Why do cells reproduce? Why does a cell split into two to become two cells? Our biologists don't even understand this.
On a web page entitled "The Mystery of Cell Division," a scientist confesses that scientists don't understand how cells -- with a complexity of "airplanes" -- could self-reproduce.
If you do a Google search for “why do cells divide,” you will get various answers referring to "grand purpose" type of causes -- what are called "final causes" in the terminology of Aristotle's philosophy. A web site may state that cells divide to replace old, dead or damaged cells, or that cells divide so that an organism can grow, or that cells divide so that an organism can reproduce. But these are all “grand purpose” reasons, and none of them is a low-level reason. What we do not understand is: what cell-level reason is it that very complex cells divide into two identical complex cells? Considering only the cell itself, and not some higher purpose, what would cause a very complex cell to reproduce by splitting into two?
Scientists do not understand such a thing. They have identified particular stages in the most common type of cell reproduction (called mitosis): stages such as prophase, metaphase, anaphase and telophase. But without referring to higher-level “grand purpose” reasons, scientists do not understand why (on the individual cell level) a cell would pass through such phases and reproduce. A university press release confesses that "there are many remaining mysteries about how cells perform this remarkable feat." The answer is not at all "the cells follow the instructions in DNA." DNA and its genes do not contain any instructions for making cells or any specification or blueprint of a cell (contrary to the misstatements so often made about DNA and genes).
M. Pitkanen (who has a PhD in theoretical physics) has written the following about cell division:
"Replication is one of the deepest mysteries of biology. It is really something totally counterintuitive if cell is seen as a sack of water plus some chemicals. We have a lot [of] facts about what happens in the replication at DNA level but how this miracle happens is a mystery. At cell level the situation gets even more complex."
A university press release discusses scientific ignorance about the basic question of cell division. It states the following:
"When a rapidly-growing cell divides into two smaller cells, what triggers the split? Is it the size the growing cell eventually reaches? Or is the real trigger the time period over which the cell keeps growing ever larger?...'How cells control their size and maintain stable size distributions is one of the most fundamental, unsolved problems in biology,' said Suckjoon Jun, an assistant professor of physics and molecular biology at UC San Diego...'Even for the bacterium E. coli, arguably the most extensively studied organism to date, no one has been able to answer this question.' ”
The press release claims that some study has "shed light" on this mystery, but the study mentioned doesn't sound very impressive, merely being something that mathematically analyzed cell growth, and claimed to have found a "principle of cell-size control," without discussing a cause for such a thing.
It would be easy to understand cell reproduction if cells were very simple. Imagine if a cells were just uncomplicated little blobs kind of like little bubbles. Then a cell might be able to reproduce easily enough by a simple collision. When one cell collided with another, it might cause a large cell to break up two smaller cells. But what goes on in cell reproduction is gigantically more complicated than that.
Cells are so complicated that they are sometimes compared to cities, and the organelles in cells (such as the mitochondria, ribosomes and Golgi apparatus) are sometimes compared to buildings in a city. You will vastly underestimate the complexity of a eukaryotic cell (the type of cells in the human body) if you look at one of those cell diagrams that shows only a few organelles in the cell. In some cells there are millions of ribosomes, and thousands of mitochondria, as well as many other types of organelles. So when a cell reproduces, it's like some complicated machine made an exact copy of itself. Using Morgan's statement that cells are as complex as airplanes, this is as much a wonder as if some airplane were able to make an exact copy of itself.
The discussion above clarifies a point of the greatest importance: scientists do not understand the origin of cells. Specifically:
- Scientists do not understand the origin of the simplest types of cells, called prokaryotic cells. The question of the origin of the first prokaryotic is pretty much equivalent to the question of the origin of life. Scientists have made no real progress in understanding the origin of life. Even the simplest prokaryotic cell is an enormously complex thing, with roughly the same amount of functional information as a 100-page technical manual. Even the simplest self-reproducing cell scientists study is a cell requiring hundreds of different types of proteins, each a separate complex invention requiring hundreds of well-arranged parts. The total number of well-arranged parts needed for even the simplest life is greater than 10,000. No experiments realistically simulating early Earth conditions have ever produced life from non-life. No experiments realistically simulating early Earth conditions have ever produced the building components of one-celled life (protein molecules). If fact, no experiments realistically simulating early Earth conditions have ever even produced the building components (amino acids) of the building components of one-celled life (protein molecules). The much discussed Miller-Urey experiment did produce amino acids, but that experiment was not a realistic simulation of early Earth conditions.
- Scientists do not understand the origin of eukaryotic cells, the more complex type of cells used by humans and other mammals. The problem of explaining the origin of eukaryotic cells is gigantically greater than the problem of explaining the origin of prokaryotic cells, because eukaryotic cells are many thousands or millions of time more complex than prokaryotic cells.
- Scientists do not understand how extremely complex eukaryotic cells are able to reproduce. The answer is not that cells read instructions in DNA specifying how to build eukaryotic cells. There is no such set of instructions in DNA or its genes. DNA merely specifies low-level chemical information, such as which amino acids make up a particular protein molecule. Eukaryotic cells are built of building components called organelles. DNA and its genes do not even specify how to construct organelles. In fact, DNA and its genes do not even specify a layer of structure between protein molecules and organelles: the layer of protein complexes (specialized teams of proteins).
In the book Aliens, biologist Matthew Cobb gives a description of current thinking on this topic, emphasizing the improbability of it:
"What happened on Earth – known as eukaryogenesis – was not the product of random mutation and the subsequent sifting of acquired characters that have differential fitness (the essence of natural selection). Instead there appears to have been a single event of mind-boggling improbability, for it involved two life forms interacting in a most novel way....Prior to that moment, all life had consisted of small microbes with no cell nucleus and no mitochondria. Everything changed when one unicellular life form, known as an archaebacterium, ended up inside another, called a eubacterium."
On another page Cobb says this:
"We could in principle calculate the probability of the appearance of eukaryotes, but we would soon run out of zeros...That weird hybrid was our ancestor, and its existence – and therefore ours – was incredibly improbable. As far as we are aware, no such event happened before or since."
Obviously we have here a fairy tale, an "old wives' tale." Scientists have no credible tale to tell of how eukaryotic cells originated, just as they have no credible tale to tell of how prokaryotic cells originated. Whenever they refer to eukaryotic cells arising by fantastically improbable combination accidents, biologists are merely engaging in the most farfetched hand-waving. Because neither prokaryotic cells nor eukaryotic cells specify in their DNA how to make either a eukaryotic cell nor any of its organelle components, there is no conceivable lucky combination accident of prokaryotic cells that would result in eukaryotic cells with the ability to reproduce to make other eukaryotic cells.
In light of all of these ocean-sized explanatory shortfalls, what are we to make of a recent statement at the beginning of an essay by neuroscientist Hannah Critchlow? Simply that it is a gigantically unbelievable "old wives' tale," a tall tale that should not at all be classified as science. Here is how Critchlow begins her essay (which you can read here):
"About 2 billion years ago, evolution performed an improbable experiment. A larger ancestral cell engulfed a smaller bacterium. It should have been a meal. Instead, it became a merger. The bacterium survived inside its host, and together they forged one of the most consequential partnerships in the history of life. The host offered shelter and access to oxygen. The bacterium supplied something revolutionary: a vastly more efficient way to generate energy. From this intimate alliance emerged the eukaryotic cell – and with it, the possibility of complex life. Every plant, animal and thinking being traces its lineage back to that ancient symbiosis."
This is the preposterous tall tale called endosymbiosis or eukaryogenesis. It's a ridiculous story along the lines of "we got eukaryotic cells after a prokaryotic cell gulped its way to becoming 1000 times more complex." No sensible theorist should ever tell this tale, which has zero credibility. The tale is not an example of science with a capital "S," because no one has ever observed any such event occurring. Science with a capital "S" is facts established by observations, not math-oblivious wild tales describing events unlike any that have ever been observed.
The truth is that scientists do not have any credible explanation for the origin of either of the two major classes of cells. Scientists do not have any credible explanation for the origin of prokaryotic cells, and scientists do not have any credible explanation for the origin of vastly more complex eukaryotic cells. Neither one of these origins has any Darwinian explanation. You may start to realize how bogus are all "Darwin explained it all" claims when you realize that scientists these days are not providing a Darwinian explanation for either the origin of prokaryotic cells or the origin of eukaryotic cells. The "giant complexity leap by engulfing" tall tale Critchlow gives is not any type of Darwinian explanation, and is actually an explanation attempt hugely contradicting Darwin's favorite principle that "nature does not make leaps."
Critchlow makes the untrue claim that an origin of eukaryotic cells created "the possibility of complex life," ignoring the fact that even the simplest type of cell (prokaryotic cells) is itself a very complex thing requiring half a million very well-arranged base pairs and hundreds of types of proteins, most being a separate type of complex invention requiring hundreds of well-arranged parts. Her little "gulping" tale does not even try to explain more than one of the many differences between prokaryotic cells and eukaryotic cells. It's kind of like someone saying that a real working car arose from a palm-sized toy car, because the toy car got bigger.
As many scientists have confessed, DNA and its genes contain no specifications for building the structure of bodies, and no specifications for building the structure of eukaryotic cells. So there is no conceivable event by which some combination accident or gulping accident involving prokaryotic cells could explain the origin of eukaryotic cells. One prokaryotic cell might make itself more complex by gulping something, but that would not do anything to cause future cells to have the same increased complexity.
After reading the neuroscientist Critchlow tell the enormously unbelievable fairy tale quoted above, you might start to get a suspicion along these lines: maybe neuroscientists may tend to tell tall tale yarns having no credibility, while reciting such groundless "just so" stories as if they were facts. And such a suspicion would actually be correct, because of many other examples of absurd unwarranted narratives that neuroscientists like to tell. One of the most ridiculous is the claim that some mere strengthening of synapses can explain the wonder of human memory storage. It is a tale as absurd as the "huge leap in organization by a gulping accident" tale Critchlow tells to try to explain the origin of eukaryotic cells. Complex information never gets stored by some mere act of strengthening. Equally absurd is the tale that your ability to instantly recall complex relevant answers occurs from some process in neural tissue lacking any addresses, indexes or sorting, the type of things that make a fast retrieval of information possible in physical systems.
What should neuroscientists be saying when they address the question of the origin of prokaryotic cells? They should be saying something like, "I don't understand how the first prokaryotic cells arose." What should neuroscientists be saying when they address the question of the origin of vastly more complex eukaryotic cells? They should be saying something like, "I don't understand how the first eukaryotic cells arose." What should neuroscientists be saying when they address the question of how human cells reproduce? They should be saying something like, "I don't understand how cells as complex as humans have are able to reproduce." What should neuroscientists be saying when they address the question of how humans learn things? They should be saying something like, "I don't understand how a human being can learn anything using a brain in which learned information has never been found by microscopic examination." What should neuroscientists be saying when they address the question of how humans recall things? They should be saying something like, "I don't understand how a human being can recall anything using a brain lacking any addresses, indexes and sorting, in which learned information has never been found by microscopic examination."
Yesterday I discovered a 2021 paper by two scientists who attempt to persuade us that some progress was made by neuroscientists in learning about a physical basis for memory. In the last few paragraphs, their pretensions fall apart, as the scientists make this confession, which makes it sound as if scientists have no real understanding of any physical basis for memory:
"Despite the tremendous efforts in the field to clarify the molecular basis of memory processes, some very important questions remain unanswered... How does one singular memory get recalled when it is behaviorally relevant? How are the molecular mechanisms in memory systems not only flexible to allow immediate and quick learning but also persistent to store information during long-lasting periods?...Where is the information stored for long-term? Is there such thing as a memory code?...Despite half a century of research, we are still only scratching the surface of the molecular basis for memory function."
Schematic depiction of some types of experts
