5 ms·
This is mind blowing: > For the first half of the twentieth century, the going theory was that the invading element—the “antigen”—served as a template around w
by nahuel0x 6y ago
This is mind blowing:
> For the first half of the twentieth century, the going theory was that the invading element—the “antigen”—served as a template around which a corresponding antibody was molded. Only in 1955 did scientists discover the much stranger truth. It turned out that the cells that produce antibodies—called B cells, because they were first discovered in the bursa of Fabricius, an organ that does for birds what bone marrow does for humans—can produce only one kind each. Its structure is random, and nearly every B cell is discarded unused. If, however, an antibody created by a B cell happens to match some part of an antigen, that B cell will not just survive but clone itself. The clone incorporates many mutations, which offer the possibility of an even better match. After a few generations, an antibody with the best fit is “constructed” through a process of mini-evolution that occurs continuously in our lymph nodes and spleen. (Our ancestors the bony fish adapted the machinery of the B-cell system from an even more ancient parasite.)
So, natural selection discovered a way to run an embedded natural selection search process in an individual. Talk about meta.
- divbzero 6y agoIt’s mind blowing not only how our body mimics natural selection with B cells, but also how it generates the genetically diverse B cells in the first place. [1] [1]: https://en.wikipedia.org/wiki/V(D)J_recombination https://en.wikipedia.org/wiki/V(D)J_recombination "V(D)J recombination"
- nextos 6y agoYes, and if you have different versions of the HLA gene, you get different distributions as a result of V(D)J recombination. So, in a way, different individuals have different immune strategies. For example, super-responders to HIV tend to be HLA-B57. This HLA "version" trades better response to virus that mutate quickly for more chances of autoimmunity as thymic selection is less stringent (because HLA-B57 presents less selfpeptides in the thymus).
- DrAwdeOccarim 6y agoWoah. Thanks for sharing that. I did not know that. What a fine balance!
- TwoBit 6y agoThat's cool, but realistically how else could it do it?
- cma 6y agoThere are already examples of alternatives, like it could have some kind of brain and communication apparatus to work with others of its species and put together things like GPU simulations of protein modeling to generate optimized artificial antibodies.
- andromeduck 6y agoHow are you going to run a GPU sim on a bunch of meat?
- ggghhhfff 6y agoI believe what is meant here is that the alternative is to have a highly developed capacity for abstract thought that you then use to collaborate with your species to develop antibodies in a laboratory (humans are an example of this, although we don’t rely upon this mechanism)
- andromeduck 6y agoYeah but how is that going to arise out of nature? It's like asking why birds use vision + magnetism to navigate when they could just use GPS -- the MVP is too massive and inflexible.
- porknubbins 6y agoAfter learning CS I can’t help but see biology as crazy algorithms run on a living computer. Like someone was thinking “how can we match possibly any shape of invader? Screw it cells are cheap we’ll brute force randomly try them all.”
- nahuel0x 6y agocheck this: https://en.wikipedia.org/wiki/Amorphous_computing https://en.wikipedia.org/wiki/Amorphous_computing
- asdff 6y agoTons of biology can be modeled mathematically strikingly well, and most of that was figured out a long time ago. Sewall Wright was developing graphical models of evolution in the 1920s.
- deleted 6y ago[deleted]
- panabee 6y agoextremely naive, dumb questeion: could cancer cells stem from some errant mutation of B cells? this might help explain why cancer cells grow uncontrollably and also escape detection by the immune system.
- deergomoo 6y agohttps://en.wikipedia.org/wiki/B-cell_lymphoma https://en.wikipedia.org/wiki/B-cell_lymphoma
- panabee 6y agothanks for sharing this link. is it possible that other cancer cells are further downstream mutations of B cells?
- flobosg 6y ago> could cancer cells stem from some errant mutation of B cells? That is exactly how lymphomas originate.
- AstralStorm 6y agoAlso the replication machinery being easy to trigger is why it's the second most common cancer after skin cancers. (Which shares some of those features in addition to being even more exposed to insults and less controlled.)
- Engineering-MD 6y agoWhere do you get that figure from? All the figures I have state lung and bowel cancers are the most common, along with prostrate and breast for sex specific cancers (although looking at their rates they would be the higher even though their rates in the other sex are exceedingly low).
- AstralStorm 6y ago
- longtom 6y agoCulture, intelligence, memes, innovation etc. are also evolutionary subprocesses of our species. Evolution is gradient descent, so is learning. It's all the same. Entropy minimization or competitive negentropy consumption, if you want.
- nahuel0x 6y agoyes, but this process is running inside a single individual. As above, so below.
- longtom 6y agoOur brain also produces hypotheses, tests them and repurposes the most successful ones as program fragments stored in synaptic weights. Trial and error, exploration, mutation, survival of the best hypotheses etc.
- kgc 6y agoUnfortunately the thymus also loses mass in the process, so as you age, its function decreases.
- ajuc 6y agoAnd then we're replicating that in our computer systems :) https://en.wikipedia.org/wiki/Artificial_immune_system https://en.wikipedia.org/wiki/Artificial_immune_system