Self-declared atheist and evolutionary biologist Richard Dawkins, concludes his book The Ancestor’s Tale with
“My objection to supernatural beliefs is precisely that they miserably fail to do justice to the sublime grandeur of the real world. They represent a narrowing-down from reality, an impoverishment of what the real world has to offer.” (p. 614)
In this book, Dawkins tries to explain the evolution of life on planet Earth strictly through the Darwinian principles of random mutation coupled with natural selection, in its supposed journey from bacteria to us humans. He tries to do this by pointing to current examples in nature of what he considers ‘re-enactments,’ which he believes suggest to us what happened in life’s journey through the ages. He writes,
“This book’s pattern [uses] some tales as modern re-enactments of evolutionary happenings.” (p. 487)
He fails to show, however, that God’s finger was never in the pie: he fails to show that random mutation coupled with natural selection (rather than ingenious ‘design’) were the driving forces of life’s journey from unicellular bacteria to multicellular organisms, to complex animals, and eventually to ultra-intelligent beings—us humans.
Yet, in his book The God Delusion, Dawkins insists that whether God exists or not is a scientific question. He writes,
“The presence or absence of a creative super-intelligence is unequivocally a scientific question, even if it is not in practice—or not yet—a decided one.” (p. 82) And again,
“A universe in which we are alone except for other slowly evolved intelligences is a very different universe from one with an original guiding agent whose intelligent design is responsible for its very existence.” (p. 85)
In other words, following his own beliefs and implicit suggestion, Dawkins needs to prove (from a scientific point of view) that God’s intervention was never the case in life’s journey on Earth, nor did God have anything to do with the laws governing evolution. In this article, I hold Dawkins to his own requirement: that is, showing whether a Supernatural Being is responsible for what we observe through science or not—in particular, the evolution of life on Earth.
Of course, one cannot simply say, “I cannot see how this could have happened by chance alone, therefore God must have intervened.” So, Dawkins is absolutely right when, in The Ancestor’s Tale, he states,
“The ‘Argument from Personal Incredulity’ would lead us to invoke the supernatural every time we see a good conjurer whose tricks we cannot fathom.” (p. 549)
Deep down, as a scientist, I wish Dawkins is right! In the seventeenth century, science (Isaac Newton) showed that God is not constantly moving the planets around the sun, as ancient scientists thought: they moved unaided under gravity. And just as God never touched the planets, God may not have edged evolution along, as it might seem to us at first blush. However, the evidence so far shows otherwise in the case of evolution—not to mention the origin of both the universe and of life (see my article “God of the Gaps?”) Indeed there are scientists, like one of the two discoverers of deoxyribonucleic acid (DNA), Francis Crick, who believe that life originated extra-terrestrially. In The Ancestor’s Tale, Dawkins does not even attempt to eliminate the possibility of extraterrestrial intervention; he simply shoots it down saying,
“Crick himself … finds little good evidence to support his own theory of Directed Panspermia. ” (p. 550)
As if, a priori, Darwinian evolution is the only possible solution. But I’m sure the reader agrees that Dawkins needs, at least, to rule out extraterrestrial intervention—not to mention God’s intervention. As we shall see, he never even tries to rule out, for example, that the animals whose fossils are found in the Cambrian explosion (see “Fossil Record” below) were not planted by extraterrestrial aliens.
There is no doubt that microevolution is a fact: organisms do change slightly (peripherally) with time.
(1) For example, we have evidence of vestigial (useless) parts in animals: like the tailbone and appendix in humans, the hoof in horses (which is the middle ‘toe’—it has four small digits around it), and so on. I don’t think God would design a useless anatomical part in the first place.
(2) Moreover, dogs, horses, pigeons, and other animals can be tailored to acquire certain qualities through careful selective breeding.
(3) Furthermore, in an ongoing experiment involving Escherichia coli (E. coli) bacteria, evolutionary biologist Richard Lenski showed that one group, out of twelve, developed the ability to assimilate citrate (C6H5O73-) in the presence of oxygen—something never experienced before. (Wikipedia: https://en.wikipedia.org/wiki/E._coli_long-term_evolution_experiment, accessed June 7, 2021.)
With regard to macroevolution, however, I feel myself in the awkward position of those ancient scientists who tried to defend the concept of God’s constantly moving the planets around the sun before Isaac Newton came along and explained planetary motion (to some extent) by his ‘law of gravitation.’ (In all fairness, science still did not explain how this law of gravity came about: that is, whether God was its designer.) Anyway, I’m only interested in finding the truth, possibly without making assumptions, following the evidence we have so far—today.
The reason I still feel that God intervened in macroevolution is because there is hardly any evidence of transition forms: like the bat (a mammal with wings), the penguin (a bird with flippers), and the lungfish (a fish that breathes air). Likewise in the fossil record, we have hardly any evidence of transition forms: life forms appear suddenly, evolve slightly for a while, and become extinct. But according to Darwin’s ‘theory of evolution,’ transition forms should be numerous—the norm rather than the exception.
Before we proceed further, for the benefit of the reader who might be unfamiliar with the subject, let me summarize briefly the salient stages in the evolution of life on Earth, according to the ‘theory of evolution.’
(1) Proponents of the theory of evolution contend that life on Earth started with bacteria, which are single-celled (unicellular) organisms that have no nucleus in this cell (termed prokaryotes).
Note: How bacteria came about in the first place is a question of the origin of life, not a question of evolution: which deals with the development of life forms after life had started.
(2) Next came the protozoa, which are also single-celled organisms, but they have a nucleus in the cell (termed eukaryotes) containing their genetic code in various chromosomes (strings of DNA).
(3) Then came organisms having many cells (multicellular): first those that had identical cells and then those that had differentiated cells.
(4) They were followed by vegetation (grass, plants, and trees), which are able to convert carbon dioxide (CO2) into oxygen (O2) using sunlight energy: a process termed photosynthesis.
(5) Then emerged the sea animals, followed by the land animals, including the flying animals: these animals gradually grew in size and became more and more intelligent.
(6) Of particular intelligence were dolphins and primates (apes, chimpanzees, monkeys, etc.). Finally, humans appeared on the scene; their body was somewhat similar to that of primates, but their intelligence was many orders of magnitude higher than that of any of the other animals.
Note: Viruses are not exactly living organisms since they cannot reproduce themselves: they need the replicating mechanism of living cells which they hijack to multiply—usually to the detriment of the host cell. There are more types of viruses than stars in the universe (which number around 1024); Vincent Raniello, in his Virology Blog, estimates 1031. (Raniello, Virology Blog: https://www.virology.ws/2013/09/06/how-many-viruses-on-earth/, accessed June 7, 2021.) Admittedly, it’s hard to see what God had in mind in creating viruses!
What Dawkins tries to show in his Ancestor’s Tale is that we see evolutionary occurrences, even nowadays, that could explain how life diversified, little by little, from bacteria to humans. It seems that, in this book, he abandons the old concept of Darwinian evolution to some extent: which assumes that random mutation takes place one nucleotide (basic DNA ‘letter’) at a time. He here assumes that evolution happens in ‘chunks,’ so to speak: that is, entire ‘paragraphs’ of DNA are incorporated at intervals in its ‘ascending’ journey from a simple to a complex organism. Of course, this is a more plausible scenario than the one-letter-at-a-time concept. However, on the other hand, this is exactly what a design engineer would do: he would incorporate partial designs, one at a time as needed, into more complex machinery. In other words, God could have intervened time and again, or designed life in such a way as to be able to incorporate more and more features in a ‘down-up’ (i.e., from simple organisms to complex ones) evolutionary journey.
Do we have any evidence of major changes in organisms happening in real life? I think we do.
(1) The metamorphosis of certain animals, like the butterfly, the fly, or the frog, say, is a wonder of nature to anyone who has seen it.
(2) In botany one might be familiar with the phenomenon of grafting a branch of a desirable fruit—like an orange, say—onto its wild-counterpart tree.
(3) In 1924, embryologists Hans Spemann and Hilde Mangold used microsurgery to cut a portion of a newt (lizard-like amphibian) embryo and transplanted it onto another newt embryo. The second embryo produced two bodies, each with a head and tail, joined at the belly: very much like Siamese twins. (Spemann & Mangold, pp. 13–38). So, although Spemann and Mangold did not change the second embryo’s DNA, they managed to alter its anatomy drastically.
(4) As Dawkins writes in The Ancestor’s Tale, “A Hox gene … is a gene whose mission in life is to know whereabouts in the body it is, and so inform other genes in the same cell. … When things go wrong with a Hox gene, the cells in a segment are misinformed about which segment they are in, and they make the segment they ‘think’ they are in. So, for instance, [in a fruit fly] we see a leg growing in the segment that would normally grow an antenna. … The instructions for making any segment lurk in the cells of every segment. It is the Hox genes, under normal conditions, that call forth the ‘correct’ instructions for making the anatomy appropriate to each segment.” (p. 418)
(5) Similarly, the wings and the eyes of a fly can be grown in the wrong place, but they end up somewhat disconnected from the rest of the body. (p. 418)
In other words, it’s all a matter of switching on and off the right signals at the right time and a significant mutation can be made to occur. However, constructing a viable animal this way shows mindboggling intelligent design and versatility: the problem is that unless there is proper planning (design), random mutations normally cause the wrong thing to be constructed in a given location: which will naturally serve the animal no good purpose—thus normally ending up in premature death without replication.
Dawkins places his trust for the occurrence of ‘down-up’ evolution in what is commonly referred to as the evolutionary arms race: he believes that organisms improve themselves continuously through competition because otherwise they would not survive. (Dawkins, The Ancestor’s Tale, p. 599–603) He writes,
“The improvements to be seen in an animal arms race are improvements in equipment to survive, not generally improvements in survival itself …. In an arms race between attack and defence, there may be episodes during which one side or other pulls ahead. But in general, improvements on one side cancel out improvements on the other.” (p. 600)
Thus, the sky is the limit. Although this sounds logical and easy to accept as fact, unfortunately, there is no evidence of novelty at the genome level.
Indeed, in his book The Edge of Evolution: The Search for the Limits of Darwinism, biochemist Michael J. Behe shows biochemically that humans’ centuries-long struggle for survival with malaria (Plasmodium Falciparum—a eukaryotic unicellular organism) was more like evolutionary trench warfare rather than an arms race. In trench warfare, the warring parties destroy rather than build each other’s already existing armaments and structures. In a sort-of introduction to the book, he writes,
“In its real war with malaria, the human genome has only diminished.” (p. 43)
Nor did the malaria genome improve, despite its enormous populations over the centuries (thus enhancing its ability to mutate beneficially). In other words, history (evidence) shows that, seemingly, ‘down-up’ evolution is beyond the limits of Darwinism.
In other words, microevolution (peripheral adaptation) occurs spontaneously, but not macroevolution (core adaptation).
How did single-celled prokaryotes (having no nucleus—like bacteria) at the dawn of life, supposedly evolve into single-celled eukaryotes (having a nucleus—like malaria)? According to Dawkins,
“The evolution of the eukaryotic cell, with its nucleus to contain the chromosomes, its complicated ultrastructure of membranes, and its self-reproducing miniature organelles, such as mitochondria and (in plants) chloroplasts … was actually two or three events, perhaps widely spaced in time. Each one of these historic … events was a merging of bacterial cells to form a larger cell. … Perhaps 2 billion years ago, an ancient single-celled organism, some kind of proto-protozoan, entered into a strange relationship with a bacterium.” (Dawkins, The Ancestor’s Tale, p. 536)
Interesting as this might be, it begs the question: are all the varieties in life packed into the genome of a bacterial cell, or was more information subsequently added somehow to more complex cells and organisms? In which case, evolution wreaks of design.
Moreover, unless I am misunderstanding, it seems to me that Dawkins wants to have it both ways when he writes that “some kind of proto-protozoan” cooperated with a bacterium: a protozoan already has a nucleus.
Needless to reiterate, the above assumes, in the first place, the existence of an intelligent bacterium cell (often compared to a whole factory) being incorporated into another equally (or more) intelligent cell: Dawkins never explains how the prokaryotic (i.e., bacterium) cell came about. As I mentioned in my article “God of the Gaps?” the odds against a bacterium cell evolving by chance alone, in all the time the universe has existed, is one to 1040860: which is practically impossible.
Dawkins even admits, “All our cells are like individual [cells], stuffed with bacteria which have become so transformed by generations of cooperation with the host cell that their bacterial origins are almost lost to sight. (Dawkins, The Ancestor’s Tale, p. 537)
Which throws serious doubt as to the validity of the above hypothesis: making it sound more like wishful thinking rather than scientific conclusion.
The Encyclopaedia Britannica Online defines the Cambrian explosion as “the unparalleled emergence of organisms between 541 million and approximately 530 million years ago at the beginning of the Cambrian Period. The event was characterized by the appearance of many of the major phyla (between 20 and 35) that make up modern animal life.” (Encyclopaedia Britannica Online: https://www.britannica.com/science/Cambrian-explosion, accessed June 7, 2021.)
In his book The Ancestor’s Tale, Dawkins tries to downplay the Cambrian explosion, by associating it with Creationists, who believe strictly in the science (or rather pseudoscience) found in the Bible (see my article “Science in the Bible”). He writes,
“Creationists love the Cambrian Explosion because it seems, to their carefully impoverished imaginations, to conjure a sort of paleontological orphanage inhabited by parentless phyla: animals without descendants, as if they had suddenly materialized overnight from nothing.” (Dawkins, The Ancestor’s Tale, p. 436)
The fact that Creationists love it does not make it less real, nor does denigrating them. He even tries to throw doubt about the reliability of the fossils found in the Cambrian explosion.
“We must remember what a lot of imagination necessarily intervenes between the blurred and squashed fossil in a rock and the reconstruction that is eventually drawn, often in daring colour, on the page.” (Dawkins, The Ancestor’s Tale, p. 438)
But Dawkins doesn’t have similar misgivings regarding the hominid fossils (pp. 87–89), of which we mainly have only the skulls (except for one case—pp. 68, 71): he seems to regard hominid-fossil evidence as cast in stone simply because he agrees with it.
He even goes as far as to try to discredit one of the Cambrian fossils (Hallucigenia) as only being a part of an animal, (Dawkins, The Ancestor’s Tale, p. 438) despite its being found the same way in several sites. (Wikipedia: “Hallucigenia,” https://en.wikipedia.org/wiki/Hallucigenia#:~:text=Hallucigenia%20is%20a%20genus%20of,isolated%20spines%20around%20the%20world, accessed June 3, 2021)
At the same time, Dawkins lumps Intelligent Design advocates with Creationists, describing them as an offshoot of Creationism. (Dawkins, The Ancestor’s Tale, pp. 549, 551) However, proponents of Intelligent Design believe in practically all that science has to say, even though most of the time it disagrees with the Bible, but they see the universe, life, and intelligence (the mind/soul) as being designed by a Supreme Being, commonly referred to as God.
In contrast, Intelligent Design advocate, philosopher of science, and geophysicist Stephen C. Meyer summarizes the Cambrian explosion in the epilogue of his book Darwin’s Doubt as follows:
“Darwin’s Doubt makes its case for the reality of the Cambrian explosion chiefly, but not entirely, on the basis of the fossil record. Representatives of twenty-three of the roughly twenty-seven fossilized animal phyla (and of the roughly thirty-six total animal phyla) are present in the Cambrian fossil record. Twenty of these twenty-three major groups of animals make their first appearance in the Cambrian period with no discernable ancestral forms present in either earlier Cambrian or Precambrian strata.” (Mayer, p. 417–18)
Moreover, Dawkins tries to explain away the Cambrian explosion by the usual unimaginative assumption that organisms in the Precambrian were too small or too soft to form fossils (pp. 436, 441–42): as if shells and bones evolve overnight, from very soft to very hard, with no intermediate stages whatsoever in between. This, notwithstanding the fact that we do have Precambrian fossils of very small and very soft organisms: like bacteria and embryos respectively.
Ape to Human Evolution
On the other hand, Dawkins enhances the fossil evidence suggesting the evolution of humans from primates (apes, chimpanzees, monkeys, etc.) even though it is so flimsy: we practically only have fossils of skulls; we only have one near-complete hominid skeleton. Meanwhile, as I shall show under “Intelligence” below, he gives absolutely no explanation for the origin of our far superior intelligence compared to that of all the animals including primates. Although, personally, I do believe that our bodies have somehow evolved from that of primates, in my opinion, Dawkins misrepresents the flimsy scientific evidence in favor of this hypothesis, simply he believes in it.
Furthermore, his arguments for the inexistence of anything irreducibly complex is totally unconvincing to any engineer. (Dawkins, The Ancestor’s Tale, pp. 549–52) (I spent a career of a lifetime in engineering—I even possess a Canadian & US patent.) Any seasoned engineer knows intuitively that in most system designs, if one removes any one of the items constituting the system, it will not work at all: in other words, it becomes totally useless. Consequently, Darwinian evolution will reject a partial inoperative system immediately, without giving it a chance to completion. Indeed, in particular, in his book The Edge of Evolution (p. 100), molecular biologist Michael Behe totally disagrees with Dawkins that the bacterial flagellar motor is not an example of irreducible complexity. (p. 550)
Dawkins then also tries to explain the origin of multicellular organisms; he writes,
“Cellular slime moulds are social amoebas [eukaryotic unicellular organisms]. They literally blur the distinction between a social group of individuals and a single multicellular individual. In part of their life cycle, separate amoebas creep through the soil, feeding on bacteria and reproducing, as amoebas will, by dividing in two, feeding some more, then dividing again. Then, rather abruptly, the amoebas switch into ‘social mode.’ They converge on aggregation centres, from which chemical attractants radiate outwards. As more and more amoebas stream in on an attraction centre, the more attractive it becomes, because more of the beacon chemical is released. It is a bit like the way planets form from aggregating debris. The more debris accumulates in a given attraction centre, the more its gravitational attraction. So, after a while, only few attraction centres remain, and they become planets. Eventually the amoebas in each major attraction centre unite into a multicellular ‘slug.’ About a millimeter long, it even moves like a slug, with a definite front and back end, and is capable of steering in a coherent direction—for example towards light. The amoebas have suppressed their individuality to forge a whole organism. After crawling around for a while, the slug initiates the final phase of its life cycle, the erection of a mushroom-like ‘fruiting body.’ It begins the process by standing on its ‘head’ (the front end as defined by its crawling direction), which becomes the ‘stalk’ of the miniature mushroom. The inner core of the stalk becomes a hollow tube made of swollen cellulose carcasses of dead cells. Now cells around the top of the tube pour into the tube like … a fountain flowing in reverse. The result is that the tip of the stalk rises into the air, with the originally posterior end of the stalk at the top. Each of the amoebas in the originally posterior end now becomes a spore encased in a thick protective coat. Like the spores of a mushroom, they are now shed, each one bursting out of its coat a free-living, bacteria-devouring amoeba, and the life cycle begins again.”(Dawkins, The Ancestor’s Tale, p. 504)
This is all very interesting, no doubt, and it might explain the origin of multicellularity and even that of plants to some extent (except for photosynthesis). However, it doesn’t explain much: for example, how or why the beacon chemical is emitted: just like we don’t know how gravity came about to form planets. For all we know, all these phenomena could be God’s designs in nature. Moreover, Dawkins omits a crucial point in explaining how multicellularity came about. In a complex multicellular organism, different organs consist of different tissues with different functions. One cannot write a book by copying a paragraph thousands of times. So, what guides the organism to the next levels of complexity? Chance? Can chance produce an entire book from a single paragraph?
One thing we do not observe is a gradual (evolutionary) increase in intelligence from animals to humans: our intelligence is orders of magnitude superior to that of animals; and there is absolutely no evidence of a transition ladder. Dawkins seems to think that intelligence is a matter of brain size alone, and bases the supposed human evolution from apes mostly on brain size (and bipedalism, to some extent). (Dawkins, The Ancestor’s Tale, pp. 63, 66, 76, 68, 86, 94) I do believe intelligence is somewhat related to brain size, of course; but it is not the only factor: as is shown by the fact that although Neanderthals were apparently not as intelligent as Homo sapiens, they had larger brains. That is, unless they were the same species as Homo sapiens—just slightly different physically—as I believe: in fact they interbred. If brain size were the only measure of intelligence, as I mention in my article on “Evolution,” the African elephant’s brain is more than three times the size of the human brain, but the elephant’s intelligence is nowhere close to ours.
Dawkins makes a good job of comparing apples to apples regarding brain size by plotting the ‘logarithm of brain mass’ versus the respective ‘logarithm of body mass’ of animals: which turns out to be approximately a straight line. Clearly humans are well above the average (i.e., the best straight line drawn through all the points), but although dolphins come pretty close to the humans’ ratio, (Dawkins, The Ancestor’s Tale, pp. 77–85) dolphins are nowhere close to us in their intelligence. How do I know this? Judging from the works of humans (abstract concepts, art, books, bridges, buildings, games, machinery, mathematics, medicine, paintings, problem solving, religion, roads, science, tools, etc.) human intelligence must be many orders of magnitude (a trillion times, say, or more) higher than that of dolphins (not just nearly the same) or the primates from which humans supposedly evolved. Is it unreasonable to conclude that this intelligence was infused in us directly by God, rather than having evolved by chance? God’s language is not English, French, Chinese, or any other language humans speak: it is intelligence. Intelligence and reason are what, I believe, make us resemble God most—much more than all the other animals—so that we can communicate with him, I suppose.
Dawkins also makes a big deal of what is commonly referred to as the molecular clock method of determining branching or common ancestor dates. (By counting the number of changes in DNA nucleotides (letters) of a given gene (or protein) for two animals gives the mutation rate since their known common ancestor if its fossil age is determined by radioactive methods. Using this rate of mutation, the separation date of any other two animals can be determined from the change in DNA nucleotides of their respective gene.) For example, on p. 455 of The Ancestor’s Tale, Dawkins writes,
“Carefully deployed … the molecular clock has produced some stunning results.” Notice the introductory proviso “carefully deployed.” What does he mean by it? He explains,
“It does seem to be the case in practice that, with known exceptions that we can usually allow for (by carefully choosing our clock genes, and avoiding species such as rodents with exceptional rates of mutation), the molecular clock has proved itself a workable instrument. To use it, we need to draw the evolutionary tree that relates the set of species we are interested in, and estimate the amount of evolutionary change in each lineage.” (p. 455)
In other words, one has to know the final result beforehand, and then choose a gene that matches the result. Crazy so-called science! As I have shown clearly in my book Is God a Reality?, the mutation rate of different genes is not constant, and so molecular clock determinations give contradicting or widely varying results: dates only match when genes are cherry-picked with preconceived notions of elapsed time and ancestry; but that is not a valid scientific process. (Attard, pp. 182–90)
This article may be considered a critique or review of Richard Dawkins’s book The Ancestor’s Tale, which tries to trace human evolution through all sorts of living (and a few extinct) organisms from the first living organisms—bacteria. Although Dawkins’s book is a great work (“a magnum opus”) possibly giving us a lot of pieces of the evolutionary puzzle, which might eventually lead us to the final true picture of what actually happened in life’s history, he misses the big picture. He fails to notice the obvious concept of design in every step of all living organisms, which needs to be explained. The situation inevitably leads one to conclude that there exists a Supremely Intelligent Being guiding this ‘down-up’ evolution, rather than things happening by mere chance; just as one inevitably concludes that the universe seems to have been ‘fine-tuned’ for our existence to eventually come along, and life on Earth seems to have been initiated by a Supreme Intelligence (see my article “God of the Gaps?”) Of course, I do not preclude the possibility that this situation (resulting from the evidence we currently have today) regarding evolution might change in the future. Science must keep an open mind, but, so far, it seems that God is in the background of all our science: the existence of matter, the origin and fine-tuning of our universe, the origin of life on Earth, and the design in life’s evolution on our planet.
Attard, Carmel Paul, Is God a Reality?—A Scientific Investigation. Bloomington, IN: iUniverse, 2017. (ISBN: 9781532012228.)
Behe, Michael J. The Edge of Evolution: The Search for the Limits of Darwinism. New York, NY: Free Press, 2007 (ISBN: 139780743296229, 100743296222.)
Dawkins, Richard. The Ancestor’s Tale: A Pilgrimage to the Dawn of Evolution. New York, NY: Mariner Books, 2005 (ISBN: 9780618619160.)
Dawkins, Richard. The God Delusion; New York, NY: Mariner Books, 2008. (ISBN 0618918248, 9780618918249.)
Encyclopaedia Britannica Online s.v. “Cambrian explosion”: https://www.britannica.com/science/Cambrian-explosion.
Meyer, Stephen C. Darwin’s Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design. New York, NY: HarperOne, 2014. (ISBN 9780062071484.)
Spemann, Hans & Hilde Mangold. “Induction of Embryonic Primordia by Implantation of Organizers from a Different Species.” Translated by Viktor Hamburger; edited by Klaus Sander; International Journal of Developmental Biology vol. 45 (2001).
Racaniello, Vincent. Virology Blog, posted September 6, 2013: https://www.virology.ws/2013/09/06/how-many-viruses-on-earth/.
Wikipedia s.v. “E. coli Long Term Evolution Experiment,” last edited May 27, 2021: https://en.wikipedia.org/wiki/E._coli_long-term_evolution_experiment.
Wikipedia s.v. “Hallucigenia,” last edited May 17, 2021: https://en.wikipedia.org/wiki/Hallucigenia#:~:text=Hallucigenia%20is%20a%20genus%20of,isolated%20spines%20around%20the%20world.)