Space germs

I'm fully in support of pure research, which should be obvious to anyone who is a regular reader of Skeptophilia.  But sometimes I run into a paper that leaves me scratching my head.

This happened this past weekend when I stumbled upon a press release from the University of Exeter entitled, "Mammals Could Struggle to Fight Space Germs."  The gist was that a team led by microbiologist Neil Gow did a series of experiments exposing mammalian cells to lab-synthesized peptides containing two amino acids that have been detected in space but not found in terrestrial proteins (isovaline and α-aminoisobutyric acid), and they found that the cell cultures had a "weak immune response."  From this, they concluded that if we're exposed to extraterrestrial microbes, we might really suck at fighting them off.

[Image licensed under the Creative Commons Phoebus87 at English Wikipedia, Symian virus, CC BY-SA 3.0]

This seemed like a rather overblown conclusion, so I went to the original paper (always a good idea; even university press releases are often oversimplifications or miss important points).  In this case, though, the press release was pretty much spot-on.  Here it is, straight from the paper:

The discovery of liquid water at several locations in the solar system raises the possibility that microbial life may have evolved outside Earth and as such could be accidently introduced into the Earth’s ecosystem.  Unusual sugars or amino acids, like non-proteinogenic isovaline and α-aminoisobutyric acid that are vanishingly rare or absent from life forms on Earth, have been found in high abundance on non-terrestrial carbonaceous meteorites.  It is therefore conceivable that exo-microorganisms might contain proteins that include these rare amino acids.  We therefore asked whether the mammalian immune system would be able to recognize and induce appropriate immune responses to putative proteinaceous antigens that include these rare amino acids. To address this, we synthesised peptide antigens based on a backbone of ovalbumin and introduced isovaline and α-aminoisobutyric acid residues and demonstrated that these peptides can promote naïve OT-I cell activation and proliferation, but did so less efficiently than the canonical peptides.  This is relevant to the biosecurity of missions that may retrieve samples from exoplanets and moons that have conditions that may be permissive for life, suggesting that accidental contamination and exposure to exo-microorganisms with such distinct proteomes might pose an immunological challenge.

Okay, I'll admit that this is one possible conclusion you could draw; it certainly has been riffed on often enough in science fiction, starting all the way back in 1969 with The Andromeda Strain.  (You could argue that it goes back further than that, given that at the end of H. G. Wells's 1898 novel The War of the Worlds, the invading Martians are destroyed by terrestrial microbes to which they have no natural immunity.)

The other possibility, however, is that the microbes wouldn't affect us at all.  When pathogens attack our cells, they usually obtain ingress by bonding to receptors on the surface.  Those receptors can be amazingly specific; this is why there are so many strains of flu, some of which only attack birds or pigs... or humans.  The immune species, in this case, lack the surface proteins that can form bonds to the viral proteins, so they don't get in.  The result: no disease.

In fact, it's even more specific than that.  In 2006, an outbreak of H5N1 bird flu generated worries about a pandemic, until it was learned that although highly contagious in birds, it only affects humans if the virus binds deep in the lung tissue -- the receptors in the upper respiratory system aren't able to bind to the virus efficiently (fortunately for us).  The only ones who became ill were poultry workers who were exposed to dust and debris in poultry houses.  No cases of human-to-human transmission were recorded.

So my suspicion is that extraterrestrial microbes probably wouldn't be able to attack us at all.  And given that our tissues would lack the two oddball amino acids the researchers used in their experiments, it seems pretty likely that if the microbes did get in, they'd starve to death.  (Put more scientifically, our proteins would lack two amino acids they need, so we wouldn't be of much use to them as a food source.)

Of course, it's possible that Gow et al. are right, and extraterrestrial microorganisms would consider the Earth an all-you-can-eat buffet.  But given that (1) the number of extraterrestrial microorganisms we've actually studied is zero, and (2) there are equally persuasive arguments to the contrary, it might be a little bit of a premature conclusion.

Now, that doesn't mean we should be bringing outer space debris to Earth, sans quarantine.  Hell, I've read The Colour Out of Space, and last thing I want is to have a gaseous entity from a meteorite cause my limbs to crumble and fall off.  COVID-19 is bad enough, thanks.  We really don't need any more reasons to panic, however.  So for now, let's confine ourselves to dealing with threats that currently exist.

*****************************

Being in the middle of a pandemic, we're constantly being urged to wash our hands and/or use hand sanitizer.  It's not a bad idea, of course; multiple studies have shown that communicable diseases spread far less readily if people take the simple precaution of a thirty-second hand-washing with soap.

But as a culture, we're pretty obsessed with cleanliness.  Consider how many commercial products -- soaps, shampoos, body washes, and so on -- are dedicated solely to cleaning our skin.  Then there are all the products intended to return back to our skin and hair what the first set of products removed; the whole range of conditioners, softeners, lotions, and oils.

How much of this is necessary, or even beneficial?  That's the topic of the new book Clean: The New Science of Skin by doctor and journalist James Hamblin, who considers all of this and more -- the role of hyper-cleanliness in allergies, asthma, and eczema, and fascinating and recently-discovered information about our skin microbiome, the bacteria that colonize our skin and which are actually beneficial to our overall health.  Along the way, he questions things a lot of us take for granted... such as whether we should be showering daily.

It's a fascinating read, and looks at the question from a data-based, scientific standpoint.  Hamblin has put together the most recent evidence on how we should treat the surfaces of our own bodies -- and asks questions that are sure to generate a wealth of discussion.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Tales of contagion

I have to admit to a morbid fascination with things that can kill you in nasty ways.

Tornadoes, hurricanes, earthquakes, mass extinctions from giant meteorite collisions -- and epidemics.  I remember first reading Daniel Defoe's A Journal of the Plague Year, about an outbreak of the Black Death in London in 1664 and 1665, when I was in college, and being simultaneously horrified and mesmerized at the scale of it.  An estimated 100,000 people died in two years -- a quarter of London's population.

But even that is dwarfed by two other epidemics.  First, there's the infamous outbreak of bubonic plague that started in 1347 and, by some estimates, killed one-third of the human population of the Earth -- something on the order of fifty million people.  The worst, though, was the "Spanish flu" epidemic of 1918 and 1919.  Odd that an event only a hundred years ago, and that killed an estimated 75 million people worldwide -- twice as many as World War I, which was happening at the same time -- is much less known.  Mention the Black Death, and almost everyone has an idea of what it is; mention the Spanish flu, and often all you get is a puzzled look.

Danse Macabre by Michael Wolgemut [image is in the Public Domain]

This all comes up because of a paper by Maria Spyrou et al. that appeared in Nature: Communications last week.  In it, the researchers describe looking for evidence of pathogens in the Bronze-Age burial sites -- and finding evidence that the bubonic plague has been with us for a long, long time.  The authors write:

The origin of Yersinia pestis and the early stages of its evolution are fundamental subjects of investigation given its high virulence and mortality that resulted from past pandemics.  Although the earliest evidence of Y. pestis infections in humans has been identified in Late Neolithic/Bronze Age Eurasia (LNBA 5000–3500y BP), these strains lack key genetic components required for flea adaptation, thus making their mode of transmission and disease presentation in humans unclear.  Here, we reconstruct ancient Y. pestis genomes from individuals associated with the Late Bronze Age period (~3800 BP) in the Samara region of modern-day Russia.  We show clear distinctions between our new strains and the LNBA lineage, and suggest that the full ability for flea-mediated transmission causing bubonic plague evolved more than 1000 years earlier than previously suggested.  Finally, we propose that several Y. pestis lineages were established during the Bronze Age, some of which persist to the present day.

Which is fascinating enough, but it bears mention that there are still a number of epidemics that scientists have no clear explanation for.  Here are three of the most puzzling:

1. "Sweating sickness."  In the late 15th and early 16th centuries, several waves of contagious illness swept through western Europe.  It killed fast -- starting with disorientation, fever, chills, aching joints, and finally progressing to delirium and copious sweating.  Most of the victims died within 36 hours of the onset.  It claimed a number of well-known victims, including Prince Arthur of England -- the son of King Henry VII, and brother of King Henry VIII.  Arthur's death at the age of fifteen put Henry in line for the throne, and set into motion events that would change the world -- such as the English Reformation and the founding of the Anglican Church.  Sweating sickness went as quickly as it started -- the last outbreak was in 1551, and it hasn't been seen since.  Scientists are still mystified as to the cause, but the speculation is it might have been a hantavirus, carried by mice.
2. The Dancing Plague of 1518.  In eastern France and western Germany, people were stricken by a disorder that caused shaking, mania, and... a desperation to dance.  People took to the streets, dancing desperately, many of them until they died of hunger, exposure, heat exhaustion, or stroke.  In Strasbourg alone, at the height of the plague, it was killing fifteen people a day.  It, like the sweating sickness, vanished as soon as it appeared, leaving everyone mystified as to its cause -- although some researchers suspect it might have been caused by ergot, a fungus that grows on wheat and rye and produces lysergic acid diethylamide -- LSD.
3. "Nodding syndrome."  This one is much more recent, having first emerged in the 1960s in Sudan.  It affects children, causing listlessness, stunting of growth (especially of the brain), and a peculiar symptom called a "nodding seizure," often triggered by eating or becoming cold.  The child's head bobs, and (s)he becomes unresponsive, the seizures lasting for up to ten or fifteen minutes.  It's progressive and fatal -- the usual duration being about three years.  To this day no one knows the cause, although some suspect it might be connected to parasitism by the roundworm Onchocercus volvulus, which is endemic in the area and also causes "river blindness."

So this combines my love of horrible things that can kill you with my love of unsolved mysteries.

Anyhow, I realize this is all kind of morbid, and I have no desire to ruin your mood.  After all, we live in an age where most of the worst diseases of antiquity have been vanished; even bubonic plague, if it's caught quickly, can be cured with antibiotics (and yes, there are still cases of it today).  Thankfully, we seem to have gotten rid of sweating sickness and the dancing plague, even if we've replaced them with Ebola fever and chikungunya and West Nile virus.  I'll still take what we've got today over life in the past, which was (accurately) described by Thomas Hobbes as "solitary, nasty, poor, brutish, and short."

Have a nice day.

***************************************

This week's recommended read is Wait, What? And Life's Other Essential Questions by James E. Ryan.  Ryan frames the whole of critical thinking in a fascinating way.  He says we can avoid most of the pitfalls in logic by asking five questions: "What?"  "I wonder..." "Couldn't we at least...?" "How can I help?" and "What truly matters?"  Along the way, he considers examples from history, politics, and science, and encourages you to think about the deep issues -- and not to take anything for granted.