
Why Do We Have Blood Types? (2014) - Hooke
https://mosaicscience.com/story/why-do-we-have-blood-types
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pjc50
TLDR: nobody knows. Blood type arises from variations on a single gene called
ABO. But it's always hard to infer "why" from genes, genetics is not a source
of just-so stories.

Hypothesis given: "So it’s possible that each strain of norovirus has proteins
that are adapted to attach tightly to certain blood type antigens, but not
others. That would explain why our blood type can influence which norovirus
strains can make us sick."

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JohnStrange
There is no purpose or planning behind evolution, so blood types could just be
a random genetic mutation that does not reduce the chances for individuals of
having offspring that survives long enough to have children. Just like curly
vs flat hair or blue vs green eyes.

I'm not a biologist so I might very well be wrong about that, but it seems
that one possible explanation is that the question has no meaningful answer.

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folli
Given your hypothesis you also need an explanation why there aren't thousands
of blood types.

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ivanhoe
Actually there's quite a few, if you count all the subtypes and antigens
[https://en.wikipedia.org/wiki/Human_blood_group_systems](https://en.wikipedia.org/wiki/Human_blood_group_systems)

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csense
I think the theory at the end of the article sounds quite plausible.

Namely that blood types are playing rock-paper-scissors against bacteria /
viruses. Pathogens can learn to target a single blood type if it's predominant
(just like you can learn you should play Paper if your opponent usually goes
for Rock). So it's better to have a population of mixed blood types, and
anytime it starts to get out of whack, disease exerts a force that
disproportionately takes the newly popular blood type out of the gene pool,
pushing back toward equilibrium. Just like the Nash equilibrium RPS strategy
is rand().

How to test this experimentally? I'm no molecular biologist, but maybe let
viruses reproduce in an environment where one antigen is present for enough
generations for them to mutate to have increased effectiveness attacking it
(maybe you can determine this from an increasing viral reproduction rate?),
then a testable hypothesis that would confirm the theory is the mutation also
caused the viruses to lose efficiency at attacking another blood type's
antigen.

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sandworm101
Genetic variety does not need immediate purpose. Where slight changes to gene
make no real difference to survivability one should expect changes to arrise
and be maintained in a populations. Perhaps one day that gene will matter
more. The population will then be ready for the test because it has already
fielded a bunch of options. Being more ready to evolve as needed is itself an
advantage.

Random mutation is a cornerstone of evolution. Where those mutations are not
being naturally selected the randomness builds into a greater number of types.
If we didn't see that, if genes not tied to survivability were homogeneous,
then we would need to reevaluate core theory.

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passivepinetree
Fascinating.

This is an example of a non-tech-related article that's perfect for HN because
of the "intellectual curiosity" guidelines.

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robabby
I tested out the blood type diet for a few months. I am a type AB+ and I
followed it very closely. I will say I slept better, had more sustained and
balanced energy levels, and better focus. I also didn't get that faint, dizzy
feeling if I couldn't eat right on schedule. I don't have any hard evidence
for the diet, but my results were intriguing enough for me to think there is
something to it. However, given what we know about placebo I wouldn't be
surprised if I was just releasing everything I needed based on belief.

TLDR: Who knows...

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golanggeek
Very nice article. Also about the Bombay Blood Type

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hoagiefest
most easily digestible explanation of blood types I've seen

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PetoU
tldr someone ? :D

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pwinnski
"More than a century after their discovery, we still don’t really know what
blood types are for. Do they really matter? Carl Zimmer investigates."

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godshatter
Quick rant about websites that continually bug you about cookies, even to the
point of having a page that describes how they track you across sites using
their cookies, for your benefit of course. I miss the pre-corporate web.
Geocities sites and all.

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bradfitz
Blame Europe. :)

[https://www.cookielaw.org/faq/#WereoutsideoftheEUareweaffect...](https://www.cookielaw.org/faq/#WereoutsideoftheEUareweaffected)

