I decided to look up bacteria and Viruses in relation to evolution.
Bacteria are single-celled so would be a very early specialisation, but they seem to need the larger organisms to dwell and survive? Most articles seem to concentrate o how they evolve now rather than any historical thesis.
Viruses might not even be living creatures by the usual definitions but seem to be random DNA separated from its double Helix which will then disrupt if it comes back into contact. I am sure this is simplistic but it might explain why viruses seem to be species-specific. However if viruses are just strands of DNA, and all creatures share the basic DNA why should they not affect all creatures the same?
A further interest was the following article on how viruses might have directly affected human evolution Untamed Science. important role played by viruses
From a theistic or creationist standpoint:
Are viruses deliberate and for what purpose?
There are cooperative or beneficial bacteria but why create bacteria that kills or debilitates?
Perhaps this is an area we have not covered (recently)?
PS This is not meant as some sort of trick ot trap with ulterior motives.
Bacteria do fine without other organisms as long as they have a food supply. Look at microbial life around geothermal vents and hot springs. It seems they are everywhere on all sorts of surfaces as biofilms
Viruses need other organisms to reproduce as they use cells biologic machinery. And questionably alive, as you said. But interestingly they evolve, as Covid has illustrated all too well
It is not their capacity to evolve that is interesting. It is how they evolved in the first place.
I doubt that anyone is going to claim bacteria along the tree of human evolution. So, they only evolved within a very limited structure and existence which seems contrary to Evolutionary theory. Doesn’t it?
Evolution is not about adapting to survive as is. It would seem to be about a progression. Or am I viewing TOE wrong?
Furthermore, both of them seem to exist purely for the way they interact wtih ether the environment or the host creature, which makes natural selection a little problematic. Developing to help (or hinder) others?
Okay, I’ll bite: obviously bacteria and viruses were created by God, but were they created on the 5th day or the 3rd day? And since they obviously survived the Flood, they must have been one or two of the Kinds that Noah brought onto the ark. But what kind of Kinds were they?
Bacteria certainly play a role in the ancestry of humans. There are three main branches of life (leaving aside viruses): bacteria, archaea, and eukaryotes, the last of which includes all multicellular life. Bacteria and archaea, which collectively are known as prokaryotes, are the main show as far as life and evolution are concerned, with eukaryotes something of an odd outgrowth. The exact evolutionary relationship between the three branches is difficult to determine, given how far back they split and given the extent to which genes may have been exchanged between branches. (Indeed, it’s not clear that ‘direct descendant’ has a well-defined meaning if horizontal gene transfer was common enough.)
It’s highly probable that eukaryotic mitochondria (including the human mitochondrion) evolved from a bacterium that resided within cells and that eventually became part of the cell. Beyond that, current sketchy information shows that eukaryotes are more closely related to a branch of the archaea than they are to bacteria, so we’re probably descended from the former rather than from bacteria. But archaea look a lot like bacteria and yes, we think we’re evolved from them.
You’re viewing it wrong. Evolution is indeed the process of change in life, but life doesn’t always need to change. Bacteria are very good at being bacteria and have been good at it for a very long time. They continue to evolve, but since they don’t compete with creatures like humans, there’s no overall reason for them to stop being bacteria.
Most bacteria (and most archaea) are free-living rather than living on another living host. They live in any environment capable of supporting life; the insides of another organism is just one more environment to them. Whether they’re free living or not, natural selection works just fine. Sometimes organisms are beneficial to other species in their environment, sometimes they’re harmful, and sometimes they’re neither. As long as it’s good for the organism in question, it’s favored by evolution.
I am no expert of viruses but I assume that viruses are ‘simplified bacteria’, originally single-cell organisms that adapted to parasitic lifestyle. Many parasitic organisms lack features that would be needed for independent life. Any feature of an organism not needed for life is a waste of energy and that energy could be used for reproduction or maintenance. Why work hard for something if you can delegate the task to someone else? Viruses could be viewed as ultimate parasites that have left almost all work to the host.
An example of the consequences of a parasitic lifestyle is the deep sea anglerfish. The female lives an independent life and has everything we expect from a fish. A young male bites the skin of a female and then transforms to a parasitic appendix of the female. The body parts of the male not needed anymore degenerate and wither away until there is just a minor appendix of brainless(?) flesh with testicles.
If a single-cell organism would adapt like a male of the deep sea anglerfish, there would not be left much else than DNA or RNA inside a casing and enough of other matter to get the genetic information to the host cell.
Degeneration and withering of unnecessary parts is favored by natural selection if that increases the amount of grandchildren relative to competitors. I could toss an awry comment about the advantages of increased stupidity in humans but it would be a questionable comment in this context as it would have nothing to do with you or viruses.
I occasionally wonder if humans “lack features that would be needed for independent life”: aren’t we dependent on the bacteria that live inside us?
I first wondered about this when reading a sci-fi novel based on the premise that humanity had broadcast a signal with the human genome described, and some aliens in Andromeda started assembling humans in order to revive the race; it occurred to me that without the genomes of all the internal bacteria humans have the project would have been a failure. In a sense humans are actually communities, not individuals, because without all those bacteria we wouldn’t survive.
Yes, we are more than just individuals. Particular type of bacteria are probably not necessary for survival, as @glipsnort wrote, but we are definitely an assemblage of organisms (holobiont). Some organisms are beneficial, others harmful but thinking of us just as independent individuals gives a misleading impression.
If we accept that mitochondria were originally degenerated mutualist bacteria, we are dependent of other members in our assemblage. As mitochondria are not anymore bacteria, it is a matter of taste whether the mutualism with bacteria is considered essential for survival.
I think this is a plausible explanation for the origin of some double-stranded DNA viruses. Viruses as a whole, however, feature wildly different mechanisms for storing and replicating genetic information, and I don’t think there’s any reason to assume that they’re all related or share a similar origin. Some (particularly those that use reverse transcriptase) might be transposable genetic elements that acquired the ability to move between cells. But for many viruses, I think the most likely explanation is that they’re survivors from an early, complex web of DNA- and RNA-based replicators. One segment of that web settled out to become the last universal ancestor of cellular life while other parts persisted as viruses.
Evolution is simply the outcome of the nature of living things to be creative (variation) and to learn (natural selection). This includes adapting to survive in a changing environment, but it also includes exploring all the possibilities available by means of incremental variations in genetics (i.e. it is not ALWAYS about survival).
But the idea of “progress” or “progression” can be rather subjective. Evolution certainly deals with challenges to survival in a changing environment. It can lead to organisms with more adaptability (able to survive in more varied environments), and I suppose that might be called progress in some sense. Certainly human adaptability is pretty high compared to most other organisms especially with its use of technology.
They do indeed. They have adapted to both parasitic and symbiotic relationships with homo sapiens, and will likely continue to adapt to such relationships with every new species which comes into being.
That is the result of some studies on some viruses. The usual methods of looking for common ancestry in the genome don’t work because viruses have a habit of stealing DNA from host organisms and inserting DNA in them as well. We know that much (8-40%) of our DNA are remnants inserted by viruses at some time in our evolutionary past. Obviously, bacteria are also difficult because of horizontal transfer between them.
P.S. I am not trying to teach such things to glipsnort. He is the biology expert not me. But his comments seemed a good start for expanding on them to share what I have been finding out when I look into the subject.
Different organisms have different defenses against viruses. Conversely, different viruses have different abilities. Seawater has lots of viruses, but most of them parasitize bacteria and don’t affect us at all, for example. That’s why one virus doesn’t infect all kinds of organisms, even though all known organisms share some basic features of DNA. Viruses (and various similar things) are inherently unable to reproduce themselves. Certain types of bacteria are entirely dependent on a host; others are free-living or able to go either way depending on the availability of a host.
Contrary to Lamarck’s (and other “Enlightenment”) ideas, bacteria are not somehow trying to evolve towards eukaryotic or multicellular forms. They are doing what works for them, competing and cooperating with other organisms and managing in their environment. I know of experiments that found that yeasts could evolve multicellularity, but I don’t recall experiments that had bacteria doing more that getting somewhat colonial, rather than reaching true multicellularity.
Besides the theory of evolution, there is no other possible starting point for explaining how viruses and bacteria fit into the theory of evolution. Bacteria and archaea share basic similarities of biochemical functioning, DNA sequence, etc. with eukaryotes. This strongly supports the idea that they do share an evolutionary heritage; the similarity is not functionally necessary and seems unlikely to be something that a designer would put in if not using an evolutionary method of creation.
The most eukaryote-like archaea known have a complex outline with many extensions to the cell. Having one of those surround a bacterium, leading to mitochondria, would not be overly astonishing.
Read the context. It is unreasonable to ask what the theory of evolution says about bacteria and viruses and then complain that the answers are given in an evolutionary context. (Also keep in mind that by “theory of evolution” I mean a biological model and am excluding claims that God is not involved.)
Might some other model explain certain features of bacteria and viruses? It is certainly possible. However, such a model has to be given in adequate detail to actually predict something. Otherwise, one can’t honestly claim that the model is actually explaining anything. It would be difficult to rule out the possibility that the ultimate origin for living things was actually on another planet; however, “evolved somewhere else, got transported as spores, and thrived on Earth” does not seem significantly different from “evolved and thrived here” for the questions you are asking. Could some forms have evolved or been designed elsewhere and then arrived here along with locally evolved forms? That seems implausible. The similarities between all bacteria, archaea, and eukaryotes strongly points to them all starting from a common ancestral form. Viruses generally mutate so fast and have so little nucleic acid that they don’t retain information about deep ancestry. However, the odds of a virus or other parasite from some other planet being able to accurately target Earth life is quite low. The “Alien” movie scenario of a space parasite that can target humans does not make much sense biologically.
Might some sort of ID-type scenario fit, with certain steps in the creation of particular viruses or prokaryotes involving intervention by some type of intelligent designer? Again, it is quite difficult to disprove. However, we don’t see any patterns that don’t fit the idea that bacteria and viruses have been created through the process of evolution. Theologically, we will have assumptions about how God may work through such natural patterns, but that is a different question from asking whether there is evidence that God has done things not using those natural patterns. The ID movement has focused on looking for similarities between human-designed systems and complex biological systems. But this fails to check whether the same features are also found in “undesigned” systems. Rather, we need to compare “designed” and “undesigned” systems to see how to distinguish them. One way that is actually done (e.g., in archaeology) is to compare the item in question with known “designed” and “undesigned” examples. But we don’t have that available for biological systems. The other is to have some idea of the possible goals of the designer(s) and see if the object fits it.
The Bible assures us that God is working out His goals through all that happens, but also tells us that His thoughts are not our thoughts and our ways are not His ways. Thus, we can confidently say that the creation of viruses and bacteria does fit in His plan and, in that sense, is designed. But exactly why and how is not something the Bible specifies. We do see a general pattern that miracles are minimized in the Bible, and they have a specific function to point to God, not just to make things easier. Given that God is smart enough to figure out how to design the pattern of evolution so as to create the diversity of organisms that He wanted, there does not seem to be a particular reason to expect some bacteria or viruses to be created separately.