Many people have discussed the dating of the book of Genesis. In this post, I will outline why I believe the original copy is indeed from the time period of the Hebrew association with the Egyptians..
Note that I am not a scholar on Hebrew. However, the average person can easily check the logic of my argument and the Hebrew vocabulary using the standard online tools like Bible Gateway or your favorite scripture tools.
The traditional view held by Jewish rabbis of the period of the early church was that Moses wrote Genesis. This could be considered a form of legend, as the book of Genesis does not specifically say anywhere that it was written by Moses. This put its date of writing during one of the Egyptian dynasties, although there is much debate about how - or whether - this was possible.. The proposal by people who hold to this view is that Moses learned all about Egyptian culture, Egyptian gods, and Egyptian way of life as an adopted son in Pharaoh's court. This was all done by God as a preparation tool for Moses to be chosen as a leader, to learn to read and write, and to then to use that knowledge write the original Tanakh / Pentateuch.
To my knowledge, there is no way to prove beyond all doubt this is the truth. However, we can search the text to look for hints as to the author and in the case of this post, the dating of the book or at least the first chapter.
A theory arose in the late 1800s that the entire Jewish scriptures were the compilation of four primary sets of contributors over a long period of time. I think it important to point out that this is not four different people. The hypothesis is that four different sets of people all over the ancient near east felt lead over time to preserve, copy, and update the Jewish traditional texts. As they made new copies of the text, changes creeped in, and we are now left with the final copy. The theory is that three of these groups were primarily involved over time with the writing of Genesis and as such the book has portions that were written at different times, much like editing a Google Doc with friends over hundreds of years.
The theory continues by proposing each group saw it as their duty to push their own theological views and as such the "flavor" of their theology can be spotted in the text through vocabulary and grammatical structure.
The debate on this is long and intense and there is no formal agreement among all scholars. I find this to be a "just so" theory that is unfalsifiable. It is a fun idea to play around with, but it was not invented until the 1800s and there is no earlier reference to anyone that thought this way.
We may not be able to find an exact date, but I think it important we recognize that with a little hard work, we can at least discover the cultural context in which a book was written. Then by learning about the cultural context, we can build up a better ability to understand the images and concepts that the words within the book would have triggered in its first readers.
First of all, I highly recommend reading the following article which outlines the Egyptian parallels in the creation story in Genesis 1:
Genesis 1 and Ancient Egyptian Creation Myths
The thing I would like to note here is that Genesis 1 appears to be taking jabs at Egyptian theology and origins by reducing the power of Egyptian gods and placing mankind as a dignified part of creation rather than as an accidental byproduct. The people of that day and in that culture would have spotted these differences from the mainstream teaching first.
We can also use clues in the text within other parts of the Bible to determine the "threads" of thought and then possibly find a date for a passage. If we can show that a text quotes another part of the Bible, then obviously that text was written later.
Note that what follows is something I discovered, and has not been reviewed by anybody. Secondly, I am guessing I am not the first one to find this, so if someone points out where this was first discovered I would love to add that to this page.
Here is the proposed historical flow of the relevant concepts in what I am presenting:
In Genesis 1:14, we find the following text (Young's Literal Translation):
"And God saith, ‘Let luminaries be in the expanse of the heavens, to make a separation between the day and the night, then they have been for signs, and for seasons, and for days and years, and they have been for luminaries in the expanse of the heavens to give light upon the earth:’ and it is so. And God maketh the two great luminaries, the great luminary for the rule of the day, and the small luminary — and the stars — for the rule of the night; and God giveth them in the expanse of the heavens to give light upon the earth"
In Psalm 136:7-9, we have (Young's literal translation):
"To Him making great lights, For to the age [is] His kindness.
The sun to rule by day, For to the age [is] His kindness.
The moon and stars to rule by night, For to the age [is] His kindness."
The sequence is clear, the passages are clearly referencing the same ideas. However, you will note that in Psalms the sun and moon are referenced by name, but in Genesis they are not. The only question, then, is which one came first? Is Genesis referencing Psalm 136 or is Psalm 136 referencing Genesis 1?
Our clue could be in the vocabulary. In Genesis, there is no reference to the Hebrew word for sun or moon. Instead, the text says there is a "big lamp" and a "little lamp" or a "big luminary" and a "small luminary". In Psalms 136, however, the sun and moon are referenced by name. Same sequence of ideas, but different vocabulary.
It seems to be that whoever wrote Genesis was intentionally avoiding the use of the Hebrew words for sun and moon, and instead opting for calling them a big light and a little light. Why?
As referenced in the former article, the working theory of many scholars is that the author of Genesis 1 was doing this as a mocking device against the other nations that believed the sun and moon were gods. By directly avoiding the Hebrew words for sun and moon, the author (whether Moses or anyone else) is doubly saying the sun and moon are not gods.
An author could conceivably write Psalm 136 and opt for the "shortened" version of the Genesis 1 account, filling in "sun" and "moon" in place of the longer version of "big light" and "little light". The author at that point in time was not in a context where mentioning sun and moon would be considered as referencing a deity. However, it makes less sense that the author of Genesis 1 would take from Psalm 136, since Psalm 136 also mentions other things that appear to be pulled from other parts of the Pentateuch. It is not impossible that Genesis 1 and Psalm 136 were pulling from another oral tradition, I am simply pointing out that it fits well if Psalm 136 is referencing Genesis 1.
And the cool thing is, we have good evidence of when Psalm 136 was probably written. Scholars are fairly confident that Psalm 136, or at least a part of it, was sung at the dedication of the temple in 2 Chronicles 7:3:
"And when all the children of Israel saw how the fire came down, and the glory of the Lord upon the house, they bowed themselves with their faces to the ground upon the pavement, and worshipped, and praised the Lord, saying, For he is good; for his mercy endureth for ever."
It is possible that this was just a standard saying and the author of Psalm 136 took from this oral tradition, but I think that is unlikely. I think it just makes sense that the writing of Psalm 136 would have been around the same generation as 2 Chronicles 7:3.
So from this, it is reasonable to conclude that Genesis 1 was written in large part before the period of the dedication of the temple, and not during the second temple period or the exile. And since the language of Genesis seems to be a polemic against Egyptian teachings, per the link above, it is reasonable to conclude it was written during a period when the Hebrews were deeply surrounded by Egyptian ideology. And the main period when that occurred would have been during the deliverance from the Egyptian slavery as recorded in the text.
In other words I see no reason to conclude that Genesis 1 could not have been written during the period of the deliverance from Egypt. This obviously says nothing about the other parts of Genesis, but it makes a lot of sense of the first chapter at least.