Ancient DNA Indicates Modern Humans Are One-of-a-Kind

By Fazale Rana – February 19, 2020

The wonderful thing about tiggers
Is tiggers are wonderful things!
Their tops are made out of rubber
Their bottoms are made out of springs!
They’re bouncy, trouncy, flouncy, pouncy
Fun, fun, fun, fun, fun!
But the most wonderful thing about tiggers is
I’m the only one!1

With eight grandchildren and counting (number nine will be born toward the end of February), I have become reacquainted with children’s stories. Some of the stories my grandchildren want to hear are new, but many of them are classics. It is fun to see my grandchildren experiencing the same stories and characters I enjoyed as a little kid.

Perhaps my favorite children’s book of all time is A. A. Milne’s (1882–1956) Winnie-the-Pooh. And of all the characters that populated Pooh Corner, my favorite character is the ineffable Tigger—the self-declared one-of-a-kind.

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A. A. Milne. Credit: Wikipedia

For many people (such as me), human beings are like Tigger. We are one-of-a-kind among creation. As a Christian, I take the view that we are unique and exceptional because we alone have been created in God’s image.

For many others, the Christian perspective on human nature is unpopular and offensive. Who are we to claim some type of special status? They insist that humans aren’t truly unique and exceptional. We are not fundamentally different from other creatures. If anything, we differ only in degree, not kind. Naturalists and others assert that there is no evidence that human beings bear God’s image. In fact, some would go so far as to claim that creatures such as Neanderthals were quite a bit like us. They maintain that these hominins were “exceptional,” just like us. Accordingly, if we are one-of-a-kind it is because, like Tigger, we have arrogantly declared ourselves to be so, when in reality we are no different from any of the other characters who make their home at Pooh Corner.

Despite this pervasive and popular challenge to human exceptionalism (and the image-of-God concept), there is mounting evidence that human beings stand apart from all extant creatures (such as the great apes) and extinct creatures (such as Neanderthals). This growing evidence can be marshaled to make a scientific case that as human beings we, indeed, are image bearers.

As a case in point, many archeological studies affirm human uniqueness and exceptionalism. (See the Resources section for a sampling of some of this work.) These studies indicate that human beings alone possess a suite of characteristics that distinguish us from all other hominins. I regard these qualities as scientific descriptors of the image of God:

  • Capacity for symbolism
  • Ability for open-ended manipulation of symbols
  • Theory of mind
  • Capacity to form complex, hierarchical social structures

Other studies have identified key differences between the brains of modern humans and Neanderthals. (For a sample of this evidence see the Resources section.) One key difference relates to skull shape. Neanderthals (and other hominins) possessed an elongated skull. In contradistinction, our skull shape is globular. The globularity allows for the expansion of the parietal lobe. This is significant because an expanded parietal lobe explains a number of unique human characteristics:

  • Perception of stimuli
  • Sensorimotor transformation (which plays a role in planning)
  • Visuospatial integration (which provides hand-eye coordination)
  • Imagery
  • Self-awareness
  • Working and long-term memory

Again, I connect these scientific qualities to the image of God.

Now, two recent studies add to the case for human exceptionalism. They involve genetic comparisons of modern humans with both Neanderthals and Denisovans. Through the recovery and sequencing of ancient DNA, we have high quality genomes for these hominins that we can analyze and compare to the genomes of modern humans.

While the DNA sequences of protein-coding genes in modern human genomes and the genomes of these two extant hominins is quite similar, both studies demonstrate that the gene expression is dramatically different. That difference accounts for anatomical differences between humans and these two hominins and suggests that significant cognitive differences exist as well.

Differences in Gene Regulation

To characterize gene expression patterns in Neanderthals and Denisovans and compare them to modern humans, researchers from Vanderbilt University (VU) used statistical methods to develop a mathematical model that would predict gene expression profiles from the DNA sequences of genomes.2 They built their model using DNA sequences and gene expression data (measured from RNA produced by transcription) for a set of human genomes. To ensure that their model could be used to assess gene expression for Neanderthals and Denisovans, the researchers paid close attention to the gene expression pattern for genes in the human genome that were introduced when modern humans and Neanderthals presumably interbred and compared their expression to human genes that were not of Neanderthal origin.

blog__inline--ancient-dna-indicates-modern-humans-2The Process of Gene
Expression.
Credit: Shutterstock

With their model in hand, the researchers analyzed the expression profile for nearly 17,000 genes from the Altai Neanderthal. Their model predicts that 766 genes in the Neanderthal genome had a different expression profile than the corresponding genes in modern humans. As it turns out, the differentially expressed genes in the Neanderthal genomes failed to be incorporated into the human genome after interbreeding took place, suggesting to the researchers that these genes are responsible for key anatomical and physiological differences between modern humans and Neanderthals.

The VU investigators determined that these 766 deferentially expressed genes play roles in reproduction, forming skeletal structures, and the functioning of cardiovascular and immune systems.

Then, the researchers expanded their analysis to include two other Neanderthal genomes (from the Vindija and Croatian specimens) and the Denisovan genome. The researchers learned that the gene expression profiles of the three Neanderthal genomes were more similar to one another than they were to either the gene expression patterns of modern human and Denisovan genomes.

This study clearly demonstrates that significant differences existed in the regulation of gene expression in modern humans, Neanderthals, and Denisovans and that these differences account for biological distinctives between the three hominin species.

Differences in DNA Methylation

In another study, researchers from Israel compared gene expression profiles in modern human genomes with those from and Neanderthals and Denisovans using a different technique. This method assesses DNA methylation.3 (Methylation of DNA downregulates gene expression, turning genes off.)

Methylation of DNA influences the degradation process for this biomolecule. Because of this influence, researchers can determine the DNA methylation pattern in ancient DNA by characterizing the damage to the DNA fragments isolated from fossil remains.

Using this technique, the researchers measured the methylation pattern for genomes of two Neanderthals (Altai and Vindija) and a Denisovan and compared these patterns with genomes recovered from the remains of three modern humans, dating to 45,000 years in age, 8,000 years in age, and 7,000 years in age, respectively. They discovered 588 genes in modern human genomes with a unique DNA methylation pattern, indicating that these genes are expressed differently in modern humans than in Neanderthals and Denisovans. Among the 588 genes, researchers discovered some that influence the structure of the pelvis, facial morphology, and the larynx.

The researchers think that differences in gene expression may explain the anatomical differences between modern humans and Neanderthals. They also think that this result indicates that Neanderthals lacked the capacity for speech.

What Is the Relationship between Modern Humans and Neanderthals?

These two genetic studies add to the extensive body of evidence from the fossil record, which indicates that Neanderthals are biologically distinct from modern humans. For a variety of reasons, some Christian apologists and Intelligent Design proponents classify Neanderthals and modern humans into a single group, arguing that the two are equivalent. But these two studies comparing gene regulation profiles make it difficult to maintain that perspective.

Modern Humans, Neanderthals, and the RTB Human Origins Model

RTB’s human origins model regards Neanderthals (and other hominins) as creatures made by God, without any evolutionary connection to modern humans. These extraordinary creatures walked erect and possessed some level of intelligence, which allowed them to cobble together tools and even adopt some level of “culture.” However, our model maintains that the hominins were not spiritual beings made in God’s image. RTB’s model reserves this status exclusively for modern humans.

Based on our view, we predict that biological similarities will exist among the hominins and modern humans to varying degrees. In this regard, we consider the biological similarities to reflect shared designs, not a shared evolutionary ancestry. We also expect biological differences because, according to our model, the hominins would belong to different biological groups from modern humans.

We also predict that significant cognitive differences would exist between modern humans and the other hominins. These differences would be reflected in brain anatomy and behavior (inferred from the archeological record). According to our model, these differences reflect the absence of God’s image in the hominins.

The results of these two studies affirm both sets of predictions that flow from the RTB human origins model. The differences in gene regulation between modern human and Neanderthals is precisely what our model predicts. These differences seem to account for the observed anatomical differences between Neanderthals and modern humans observed from fossil remains.

The difference in the regulation of genes affecting the larynx is also significant for our model and the idea of human exceptionalism. One of the controversies surrounding Neanderthals relates to their capacity for speech and language. Yet, it is difficult to ascertain from fossil remains if Neanderthals had the anatomical structures needed for the vocalization range required for speech. The differences in the expression profiles for genes that control the development and structure of the larynx in modern humans and Neanderthals suggests that Neanderthals lacked the capacity for speech. This result dovetails nicely with the differences in modern human and Neanderthal brain structure, which suggest that Neanderthals also lacked the neural capacity for language and speech. And, of course, it is significant that there is no conclusive evidence for Neanderthal symbolism in the archeological record.

With these two innovative genetic studies, the scientific support for human exceptionalism continues to mount. And the wonderful thing about this insight is that it supports the notion that as human beings we are the only ones who bear God’s image and can form a relationship with our Creator.

Resources

Behavioral Differences between Humans and Neanderthals

Biological Differences between Humans and Neanderthals

Endnotes
  1. Richard M. Sherman and Robert B. Sherman, composers, “The Wonderful Thing about Tiggers” (song), released December 1968.
  2. Laura L. Colbran et al., “Inferred Divergent Gene Regulation in Archaic Hominins Reveals Potential Phenotypic Differences,” Nature Evolution and Ecology 3 (November 2019): 1598-606, doi:10.1038/s41559-019-0996-x.
  3. David Gokhman et al., “Reconstructing the DNA Methylation Maps of the Neandertal and the Denisovan,” Science 344, no. 6183 (May 2, 2014): 523–27, doi:1126/science.1250368; David Gokhman et al., “Extensive Regulatory Changes in Genes Affecting Vocal and Facial Anatomy Separate Modern from Archaic Humans,” bioRxiv, preprint (October 2017), doi:10.1101/106955.

Reprinted with permission by the author

Original article at:

https://reasons.org/explore/blogs/the-cells-design


Can Evolution Explain the Origin of Language?

canevolutionexplain

BY FAZALE RANA – OCTOBER 10, 2018

Oh honey hush, yes you talk too much
Oh honey hush, yes you talk too much
Listenin’ to your conversation is just about to separate us

—Albert Collins

He was called the “Master of the Telecaster.” He was also known as the “Iceman,” because his guitar playing was so hot, he was cold. Albert Collins (1932–93) was an electric blues guitarist and singer whose distinct style of play influenced the likes of Stevie Ray Vaughn and Robert Cray.

origin-of-language

Image: Albert Collins in 1990. Image Credit: Masahiro Sumori [GFDL (https://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (https://creativecommons.org/licenses/by-sa/3.0/) or CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)], from Wikimedia Commons.

Collins was known for his sense of humor and it often came through in his music. In one of Collins’s signature songs, Honey Hush, the bluesman complains about his girlfriend who never stops talking: “You start talkin’ in the morning; you’re talkin’ all day long.” Collins finds his girlfriend’s nonstop chatter so annoying that he contemplates ending their relationship.

While Collins may have found his girlfriend’s unending conversation irritating, the capacity for conversation is a defining feature of human beings (modern humans). As human beings, we can’t help ourselves—we “talk too much.”

What does our capacity for language tell us about human nature and our origins?

Language and Human Exceptionalism

Human language flows out of our capacity for symbolism. Humans have the innate ability to represent the world (and abstract ideas) using symbols. And we can embed symbols within symbols to construct alternative possibilities and then link our scenario-building minds together through language, music, art, etc.

As a Christian, I view our symbolism as a facet of the image of God. While animals can communicate, as far as we know only human beings possess abstract language. And despite widespread claims about Neanderthal symbolism, the scientific case for symbolic expression among these hominids keeps coming up short. To put it another way, human beings appear to be uniquely exceptional in ways that align with the biblical concept of the image of God, with our capacity for language serving as a significant contributor to the case for human exceptionalism.

Recent insights into the mode and tempo of language’s emergence strengthen the scientific case for the biblical view of human nature. As I have written in previous articles (see Resources) and in Who Was Adam?, language appears to have emerged suddenly—and it coincides with the appearance of anatomically modern humans. Additionally, when language first appeared, it was syntactically as complex as contemporary language. That is, there was no evolution of language—proceeding from a proto-language through simple language and then to complex language. Language emerges all at once as a complete package.

From my vantage point, the sudden appearance of language that uniquely coincides with the first appearance of humans is a signature for a creation event. It is precisely what I would expect if human beings were created in God’s image, as Scripture describes.

Darwin’s Problem

This insight into the origin of language also poses significant problems for the evolutionary paradigm. As linguist Noam Chomsky and anthropologist Ian Tattersall admit, “The relatively sudden origin of language poses difficulties that may be called ‘Darwin’s problem.’”1

Anthropologist Chris Knight’s insights compound “Darwin’s problem.” He concludes that “language exists, but for reasons which no currently accepted theoretical paradigm can explain.”2 Knight arrives at this conclusion by surveying the work of three scientists (Noam Chomsky, Amotz Zahavi, and Dan Sperber) who study language’s origin using three distinct approaches. All three converge on the same conclusion; namely, evolutionary processes should not produce language or any form of symbolic communication.

Chris Knight writes:

Language evolved in no other species than humans, suggesting a deep-going obstacle to its evolution. One possibility is that language simply cannot evolve in a Darwinian world—that is, in a world based ultimately on competition and conflict. The underlying problem may be that the communicative use of language presupposes anomalously high levels of mutual cooperation and trust—levels beyond anything which current Darwinian theory can explain . . . suggesting a deep-going obstacle to its evolution.3

To support this view, Knight synthesizes the insights of linguist Noam Chomsky, ornithologist and theoretical biologist Amotz Zahavi, and anthropologist Dan Sperber. All three scientists determine that language cannot evolve from animal communication for three distinct reasons.

Three Reasons Why Language Is Unique to Humans

Chomsky views animal minds as only being capable of bounded ranges of expression. On the other hand, human language makes use of a finite set of symbols to communicate an infinite array of thoughts and ideas. For Chomsky, there are no intermediate steps between bounded and infinite expression of ideas. The capacity to express an unlimited array of thoughts and ideas stems from a capacity that must have appeared all at once. And this ability must be supported by brain and vocalization structures. Brain structures and the ability to vocalize would either have to already be in place at the time language appeared (because these structures were selected by the evolutionary process for entirely different purposes) or they simultaneously arose with the capacity to conceive of infinite thoughts and ideas. To put it another way, language could not have emerged from animal communication through a step-evolutionary process. It had to appear all at once and be fully intact at the time of its genesis. No one knows of any mechanism that can effect that type of transformation.

Zahavi’s work centers on understanding the evolutionary origin of signaling in the animal world. Endemic to his approach, Zahavi divides natural selection into two components: utilitarian selection (which describes selection for traits that improve the efficiency of some biological process—enhancing the organism’s fitness) and signal selection (which involves the selection of traits that are wasteful). Though counterintuitive, signal selection contributes to the fitness of the organism because it communicates the organism’s fitness to other animals (either members of the same or different species). The example Zahavi uses to illustrate signal selection is the unusual behavior of gazelles. These creatures stot (jump up and down, stomp the ground, loudly snort) when they detect a predator, which calls attention to themselves. This behavior is counterintuitive. Shouldn’t these creatures use their energy to run away, getting the biggest jump they can on the pursuing predator? As it turns out, the “wasteful and costly” behavior communicates to the predator the fitness of the gazelle. In the face of danger, the gazelle is willing to take on risk, because it is so fit. The gazelle’s behavior dissuades the predator from attacking. Observations in the wild confirm Zahavi’s ideas. Predators most often will go after gazelles that don’t stot or that display limited stotting behavior.

Animal signaling is effective and reliable only when actual costly handicaps are communicated. The signaling can only be effective when a limited and bounded range of signals is presented. This constraint is the only way to communicate the handicap. In contrast, language is open-ended and infinite. Given the constraints on animal signaling, it cannot evolve into language. Natural selection prevents animal communication from evolving into language because, in principle, when the infinite can be communicated, in practice, nothing is communicated at all.

Based in part on fieldwork he conducted in Ethiopia with the Dorze people, Dan Sperber concluded that people use language to primarily communicate alternative possibilities and realities—falsehoods—rather than information that is true about the world. To be certain, people use language to convey brute facts about the world. But most often language is used to communicate institutional facts—agreed-upon truths—that don’t necessarily reflect the world as it actually is. According to Sperber, symbolic communication is characterized by extravagant imagery and metaphor. Human beings often build metaphor upon metaphor—and falsehood upon falsehood—when we communicate. For Sperber, this type of communication can’t evolve from animal signaling. What evolutionary advantage arises by transforming communication about reality (animal signaling) to communication about alternative realities (language)?

Synthesizing the insights of Chomsky, Zahavi, and Sperber, Knight concludes that language is impossible in a Darwinian world. He states, “The Darwinian challenge remains real. Language is impossible not simply by definition, but—more interestingly—because it presupposes unrealistic levels of trust. . . . To guard against the very possibility of being deceived, the safest strategy is to insist on signals that just cannot be lies. This rules out not only language, but symbolic communication of any kind.”4

Signal for Creation

And yet, human beings possess language (along with other forms of symbolism, such as art and music). Our capacity for abstract language is one of the defining features of human beings.

For Christians like me, our language abilities reflect the image of God. And what appears as a profound challenge and mystery for the evolutionary paradigm finds ready explanation in the biblical account of humanity’s origin.

Is it time for our capacity for conversation to separate us from the evolutionary explanation for humanity’s origin?

Resources:

Endnotes

  1. Johan J. Bolhuis et al., “How Could Language Have Evolved?” PLoS Biology 12 (August 2014): e1001934, doi:10.1371/journal.pbio.1001934.
  2. Chris Knight, “Puzzles and Mysteries in the Origins of Language,” Language and Communication 50 (September 2016): 12–21, doi:10.1016/j.langcom.2016.09.002.
  3. Knight, “Puzzles and Mysteries,” 12–21.
  4. Knight, “Puzzles and Mysteries,” 12–21.
Reprinted with permission by the author
Original article at:
https://www.reasons.org/explore/blogs/the-cells-design/read/the-cells-design/2018/10/10/can-evolution-explain-the-origin-of-language