T4C: Ancient vs. Modern Humans

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. . . continuing SECTION TWO – EXPLAINING THE EVIDENCE FOR AN EVOLUTIONARY CREATION . . . 

Reflecting on the archaeological examples such as the Natufian, Mehrgarh, and Yangshao cultures showing there were other races that pre-date Adam and Eve, and then the Biblical hints that there were other races contemporary with Adam and Eve; the question we are now considering is whether or not the people contemporary with Adam and Eve were descended from these earlier races, or to put it simply: What genetic evidence exists to support the hypothesis that modern humans are descended from ancient humans?

The genetic evidence

The genetic evidence proving there were other people contemporary with Adam and Eve is robust and extensive - but it does take some explaining (that’s what these next few chapters are about). However, the high-level summary of the genetic evidence is this:

The amount of genetic diversity in the human population rules out a common parentage from just two people six to ten thousand years ago. This means that there were other people besides just Adam and Eve, and so the Biblical and archaeological evidence that we have seen so far is supported by the genetic evidence.

The genetic evidence also shows that modern generations are directly descended from pre-Adamic ancestors. Researchers have been able to map genetic information from human remains spanning tens of thousands of years, and by comparing those ancient DNA sequences with modern sequences one can see the genetic heritage of humans and populations. These shared genetic sequences show that there has been a continuous human population on the earth that long predates Adam and Eve.

To be clear on where this is going: Just because the evidence shows continuity of human life, it does not change the miraculous origins of life. It doesn't change God's covenant with Adam, Abraham, David, or the faithful. It doesn't change the teachings of Christ, it doesn't change the promises of the Kingdom, and it doesn't change the importance of baptism or faith. What it does do, is give a clear picture of the history of God’s creation, and his creative methods.

Anatomically modern

Anatomically modern remains (i.e. those whose skeletal features resemble modern humans) appear in the fossil record from about 190,000 years ago. The oldest of these anatomically modern remains are known as the Omo remains, named after the Omo River in South Western Ethiopia where they were found. The remains include two partial skulls as well as arm, leg, foot and pelvis bones. The geological layers around the fossils were dated to be about 195,000 years old (with about a 2% margin of error).

Another well known set of remains are the Skhul remains. These were found in the Es Skhul caves in Israel and are about 90,000 years old. What makes these remains particularly interesting is the fact that they have a mix of traits found in archaic and anatomically modern humans.

The problem with these sorts of remains is that it’s practically impossible to find a complete skeleton, and so obviously analysis can only be done on the bones that are found. Whilst it’s easy to compare the remains that are preserved with modern equivalents, it’s unfortunate that we don’t have the whole skeleton to give us the full picture. This is where genetic evidence has been of tremendous benefit in helping to understand these human remains, and has helped to complete the story that archaeology and skeletal remains began to tell.

Insights from DNA

Based on the remains found across Europe - and prior to the ability to sequence DNA - it was suggested that the first modern humans migrated into Europe roughly 45,000 years ago and perhaps occasionally encountered Neanderthals, whose ancestors had inhabited Europe for over 400,000 years. DNA has since provided some highly interesting perspectives on human history in Europe. Below are a few examples:

Ust'-Ishim: The oldest human remains from which an entire genome has been extracted belong to the Ust'-Ishim man, who lived about 45,000 years ago in Western Siberia. Some have suggested this was about the time that modern humans entered Europe. The Ust’-Ishim genome has a number of mutations that are common across most of the world’s populations, except those in Africa. This implies he was a descendant of a population that moved from Africa and sojourned in the Middle East during which time some of the mutations occurred (this is why they’re not found in African populations). From there, subsets of that population migrated to Europe and Russia where more mutations would have occurred. Thus, by working out which population groups share mutations, and which mutations are unique to certain groups, it’s possible to trace the spread of populations around the world. (Studying the genetic characteristics of various populations is known as population genetics).

Another interesting aspect about the Ust’-Ishim genome is that 2.3% of it is Neanderthal. How sure are they that it was Neanderthal DNA? Well, remember this would equate to roughly 23 Bibles worth of characters. This is a curious percentage that is worth explaining, because it’ll come in useful later to understand this. . . 

Depending on the point being discussed, there are two percentages that are often mentioned. For example, researchers will say that the Neanderthal genome is 99.5% the same as a human genome, and yet the point above is that the Ust’-Ishim genome is 2.3% Neanderthal. Why such vastly different percentages? The difference is this: When discussing the homology (i.e. having a similar position or structure) of two genomes, the genome is 99.5% similar in structure. The 2.3% refers to specific genes that can be identified as belonging to Neanderthals only, and yet which appear in the human genome. Perhaps the following analogy is a useful way to explain this. . . 

Imagine you are an explorer from another time, and you stumble across the remains of a small publisher’s studio with several hundred books. You began your analysis by ‘sequencing’ the text, and when that task is complete you can begin to compare them. In doing so, you find three books that are almost identical. One is a King James Version Bible (KJV), one is an English Standard Version Bible (ESV), and the third one seems to be a hybrid of some sort. You know this because when you compared the hybrid with the ESV it had an almost identical structure; 66 books, in the same order, with the same number of verses, communicating the same thoughts. Comparing the ESV with the Hybrid Version, they are almost identically structured (with a few small differences), and therefore they are 99.5% homologous. But in the Hybrid Version, you notice that some of the verses seem to have been replaced by verses from the King James Version (for whatever reason). They say much the same thing, just expressed differently. Thus you can confidently say the Hybrid version is 99.5% homologous with the ESV, and 2.3% of it is from the KJV.

This is a crude and simplified analogy, but is essentially what has happened in the case of the Ust’-Ishim genome. It has a 99.5% homology with the human genome (so we know he was human) and yet 2.3% of the genome contains Neanderthal Version genes. The only way that could have happened is through interbreeding between Neanderthals and what were to become modern humans. It’s also not the only example. . . 

Kostenki: This is a village on the Don River in the Russian Federation where more than twenty open-air Palaeolithic sites have revealed the skeletal remains of anatomically modern humans from the Upper Palaeolithic period, covering a date range between 42,000 to 30,000 years ago. Because the strata comprise various materials (loam, alluvium, volcanic deposits) it means archaeologists have been able to use different dating methods to cross-reference and calibrate dating results.

In the years following the Second World War, substantial evidence of early Upper Palaeolithic occupation was discovered at Kostenki. In 1954, the skeleton of a young man who lived between 38,700 to 36,200 years ago was discovered, and in recent years biologists were able extract almost the entire genome from the skeleton, making this the second oldest human genome to be sequenced.

In 2014 they published their findings showing that the Kostenski man was short and dark-skinned, sharing genetic ancestry with hunter-gatherers in Europe, as well as some Middle Eastern populations. It also supported the findings from Ust’-Ishim that humans had at some stage cohabited with Neanderthals.

Today, with the exception of African populations, every other population group has inherited between 1% and 4% of Neanderthal DNA. Even more interesting, is that some of these genes have been linked to medical and physical traits.

Denisovans: In 2008, at the Denisova Caves in southern Siberia, archaeologists discovered a tiny piece of bone. It was so small one palaeoanthropologist described it as the “most unspectacular fossil” they’d ever seen. However, it was still a bone, and it looked like it came from a finger tip. Archaeologists suspected it might be human because of other artefacts found in the cave, and so the bone was sent to laboratories to see if any DNA could be obtained from it.

Fortunately the cold cave had preserved the DNA especially well, and one of the laboratories was able to extract very high quality sequences from the bone. They found that the DNA wasn’t that of a modern human or a Neanderthal, but was a completely new type of hominin. (Hominin comprises those species regarded as human, directly ancestral to humans, or very closely related to humans).

Like the Neanderthals, although the Denisovan population eventually disappeared, it was able to interbreed with modern humans, leaving its legacy in the genomes of what are modern-day Melanesian populations including Australian aborigines and those from Southeast Asian islands also have roughly 4% to 6% of Denisovan DNA. This suggests that the two groups might have crossed paths in central Asia and then the modern humans continued on to colonise the islands of Oceania.

The point is this. . . 

These examples above discuss ancient humans who share DNA with modern descendants. Not just DNA in terms of building blocks, but specific sequences that help us to identify the lineages of certain population groups. This genetic connection between ancient and modern humans demonstrates that modern population groups are direct descendants of these ancient peoples, and not a ‘recreated’ population.

These findings have helped to validate (or in some cases correct) inferences that had been made by disciplines such as comparative anatomy and palaeontology. The fossil evidence is what led researchers to surmise about evolution and common descent, but the impact of genetics and DNA evidence has been powerful. Although by now many thousands of genetic tests have been conducted, not one has given evidence contrary to the view of an evolutionary creation.

These examples discussed above support the archaeological evidence that there were other populations present at the time of Adam. The fact that DNA from pre-Adamic populations is present in modern day humans proves that there has been a continuous lineage from before Adam through to today.

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