The bad news for creationists continues unabated as science discovers more facts, as we would expect of a counter-factual superstition.
This time it's news that new research led by University of Utah geoscientists has shown how there is a record of climate change in the fossil record in the form of traces of boron isotopes in the fossilised shells of microscopic foraminifera.
The record, 59-51 million years before creationists think Earth was created, is just another record of events in that 99.9975% of Earth's history that creationists try to shoe-horn into 10,000 to make it seem like their childish creation myth has some merit.
The record of change itself depends not on radioactive decay rates but on the ratios of stable isotopes of boron that get incorporated in the shells of microscopic foraminifera during their growth and then remain locked up as their bodies fossilise in marine sediment.
Dating of this marine sediment is done using several strands of evidence, one of which is U-Pb dating of zircon crystals, and all of which converge on the same dates (see the AI panel on the right).
What changes is the ratio of 11B (δ11B) incorporated in the shells of foraminifera during their lifetime, and this is related to the pH of the seawater. pH of sea water is in turn determined by the level of atmospheric CO2 - the higher the level of CO2, the lower the pH due to dissolved carbonic acid H3CO4.
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The 'Pillars of Creation'.
The 'fine-tuned Universe' argument appeals particularly to those who understand neither physics nor probability and for whom the argument from ignorant incredulity and the false dichotomy fallacies are compelling, partly due to parochial ignorance in assuming that the locally popular god is the only entity capable of creating a universe, and that nothing else, supernatural or otherwise is capable of it.
The most compelling argument against it is the anthropic principle. This means the fact that we are discussing it means we must exist in a universe in which intelligent life is certain.
There is also the subtle blasphemy that most creationists seem not to have thought of in that the argument assumes their putative creator god could only create life within fine-tuned' parameters, so is itself constrained by the same parameters. This denies it's omnipotence and implies the existence of a higher power which set these constraints.
Incidentally, although it's not strictly speaking an argument against the 'fine-tuned' fallacy, note that one of the fundamental forces is the weak nuclear force which governs the rate of radioactive decay. Creationists try to dismiss geochronology based on radiometric dating, claiming, with no evidence whatsoever, that the decay rates used to be much faster, so millions of years can look like 10,000 years or less. This would mean the weak nuclear force was even weaker, by several orders of magnitude.
Probability of dealing a specific bridge hand from a 52-card pack:
\[
P = \frac{1}{\binom{52}{13} \times \binom{39}{13} \times \binom{26}{13} \times \binom{13}{13}}
\]
Which can be simplified to:
\(
P = \frac{1}{\frac{52!}{(13!)^4}}
\) or \(
P \approx 1.86 \times 10^{-29}
\)
Creationists will look at a tiny probability like this and conclude that dealing four bridge hands from a 52-card pack is so improbable as to be impossible, therefore a god must have dealt the cards, and then wave that 'fact' as 'proof' of the locally popular god.
If that were true, as the following dialogue shows, the formation of anything other than hydrogen would not be possible, so stars (which depend on the nuclear fusion of hydrogen to form helium to prevent them collapsing under their own gravity) could not exist, nor could the heavier elements of which living organisms are composed.
Creationists are, probably because they lack the understanding to realise it, and their 'scientists' aren't going to tell them, arguing two mutually contradictory claims simultaneously. They can't both be right, but they can both be wrong.
Of course, given their willingness to try to mislead gullible people into joining their cult, we can never be sure that creationists who try to get away with this fallacy aren't aware they are using a false argument in order to deceive.
The following is a dialogue with ChatGPT4.0, which not only debunks the argument, but shows how it's actually a blasphemy because it argues more strongly against a supreme, omnipotent creator god than for one:
Fungi, like some primitive plants such as ferns and mosses reproduce with spores - tiny packages that contain the entire genome of the parent which have the capacity to grow and develop into a new adult able to produce spores of its own. The key to success is getting those spores dispersed and how a fungus manages that will depend on the environment in which it lives and reproduces.
Most fungi use wind dispersal, their spores being light enough to be carried considerable distances but where they land is a matter of chance, so must wind-dispersed fungi produce millions of spores to give them a good chance of just one or two landing in a suitable place.
A few others have evolved a different, more targeted strategy such as being eaten by animals and excreted in their faeces. This increases the chance of being deposited in the same environment in which the parent fungi lived as the dispersing animal also lives in that environment. This is the method adopted by truffles which produce their fruiting body (where the spores are produced) underground and emit a scent which is attractive to the target animal (pigs, dogs, etc.) which dig up the fruiting body and eventually disperse the spores. This is probably the reason that humans like the taste of truffles, although we lack the ability to sniff them out for ourselves, but possibly an early ancestral species could.
But what happens to these fungi if there are no mammals, other than bats, as was the case with New Zealand before humans brought their commensal species with them? This is the subject of an article in The Conversation by three experts: Jamie Wood, Senior Lecturer in Ecology and Evolution, University of Adelaide, Australia, and Amy Martin, Post-Doctoral Researcher in Evolutionary Ecology and Anne Gaskett, Associate Professor of Biology, both of the University of Auckland, Waipapa Taumata Rau, New Zealand.
Their article is reproduced here under a Creative Commons license, reformatted for stylistic consistency:
One of creationism's putative major success in the last 100 years, has been its new (as of 2019) coronavirus, SARS-CoV-2 (Severe Acute Respiratory Syndrome – Corona Virus - 2.
Creationist have been fooled by their cult to believe that the Universe is 'fine-tuned' for life and that this 'fine-tuning' is proof of their particular god and its particular holy book.
This is a blatant false dichotomy fallacy; even if it could be proved to be true by showing that the various (and usually ill-defined) parameters could have other values it does not follow that a randomly designated god is responsible for 'tuning' them.
It's also a blasphemy, if creationists did but realise it, because it assumes their supposedly omnipotent god is itself constrained by the fundamental laws of chemistry and physics and could only work to create life within very narrow constraints - which implies a higher power to set that constraint.
How many black holes are there in the known Universe?
Estimating the exact number of black holes in the known Universe is challenging, but astronomers have made some educated guesses based on our current understanding.
Stellar-Mass Black Holes
Stellar-mass black holes, which form from the collapse of massive stars, are the most common type. Based on the number of stars in the Universe and the fraction of those stars that are massive enough to form black holes, it is estimated that there are around 100 million to 1 billion stellar-mass black holes in the Milky Way galaxy alone. Given that the Milky Way is just one of about 2 trillion galaxies in the observable Universe, the number of stellar-mass black holes across the Universe could be in the range of \({10^{18}}\) to \({10^{19}}\) (a billion trillion to 10 billion trillion).
Supermassive Black Holes
Supermassive black holes, which exist at the centers of galaxies, are much rarer. Almost every galaxy with a significant size is thought to have a supermassive black hole at its center. This suggests there could be around 2 trillion supermassive black holes in the observable Universe, one for each galaxy.
Primordial Black Holes
There is also the theoretical possibility of primordial black holes, which might have formed in the early Universe. These could range in mass from very small to large and could number in the vast quantities, though their existence has not been confirmed.
Total Estimate
In total, combining these different types, the number of black holes in the observable Universe could be as high as \({10^{19}}\) or more. This estimate is still very rough, as it depends on many factors, including the formation rates of black holes, the life cycle of stars, and the evolution of galaxies.
But it is nonsensical for another reason: life is not the most abundant manifestation of the laws of physics in the Universe; that honour goes more deservedly to black holes, of which there are estimated \(\small {10^{19}}\) in the observable Universe - far more than there are living organisms - and black holes don't require special conditions in which to exist, other than a Universe with enough mass.
And black holes, far from showing that the Universe is a place designed to be friendly to life (which only the most parochial and naive simpletons could imagine, given that most of it above a few thousand feet of the surface of Earth is hostile to most forms of life and only a fraction of the surface is hospitable without special adaption or complex technology), are about the most destructive thing in the Universe, reducing everything that comes within their event horizon to energy which can only escape in the form of Hawking radiation.
So, if anything, the Universe appears to be 'fine-tuned' for self-destruction and the eventual extermination of life. Not exactly what the creation cults want their dupes to believe.
This theory has the advantage of a possible explanation for the appearance of design just as living organisms have, in the form of the Theory of Evolution. Black holes are believed to contain the quantum conditions for universes to spontaneously arise, so, if there were a mechanism for passing information through a black hole from the parent universe to a descendant one, natural selection should mean universes get better at making black holes.
How black holes swallow up entire suns, compete with any orbiting planets is the subject of a recent paper in Astrophysical Journal Letters which show computer generated simulations of the event. One notable observation if the 'spaghettification' effect where, from the point of view of a distant observer, an object falling into a black hole becomes drawn out into a thin string, like toothpaste out of a tube. This is caused by the dilation of space and time due to the increasing gravity as the black hole is approached and is an effect of General Relativity.
One of the authors of this paper, Professor Daniel Price of Monash University, Australia, has published an article about the team's findings in The Conversation. His article is reprinted here under a Creative Commons license, reformatted for stylistic consistency:
Watch a star get destroyed by a supermassive black hole in the first simulation of its kind
Giant black holes in the centres of galaxies like our own Milky Way are known to occasionally munch on nearby stars.
This leads to a dramatic and complex process as the star plunging towards the supermassive black hole is spaghettified and torn to shreds. The resulting fireworks are known as a tidal disruption event.
In a new study published today in the Astrophysical Journal Letters, we have produced the most detailed simulations to date of how this process evolves over the span of a year.
A black hole tearing apart a sun
American astronomer Jack G. Hills and British astronomer Martin Rees first theorised about tidal disruption events in the 1970s and 80s. Rees’s theory predicted that half of the debris from the star would remain bound to the black hole, colliding with itself to form a hot, luminous swirl of matter known as an accretion disc. The disc would be so hot, it should radiate a copious amount of X-rays.
An artist’s impression of a moderately warm star – not at all what a black hole with a hot accretion disc would be like.
But to everyone’s surprise, most of the more than 100 candidate tidal disruption events discovered to date have been found to glow mainly at visible wavelengths, not X-rays. The observed temperatures in the debris are a mere 10,000 degrees Celsius. That’s like the surface of a moderately warm star, not the millions of degrees expected from hot gas around a supermassive black hole.
Even weirder is the inferred size of the glowing material around the black hole: several times larger than our Solar System and expanding rapidly away from the black hole at a few percent of the speed of light.
Given that even a million-solar-mass black hole is just a bit bigger than our Sun, the huge size of the glowing ball of material inferred from observations was a total surprise.
While astrophysicists have speculated the black hole must be somehow smothered by material during the disruption to explain the lack of X-ray emissions, to date nobody had been able to show how this actually occurs. This is where our simulations come in.
A slurp and a burp
Black holes are messy eaters – not unlike a five-year-old with a bowl of spaghetti. A star starts out as a compact body but gets spaghettified: stretched to a long, thin strand by the extreme tides of the black hole.
As half of the matter from the now-shredded star gets slurped towards the black hole, only 1% of it is actually swallowed. The rest ends up being blown away from the black hole in a sort of cosmic “burp”.
Simulating tidal disruption events with a computer is hard. Newton’s laws of gravity don’t work near a supermassive black hole, so one has to include all the weird and wonderful effects from Einstein’s general theory of relativity.
But hard work is what PhD students are for. Our recent graduate, David Liptai, developed a new do-it-Einstein’s-way simulation method which enabled the team to experiment by throwing unsuspecting stars in the general direction of the nearest black hole. You can even do it yourself.
Spaghettification in action, a close up of the half of the star that returns to the black hole.
The resultant simulations, seen in the videos here, are the first to show tidal disruption events all the way from the slurp to the burp.
They follow the spaghettification of the star through to when the debris falls back on the black hole, then a close approach that turns the stream into something like a wriggling garden hose. The simulation lasts for more than a year after the initial plunge.
Zoomed-out view, showing the debris from a star that mostly doesn’t go down the black hole and instead gets blown away in an expanding outflow.
What did we discover?
To our great surprise, we found that the 1% of material that does drop to the black hole generates so much heat, it powers an extremely powerful and nearly spherical outflow. (A bit like that time you ate too much curry, and for much the same reason.)
When observed like they would be by our telescopes, the simulations explain a lot. Turns out previous researchers were right about the smothering. It looks like this:
The same spaghettification as seen in the other movies, but as would be seen with an optical telescope [if we had a good-enough one]. It looks like a boiling bubble. We’ve called it the “Eddington envelope”.
The new simulations reveal why tidal disruption events really do look like a solar-system-sized star expanding at a few percent of the speed of light, powered by a black hole inside. In fact, one could even call it a “black hole sun”.
Daniel Price, Professor of Astrophysics, Monash University
Published by The Conversation. Open access. (CC BY 4.0)
For the technically-minded, more detail is given in the paper in Astrophysical Journal Letters:
Any creationists wishing to refute this paper will need to refute the details given here:
Abstract
Stars falling too close to massive black holes in the centres of galaxies can be torn apart by the strong tidal forces. Simulating the subsequent feeding of the black hole with disrupted material has proved challenging because of the range of timescales involved. Here we report a set of simulations that capture the relativistic disruption of the star, followed by one year of evolution of the returning debris stream. These reveal the formation of an expanding asymmetric bubble of material extending to hundreds of astronomical units — an outflowing Eddington envelope with an optically thick inner region. Such outflows have been hypothesised as the reprocessing layer needed to explain optical/UV emission in tidal disruption events, but never produced self-consistently in a simulation. Our model broadly matches the observed light curves with low temperatures, faint luminosities, and line widths of \(\small {10,000}–{20,000}\;\text{km/s}\).
1 Introduction
In the classical picture of tidal disruption events (TDEs), the debris from the tidal disruption of a star on a parabolic orbit by a supermassive black hole (SMBH) rapidly circularises to form an accretion disc via relativistic apsidal precession (Rees, 1988). The predicted mass return rate of debris (Phinney, 1989) is \(\small \propto t^{5/3}\) and the light curve is assumed to be powered by accretion and to follow the same decay.
This picture alone does not predict several properties of observed TDEs, mainly related to their puzzling optical emission (van Velzen et al., 2011; van Velzen, 2018; van Velzen et al., 2021). These properties include: i) low peak bolometric luminosities (Chornock et al., 2014) of \(\small \sim {10^{44}}\;\text{ergs/s}\) \(\small \sim\) 1 per cent of the value expected from radiatively efficient accretion (Svirski et al., 2017); ii) low temperatures, more consistent with the photosphere of a B-type star than with that of an accretion disc at a few tens of gravitational radii (\(\small R_{g}\equiv GM_{\mathrm{BH}}/c^{2}\)) (Gezari et al., 2012; Miller, 2015), and consequently large emission radii, \(\small \sim {10}-{100}\) au for a \(\small 10^{6}M_{\odot}\) black hole (Guillochon et al., 2014.1; Metzger & Stone, 2016); and iii) spectral line widths implying gas velocities of \(\small \sim {10^4}\;\text{km/s}\), much lower than expected from an accretion disc (Arcavi et al., 2014.2; Leloudas et al., 2019; Nicholl et al., 2019.1).
As a consequence, numerous authors have proposed alternative mechanisms for powering the TDE lightcurve, via either shocks from tidal stream collisions during disc formation (Lodato, 2012.1; Piran et al., 2015.1; Svirski et al., 2017; Ryu et al., 2023; Huang et al., 2023.1), or the reprocessing of photons through large scale optically thick layers, referred to as Eddington envelopes (Loeb & Ulmer, 1997), super-Eddington outflows (Strubbe & Quataert, 2009), quasi-static or cooling TDE envelopes (Roth et al., 2016.1; Coughlin & Begelman, 2014.3; Metzger, 2022) or mass-loaded outflows (Jiang et al., 2016.2; Metzger & Stone, 2016). Recent spectro-polarimetric observations suggest reprocessing in an outflowing, quasi-spherical envelope (Patra et al., 2022.1).
The wider problem is that few calculations exist that follow the debris from disruption to fallback for a parabolic orbit with the correct mass ratio. The challenge is to evolve a main-sequence star on a parabolic orbit around a SMBH from disruption and to follow the subsequent accretion of material (Metzger & Stone, 2016). The dynamic range involved when a \(\small 1M_{\odot}\) star on a parabolic orbit is tidally disrupted by a \(\small {10^6}_{\odot}\) SMBH is greater than four orders of magnitude: the tidal disruption radius is 50 times the gravitational radius, where general relativistic effects are important, while the apoapsis of even the most bound material is another factor of 200 further away. This challenge led previous studies to consider a variety of simplifications (Stone et al., 2019.2): i) reducing the mass ratio between the star and the black hole by considering intermediate mass black holes (Ramirez-Ruiz & Rosswog, 2009.1; Guillochon et al., 2014.1); ii) using a Newtonian gravitational potential (Evans & Kochanek, 1989.1; Rosswog et al., 2008; Lodato et al., 2009.2; Guillochon et al., 2009.3; Golightly et al., 2019.3), pseudo-Newtonian (Hayasaki et al., 2013; Bonnerot et al., 2016.3) or post-Newtonian approximations (Ayal et al., 2000; Hayasaki et al., 2016.4); iii) simulating only the first passage of the star (Evans & Kochanek, 1989.1; Laguna et al., 1993; Khokhlov et al., 1993.1; Frolov et al., 1994; Diener et al., 1997.1; Kobayashi et al., 2004; Guillochon et al., 2009.3; Guillochon & Ramirez-Ruiz, 2013.1; Tejeda et al., 2017.1; Gafton & Rosswog, 2019.4; Goicovic et al., 2019.5); and iv) assuming stars initially on bound, highly eccentric orbits instead of parabolic orbits (Sadowski et al., 2016.5; Hayasaki et al., 2013, 2016.4; Bonnerot et al., 2016.3; Liptai et al., 2019.6; Hu et al., 2024).
These studies have, nevertheless, provided useful insights into the details of the tidal disruption process. In particular, it has been shown that the distribution of orbital energies of the debris following the initial disruption is roughly consistent with \(\small dM/dE\) = const, consistent with the analytic prediction of a \(\small \propto t^{5/3}\) mass fallback rate, although the details can depend on many factors such as stellar spin, stellar composition, penetration factor and black hole spin (Lodato et al., 2009.2; Kesden, 2012.2; Guillochon & Ramirez-Ruiz, 2013.1; Golightly et al., 2019.3; Sacchi & Lodato, 2019.7). The importance of general relativistic effects in circularising debris has also been demonstrated. The self-intersection of the debris stream, which efficiently dissipates large amounts of orbital energy, is made possible by relativistic apsidal precession (Hayasaki et al., 2016.4; Bonnerot et al., 2016.3; Liptai et al., 2019.6; Calderón et al., 2024.1). But until recently debris circularisation has only been shown for stars on bound orbits, with correspondingly small apoapsis distances and often deep penetration factors (we define the penetration factor as \(\small \beta\equiv R_{\mathrm{t}}/R_{\mathrm{p}}\), where \(\small R_{\mathrm{t}}=R_{*}(M_{\mathrm{BH}}/M_{*})^{1/3}\) is the tidal radius and \(\small R_{\mathrm{p}}\) is the pericenter distance).
Recent works have shown that circularisation and initiation of accretion is possible in the parabolic case, by a combination of energy dissipation in the ‘nozzle shock’ that occurs on second pericenter passage (Steinberg & Stone 2024.2; but see Bonnerot & Lu 2022.2 and Appendix E for convergence studies of the nozzle shock) and/or relativistic precession leading to stream collisions (Andalman et al., 2022.3).
In this paper, we present a set of simulations that self-consistently evolve a one solar mass polytropic star on a parabolic orbit around a \(\small {10^6}\) solar mass black hole from the star’s disruption to circularization of the returning debris and then accretion. We follow the debris evolution for one year post-disruption, enabling us to approximately compute synthetic light curves which appear to match the key features of observations.
Figure 1:One year in the life of a tidal disruption event. We show shapshots of column density in the simulation of a \(\small 1M_{\odot}\) star on a parabolic orbit with \(\small \beta = {1}\), disrupted by a \(\small {10^6} M_{\odot}\) black hole, using \(\small 4\times 10^{6}\) SPH particles in the Schwarzschild metric. Main panel shows the large scale outflows after 365 days projected in the \(\small {x}-{y}\) plane with log scale. Inset panels show the stream evolution on small scales (\(\small{100}\times {100}\) au), showing snapshots of column density projected in the \(\small {x}-{y}\) plane on a linear scale from \(\small {0}\;\text{to}\; {1500}\;{g/cm^2}\) (colours are allowed to saturate). Animated versions of this figure are available in the online article. Data and scripts used to create the figure are available on Zenodo:https://doi.org/10.5281/zenodo.11438154 (catalog doi:10.5281/zenodo.11438154)
The Universe is far from the ideal environment for life to thrive in - known life only exists as an encrustation on or near the surface of a single planet. Instead, it is a violent and unstable chaos of competing forces with an estimated \(\small {10^{19}}\) supper-dense, massive black holes, which far exceeds the number of life forms in the known Universe, drawing to inevitable annihilation any body that strays too close.
It requires parochial ignorance of the first order to imagine that the entire Universe is designed for life. It is far easier to make a case for it being designed for black holes, although that, as with the 'designed for life' case, case would require a priori evidence of the existence of a creative entity in the form of an explanation of its origins and definitive evidence of it ever being recorded as creating anything. And by recorded, I don't mean written in the mythology of Bronze Age pastoralists who thought the Universe was a small flat place with a dome over it and containing nothing that was unknown within a day or two's walk of the Canaanite Hills where they grazed their goats, and later decreed to be literal history by people with a vested interest in people believing the myths.
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Immunofluorescence staining of human gastric cells grown in a microplate and infected with Chlamydia trachomatis. Blue: cell nuclei, green: C. trachomatis, grey: actin.
Image: Pargev Hovhannisyan / Universität Würzburg
Chlamydia doesn’t always cause symptoms, but when it does, these are some of the most common.
Chlamydia is a sexually-transmitted bacterial infection in which the bacteria are passed to a new victim during sexual intercourse. It caused few or no symptoms to begin with - usually nothing worse than mild itching - but if left untreated it can cause infertility and sometimes cancer. Fortunately, it can be treated successfully with antibiotics.
However, it is not unusual for people who have been successfully treated to develop a new infection with exactly the same strain as the previous infection, suggesting that the bacteria had somehow survived the antibiotic treatment although symptoms had disappeared, and traces of the bacteria had gone.
Researchers have now shown that chlamydia can take up residence in the gut where it can survive for some considerable time and develop increasing resistance to antibiotics with each course of treatment. The mechanism of this increasing resistance is a classic example of evolution as the antibiotic acts as an environmental selector which removes the non-resistant bacteria from the population gene pool, leaving the resistant form to become dominant in the gene pool.
Mono Lake, located east of the Sierra Nevada, just outside Yosemite National Park. Dotted with tufa formations, the lake’s salty water is laced with arsenic and cyanide, but is home to unique flies and brine shrimp as well as choanoflagellates.
Nicole King.
To be fair to them, the simple pastoralists from the ignorant and fearful infancy of out species who invented the creation myths that got included in the Bible, later decreed to be the inerrant word of a creator god and therefore deemed to be real science and history, could have known nothing of Mono Lake in Present day California and even less about the microscopic organisms about the size of a dust grain known now as choanoflagellates because, quite simply they lacked the technology to be able to see them - which is also why neither cells nor micro-organisms are mentioned nor even hinted at, anywhere in the Bible.
What are choanoflagellates and how do they relate to other organisms?
Choanoflagellates are a group of free-living, single-celled organisms that are considered to be the closest living relatives of animals (metazoans). They are part of the clade Opisthokonta, which also includes fungi, animals, and some protists. Here’s a closer look at what choanoflagellates are and their relationship to other organisms:
Characteristics of Choanoflagellates
Structure: Choanoflagellates are characterized by a distinctive cell structure. Each cell has a single flagellum, which is a whip-like structure used for movement, surrounded by a collar of microvilli (tiny, finger-like projections). The flagellum beats, drawing water through the collar, which traps bacteria and other small particles for the choanoflagellate to feed on.
Habitat: These organisms are commonly found in aquatic environments, including both freshwater and marine ecosystems.
Lifestyle: Choanoflagellates can exist as single cells, but some species form colonies. Their colonial forms are of particular interest because they offer insights into the possible evolutionary steps that led to multicellularity in animals.
Relationship to Other Organisms
Closest Relatives to Animals: Genetic and molecular studies have shown that choanoflagellates are the closest living relatives to animals. This means that they share a common ancestor with animals, which is believed to have lived over 600 million years ago.
Evolutionary Significance: The relationship between choanoflagellates and animals is crucial for understanding the origin of multicellularity. It is thought that the transition from single-celled to multicellular organisms may have occurred through mechanisms similar to those seen in choanoflagellate colonies. The study of choanoflagellates helps scientists understand the early evolution of animals and the development of complex tissues and organs.
Shared Genes: Choanoflagellates possess many genes that are also found in animals, including those involved in cell adhesion, signaling, and extracellular matrix formation. These genes are essential for the development and maintenance of multicellular structures in animals, suggesting that the genetic toolkit required for multicellularity was already present in the last common ancestor of choanoflagellates and animals.
In summary, choanoflagellates are not only fascinating in their own right as unique protists, but they also play a key role in understanding the evolutionary steps that led to the rise of the animal kingdom.
And, being unaware of the history of life on a planet that they thought was only a few thousand years old and had been created out of nothing by magic with all the animals and plants fully formed, they could never in a million years, have guessed how multicellular animals evolved several hundred million years ago out of colonies of single-celled organisms.
And, of course, it's the yawning chasm between what the Bible's authors believed and what we now know, that tells us the Bible can't be the work of an omniscient creator god.
But of course, there are still a few (shrinking) gaps in what we know too. For example, although we have the genetic and structural evidence that multicellular organisms evolved out of single-celled organisms, we don't yet know the precise details, which is why a team of researchers from University of California, Berkeley have been studying a little-known choanoflagellates found in Mono Lake, near the Sierra Nevada, California. choanoflagellates are known to form colonies of organisms so can help shed some light on how related organisms originally got together to form simple multicellular organisms.
An additional discovery of this research was how these colonies incorporate a bacterial biome in a process analogous to the way most multicellular animals have associated biomes like out gut biome, for example.
The Berkely team's work is the subject of an open access paper in the American Society for Microbiology (ASM) journal mBio. It is also explained in a University of California Berkely news release:
Creature the size of a dust grain found hiding in California’s Mono LakeColonies of these choanoflagellates — members of a group considered to be the closest living relatives of all animals — have their own unique microbiomes.
Mono Lake in the Eastern Sierra Nevada is known for its towering tufa formations, abundant brine shrimp and black clouds of alkali flies uniquely adapted to the salty, arsenic- and cyanide-laced water.
University of California, Berkeley, researchers have now found another unusual creature lurking in the lake’s briny shallows — one that could tell scientists about the origin of animals more than 650 million years ago.
The organism is a choanoflagellate, a microscopic, single-celled form of life that can divide and develop into multicellular colonies in a way that’s similar to how animal embryos form. It’s not a type of animal, however, but a member of a sister group to all animals. And as animals’ closest living relative, the choanoflagellate is a crucial model for the leap from one-celled to multicellular life.
Surprisingly, it harbors its own microbiome, making it the first choanoflagellate known to establish a stable physical relationship with bacteria, instead of solely eating them. As such, it’s one of the simplest organisms known to have a microbiome.
Very little is known about choanoflagellates, and there are interesting biological phenomena that we can only gain insight into if we understand their ecology.
Professor Nicole King, senior author
Professor of molecular and cell biology
Howard Hughes Medical Institute and Department of Molecular and Cell Biology
University of California, Berkeley, California, USA.
Globular colonies of the choanoflagellate B. monosierra seen under a microscope. As indicated by the 50-micron scale bar, these colonies are at the limit of what’s visible to the naked eye.
Alain Garcia De Las Bayonas, Nicole King lab.
Typically visible only through a microscope, choanoflagellates are often ignored by aquatic biologists, who instead focus on macroscopic animals, photosynthetic algae or bacteria. But their biology and lifestyle can give insight into creatures that existed in the oceans before animals evolved and that eventually gave rise to animals. This species in particular could shed light on the origin of interactions between animals and bacteria that led to the human microbiome.
Animals evolved in oceans that were filled with bacteria. If you think about the tree of life, all organisms that are alive now are related to each other through evolutionary time. So if we study organisms that are alive today, then we can reconstruct what happened in the past.
Professor Nicole King.
King and her UC Berkeley colleagues described the organism — which they named Barroeca monosierra, after the lake — in a paper published online Aug. 14 in the journal mBio.
A beautiful colony
Nearly 10 years ago, then-UC Berkeley graduate student Daniel Richter came back from a climbing trip in the Eastern Sierra Nevada with a vial of Mono Lake water he’d casually collected along the way. Under the microscope, it was alive with choanoflagellates. Aside from brine shrimp, alkali flies and various species of nematode, few other forms of life have been reported to live in the inhospitable waters of the lake.
The newly named species Barroeca monosierra discovered in Mono Lake. Colonies of these organisms consist of numerous identical cells (cyan), each with flagella (green) that allow them to propel themselves through the water. This choanoflagellate colony hosts its own microbiome (red), something never before seen in these organisms. The extracellular matrix with which the bacteria interact is shown in white.
Video credit: Davis Laundon and Pawel Burkhardt, Sars Centre, Norway; Kent McDonald and Nicole King, UC Berkeley.
It was just packed full of these big, beautiful colonies of choanoflagellates. I mean, they were the biggest ones we’d ever seen.
Professor Nicole King.
The colonies of what seemed to be close to 100 identical choanoflagellate cells formed a hollow sphere that twirled and spun as each individual cell kicked its flagella.
One of the things that’s interesting about them is that these colonies have a shape similar to the blastula — a hollow ball of cells that forms early in animal development. We wanted to learn more about it.
Professor Nicole King.
At the time, however, King was occupied with other species of choanos, as she calls them, so the Mono Lake choanos languished in the freezer until some students revived and stained them to look at their unusual, doughnut-shaped chromosomes. Surprisingly, there was also DNA inside the hollow colony where there should have been no cells. After further investigation, graduate student Kayley Hake determined that they were bacteria.
A colony of choanoflagellates stained to show its features. Cyan indicates DNA — the doughnut-shaped DNA of the choanoflagellate cells and a cloud of bacterial DNA inside the colony — while flagella are white and microscopic hairs (villi) on each cell are red.
Kayley Hake, Nicole King lab
The bacteria were a huge surprise. That just was fascinating.
Professor Nicole King.
Hake also detected connective structures, called extracellular matrix, inside the spherical colony that were secreted by the choanos.
Only then did it occur to Hake and King that these might not be the remains of bacteria the choanos ate, but bacteria living and grazing on stuff secreted by the colony.
No one had ever described a choanoflagellate with a stable physical interaction with bacteria. In our prior studies, we found that choanos responded to small bacterial molecules that were floating through the water, or [that] the choanos were eating the bacteria, but there was no case where they were doing anything that could potentially be a symbiosis. Or in this case, a microbiome.
Professor Nicole King.
King teamed up with Jill Banfield, a pioneer in metagenomics and a UC Berkeley professor of environmental science, policy and management and of earth and planetary science, to determine which bacterial species were in the water and inside the choanos. Metagenomics involves sequencing all the DNA in an environmental sample to reconstruct the genomes of the organisms living there.
After Banfield’s lab identified the microbes in Mono Lake water, Hake created DNA probes to determine which ones were also inside the choanos. The bacterial populations were not identical, King said, so evidently some bacteria survive better than others inside the oxygen-starved lumen of the choanoflagellate colony. Hake determined that they were not there accidentally; they were growing and dividing. Perhaps they were escaping the toxic environment of the lake, King mused, or maybe the choanos were farming the bacteria to eat them.
Much of this is speculation, she admits. Future experiments should uncover how the bacteria interact with the choanoflagellates. Past work in her lab has already shown that bacteria act like an aphrodisiac to stimulate mating in choanoflagellates, and that bacteria can stimulate single-celled choanos to aggregate into colonies.
For her, the Mono Lake choanoflagellate will become another model system in which to study evolution, just like the choanos that live in splash pools on the island of Curaçao in the Caribbean — her main focus at the moment — and the choanos in pools at the North and South Poles. It might be a challenge to get more samples from Mono Lake, however. On a recent visit, only six of 100 samples contained these energetic microorganisms.
I think there’s a great deal more that needs to be done on the microbial life of Mono Lake, because it really underpins everything else about the ecosystem,. I’m excited about B. monosierra as a new model for studying interactions between eukaryotes and bacteria. And I hope it tells us something about evolution. But even if it doesn’t, I think it’s a fascinating phenomenon.
Professor Nicole King.
In addition to King, Banfield, Hake and Richter, UC Berkeley co-authors of the paper include former doctoral student Patrick West, electron microscopist Kent McDonald and postdoctoral fellows Josean Reyes-Rivera and Alain Garcia De Las Bayonas. The work is supported by HHMI and the National Science Foundation.
ABSTRACT
As the closest living relatives of animals, choanoflagellates offer insights into the ancestry of animal cell physiology. Here, we report the isolation and characterization of a colonial choanoflagellate from Mono Lake, California. The choanoflagellate forms large spherical colonies that are an order of magnitude larger than those formed by the closely related choanoflagellate Salpingoeca rosetta. In cultures maintained in the laboratory, the lumen of the spherical colony is filled with a branched network of extracellular matrix and colonized by bacteria, including diverse Gammaproteobacteria and Alphaproteobacteria. We propose to erect Barroeca monosierra gen. nov., sp. nov. Hake, Burkhardt, Richter, and King to accommodate this extremophile choanoflagellate. The physical association between bacteria and B. monosierra in culture presents a new experimental model for investigating interactions among bacteria and eukaryotes. Future work will investigate the nature of these interactions in wild populations and the mechanisms underpinning the colonization of B. monosierra spheres by bacteria.
IMPORTANCE
The diversity of organisms that live in the extreme environment of Mono Lake (California, USA) is limited. We sought to investigate whether the closest living relatives of animals, the choanoflagellates, exist in Mono Lake, a hypersaline, alkaline, arsenic-rich environment. We repeatedly isolated members of a new species of choanoflagellate, which we have named Barroeca monosierra. Characterization of B. monosierra revealed that it forms large spherical colonies containing diverse co-isolated bacteria, providing an opportunity to investigate mechanisms underlying physical associations between eukaryotes and bacteria.
OBSERVATION
A newly identified choanoflagellate species forms large spherical colonies
Choanoflagellates are the closest living relatives of animals and, as such, provide insights into the origin of key features of animal biology (1, 2). Over five sampling trips to Mono Lake, California (Fig. 1A; Table S1), we collected single-celled choanoflagellates and large spherical choanoflagellate colonies, many of which were seemingly hollow (Fig. 1B). In colonies and single cells, each cell bore the diagnostic collar complex observed in other choanoflagellates: an apical flagellum surrounded by a collar of microvilli (1, 2). In the spherical colonies, each cell was oriented with the basal pole of the cell body facing inwards and the apical flagellum facing out (Fig. 1B). We know of no prior reports of choanoflagellates having been isolated and cultured from any hypersaline alkaline lake, including Mono Lake.
Fig 1
Fig 1 A colonial choanoflagellate isolated from Mono Lake. (A) Choanoflagellates were collected from three sampling sites (asterisks) near the shore of Mono Lake, California (modified from a map in the public domain, formatted as USGS Imagery Only; https://www.usgs.gov/volcanoes/long-valley-caldera) (B) B. monosierra forms large colonies (differential interference contrast image). Scale bar = 50 µm. (C) B. monosierra (shown in bold) is a craspedid choanoflagellate closely related to S. rosetta and Microstomoeca roanoka. Phylogeny based on sequences of three genes: 18S rRNA, EFL, and HSP90. Metazoa (seven species) were collapsed to save space. Bayesian posterior probabilities are indicated above each internal branch, and maximum likelihood bootstrap values are below. (A “—” value indicates a bifurcation lacking support or not present in one of the two reconstructions.) Also see Fig. S1C for further phylogenetic analyses. (D and E) Two colonies from the ML2.1G culture (Fig. S1, Box2) reveal the extremes of the B. monosierra colony size range (D, 58 µm diameter; E, 19 µm diameter; scale bar = 20 µm). In B. monosierra colonies, each cell is oriented with its apical flagellum (white; labeled with anti-tubulin antibody) and the apical collar of microvilli (red; stained with phalloidin) pointing out. Nuclei (cyan) were visualized with the DNA-stain Hoechst 33342. (F) Colonies of B. monosierra span from 10 µm in diameter, a size comparable to that of small S. rosetta colonies, to 120 µm, over an order of magnitude larger. The diameters of B. monosierra and S. rosetta colonies were plotted as a violin plot; the median is indicated as a thick black line. Diameters of the colonies in panels D and E are indicated as colored bars behind the violin plot (D, red bar; E, blue bar).
Fig 2
Fig 2 Bacteria reside in the lumina of B. monosierra colonies. (A and A′) The center of a B. monosierra colony from culture ML2.1G (Fig. S1, Box 2), shown as a maximum intensity projection (A) and optical z-section (A′), contains DNA (revealed by Hoechst 33342 staining; cyan). Apical flagella were labeled with anti-tubulin antibody (white); microvilli were stained with phalloidin (red). Hoechst 33342 staining (cyan) revealed the spherical choanoflagellate nuclei along the colony perimeter and an amorphous cloud of DNA sitting within the central cavity formed by the monolayer of choanoflagellate cells. (B, B’’ and B′) A thin section through a B. monosierra colony, imaged by transmission electron microscopy (TEM), revealed the presence of small cells in the central cavity. (B′) Inset (box from panel B) reveals that the interior cells are each surrounded by a cell wall. (C, C’’, C’’’, and C″′′) The small cells inside B. monosierra colonies (grown from cultures ML2.1E/ML2.1EC) are bacteria, as revealed by hybridization with a broad-spectrum 16S rRNA probe (C, green) and a probe targeting Gammaproteobacteria (C′, red). Choanoflagellate nuclei and bacterial nucleoids were revealed by staining with Hoechst (C″, cyan). (C″′) Merge of panels C, C′, and C″. Scale bar for all = 5 µm. (D, D’ and D″) 3D reconstruction of a 70-cell B. monosierra colony from transmission electron micrographs of serial ultrathin sections revealed that the bacteria are closely associated with and wrapped around the extracellular matrix (ECM) inside the colony. (D) Whole colony view. (D′) Cut-away view of colony center. False colors indicate cell bodies (cyan), microvilli (orange), flagella (green), bacteria (red), ECM (white), intercellular bridges (yellow; see also Fig. S5), and filopodia (purple). (D″) Reducing the opacity of the choanoflagellate cell renderings revealed the presence of bacteria positioned between the lateral surfaces of choanoflagellate cells (brackets; see also Fig. S7). (E) Representative B. monosierra colony from an environmental sample shown as an average intensity projection (planes 17–27 from 1-µm optical sections). Choanoflagellate nuclei and bacterial nucleoids (examples indicated by arrowheads) were revealed by staining with Hoechst (cyan). To allow visualization of the much smaller bacterial nucleoids, the imaging of the choanoflagellate nuclei was saturated. Concanavalin A staining (magenta) revealed the branched extracellular matrix. (F and G) Optical sections 19 and 24, respectively, of the B. monosierra colony shown in panel E. (F′ and G′) Higher magnification Hoechst-stained DNA from the boxed regions in F and G, highlighting the resident bacteria (examples indicated by arrowheads). Scale bars in panels E–G = 10 μm.
This discovery shows a plausible route to multicellularity from a related single-celled eukaryote organism and offers an explanation for the early stages of embryo development where a single-cell zygote gives rise early on to a hollow gastrula. This could have formed in an ancestral multicellular metazoan as somewhere for a symbiotic colony of bacteria to reside and provide nutrients in return for protection. It also offers a plausible explanation for our commensal, symbiotic microbiome in our gut which has its embryonic origins in the hollow gastrula.
Creationists might also like to ignore the fact that the research team believe they are explaining a fundamental step in the evolution of multicellularity 650 million years ago, and have found no need to abandon science and the scientific method and turn to creationism with its magic and unproven entities for a more rational explanation of the facts.
And of course, as with 99.9975% of all history, this stage in the evolution of multicellular life happened in that long, pre-'Creation Week', period of Earth's history.
