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The Cell's Design

New Genetic Evidence Affirms Human Uniqueness

By Fazale Rana - March 4, 2020
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It’s a remarkable discovery—and a bit gruesome, too.

It is worth learning a bit about some of its unseemly details because this find may have far-reaching implications that shed light on our origins as a species.

In 2018, a group of locals discovered the remains of a two-year-old male puppy in the frozen mud (permafrost) in the eastern part of Siberia. The remains date to 18,000 years in age. Remarkably, the skeleton, teeth, head, fur, lashes, and whiskers of the specimen are still intact.

Of Dogs and People

The Russian scientists studying this find (affectionately dubbed Dogor) are excited by the discovery. They think Dogor can shed light on the domestication of wolves into dogs. Biologists believe that this transition occurred around 15,000 years ago. Is Dogor a wolf? A dog? Or a transitional form? To answer these questions, the researchers have isolated DNA from one of Dogor’s ribs, which they think will provide them with genetic clues about Dogor’s identity—and clues concerning the domestication process.

Biologists study the domestication of animals because this process played a role in helping to establish human civilization. But biologists are also interested in animal domestication for another reason. They think this insight will tell us something about our identity as human beings.

In fact, in a separate study, a team of researchers from the University of Milan in Italy used insights about the genetic changes associated with the domestication of dogs, cats, sheep, and cattle to identify genetic features that make human beings (modern humans) stand apart from Neanderthals and Denisovans.1 They conclude that modern humans share some of the same genetic characteristics as domesticated animals, accounting for our unique and distinct facial features (compared to other hominins). They also conclude that our high level of cooperativeness and lack of aggression can be explained by these same genetic factors.

This work in comparative genomics demonstrates that significant anatomical and behavioral differences exist between humans and hominins, supporting the concept of human exceptionalism. Though the University of Milan researchers carried out their work from an evolutionary perspective, I believe their insights can be recast as scientific evidence for the biblical conception of human nature; namely, creatures uniquely made in God’s image.

Biological Changes that Led to Animal Domestication

Biologists believe that during the domestication process, many of the same biological changes took place in dogs, cats, sheep, and cattle. For example, they think that during domestication, mild deficits in neural crest cells resulted. In other words, once animals are domesticated, they produce fewer, less active neural crest cells. These stem cells play a role in neural development; thus, neural crest cell defects tend to make animals friendlier and less aggressive. This deficit also impacts physical features, yielding smaller skulls and teeth, floppy ears, and shorter, curlier tails.

Life scientists studying the domestication process have identified several genes of interest. One of these is BAZ1B. This gene plays a role in the maintenance of neural crest cells and controls their migration during embryological development. Presumably, changes in the expression of BAZ1B played a role in the domestication process.

Neural Crest Deficits and Williams Syndrome

As it turns out, there are two genetic disorders in modern humans that involve neural crest cells: Williams-Beuren syndrome (also called Williams syndrome) and Williams-Beuren region duplication syndrome. These genetic disorders involve the deletion or duplication, respectively, of a region of chromosome 7 (7q11.23). This chromosomal region harbors 28 genes. Craniofacial defects and altered cognitive and behavioral traits characterize these disorders. Specifically, people with these syndromes have cognitive limitations, smaller skulls, and elf-like faces, and they display excessive friendliness.

Among the 28 genes impacted by the two disorders is the human version of BAZ1B. This gene codes for a type of protein called a transcription factor. (Transcription factors play a role in regulating gene expression.)

The Role of BAZ1B in Neural Crest Cell Biology

To gain insight into the role BAZ1B plays in neural crest cell biology, the European research team developed induced pluripotent stem cell lines from (1) four patients with Williams syndrome, (2) three patients with Williams-Beuren region duplication syndrome, and (3) four people without either disorder. Then, they coaxed these cells in the laboratory to develop into neural crest cells.

Using a technique called RNA interference, they down-regulated BAZ1B in all three types of neural crest cells. By doing this, the researchers learned that changes in the expression of this gene altered the migration rates of the neural crest cells. Specifically, they discovered that neural crest cells developed from patients with Williams-Beuren region duplication syndrome migrated more slowly than control cells (generated from test subjects without either syndrome) and neural crest cells derived from patients with Williams syndrome migrated more rapidly than control cells.

The discovery that the BAZ1B gene influences neural crest cell migration is significant because these cells have to migrate to precise locations in the developing embryo to give rise to distinct cell types and tissues, including those that form craniofacial features.

Because BAZ1B encodes for a transcription factor, when its expression is altered, it alters the expression of genes under its control. The team discovered that 448 genes were impacted by down-regulating BAZ1B. They learned that many of these impacted genes play a role in craniofacial development. By querying databases of genes that correlate with genetic disorders, researchers also learned that, when defective, some of the impacted genes are known to cause disorders that involve altered facial development and intellectual disabilities.

Lastly, the researchers determined that the BAZ1B protein (again, a transcription factor) targets genes that influence dendrite and axon development (which are structures found in neurons that play a role in transmissions between nerve cells).

BAZ1B Gene Expression in Modern and Archaic Humans

With these findings in place, the researchers wondered if differences in BAZ1B gene expression could account for anatomical and cognitive differences between modern humans and archaic humans—hominins such as Neanderthals and Denisovans. To carry out this query, the researchers compared the genomes of modern humans to Neanderthals and Denisovans, paying close attention to DNA sequence differences in genes under the influence of BAZ1B.

This comparison uncovered differences in the regulatory region of genes targeted by the BAZ1B transcription factor, including genes that control neural crest cell activities and craniofacial anatomy. In other words, the researchers discovered significant genetic differences in gene expression among modern humans and Neanderthals and Denisovans. And these differences strongly suggest that anatomical and cognitive differences existed between modern humans and Neanderthals and Denisovans.

Did Humans Domesticate Themselves?

The researchers interpret their findings as evidence for the self-domestication hypothesis—the idea that we domesticated ourselves after the evolutionary lineage that led to modern humans split from the Neanderthal/Denisovan line (around 600,000 years ago). In other words, just as modern humans domesticated dogs, cats, cattle, and sheep, we domesticated ourselves, leading to changes in our anatomical features that parallel changes (such as friendlier faces) in the features of animals we domesticated. Along with these anatomical changes, our self-domestication led to the high levels of cooperativeness characteristic of modern humans.

On one hand, this is an interesting account that does seem to have some experimental support. But on the other, it is hard to escape the feeling that the idea of self-domestication as the explanation for the origin of modern humans is little more than an evolutionary just-so story.

It is worth noting that some evolutionary biologists find this account unconvincing. One is William Tecumseh Fitch III—an evolutionary biologist at the University of Vienna. He is skeptical of the precise parallels between animal domestication and human self-domestication. He states, “These are processes with both similarities and differences. I also don’t think that mutations in one or a few genes will ever make a good model for the many, many genes involved in domestication.”2

Adding to this skepticism is the fact that nobody has anything beyond a speculative explanation for why humans would domesticate themselves in the first place.

Genetic Differences Support the Idea of Human Exceptionalism

Regardless of the mechanism that produced the genetic differences between modern and archaic humans, this work can be enlisted in support of human uniqueness and exceptionalism.

Though the claim of human exceptionalism is controversial, a minority of scientists operating within the scientific mainstream embrace the idea that modern humans stand apart from all other extant and extinct creatures, including Neanderthals and Denisovans. These anthropologists argue that the following suite of capacities uniquely possessed by modern humans accounts for our exceptional nature:

  • symbolism
  • open-ended generative capacity
  • theory of mind
  • capacity to form complex social systems

As human beings, we effortlessly represent the world with discrete symbols. We denote abstract concepts with symbols. And our ability to represent the world symbolically has interesting consequences when coupled with our abilities to combine and recombine those symbols in a countless number of ways to create alternate possibilities. Our capacity for symbolism manifests in the form of language, art, music, and even body ornamentation. And we desire to communicate the scenarios we construct in our minds with other human beings.

But there is more to our interactions with other human beings than a desire to communicate. We want to link our minds together. And we can do this because we possess a theory of mind. In other words, we recognize that other people have minds just like ours, allowing us to understand what others are thinking and feeling. We also have the brain capacity to organize people we meet and know into hierarchical categories, allowing us to form and engage in complex social networks. Forming these relationships requires friendliness and cooperativeness.

In effect, these qualities could be viewed as scientific descriptors of the image of God, if one adopts a resemblance view for the image of God.

This study demonstrates that, at a genetic level, modern humans appear to be uniquely designed to be friendlier, more cooperative, and less aggressive than other hominins—in part accounting for our capacity to form complex hierarchical social structures.

To put it differently, the unique capability of modern humans to form complex, social hierarchies no longer needs to be inferred from the fossil and archaeological records. It has been robustly established by comparative genomics in combination with laboratory studies.

A Creation Model Perspective on Human Origins

This study not only supports human exceptionalism but also affirms RTB’s human origins model.

RTB’s biblical creation model identifies hominins such as Neanderthals and the Denisovans as animals created by God. These extraordinary creatures possessed enough intelligence to assemble crude tools and even adopt some level of “culture.” However, the RTB model maintains that these hominids were not spiritual creatures. They were not made in God’s image. RTB’s model reserves this status exclusively for Adam and Eve and their descendants (modern humans).

Our model predicts many biological similarities will be found between the hominins and modern humans, but so too will significant differences. The greatest distinction will be observed in cognitive capacity, behavioral patterns, technological development, and culture—especially artistic and religious expression.

The results of this study fulfill these two predictions. Or, to put it another way, the RTB model’s interpretation of the hominins and their relationship to modern humans aligns with “mainstream” science.

But what about the similarities between the genetic fingerprint of modern humans and the genetic changes responsible for animal domestication that involve BAZ1B and genes under its influence?

Instead of viewing these features as traits that emerged through parallel and independent evolutionary histories, the RTB human origins model regards the shared traits as reflecting shared designs. In this case, through the process of domestication, modern humans stumbled upon the means (breeding through artificial selection) to effect genetic changes in wild animals that resemble some of the designed features of our genome that contribute to our unique and exceptional capacity for cooperation and friendliness.

It is true: studying the domestication process does, indeed, tell us something exceptionally important about who we are.

Resources

Endnotes
  1. Matteo Zanella et al., “Dosage Analysis of the 7q11.23 Williams Region Identifies BAZ1B as a Major Human Gene Patterning the Modern Human Face and Underlying Self-Domestication,” Science Advances 5, no. 12 (December 4, 2019): eaaw7908, doi:10.1126/sciadv.aaw7908.
  2. Michael Price, “Early Humans Domesticated Themselves, New Genetic Evidence Suggests,” Science (December 4, 2019), doi:10.1126/science.aba4534.

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  • Neanderthals/Hominids
  • Human Uniqueness
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