Is life really worth it?

Existentially, what does atheism have to offer atheists? An atheist answers:

Q: At 42 I feel like I've fulfilled my obligations and done everything I needed to do in this world. I'm not sure that it's necessary for me to remain in here any longer. There's really nothing more that I want or need to do. Is it time for me to go?

A: Sure. You have to ask yourself, “what is the point to being alive”. There is no point. Procreating to protect the race against extinction can be handled by the other 7 billion people. Other than that, living is . . . living. What is the point of a tree, a turtle, a bacteria? Why should we be any different?

Q: What is the best thing that’s happened in your life?

A: Living to 76 years old. The alternative is terrible.

Q: Is life really worth it?

A: No. I’m 76. I’ve backpacked through more than 100 countries since 1957, many with my two sons. Started four successful companies. Retired at 45 and again at 49 after stumbling into another successful company. I’m married to an Asian woman 27 years younger than me who was a model in Japan for six years. I can buy what I want, when I want. And, no, it isn’t worth it. Mainly because there really isn’t any point to any of it. I’m sitting in front of my computer at 10:48 pm wasting time typing this reply to you. Why? Is this reply “worth it”? Hell no. Your life at any point in time is the result of memories that don’t exist. There is nothing but “now”. Is “now” worth it? I guess the answer is subjective.

Q: Is it possible to improve myself as a person while homeless? I’ve been pretty financially unstable and crashing on various couches for the last six months, and it’s been very hard to keep up with my spiritual side.

A: Why bother? If you have enough to eat, are in good health, and have a place to crash, why bring on problems by “improving yourself”. Spirituality has nothing to do with bucks. I think you mean “self esteem”, which is highly over-rated. Civilization hasn’t made anyone happier. Owning “stuff” doesn’t make anyone happier. Read, “Richard Corey” online.

"Richard Cory"
Edwin Arlington Robinson

Whenever Richard Cory went down town,
We people on the pavement looked at him:
He was a gentleman from sole to crown,
Clean favored, and imperially slim.

And he was always quietly arrayed,
And he was always human when he talked;
But still he fluttered pulses when he said,
"Good-morning," and he glittered when he walked.

And he was rich—yes, richer than a king—
And admirably schooled in every grace:
In fine, we thought that he was everything
To make us wish that we were in his place.

So on we worked, and waited for the light,
And went without the meat, and cursed the bread;
And Richard Cory, one calm summer night,
Went home and put a bullet through his head.

Cuteness

Given atheism and evolution, it's odd we find small furry animals "cute". From an evolutionary perspective, wouldn't it make more sense (such as be better for our survival as a species) to be neutral about cuteness?

If we didn't find small furry animals cute, then we could kill and eat them without hesitation. It's not as if other animals seem to find small furry animals cute. Like foxes don't find bunnies cute. Like sea lions don't think about baby penguins that way. (Not that penguins have fur as such, but you get the idea.)

Perhaps evolutionists will explain it by saying we only find small furry animals that look most like our own babies cute. We see our own babies as cute since it helps us bond with our own babies which in turn helps us want to raise our own babies rather than toss them aside the moment they're born. However, even if so, why should that apply to babies that aren't our own? It's not as if chimps think of other baby chimps as cute when they kill other baby chimps (e.g. here).

Delta Delta Delta force, can I help ya, help ya, help ya?

A friend emails to ask:

On the transgender troops issue, would a woman who's having her period be a problem when elite forces go out on a mission?

Definitely:

1. We can distinguish between three categories: premenstrual symptoms, premenstrual syndrome (PMS), and premenstrual dysphoric disorder (PMDD). Each subsequent category is worse than the previous category. Premenstrual symptoms occur in approximately 75%-85% of all women, PMS occurs in approximately 5%-10% of all women, and PMDD occurs in approximately 3%-5% of all women.

   PMS and especially PMDD would be particularly destabilizing for women in special forces. I think that's fairly obvious to most people. So I'll simply focus on premenstrual symptoms.

2. Premenestrual symptoms can be physical as well as psychological or emotional. The most common physical symptoms include swollen and tender breasts, pelvic pain, abdominal pain, diarrhea or constipation, headaches (e.g. migraines), skin changes (e.g. acne), hot flashes, altered cravings (e.g. craving candy), weight gain, local or generalized aches and pains (e.g. back pain). The most common psychological or emotional symptoms include moodiness, irritability, depression, confusion, temporary mild amnesia, anxiety, malaise, fatigue, insomnia, a sense of being "out of control".

   Again, keep in mind PMS and PMDD would have worse premenstrual symptoms and/or significantly more premenstrual symptoms.

   It should be fairly obvious none of these symptoms would be beneficial as a Navy SEAL or other special forces member. What's worse, most of these symptoms could be detrimental in certain situations operating as a member of the special forces. Not only to the woman herself, but to her fellow team members.

3. Premenstrual symptoms generally peak around age 25-30 which would coincide with the time people tend to be at their physical peak as well.

4. A woman could attempt to treat or manage her premenstrual symptoms (e.g. oral contraceptive combinations, depot injections, oophorectomy would be very radical). These have varying degrees of effectiveness as well as varying degrees of risks, even in ones that are deemed "safe". And I'm not sure how practical or effective these would be on a mission where the woman is sleeping in the rough, crisscrossing challenging terrain, in hostile enemy territory, etc.

Miscarriages

A friend asks about miscarriages. For what it's worth, here's my response:

1. Definitions

   a. Miscarriage is also known as spontaneous abortion. Spontaneous abortion isn't the best term because it can confuse people to think it's associated with elective abortion.

   b. Miscarriage is such a broad term. In general it refers to a pregnancy that spontaneously ends before the embryo or fetus has reached a viable gestational age. A complication is "viable gestational age" is itself a vague term susceptible to change, depending on medical science and technology. Currently that would be around the 20th week of gestation (as calculated from the date of the last menstrual period). However, it's possible future medical science and technology will alter the age of viability.

   c. Another common definition of miscarriage (such as the World Health Organization uses) is the spontaneous expulsion of an embryo or fetus weighing 500 g or less. A 500 g fetus would approximately correspond to the 20th week of gestation.

   d. Miscarriages can be subdivided into complete or incomplete miscarriages. If it's complete, then the uterus is entirely emptied, whereas if it's incomplete, then some tissue remains.

   e. One could make further distinctions such as induced (usually elective) abortions, threatened abortions, inevitable abortions, missed abortions, and tubal abortions or ectopic pregnancies.

2. Incidence

   a. It's somewhat difficult to obtain accurate numbers (e.g. it depends how miscarriages are detected).

   b. To my knowledge, most of these studies on miscarriages are based on tests measuring β-hCG. However, measuring β-hCG has its limitations. Other tests measure other factors like early pregnancy factor (EPF), but these tests have their limitations too.

   c. The popular belief is the incidence of spontaneous abortion is ~50%. To my knowledge, that's only the case when preimplantation losses are factored in. An extremely pertinent question to ask is, what is the exact nature of these preimplantations? Specifically, how many are viable zygotes/embryos? Unfortunately this is a highly politicized question to ask, but my own research suggests the majority are not viable zygotes/embryos.

   d. What then is the incidence of spontaneous abortions or miscarriages? Estimates range from 8-20% of all clinically recognized pregnancies under 20 weeks. The incidence is significantly lower at 5% among women who have previously had a child. The incidence of spontaneous abortion is higher at 13-26% if we include unrecognized or subclinical pregnancies. (Sources: here, here, here, here, here.)

   e. Finally these figures appear to be largely based on fertilized oocytes. Fertilized oocytes are not necessarily equivalent to what pro-lifers mean when they argue life begins at conception. For one thing, a fertilized oocyte is not necessarily a viable zygote/embryo. Not all fertilized oocytes are chromosomally or structurally normal.

3. Etiology

   a. The most common cause of spontaneous abortions is most likely due to genetic abnormalities in the embryo or fetus. This is thought to account for ~75% of all spontaneous abortions. The most common genetic abnormalities are autosomal trisomies (50% of all genetic abnormalities). And trisomy 16 (which is 100% lethal) is the most common of the trisomies.

   b. Other causes of spontaneous abortions (~25%) are infections, autoimmune diseases, endocrine issues, uterine issues, and drug or substance abuse.

4. Risk factors

   The biggest risk factors for spontaneous abortions are: advanced maternal age, previous spontaneous abortion, and maternal smoking (10 cigarettes per day or more).

   It may come as no surprise that Western societies have a significantly increased risk for spontaneous abortion primarily due to advanced maternal age.

5. Fertilization/conception

   a. I think it's worth noting an important distinction: fertilization is not identical to conception and vice versa. Fertilization occurs when the sperm enters or penetrates the oocyte (later ovum) or egg. Conception occurs when the sperm and egg cease to exist as sperm and egg in order to become a zygote which has its own unique genetic material and which has its own unique behavior.

   b. I think it's possible to argue human life begins either at fertilization or conception. I see merits to both. It's arguable we should play it safe and err on the side of fertilization. I'd argue conception (syngamy) is certainly the latest it could be.

   c. I realize many or most state the sperm and egg fuse, unite, or the like. That's fine as far as it goes, and I don't object to the terminology. However, at certain times it could be misleading language, scientifically speaking. More on this below.

   d. After the sperm has entered the egg, but prior to the creation of the zygote, the sperm and egg duplicate their respective genetic information in becoming paternal pronuclei and maternal pronuclei. The two pronuclei line up and move toward one another within the egg, their nucleic membranes dissolve (not fuse), and the chromosomes pair up to eventually become a new human genome.

   e. Overall it takes approximately 12-18 hours after fertilization for the zygote appear.

6. References

   Beckmann, C. Obstetrics and Gynecology (2009). (6th ed.).
   Cunnigham et al. (2014). Williams Obstetrics (24th ed.).
   Mularz, A., Dalati, S., & Pedigo, R. (eds.). (2016). OB/GYN Secrets (4th ed.).
   Tulandi, T., & Al-Forzan, H.M. (2017). "Spontaneous abortion: Risk factors, etiology, clinical manifestations, and diagnostic evaluation". In D. Levine, R. Barbieri, & K. Eckler (eds.), UpToDate. Retrieved April 28, 2017, from https://www.uptodate.com/contents/spontaneous-abortion-risk-factors-etiology-clinical-manifestations-and-diagnostic-evaluation

Zoological diversity

I just wanted to pick up on what Steve Hays astutely said:

Finally, suppose we ask ourselves what biology would look like if God wanted to create a world with maximal zoological diversity. That would mean you could arrange species along a continuum of similarity and dissimilarity. Some species would be more alike while others would be less alike. Some would occupy the extreme ends of greatest similarity and dissimilarity while others would represent gradations in-between. For any two species, they are either more alike or less alike. You'd have a nearly infinite range of fine-grained variations.

If so, then man is bound to resemble some species more than others, and there will be a few species he most closely resembles. But is that due to common descent, or is that just the inevitable result of God making a world in which he rings the changes on body plans?

If God wanted to make humans completely discontinuous with all other life on Earth, then he could have made our entire genome fundamentally different from all other life on Earth. Perhaps instead of DNA or RNA, God could have based it on something different like XNA. Or God could easily not even use nucleic acid or nucleotides at all. Perhaps he could have used XYZ, ABCXYZ, or whatever.

However, if God did this, then it's possible we would suffer various incompatibilities as a result. For example, perhaps consuming water, plants, and animals on Earth would not give us energy (ATP). Worse, maybe doing so would be toxic to us. Scifi often explores these sorts of things. A human astronaut travels to a distant planet orbiting a distant star, but finds he or she can't breathe in the alien atmosphere. An alien species (a plant or animal analogue) which is innocuous to other aliens in their system is introduced to humanity only to pose an imminent threat to our existence. And so on. Hence, presumably, God would need to make us compatible enough to other lifeforms on Earth so we can all co-exist, etc., but unique enough to reflect his special handiwork (imago Dei). If so, then there would be various degrees of compatibility as well as incompatibility with one another.

Moreover, if God did create us with fundamentally different genetics, I assume secular scientists (among others) would still find a way to argue we're not God's creation. Perhaps they'd argue we're aliens on Earth à la Crick's panspermia theory except applied only to humans rather than all life on Earth, which would be "proof" of extraterrestrial intelligence and civilization, which in turn would somehow evidence God did not exist. In any case, secularists would find a way to conclude heads they win, tails we lose - and "life"? It just happens.

Mystery lady

A couple of months ago I met an older Caucasian gentleman. I'd guess in his 60s. He told me he was a cancer survivor. He said he had had a tumor the size of his hand in his left kidney back in 1996. It was removed, along with an adrenal gland, but he suffered complications from the surgery including a collapsed left lung. As a result he had to spend two weeks in the ICU at a local hospital.

He said sometime during his ICU stay when he was feeling at his worst and in fact fearing he'd die, he saw a lady who looked to be in her late 60s and dressed in a maroon colored gown walk into the ICU where he was and immediately make a bee line toward him. According to the gentleman, she walked right up to him while he was in bed, grabbed his left arm, and with the deepest blue eyes he had ever seen, eyes which he said "saw straight through me," "piercing" through him, she said in an authoritative and commanding voice, "Fear not, for God is with you!"

Then she spun around and walked out of the ICU. He said when she spoke these words, he suddenly felt such immense peace and comfort, and he knew all would be well.

He said he would've thought he was just hallucinating all this had it not been for his brother who happened to be there by his bedside visiting him while he was in the ICU. He said his brother also saw the woman say and do all this.

The following day he said he tried to look for the woman so he could thank her. He asked all the doctors and nurses and other staff who she was and how he could find her. He thought she was another patient because she was dressed in what he thought must've been a hospital gown. But he said no one else had ever even seen or heard of such a woman. He never figured out who she was.

However it was after this that he began attending church (or attending church again).

Spontaneous remission

Just a few (preliminary) thoughts about "spontaneous remission" in the context of cancer:

1. A side note regarding terminology:

   a. The term "spontaneous" isn't used only in cancer, but applied to other diseases or pathologies as well. For example, spontaneous mutations, spontaneous abortions, spontaneous pneumothorax, some leprosy (tuberculoid) patients often spontaneously recover, etc. There seems to be a degree of indiscrimination in the use of the term "spontaneous".

   b. Focusing on cancer, I've seen and heard physicians use both "spontaneous regression" as well as "spontaneous remission". Likewise that's what I read in the relevant medical literature. If I had to pick, I'd say I see "spontaneous regression" more often used. However, I'm not sure if there's meant to be a significant distinction between the two or if they're both interchangeable. Perhaps "remission" is meant to suggest permanency in a way "regression" is not? In any case, I don't see how one term makes an important enough difference over the other, but it could be I'm missing some subtleties or nuances.

2. A few complications which make it more difficult to address spontaneous regression cases:

   a. I think one of the main complications is simply that cancer isn't a single disease. It's a collection of many diseases. What ties them all together into "cancer" is mutations in DNA which lead to a cell growing out of control. There's a plethora of possible mutations which cause cancer. It's not at all uncommon to see 100 mutated genes in a single tumor.

   b. Another major complication is cancer cells are adaptive. Cancer cells can adapt to drugs such as chemotherapies and become resistant to these drugs, similar to bacteria becoming antibiotic resistant.

   c. The last big complication is cancer needs a receptive environment in which to thrive. For example, I've read some people have molecular and cellular changes which are characteristic of leukemia, but they don't have leukemia. That seems to be because the environment of their bodies wasn't receptive to developing leukemia.

3. Keeping the above complications in mind:

   a. Spontaneous regression can depend on the kind of cancer one has. Spontaneous regression is known to happen in some cancers far more frequently than others (e.g. as many as one-third of low grade lymphomas are known to spontaneously regress without any treatment).

   b. At the same time, it can depend on the patient. That's because it's thought spontaneous regression is most likely an immune phenomenon (i.e. related to immune checkpoint inhibition; cf. PD-1/PD-L1). Our immune system is able to distinguish between friend and foe. Yet cancers can mask themselves as friends when they're really foes, thereby circumventing our immune system. However, it seems some people's immune systems can aid the environment of their bodies, making it less congenial to developing some cancers. (Hence much of the future of cancer therapies is focused on changing the body's environment to make it inhospitable to developing cancer.)

4. I think all this is actually helpful to know:

   a. For one thing, if some cancers are known to have extremely low spontaneous regression or remission rates, then, if, say, someone prayed over a patient with a cancer with extremely low rates, and their cancer spontaneously regressed, then it'd seem to have the backing of scientific evidence that this type of cancer is highly unlikely to spontaneously regress or remit.

   b. Of course, God could use means by which to spontaneously regress or remit cancers. For example, perhaps prayer "activated" or "deactivated" something in someone's immune system for them to spontaneously regress or remit the cancer. So prayer healing cancer and a known mechanism for spontaneous regression are not necessarily mutually exclusive.

5. I don't know what kind of cancer Joy Davidman had. I've read she had some sort of bone cancer that metastasized to her breast.

   I'm not sure if the breast metastasis was in her initial diagnosis or if it came later when she finally succumbed to it.

   If her bone cancer had already metastasized to her breast in her initial presentation, then I'd guess it'd be highly unlikely to go into remission. Of course, I'm no oncologist, but given how rare bone cancers are in adults (metastasis to the bones are way more common), given her bone cancer metastasized to her breast, and given back in the 1950s they didn't have a whole lot of the understanding about cancer and how to treat it like we do today (e.g. Watson and Crick had just discovered the structure of DNA in 1953 and cancer is fundamentally a molecular and cellular disease), that's my working assumption.

   If all this is so, then the fact that it did go into remission after prayer should be deemed "miraculous".

Marvel on Netflix

Here are my rankings for Netflix's Marvel comic book shows (spoilers):

1. Daredevil season 1. Its success set a high standard for the rest of the Marvel Netflix shows to follow. If it hadn’t succeeded, then it’s possible the other Netflix shows wouldn’t have had as much viewer interest, not as much money allocated, the quality could have suffered as a result, etc. So Daredevil season 1 was exemplary in that respect. What’s more, it was a refreshing turn for Marvel if we contrast the naked realism, the grit and grime of Daredevil with the more (shall we say) colorful and flamboyant Marvel movies (e.g. X-Men, Iron Man, Captain America, Avengers). In fact, Marvel’s Netflix tv series are arguably more sophisticated in literary terms than its movies. Not to mention Kingpin was an excellent counterpoint to Daredevil. A villain who might even be said to outshine the hero.

2. Daredevil season 2a. The first half with the Punisher storyline was fantastic. Perhaps equaling Daredevil season 1. We felt Punisher as a real individual, one with searing scars burned deeply into his psyche in the tragic loss of his family, rather than the caricature he usually is portrayed in comic books and lesser films. The character Frank Castle could have been very one dimensional (i.e. all about revenge), but the story here made Castle far more nuanced than he’s ever been. That’s a credit to the writers as well as actor who played Frank Castle i.e. Jon Bernthal. And the contrast between Daredevil and the Punisher, such as in how best to serve justice (lethally or non-lethally), makes for a lively ethical debate.

3. Jessica Jones season 1. As others have noted, it’s more psychological thriller than action-oriented (like Daredevil). I thought it worked very well overall, and very much enjoyed it. However, there were some themes which could’ve been better teased out and a couple of storylines which felt tacked on rather than smoothly integrated (e.g. Simpson). Kilgrave was an excellent villain, as good as Vincent D'onofrio Kingpin, and David Tennant did a fine job (I loved Tennant in Doctor Who as well), though the Purple Man was ultimately too powerful. Sort of in the vein of X-Men’s Professor X since Kilgrave could similarly control minds. Perhaps that’s why Kilgrave had to be killed off, because there would be virtually no limit to his power and who he could control (and it was never completely explained how Jessica Jones could resist him, one assumes it had something to do with her superpowers, but what exactly). Jessica snapping Kilgrave’s neck like a twig stands in sharp contrast to Daredevil who has to wrestle his own inner demons about not killing his archnemesis, among other enemies, as if killing even in self-defense is somehow intrinsically wrong.

4. Luke Cage season 1a. The first half with Cottonmouth and Mariah, before Diamondback shows up was saturated with African-American culture focused on the culture of Harlem. Luke is in many respects the anti-stereotype of the stereotypical black man (a la blaxploitation flicks) - not loud and angry, but calm, cool, and collected; not drive by an abundance of testosterone, but manly in both brawn and brains, in both physicality and cognition, sharp and intelligent as much as a force of (super)nature - which was a welcome breath of fresh air. The action wasn’t as good as it could’ve been, but perhaps I’ve been overly captivated and thus biased by Daredevil’s amazing martial arts, whereas Luke Cage is more about nearly invincible brute strength in most of its fight scenes.

5. Daredevil season 2b. This latter half of the season felt incomplete, which it doubtless was, because it was meant to be a setup for future stories involving the Hand and so on. It also came on the heels of the Punisher storyline, which regrettably only served to heighten the differences between the two - and unfavorably in regard to Elektra. In other words, Elektra’s storyline stood in stark contrast to Punisher’s, and as a result, Elektra’s storyline unfortunately paled in comparison (and I say this as someone who is a fan of Elektra). Her story stood in the shadow of the Punisher. However, there were highlights. For example, the love between her and Matt Murdock was promising, even though it didn’t sizzle quite as much as one would’ve liked. Also, as I’ve alluded, the ending intentionally left several loose ties which show a lot of future potential in the forthcoming season. And, in my modest view, the actor who plays Stick largely embodies the character quite well - a wiry, somewhat noirish and mystic figure, with a wry sense of humor, but chock full of worldly wise common sense, who, at the end of the day, has a heart of gold underneath the tough as nails exterior.

6. Luke Cage season 1b. Second half was such a disappointment in comparison to the first half. Diamondback was touted as the nefarious baddie pulling all the strings behind the events of the first half of the season, so much and so often by Shades, but ultimately the Diamondback character proved over-the-top. Diamondback instead seemed too comical rather than menacing or any sort of a real threat. He was supposed to be a bigger and badder villain than Cottonmouth, but he was quite the let-down from the expectations Shades had built up. Actually, I’d say one of Luke Cage’s biggest problems was that it had too many villains (e.g. Cottonmouth, Mariah, Shades, Diamondback, Mama Mabel in flashbacks). Having too many villains in this manner not only diluted the plot, at least more than it ought to have, but it likewise dilutes the viewing audience’s “sympathies” so to speak. Ideally, an audience should root for the hero(es), but love to hate the villain(s). However, Luke Cage built up too many of its villains in such a way that it blunted their overall effect, unlike say with Daredevil’s Kingpin or Jessica Jones’ Kilgrave. Still, the ending of Luke Cage was uniquely good in that not all the villains received their comeuppance but in fact escaped justice (for now), while our hero (voluntarily) went to prison. In short, unlike Daredevil or Jessica Jones, Luke Cage had more of a bittersweet ending, the good guys didn’t entirely win, and the bad guys didn’t entirely lose. All this said, even at its worst, Luke Cage is still a cut above many other comic book shows.

A Columbian exchange

A friend ponders:

Today I was reading some entries in The Oxford Companion to Archaeology. Among other things, I read about how the conquistadors were successful in part because the Aztecs and Maya were decimated by smallpox. The conquistadors unwittingly introduced smallpox into the indigenous populations, which had no resistance to the foreign pathogen. Fortuitous biowarfare. That, along with other factors (e.g. superior tactics and technology), enabled them to subdue these warrior civilizations, even though the conquistadors were vastly outnumbered by hostile natives.

This isn't the first time I've read that explanation. But I have some questions:

i) To begin with, why wouldn't that be a two-way street? If the conquistadors were carriers, for which the natives had no resistance–why weren't the natives carriers, for which the conquistadors had no resistance?

ii) According to the CDE, the incubation period for smallpox is between 7-17 days, during which an infected person is asymptomatic and not contagious.

So a sailor would have to become infected before he boarded a ship in Spain. And that would have to be during the incubation period, when he was still asymptomatic. I take it for granted that the captain and crew would not permit a sailor with smallpox symptoms to board the ship. So his symptoms would have to develop at sea, at which point he becomes contagious.

iii) We have to compare that with the time it took ships to sail from Europe to the Americas. Here are two estimates:

Since ships in the 1700s relied on sails to propel them, the length of the voyage greatly depended on the wind. An immigrant who made the journey in 1750 reported that it could take between eight and 12 weeks, while another who arrived in 1724 reported that the journey took six weeks and three days. The average journey was about seven weeks. (Source)

Henry Hudson was a European explorer traveling across the Atlantic during the colonial period. It took Hudson more than two months to sail from Amsterdam to New York City on his sailing ship, the Half Moon. (Source)

Assuming that's accurate, an infected sailor would become visibly symptomatic and contagious during the transatlantic passage. Assuming the crew didn't chuck him overboard, wouldn't there be a raging epidemic onboard by the time the ship docked in Mexico? But from what I've read, the conquistadors were asymptomatic when they disembarked. Moreover, I haven't read reports of conquistadors developing smallpox days or weeks after their arrival. Admittedly, my knowledge of the topic is quite cursory.

Just my thoughts:

I. A two way street

I agree it was a two way street. Native Americans (presumably including the Aztecs and Mayans) did likewise transmit diseases to Europeans (presumably including the conquistadors). For example, it's thought syphilis was likely transmitted from the New World to the Old World (on the Columbian theory). And before antibiotics syphillis could be quite harmful and sometimes even fatal.

There are other diseases Native Americans transmitted to Europeans, though I don't know if these were specifically from the Aztecs or Mayans (e.g. a species of hookworm; Chagas; Rocky Mountain Fever, though this was discovered much later than the 1500s).

II. Smallpox

Some facts about smallpox:

1. Smallpox is a very large and complex virus. An ancient virus, from the dawn of civilization.

2. Smallpox is thought to have originated from a domesticated animal, but it doesn't (or no longer can) infect any domesticated or any other animal. That is, there are no animal reservoirs which harbor smallpox. Smallpox only infects humans.

3. There are actually two main types of smallpox: major and minor. Historically, smallpox major has a high mortality rate (30%), while smallpox minor a much lower one (1%). We could actually subdivide further, but it's not really all that relevant.

   However, I don't know the answer to this, but I wonder if minor existed at this time, and if so, if being infected with minor and surviving grants immunity to major?

4. Smallpox is primarily transmitted either by droplets up to 3-6 feet (e.g. sneezing) or aerosols which travel farther than droplets and remain suspended in the air for longer periods of time (e.g. coughing). It's highly contagious, though there are other diseases which are more contagious.

   For example, if we compare by herd immunity, measles require upwards of 90-95% of a community to be vaccinated in order to keep measles from spreading to the unvaccinated in a community. However, with smallpox, about 80% of a community needs to be vaccinated in order to keep smallpox from spreading to the unvaccinated in a community. Still high, but not as high as measles.

5. The average incubation period for smallpox is 10-12 days (range is usually from 7-17 days). The course of smallpox can vary, but usually symptoms will subside 14 days after onset. But (assuming the person survives) it takes another 7-14 days for the scabs to fall off. A person is considered no longer contagious until all their scabs have fallen off. Say for example: 10 days incubation period + 14 days symptoms to subside + 14 days for scabs to fall off = 38 days.

   In case anyone would like a bit more detail (though I could go in more depth than even here). After the incubation period, the patient will experience an acute onset of general signs and symptoms lasting 2-3 days (e.g. fevers, chills, rigors, malaise, aches and pains, nausea and vomiting). After these 2-3 days, the patient will develop a centrifugally distributed rash with lesions usually involving the face and extremities. Over the next 7-8 days, these lesions typically generalize across the entire body, and evolve through various stages (i.e. macular, papular, vesicular, pustular). Within a month or so, the patient will have either improved or not, but even if they improve a lot of complications may persist (e.g. permanent scarring, blindness, arthritis, infection with other opportunistic pathogens like pneumonia).

6. Smallpox doesn't have a latent state. It doesn't hide as an asymptomatic infection. There's no carrier state for smallpox. Smallpox will produce overt signs (e.g. rash, lesions). (As an aside, this is one reason smallpox was able to be "eradicated".)

7. If a person is infected with smallpox, but doesn't die, instead recovers, then (generally speaking) they should have lifelong immunity.

8. As far as anyone is aware, smallpox has been "eradicated". I think the last known case was back in the 1970s. The only official specimens are in the CDC and I believe somewhere in Russia (though it's known the Soviet Union did attempt to weaponize smallpox in the past).

   Of course, who knows if terrorists or other nefarious groups have acquired smallpox which they could weaponize? After all, at one point, there were a lot of labs around the world which had smallpox since there was a lot of research on it. They should have destroyed all the smallpox in their possession, but did everyone do so?

III. Musings and speculations

Given all this:

1. I suppose the straightforward answer (or one straightforward answer) could be if the conquistadors had already been exposed to smallpox in Spain or Europe and survived, then traveled to the New World to infect the Native Americans.

2. People like Jared Diamond and Alfred Crosby talk about human contact with animals (especially domesticated animals) in the Old World vs. New World since animals can be reservoirs for infectious diseases. Specifically, living in close proximity to more varieties of animals might be relevant in building a more robust immune system among Europeans like the Spanish in contrast to Native Americans like the Aztecs and Mayans. However, it's debatable, I think.

   More to the point, since smallpox doesn't have an animal reservoir, since smallpox only infects humans, thus humans are its only reservoir, I'm not entirely sure how arguments from Diamond and Crosby would be relevant to smallpox, except indirectly at best, even if they are relevant to other communicable diseases?

3. I believe people like Diamond and Crosby also talk about how much more dense European population centers were at the time in comparison to Native American population centers, where only a city like Tenochtitlan would've rivaled Europe. A more dense population center may mean more likelihood of exposure to various pathogens, which in turn could perhaps account for more robust immune systems among Europeans in contrast to Native Americans. That might be worth exploring as well, but again it seems to me it's a debatable topic.

4. Generally speaking, it's possible the immune systems of Aztecs and Mayans are less genetically heterogeneous to one another than the immune systems of the Spanish to other Europeans. Perhaps especially if we accept the Bering strait theory that Native Americans trace their ancestry back to those groups which crossed the Bering strait.

   Anyway, if the Aztecs and Mayans have more genetically similar immune systems to other Native Americans than the Spanish do to other Europeans (say if the immune systems of all Native Americans are 50% identical, while the immune systems of all Europeans are 10% identical, just to use completely made-up figures), then it's possible a pathogen like smallpox could wreak havoc among Native Americans more easily if the pathogen can take advantage of something in the more similar immune systems, whereas the Spanish could more likely resist it.

   However, once again, I think this is debatable. It could just as well be entirely mistaken.

5. Another consideration is the climate and environment in which infectious diseases tend to thrive and spread. Say Mesoamerica vs. the Spanish peninsula. Was there anything about each environment that made it more likely for certain diseases to thrive and spread? Or which inhibited them from thriving and spreading? Or say temperate climates vs. tropical or sub-tropical climates? And so on.

6. Quite interestingly, historian Suzanne Alchon argues the following in her book A Pest in the Land: New World Epidemics in a Global Perspective (emphasis mine):

   This study of disease among the native peoples of the New World before and after 1492 challenges many widely held notions about encounters between European and native peoples. Whereas many late twentieth century scholars blamed the catastrophic decline of postconquest native populations on the introduction of previously unknown infections from the Old World, Alchon argues that the experiences of native peoples in the New World closely resembled those of other human populations. Exposure to lethal new infections resulted in rates of morbidity and mortality among native Americans comparable to those found among Old World populations.

   Why then did native American populations decline by 75 to 90 percent in the century following contact with Europeans? Why did these populations fail to recover, in contrast to those of Africa, Asia, and Europe? Alchon points to the practices of European colonialism. Warfare and slavery increased mortality, and forced migrations undermined social, political, and economic institutions.

   This timely study effectively overturns the notion of New World exceptionalism. By showing that native Americans were not uniquely affected by European diseases, Alchon also undercuts the stereotypical notion of the Americas as a new Eden, free of disease and violence until the intrusion of germ-laden, rapacious Europeans.

7. Along similar lines, it might be useful to look at, say, contemporary tribes in places like South America or Asia (e.g. Papua New Guinea) which have been isolated from contact by civilized societies. I presume anthropologists, for example, would take care to vaccinate themselves against known native diseases, so in the case of modern tribes it might not be a two way street like it was in the past. However, would anthropologists risk bringing their own diseases to some of these tribes if they make contact with these tribes? I suppose they take care to mitigate this possibility with good hygiene, minimal contact, etc. But still the possibility is there.

   Or if these isolated tribes happened upon people from their surrounding modern society. Suppose an Amazonian tribe happening upon Brazilians without any prior warning or other preparation by either side. Would there be any relevant parallels between something like this and the Columbian exchange of disease which we could learn from?

8. By the way, I suppose if liberal violent PETA types had their way, perhaps smallpox would now be on an endangered species list, and in fact they may even try to spread it! I hope this is just an overly active imagination on my part.

IV. "Genocide"

1. I've also read (mostly from liberals) how Europeans brought smallpox and other diseases to the New World, thereby causing a "genocide" among Native Americans. I think the term "genocide" is a highly loaded term, to say the least.

   For one thing, did all Europeans in general intentionally give diseases to Native Americans with the goal of wiping out an entire peoples or population? Wasn't the situation far more complex? At the bare minimum, we need to make distinctions between different Europeans and different Native Americans. Perhaps there were some Europeans who did so, but we can't generalize from some to all (e.g. there were some Europeans who helped some Native Americans get inoculated).

   Take this example. I've read there's some debate over some Englishmen giving blankets infected with smallpox to Native Americans in order to kill them. If true, then this would indeed have been a vile and reprehensible act, worthy of all condemnation. Regardless, let's assume it is true - can we therefore conclude all English colonials did the same to all Native Americans whom they encountered?

2. I've read some people argue as much as 90% of the New World population was destroyed thanks to disease brought by Europeans. Where does this figure come from? How is it calculated?

   For example, is it based on some epidemics (e.g. the cocoliztli epidemics), which, let us say, killed 90% of the Native Americans, then extrapolated to all other Native American communities or populations?

3. A couple of Mesoamerican epidemics in the 1500s, which killed millions, were caused by what the natives called "cocoliztli". There's debate over what cocoliztli was. Was it smallpox? Was it measles? Was it some unknown disease? Did it originate from the Old World or the New World?

   I've read some argue cocoliztli was a disease indigenous to the New World rather than transmitted by Europeans. For example, see here.

   I haven't deeply looked into any of this, so I don't know.

   However, if cocoliztli was indigenous to the Americas, then it would undercut the idea that it was the European diseases alone which were responsible for the alleged "genocide" of Native Americans. Especially if cocoliztli was not smallpox.

4. Likewise, from the same article:

   In the 1530s, a band of Spanish adventurers conquered the Inca Empire. It is commonly believed that some kind of epidemic devastated the Andes immediately prior to the Spanish arrival. Noble D Cook has advanced much evidence and argued strongly that this epidemic was of Old World origin, perhaps measles combined with pneumonic plague and influenza.46 However, if our hypothesis for the Mexican case - that some pre-existing New World viral disease became epidemic due to ecological changes brought about by large-scale and relatively sudden alterations of human agricultural practices - is valid, then perhaps the Peruvian case merits further study along these lines.

5. Perhaps one reason smallpox so easily spread across Mesoamerica (and other parts of the New World) was due to the collapse of social order among the Aztecs and Mayans? I presume the Aztecs and Mayans faced disease epidemics in the past since most civilizations seem to have. If so, they would've presumably been better able to isolate and stem epidemics. Like leaders to take charge and organize, quarantine the infected, etc.

6. I've read some Native American populations didn't suffer as badly from some Old World diseases as Europeans did (e.g. the Quechua people in the Andes Mountains and malaria, due to their consuming tea from leaves containing quinine, which helps mitigate malaria). Point being, it seems more complex than simply saying, all Native Americans suffered from disease at the hands of Europeans.

7. Of course, it's not only the Europeans who brought disease. For example, it's possible African slaves brought yellow fever to the New World. Although, if true, no doubt some would still like to blame Europeans for bringing the slaves. But that would be overly simplistic to do.

8. Speaking of which, since the Europeans were planting colonies all around the world at this time, there were a lot of communicable diseases between Europe, Africa, and Asia too. Many which killed scores of people in Africa and Asia (e.g. re-occurences of the black death in northern Africa). I wonder if any of them were as catastrophic as what happened to Native Americans?

"You can do anything"

If Trump shouldn't be president because of his sexual harassment or worse of women, then (on the face of it) it seems arguable neither should some presidents have been president because they did the same or similar (e.g. JFK who may have coerced an intern named Mimi Alford to give oral sex to a friend of his while JFK watched).

If fair is fair, then the same people who have (rightly) criticized Trump should likewise criticize former presidents like JFK and Bill Clinton who sexually harassed women or worse. These same people should say something like: Trump shouldn't be president because he is a sexual predator, and neither should JFK or Bill have been president because they too were or are sexual predators.

However, I won't hold my breath because many of these same people who are criticizing Trump have a double standard when it comes to their own side. They will only criticize people who don't share their political views rather than being fair-minded and consistent and criticizing anyone (regardless of political affiliation or politics in general) who has sexually harassed women or worse.

In fact, if they were truly fair, then they would also criticize women who have sexually harassed men or worse. For example, if a woman touches or grabs a man's leg or butt, and he doesn't want it, then it's possible she has sexually harassed him.