Sometimes, things just aren’t what they seem to be. For example, when it comes to the world of biology:

• Fireflies are not flies; they are beetles
• Prairie dogs are not dogs; they are rodents
• Horned toads are not toads; they are lizards
• Douglas firs are not firs; they are pines
• Silkworms are not worms; they are caterpillars
• Peanuts are not nuts; they are legumes
• Koala bears are not bears; they are marsupials
• Guinea pigs are not from Guinea and they are not pigs; they are rodents from South America
• Banana trees are not trees; they are herbs
• Cucumbers are not vegetables; they are fruit
• Mexican jumping beans are not beans; they are seeds with a larva inside

And . . . mitochondria are not alphaproteobacteria. In fact, evolutionary biologists don’t know what they are—at least, if recent work by researchers from Uppsala University in Sweden is to be taken seriously.¹

As silly as this list may be, evolutionary biologists are not amused by this latest insight about the identity of mitochondria. Uncertainty about the evolutionary origin of mitochondria removes from the table one of the most compelling pieces of evidence for the endosymbiont hypothesis.

A cornerstone idea within the modern evolutionary framework, biology textbooks often present the endosymbiont hypothesis as a well-evidenced, well-established evolutionary explanation for the origin of complex cells (eukaryotic cells). Yet, confusion and uncertainty surround this idea, as this latest discovery attests. To put it another way: when it comes to the evolutionary explanation for the origin of complex cells in biology textbooks, things aren’t what they seem.

The Endosymbiont Hypothesis

Most evolutionary biologists believe that the endosymbiont hypothesis is the best explanation for one of the key transitions in life’s history—namely, the origin of complex cells from bacteria and archaea. Building on the ideas of Russian botanist Konstantin Mereschkowski, Lynn Margulis (1938–2011) advanced the endosymbiont hypothesis to explain the origin of eukaryotic cells in the 1960s.

Since that time, Margulis’s ideas on the origin of complex cells have become an integral part of the evolutionary paradigm. Many life scientists find the evidence for this hypothesis compelling; consequently, they view it as providing broad support for an evolutionary explanation for the history and design of life.

According to this hypothesis, complex cells originated when symbiotic relationships formed among single-celled microbes after free-living bacterial and/or archaeal cells were engulfed by a “host” microbe. (Ingested cells that take up permanent residence within other cells are referred to as endosymbionts.)

The Evolution of Eukaryotic Cells According to the Endosymbiont Hypothesis

Image source: Wikipedia

Presumably, organelles such as mitochondria were once endosymbionts. Evolutionary biologists believe that once taken inside the host cell, the endosymbionts took up permanent residence, with the endosymbiont growing and dividing inside the host. Over time, endosymbionts and hosts became mutually interdependent, with the endosymbionts providing a metabolic benefit for the host cell. The endosymbionts gradually evolved into organelles through a process referred to as genome reduction. This reduction resulted when genes from endosymbionts’ genomes were transferred into the genome of the host organism. Eventually, the host cell evolved machinery to produce proteins needed by the former endosymbiont and processes to transport those proteins into the organelle’s interior.

Evidence for the Endosymbiont Hypothesis

The morphological similarity between organelles and bacteria serve as one line of evidence for the endosymbiont hypothesis. For example, mitochondria are about the same size and shape as a typical bacterium and they have a double membrane structure like the gram-negative cells. These organelles also divide in a way that is reminiscent of bacterial cells.

Biochemical evidence also seems to support the endosymbiont hypothesis. Evolutionary biologists view the presence of the diminutive mitochondrial genome as a vestige of this organelle’s evolutionary history. Additionally, biologists also take the biochemical similarities between mitochondrial and bacterial genomes as further evidence for the evolutionary origin of these organelles.

The presence of the unique lipid cardiolipin in the mitochondrial inner membrane also serves as evidence for the endosymbiont hypothesis. Cardiolipin is an important lipid component of bacterial inner membranes. Yet, it is not found in the membranes of eukaryotic cells—except for the inner membranes of mitochondria. In fact, biochemists consider it a signature lipid for mitochondria and a vestige of this organelle’s evolutionary history.

But, as compelling as these observations may be, for many evolutionary biologists phylogenetic analysis provides the most convincing evidence for the endosymbiont hypothesis. Evolutionary trees built from the DNA sequences of mitochondria, bacteria, and archaea place these organelles among a group of microbes called alphaproteobacteria. And, for many (but not all) evolutionary trees, mitochondria cluster with the bacteria, Rickettsiales.For evolutionary biologists, these results mean that the endosymbionts that eventually became the first mitochondria were alphaproteobacteria. If mitochondria were notevolutionarily derived from alphaproteobacteria, why would the DNA sequences of these organelles group with these bacteria in evolutionary trees?

But . . . Mitochondria Are Not Alphaproteobacteria

Even though evolutionary biologists seem certain about the phylogenetic positioning of mitochondria among the alphaproteobacteria, there has been an ongoing dispute as to the precise positioning of mitochondria in evolutionary trees, specifically whether or not mitochondria group with Rickettsiales. Looking to bring an end to this dispute, the Uppsula University research team developed a more comprehensive data set to build their evolutionary trees, with the hope that they could more precisely locate mitochondria among alphaproteobacteria. The researchers point out that the alphaproteobacterial genomes used to construct evolutionary trees stem from microbes found in clinical and agricultural settings, which is a small sampling of the alphaproteobacteria found in nature. Researchers knew this was a limitation, but, up to this point, this was the only DNA sequence data available to them.

To avoid the bias that arises from this limited data set, the researchers screened databases of DNA sequences collected from the Pacific and Atlantic Oceans for undiscovered alphaproteobacteria. They uncovered twelve new groups of alphaproteobacteria. In turn, they included these new genome sequences along with DNA sequences from previously known alphaproteobacterial genomes to build a new set of evolutionary trees. To their surprise, their analysis indicates that mitochondria are not alphaproteobacteria.

Instead, it looks like mitochondria belong to a side branch that separated from the evolutionary tree before alphaproteobacteria emerged. Adding to their surprise, the research team was unable to identify any bacterial species alive today that would group with mitochondria.

To put it another way: the latest study indicates that evolutionary biologists have no candidate for the evolutionary ancestor of mitochondria.

Does the Endosymbiont Hypothesis Successfully Account for the Origin of Mitochondria?

Evolutionary biologists suggest that there’s compelling evidence for the endosymbiont hypothesis. But when researchers attempt to delineate the details of this presumed evolutionary transition, such as the identity of the original endosymbiont, it becomes readily apparent that biologists lack a genuine explanation for the origin of mitochondria and, in a broader context, the origin of eukaryotic cells.

As I have written previously, the problems with the endosymbiont hypothesis are not limited to the identity of the evolutionary ancestor of mitochondria. They are far more pervasive, confounding each evolutionary step that life scientists envision to be part of the emergence of complex cells. (For more examples, see the Resources section.)

When it comes to the endosymbiont hypothesis, things are not what they seem to be. If mitochondria are not alphaproteobacteria, and if evolutionary biologists have no candidate for their evolutionary ancestor, could it be possible that they are the handiwork of the Creator?

Resources

• “Evolutionary Paradigm Lacks Explanation for Origin of Mitochondria and Eukaryotic Cells” by Fazale Rana (article)
• “Why Do Mitochondria Have DNA?” by Fazale Rana (article)
• “Mitochondrial Genomes: Evidence for Evolution or Creation?” by Fazale Rana (article)
• “Can a Creation Model Explain the Origin of Mitochondria?” by Fazale Rana (article)
• “Complex Protein Biogenesis Hints at Intelligent Design” by Fazale Rana (article)
• “Mitochondria’s Deviant Genetic Code: Evolution or Creation?” by Fazale Rana (article)
• “Biology’s Big Bangs” by Fazale Rana (article)

For obvious ethical reasons, the experiments were not performed on human beings—they were done on mice. Biologists have long recognized that the digestive tracts of mice are an excellent proxy for those of humans.

Four research scientists and medical doctors at Georgetown University in Washington, DC, led by postdoctoral fellow Santosh Kumar, performed experiments on mice that they designed to mirror the exposure to galactic cosmic radiation that astronauts would experience (e.g., on a space flight to Mars). Kumar’s team exposed laboratory mice to the equivalent of the heavy ion radiation that is known to exist beyond Earth’s magnetosphere (see figure 1).

Figure 1: Earth’s Magnetosphere. Serious exposure to heavy ion galactic cosmic radiation occurs in regions beyond the outer red lines emanating from Earth in the above figure. Image credit: NASA

About 99 percent of galactic cosmic radiation is comprised of single protons, electrons, and helium nuclei. There are nine times as many helium nuclei as there are electrons and ten times as many protons as there are helium nuclei. Ions heavier than helium nuclei—for example, carbon-12, oxygen-16, silicon-28, and iron-56 nuclei—make up just one percent of all galactic cosmic rays.

Even though heavy nuclei make up such a tiny percentage, they inflict more biological damage than all the other forms of galactic cosmic radiation. Another reason heavy nuclei cosmic radiation caught the attention of Kumar’s team is that there is no technology available, or even conceivable, to protect astronauts in a spacecraft from heavy ion radiation. Furthermore, scientists know that at least 30 percent of astronauts’ cells will be hit by heavy ions during a round-trip to Mars.¹

Previous research done by the Georgetown University team had demonstrated that “exposure to heavy ion radiation induces persistent oxidative stress in mouse intestine.”²Another research study by the same team showed that heavy ion radiation induces intestinal malignant tumors in mice.³ The team’s goal in their present study was to determine (1) how heavy ion radiation modulates molecular events in the intestines that are associated with intestinal epithelial cell migration, and (2) the consequences of such modulation.

Epithelial cells both perform the primary functions in digestion and absorption of nutrients and form a barrier that prevents toxic chemicals and pathogens from entering into the rest of the body. The small intestine contains two regions: one housing flask-shaped structures known as crypts and the other housing finger-like protrusions known as villi.

Kumar’s team showed that even a low dose of iron-56 radiation relative to control and gamma rays persistently decreased epithelial cell migration along the crypt-villus axis.⁴ Any degradation in the coordinated, efficient migration of epithelial cells along the crypt-villus axis causes all the functions of the small intestine to be compromised. Such degradation also allows pathological processes to invade gastrointestinal tissues.

The experiments performed by Kumar’s team showed that in addition to degraded epithelial cell migration, heavy ion radiation increased intestinal cell proliferation with accompanying DNA damage, increased cell senescence without any noticeable increase in apoptosis, and compromised cell polarity, cell adhesion, and cell-extracellular matrix interactions.⁵ The team’s experiments showed that all these consequences persisted even one year after exposure to heavy ion radiation. Such consequences are known to induce inflammatory intestinal and bowel diseases and to generate malignant tumors.

In their paper the team drew the following conclusion, “When considered along with changes in barrier function and nutrient absorption factors as well as increased intestinal tumorigenesis, our in vivo data raise a serious concern for long-duration deep-space manned mission.”⁶ Their conclusion is understated. Astronauts on such missions would experience discomfort and loss of energy to a degree that would make it difficult, if not impossible, for them to perform their mission tasks. Furthermore, the likely inflammatory diseases and cancers could completely incapacitate and even kill them.

Much more significant conclusions can be drawn from the paper. First, humans should never venture outside of Earth’s magnetosphere for more than just a few days. The International Space Station orbits inside Earth’s magnetosphere. While a manned mission to the Moon entails humans spending some time outside Earth’s magnetosphere, that time can be limited to 1–3 days. Any mission beyond the Moon’s distance from Earth must be limited to machines.

For the past several billion years, Earth has possessed a strong, stable magnetic field—an outcome considered impossible for a planet as small as Earth. What made the impossible probable was that during its youth, Earth experienced a number of unique events that super-enriched its interior with exact abundances of certain heavy elements and radioisotopes. You can read about these events in my book, Improbable Planet.⁷ The most important conclusion to be drawn from the team’s study is that we should all thank God for the miraculous design of Earth’s interior that makes Earth’s magnetosphere possible.

Some people think the advance of science continues to remove any reason for believing in God, but in reality scientific discovery over the last century has opened up vistas of knowledge that are best explained by the worldview of theism over atheistic naturalism. In the three previous parts of this series (see here, here, and here), I explained that what secular scientists thought they would discover concerning the universe, the solar system, and Earth were very different from what they actually uncovered. The universe’s extraordinary beginning, the solar system’s fine-tuning for life, and Earth’s distinctiveness as a hospitable home for intelligent life have all been surprising finds for a secular view.

In this final segment, I want to explain how human beings’ distinctiveness has also surprised scientists who embrace a purely naturalistic worldview.

The Human Exceptionalism Hypothesis

A consensus of today’s scientific community holds that modern human beings evolved naturalistically from apelike ancestors (known as common descent). But modern humans appear to possess qualities and characteristics that make them different not merely in degreefrom other primates (which seems to be what evolution would predict) but different in kind. This apparent difference in kind may be called the human exceptionalism hypothesis.

RTB scientists Fazale Rana and Hugh Ross summarize human exceptionalism in this way:

A wealth of scientific evidence shows that humans alone, as distinct from Neanderthals, Homo erectus, and other species, possess the capacity for symbolic recognition, for complex language, art, and music, and for spiritual and philosophical engagement. Humans alone manifest awareness of God, sin, moral judgment, and life beyond death. Humans alone demonstrate technological advancement, including the development of agriculture and civilization. New evidence shows that even during episodes of extreme environmental instability, humans were able to maintain small mixed farms (with multiple species of crops and livestock) and to manufacture flour and clothing.¹

Imago Dei (Image of God)

From a Christian philosophical and theological perspective, humans show this difference in kind by possessing six qualities or endowments that the Bible grounds in their being made in God’s image (Genesis 1:26–27). Animals share some of these qualities in a limited degree, but humans differ profoundly from animals by being:²

1. spiritual and religious;
2. personal, self-conscious, and rational;
3. deliberative and volitional;
4. relational;
5. immortal; and
6. powerful (having dominion over nature).

The human exceptionalism hypothesis seems to comport well with a theistic, even biblical, perspective of the imago Dei, but seems unexpected and out of place from an atheistic, naturalistic perspective. So what would human beings look like if biblical theism were true? Apparently very much like they appear right now.

Thus, I would contend that for people who look to science to offer evidence that helps negate or affirm worldview claims, the verdict is in. Many atheists insist otherwise, but scientific discovery over the last century seems compatible with belief in a theistic God.

Reflections: Your Turn

In your opinion, what feature about human beings makes them the most different from animals? Visit Reflections on WordPress to comment with your response.

Resources

• For more about human exceptionalism, see Fazale Rana with Hugh Ross, Who Was Adam? A Creation Model Approach to the Origin of Humanity, 2nd ed. (Covina, CA: RTB Press, 2015), 313–25.
• For more about humans being made in the image of God and thus distinct in kind from animals, see Kenneth Richard Samples, 7 Truths That Changed the World: Discovering Christianity’s Most Dangerous Ideas (Grand Rapids, MI: Baker, 2012), chapters 11 and 12.

In many war movies that were released fifty to eighty years ago, an infantry lieutenant would challenge his platoon with the question, “Are we mice or are we men?” The platoon soldiers would shout back, “We are men! We are men!” The platoon would then charge into battle, suffering horrific casualties before ultimately winning a great victory. I do remember one spoof of such movies where the soldiers shouted, “We are mice! We are mice!” and then beat a hasty retreat.

Rodents share a lot more with humans than we realize, according to a research paper recently published in Science.¹ The new research affirms Bible passages written more than three thousand years ago that teach that God designed certain bird and mammal species to form relationships with human beings and to serve and please us—each species in its own unique way.

Four neuroscientists at Humboldt University in Berlin headed by Annika Reinhold first noted that mammals can be trained to perform complex behaviors, tasks, and games by motivating the mammals with food treats. They developed a set of experiments to determine if mammals can be trained in an environment where the rewards are not food treats but instead social interactions with humans.

Hide-and-Seek Game Behavior
A characteristic of animal play behavior is that play occurs freely (there is no compulsion for the animals to play) and it provides no material profit. The predominant benefit to the animals is social interaction.

Reinhold’s team sought to establish if rats would play with humans and if the level of play would be more complex than if rats played with one another without human intervention. In their experiments, the team also desired to discover if the rats would play with humans when the only reward for playing would be additional social interaction with the humans. Finally, they wanted to find out if certain play activities were correlated with prefrontal cortex activity.

Reinhold and her colleagues set up the role-play game hide-and-seek with ten adolescent male rats. They tested whether the rats could play a two-player rat-and-human game.

In the “seek” part of the game the human would place a rat in a box and close the lid. Closing the lid of the start box signaled that the rat was the seeker. The human then hid in one of several locations and remotely opened the box. The rat then searched for the human. A close approach (less than 40 centimeters) to the human with a clear line of sight was scored as a “find.” After the rat found the human, the human would reward the rat with playful interaction before returning the rat to the box. Readers can watch a video clip of the seek part of the game here:

In the “hide” part of the game the human left the start box open and crouched motionlessly next to it. This circumstance cued the rat to hide. The human would wait 90 seconds and search for the rat. Upon finding the rat the human would reward the rat with playful interaction. Readers can watch a video clip of the hide part of the game here:

all ten rats learned the seek part of the game in less than two weeks. nine of the rats in the same time period learned to hide and switch roles. reinhold’s team observed that the rats kept track of past hiding locations and, hence, became more proficient with practice. the rats also quickly developed a preference for opaque and cardboard boxes over transparent ones.

surprisingly, most of the rats in the hide part of the game showed re-hide and runaway behaviors. evidently, the rats preferred prolonging the game over getting a quick social reward. readers can watch a video clip of the re-hide and runaway part of the game here:

The rats would vocalize when they found the human but remained silent when the human found them. This vocalization was not shaped by human conditioning since the rat vocalizations were inaudible to the humans.

The rats were strategic. “Seeking strategies included systematic searches, use of visual cues, and targeting of past hiding locations. Hiding strategies included preferences for opaque enclosures, being silent when hiding, and changing hiding locations.”²

Neural Correlations
In testing neural correlations Reinhold’s team did tetrode (electrophysiological) recordings of single neurons in the medial prefrontal cortex, a brain area associated with encoding social proximity. The recordings revealed “neuronal activity specific to phases and events of hide-and-seek.”³

These hide-and-seek experiments showed that rats are capable of decision-making, navigation, and role-playing. The tests also demonstrated that rats are highly motivated to socially engage humans and, when doing so, manifest intellectual and relational capabilities beyond what occurs in the wild where they have no contact with humans.

Biblical Affirmations
The researchers did not discuss philosophical inferences of their experiments beyond suggesting that the behaviors they observed may have evolutionary implications. Their results, however, do affirm several principles found in Genesis 1, Exodus 21, and the book of Job 38–42.

The first biblical principle is that God created three different broad categories of life:

1. life-forms that are purely physical;
2. life-forms that are physical and soulish, meaning that they are endowed with mind, will, and emotions and the capability to form relationships with and to serve and please human beings;
3. human beings who are physical, soulish, and spiritual and endowed with the capability of forming relationships with and serving and pleasing God.

A second biblical principle is that the intellectual and relational capabilities of individuals within the second and third categories of life are much enhanced when those individuals are strongly bonded to a higher being.

Thirdly, individuals within the second and third categories of life are happiest when they are strongly bonded to a higher being.

This hierarchy of relational bonds and fulfillment displays the activity of a Creator—One who enjoys not only creating, but also seeing his creatures enjoy each other.

Resource

• Readers interested in learning about other relevant animal experiments and their affirmations of these and other biblical principles can obtain my book, Hidden Treasures in the Book of Job. A free chapter of the book is available at reasons.org/ross.