Monday, 10 June 2013

Cain did not marry his sister: correcting Christadelphian misunderstandings on palaeoanthropology

Special creationists insist that Cain married his sister, but the evidence for this view is completely lacking, and is driven entirely by an a priori belief that the entire human race descended exclusively from Adam. Its ultimate motivation is of course the doctrine of Original Sin, which falls to pieces if monogenism can be shown to be false. This is indeed the case given that the genetic evidence shows that the entire human race could not have come exclusively from two people living 6000 years ago. Cain did not marry his sister.
When we look at the Bible, nothing is said about Cain's wife other than that she existed. Gen 4:16-17 states:
Then Cain went out from the presence of the Lord, and settled in the land of Nod, east of Eden. Cain had relations with his wife and she conceived, and gave birth to Enoch; and he built a city, and called the name of the city Enoch, after the name of his son. 
Any attempt to postulate the existence of other siblings is hard to reconcile with the first few verses of chapter 4:
Now the man had relations with his wife Eve, and she conceived and gave birth to Cain, and she said, “I have gotten a manchild with the help of the Lord.”  Again, she gave birth to his brother Abel. And Abel was a keeper of flocks, but Cain was a tiller of the ground. So it came about in the course of time that Cain brought an offering to the Lord of the fruit of the ground. Abel, on his part also brought of the firstlings of his flock and of their fat portions. And the Lord had regard for Abel and for his offering; but for Cain and for his offering He had no regard. So Cain became very angry and his countenance fell.
A straightforward reading of these verses indicates that no other children other than Cain and Abel had been born to Adam and Eve at this moment. Reinforcing this view is Gen 4v25:
Adam had relations with his wife again; and she gave birth to a son, and named him Seth, for, she said, “God has appointed me another offspring in place of Abel, for Cain killed him.”
Eve's concern about replacing Seth makes no sense if Cain and Abel were not her only children at the time. [1] Finally, it is hard to see how Cain could build a city by himself; the fact that the narrative does not seek to clarify where Cain obtained his wife, whom he feared would kill him and how he built a city presupposes the existence of people other than Adam, Eve and Cain on the Earth at this time. 

This is exactly what the palaeoanthropological evidence shows. The earliest possible date for Adam and Eve is around 10,000 years ago, if we date them to the first appearance of animal and plant domestication in the Ancient Near East. Fossil evidence of anatomically modern human beings however stretches back 200,000 years which demonstrates beyond doubt that human death predated Adam:

Omo I skull

Omo II skull

The Omo I and Omo II fossils were found at the Omo Kibish sites in south-west Ethiopia, and have been dated at 195,000 years. This makes them the oldest known anatomically modern humans.

Herto skull

This has been dated at 160,000 years and was found at Herto Bouri in Ethiopia

Jebel Irhoud I

Human remains at Jebel Irhoud, a cave 100km west of Marrakesh in Morocco have been dated to 160,00 years.

Qafzeh IX

Skhul IV

The Qafzeh and Skhul remains are dated between 80,000 - 120,000 years. Both are in modern Israel; Qafzeh cave is in lower Galilee while Skhul Cave is on the slopes of Mt. Carmel.

Mungo Man

This fossil was discovered at Lake Mungo, in New South Wales, Australia and is dated between 40,000 - 60,000 years.

The fossil evidence is unarguable: anatomically modern human beings predated the earliest possible date for Adam by over 180,000 years.

Another line of evidence against universal human descent from Adam and Eve is the lack of a genetic bottleneck. If the human race really descended from only 2 people who lived between 6-10 thousand years ago, then we would not see that much genetic diversity in the human race. We'd see evidence of a very sharp genetic bottleneck. We see no evidence of this. Rather, we see way too much genetic diversity in the human genome to have arisen from 2 people in this time. The evangelical Christian geneticist Dennis Venema makes this clear in a paper published in Perspectives on Science and Christian Faith in 2010:

Taken individually and collectively, population genomics studies strongly suggest that our lineage has not experienced an extreme population bottleneck in the last nine million years or more (and thus not in any hominid, nor even an australopithecine species), and that any bottlenecks our lineage did experience were a reduction only to a population of several thousand breeding individuals. As such, the hypothesis that humans are genetically derived from a single ancestral pair in the recent past has no support from a genomics perspective, and, indeed, is counter to a large body of evidence. [2]

The evidence from human genetics is clear and unarguable. If we were descended exclusively from two people living 6-10 thousand years ago, we would see evidence of little genetic variation in the human genome, consistent with this. We do not. Rather, we see evidence that the human race was nowhere near the size of 2 people 6000 years ago. In fact, the coalescent times of various genes stretches back hundreds of thousands of years [3-4] providing further evidence against the theologically-motivated claim that the entire human race descended from Adam.Cain did not marry his sister. Seth did not marry his sister. Such unscriptural arguments are based solely on the need to preserve monogenism - the belief that the entire human race descends from a single ancestral source. This in turn is driven by the belief that the human race had to inherit the consequences of Adam's sin. We do not believe in Original Sin, and as this comment from Robert Roberts in 1869 shows, this was never the original Christadelphian position:
‘Our friend imagines there was a change in the nature of Adam when he became disobedient. There is no evidence of this whatever, and the presumption and evidence are entirely the contrary way. There was a change in Adams relation to his maker, but not in the nature of his organization. What are the facts? He was formed from the dust a living soul, or natural body. His mental constitution gave him moral relation to God.' [5] 
Adam, before transgression, though a living soul (or natural body 1 Cor. 15:445), was not necessarily destined to die, as obedience would have ended in life immortal. After transgression, his relation to destiny was changed. Death (by sentence,) was constituted the inevitable upshot of his career. He was, therefore, in a new condition as regarded the future, though not in a new condition as regarded the actual state of his nature. In actual nature, he was a corruptible groundling before sentence, and a corruptible groundling after sentence; but there was this difference: before sentence, ultimate immortality was possible; after sentence, death was a certainty. This change in the destiny lying before him, was the result of sin.' [6] (Emphasis mine)
As Roberts correctly notes, there was no physical change in nature after the Fall. Therefore, there is no theological need to insist on monogenism, which is a good thing since the genetic and fossil evidence absolutely rules out universal human descent from Adam.


Cain did not need to marry his sister. Seth did not nned marry his sister. Cain was not fearing vengeance from brothers and sisters about whom Gen 4 is entirely silent. When the text is read without the presupposition of universal human descent from Adam, what we see is a casual allusion to the existence of people other than Adam, Eve and Cain living on the Earth at this time. which is exactly what the fossil record and human genetic tells us. Once more, true science falsifies false theology.

This article first appeared on my Facebook page here


1. The reference to 'other sons and daughters' in Gen 5:4 does not provide definite proof for the idea that these were alive at the time of Abel's murder, putting the burden of proof squarely on those who make this claim to establish their case beyond reasonable doubt.

2. Venema D "Genesis and the Genome: Genomics Evidence for Human-Ape Common Ancestry and Ancestral Hominid Population Sizes" Perspectives on Science and Christian Faith (2010) 62:166-1783. 

3. Takahata et al, "Testing Multiregionality of Modern Human Origins," Mol Biol Evol (2001) 18:172-1834. 

4. Harding, Rosalind M., et al,  "Evidence for Variable Selective Pressures at MC1R" Am. J. Human Genetics (2000) 66:1351-1361.

5. Roberts R, "The Relation of Jesus to the Law of Sin and Death", The Christadelphian (1869) 6:85

6. Roberts R, "Apparent Contradictions Reconciled", The Christadelphian (1869) 6:243