelites thousands of years earlier.

The Israelites were instructed to wash themselves and their clothes in running water if they had a bodily discharge, if they came in contact with another person's discharge, or if they had touched a dead human or animal carcass. They were also instructed to wash any uncovered vessels that were in the vicinity of a dead body, and if a dead carcass touched a vessel it was to be destroyed. Items recovered during war were also to be purified through either fire or running water. In addition, the Israelites were instructed to bury their human waste outside of camp, and to burn the waste of their animals (See Numbers 19:3-22, Lev. 11:1-47; 15:1-33, Deut 23:12).

Circumcision and Blood Clotting

For centuries scholars must have been perplexed by God's law of circumcision which required the procedure to be performed on the 8th day after birth (Gen 17:12, 21:14, Lev 12:3, Luke 2:21). Medical researchers recently discovered that the two main blood clotting factors, Vitamin K and Prothrombim, reach their highest level in life, about 110% of normal, on the 8th day after birth. These blood clotting agents facilitate rapid healing and greatly reduce the chance of infection. You can verify with any Obstetrician that the 8th day of life is the ideal time for a circumcision, and that any circumcision done earlier requires an injection of Vitamin K supplement.

If you move beyond the Pentateuch and into other Old Testament books, there are other scientific statements that don't match up with the beliefs of Pagan societies at the time.

The Earth and Space

The earth's shape is perhaps the most important to deal with first since many critics claim that the Bible portrays the earth as flat. This couldn't be farther from the truth and in my opinion is one of the most vaporous arguments used by skeptics against the Bible. There is not a single passage that plainly states that the earth is flat1. The groundswell of this criticism gets its roots from the inaccurate but common belief among many that the ancients on up through the middle ages believed that the earth was flat. The truth is, virtually all learned people have known for the last 2500 years that the earth is spherical [please see footnote 2].

Before the learned ancients surmised that the earth was spherical, the divinely inspired Isaiah wrote "It is He who sits above the circle of the earth...(Isaiah 40:22)". In addition, from the Book of Job we have "He stretches out the north over empty space; he hangs the earth on nothing (Job 26:7)". It should be noted that just last century scientists believed space consisted of a hypothetical substance called Ether (not the chemical), which was the medium between the celestial bodies. Also, the pagans of that time believed in such things as a mythical Atlas character who supported the pillars that held heaven and earth apart, and later carried the earth around on his shoulders. Another interesting tidbit that illuminates the divine nature of Job 26:7 is the recent discovery of a huge hole in space in the direction of the northern hemisphere3.

and...

The Hydrologic Cycle

The circulation and conservation of earth's water is called the hydrologic cycle, which is accurately portrayed in several passages of the Bible, including the following: "For He draws up drops of water, which distill as rain from the mist, which the clouds drop down and pour abundantly on man. (Job 36:27-28)" . Centuries after the Book of Job was written, Aristotle demonstrated only a vague understanding of this process. Though he recognized that rain came from clouds, he incorrectly postulated that air turned into water and vice versa.

There are more, and the site I linked to covers them in more depth, as does this site. Putting them all here would be counter-productive (and plagiarism) so I'll stop there.