There are ideas that there was a pre-Adamic group of humans before Adam and Eve. A lot of this may be an attempt to reconcile scripture with naturalism. Some of it is driven by a misunderstanding of the Torah’s laws on sexual relationships, specifically “incestuous” ones. Unfortunately, some have taken this concept to the extreme and suggest that only those of certain ethnic heritage are true humans from Adam and Eve, meanwhile, other people groups are sub-human because they don’t come from Adam and Eve. This sounds like a syncretism with Darwinism being used to devalue some people as animals while others are seen as children of God.
Is there a pre-Adamic race of humans in Genesis? When looking at the whole bible including the new testament the answer seems to be no. Everyone comes from Adam and Eve because they are the start of all people. Paul states this in Acts 17:26, which says (NLT) “From one man (or blood) he created all the nations throughout the whole earth. He decided beforehand when they should rise and fall, and he determined their boundaries.”
He elaborates on Adam being the common ancestor of all people in 1 Corinthians 15:45-49. That is why Paul writes that all sin came through the one man Adam and affected all of humanity (Rom 5:12-17). This connects with why Jesus commands his followers to teach “all nations” in Matt 28:18. In addition, Paul says to pray that “all men” might be saved (1 Timothy 2:4). Lastly, when looking at the old testament in Genesis 6:1 says “Then the people began to multiply on the earth, and daughters were born to them…” Why is it significant that people multiply and daughters were born to them if there were a bunch of humans who had already pre-existed Adam? Does this mean Adam actually had a mother? Was Adam simply set apart as a priest with Eve rather than being created? If that is the case then why does it say he was created from dust? This is the same process God will use to resurrect all people in the end for judgment day (which happens in a day), so does that mean there is not literal then there is no literal resurrection of the dead? There is no set apart sub-human class that is in between animals and humans in the bible. More on this here.
A view of humans not related to Adam usually interprets the bible like this. In Genesis chapter 4, after Cain killed his brother Abel, he ran to the east of Eden “to a land named Nod”, to escape “people” who were trying to kill him. Then he “found a city” and met his wife from amongst the “people that built the city”, and then conquered the city and named it after his son Enoch. Is that really what the text says though?
1)I think the idea that Cain was fleeing from “some people” gets exaggerated. The only people mentioned in the text were his parents. So inductive reasoning says he was afraid that either his parents and/or his siblings. There is a possibility that before Seth, there were other unnamed children of Adam and Eve. Seth is isolated in the genealogy of Gen 5 because he was like Abel (whom Jesus called a prophet in Luke 11:51) and he was considered righteous enough by his mother to replace Abel (Gen 4:25). The people mentioned in those genealogies of Gen 5 and 11 are only the firstborn son so we know not everyone in existence at that point is recorded in Genesis. At the very least the unnamed children would have been all daughters since women are almost never mentioned in genealogy records in the bible. When they are mentioned it is for a specific reason. We see this in Genesis 46 when it mentions 66 people from Jacob’s lineage along with Jacob migrating to Egypt but listing the names for each wife the numbers don’t match. For example, Jacob has 33 descendants from Leah (Gen 46:15), but only 6 sons, one daughter, 23 grandsons, and two great-grandsons’ names are mentioned, which means that one of them is an unnamed daughter, granddaughter, or great-granddaughter. So if Adam and Eve had daughters they would be unnamed which is consistent with the convention of primarily recording male descendants found in the rest of Genesis.
What we know is that God marked Cain to protect him from anyone that sought to kill him in response to his fears of retaliation (Gen 4:13-16). By the way, it is an assumption that all of this happened in a short span of time. Just because the bible has a story that takes place in a few verses doesn’t mean that this story itself happens in a quick moment. We don’t know what age they were when Cain killed Abel nor do we know how long after he killed Abel he got the mark. The “mark of Cain” could have been implemented decades or even centuries after Abel’s murder which gives Adam and Eve plenty of time to produce a large group of children, if they didn’t already have other siblings by the time Abel was killed. There is no need for a group of people outside of Adam’s family. All we do know is that Seth was born in the year 130 from creation. So if we limit the possibility to a time frame created by a quick read, then it can create a bunch of assumptions that contradict later parts of scripture. Many parts of the bible are written like this. In some places, two verses span many years and in other places, multiple chapters take place in one day or a week. In fact, in Genesis 4, only a few verses after the mark of Cain (Gen 4:15) we jump to Cain’s sixth-generation descendant Lamach (Gen 4:19). If a time frame isn’t given directly, nor can be ascertained from doing math with given ages throughout the scriptures, then we simply don’t know. We only can know what is given based on ages and there are sometimes multiple congruent possibilities in between.
2) In Gen 4:17 Cain FOUNDED (as in started) the city, not FOUND (as in discovered) the city, and named it after his son Enoch. He didn’t have a son before he had a wife (unless he had sex with his mother, which I doubt), so, therefore, he met his wife (one of his sisters) first, then he had a son with her. Then he was inspired to build something for his son as an inheritance and that was the city. He couldn’t have gotten his wife from the city, since the city is named after his son Enoch. The Hebrew word iyr (עִיר) can mean “excitement” or “city/town”. People may assume a city has to have a large population first, but all cities/towns start smaller and grow, and this one will start small and grow from Cain its founder. There is a list of 6 generations of Cain going down to Lamach in the rest of Genesis 4, so we know the city grew bigger. Also, it’s possible that other siblings joined Cain in his city over time, so it would be an assumption to say that all of the inhabitants are his descendants. Also, who is to say he only ever had one wife? Lamach has at least two in Genesis 4:19.
3) Let’s look at another genealogy list, in Gen 5 we get Adam’s descendants going from Seth (Abel’s replacement), which goes down 10 generations to Noah. There is another Enoch from Seth, who is from the same generation as Lamach, the sixth gen from Cain. At first, Adam and Eve only had Cain then Abel, then after Cain killed Abel, Cain left the region of Eden. According to Gen 5:3-5, it wasn’t until Adam and Eve were 130 years old that they had Seth. Afterward, it says they had sons and daughters for the next 800 years until Adam died. Since no daughters are mentioned as being born until after Seth was born, it’s possible that Cain didn’t have any sisters to marry until after Seth’s birth. Again, we don’t know what years the Fall, the births of Cain and Abel, and the murder of Abel took place. We know that Adam and Eve are 130 years old, so Cain is 130 or younger. As stated before could have been unnamed daughters of Adam and Eve, and that would be consistent with how the bible presents genealogies because it primarily only shows males. In that case, both Cain (and possibly Abel) could have been married before the murder. If Cain left Eden with a wife, and his son Enoch was born before his exile from Eden (Gen 4:17) Then there is no need for him to go find a wife in the wilderness since he already had one. If his wife was born after Seth or he wasn’t paired up before the exile, then at an age of sexual maturity, she wandered out of Eden and found Cain in the wilderness and they had Enoch, then he built the city that is Enoch’s inheritance. As stated in the first point Cain could have met his wife decades or centuries after Abel’s murder, so there is an unknown time frame here, all we can know is a general order of operation.
4) Eden and Nod, may not be names given by Adam. These names are possibly given to locations in the post-flood world by Noah (or Abraham or Moses) to mark where things used to be before the Flood. The final book of Genesis was compiled by Moses long after the events in it, and when it comes to placing names, Moses often adds annotations to indicate name changes of locations, like Luz to Bethel (which is renamed by Jacob after his angel ladder dream in Genesis 28:19). There are also annotations regarding place names added by post-Exile Jews like in Judges 18:30 which says, that Jonathan the grandson of Moses through Gershom, was the priest in charge of an idol that was worshipped by members of the tribe of Dan unit the Exile. The Exile happened around 500+ years after the events of Joshua, so later scribes added updates to the text. More evidence of this is the four rivers that flowed from the garden outward from Eden in Gen 2:10-14. They are said to flow outward toward the nations of Kush, Gihon, Havilah, and Asshur. These nations didn’t exist at the time of Adam, because these nations are named after the descendants of Noah’s children, which is after the scattering at Babel. Basically, Noah got off the Ark and pointed to where the plain of Shinar was and called it Eden (“paradise”) because that was where the garden was. The garden was NOT called Eden, the garden was in a region that was called Eden. Eden itself was either surrounded by or near a desert/wilderness. This place east of Eden is where Cain fled and wandered, and it was later called Nod meaning “wandering” because it was Cain that did the wandering after fleeing his parents in Eden. There is no reason to suggest that it is the wandering place of a pre-Adamic group of humans that Cain bred with.
Often times those that defend this idea are trying to solve a problem that never existed concerning Cain’s wife. People often ask the question, “who is Cain’s wife?” A proper response to this question is to ask back “who was Seth’s wife?” The answer to both questions is relatively the same, they married their sisters. People often ask this question because they don’t actually know what the bible says about incest. The modern-day definition of incest is based on ideas about breeding offspring from parents that are genetically close, but in the ancient world siblings, half-siblings and cousins married all the time, how else would there be “royal bloodlines” in various cultures?
The Bible doesn’t limit incest to sex with blood relatives, in fact, a man is in sin if a man has sex with his non-blood-related stepmother (father’s wife or even ex-wife), because she is his father’s wife or ex-wife (Gen 35:22 & Gen 49:4, Lev 18:8, Lev 20:11, Deut 22:30, & 1 Cor 5:1). This indicates that those rules about incest are not explicitly about genetics but about relationships. In the Genesis era, it only would have been a sin to have a vertical sexual relationship (parents/grandparents having sex with their children/grandchildren). For example, Lot’s daughters get him drunk and have sex with him after escaping Sodom to the wilderness, because they are afraid they are not going to find husbands. However, horizontal relationships (siblings, half-siblings, and cousins), and diagonal relationships (aunts/nieces and uncles/nephews) are not explicitly labeled as sin and are done themselves by the pre-Moses patriarchs. Abraham and Sarah are half-siblings with the same father (Gen 20:12), Abraham’s brother, Nahor marries his other brother Haran’s daughter Milcah, making them uncle and niece (Gen 11:29), and Moses’ own parents (Amram and Jochebed) are nephew and aunt (Ex 6:20). Although Leviticus doesn’t ban niece-to-uncle marriages so Nahor isn’t a conflict with the Mosiac Law. I go more in depth on this here.