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I would expect at least some evolutionary pressure to get rid of unused things in your body. Let's just take the appendix as an example because it's probably th

by pc86 2y ago

I would expect at least some evolutionary pressure to get rid of unused things in your body. Let's just take the appendix as an example because it's probably the most common "you don't actually need this" thing that people know about. Some appendixes burst. Sometimes this kills people. Sometimes this happens before that person has been able to reproduce. Wouldn't this cause selection for people who at the very least don't have bursting appendixes (appendices just sounds wrong to my inner narrator in this context), but also for people who have smaller ones. Over time this pressure would decrease but shouldn't it theoretically over many many generations result in smaller and smaller, eventually disappearing, appendixes?

grog454 2y ago
I would think so. Who says that's not happening now? It seems reasonable that evolutionary pressure can be strong enough to have a significant impact in 1-2 generations (for example due to the introduction of a new environmental threat) or weak enough to take thousands of generations.
kjkjadksj 2y ago
Appendix is being appreciated these days as a reservoir of good gut bacteria. So there’s actually probably some pressure to keep it around. Appendicitis is a thing but of course not everyone suffers it. Maybe in the primitive world you were more likely to see your skull meet a rock before that happened in significant numbers of people in the population to the point it affected offspring counts.
4gotunameagain 2y ago
Can we be sure that we don't need the appendix ? We used to think tonsils are optional as well, and there seem to have been some studies that find a link between tonsillectomy & Crohn's, Hodgkin's or even breast cancer (from wikipedia). There surely must be vestigial parts in our organisms, like the one in the article, but more often than not we have no fucking clue how they interconnect with the whole and what their function is. I think. I'm not a doctor or anything.
evertedsphere 2y ago
for me, appendix / appendixes (organ) / appendices (to a book) too, just like index / indexes (database) / indices
sixo 2y ago
Whether a thing can be selected-out depends on the shape of the fitness landscape in the environment. For example, appendix-bursts are clearly rare enough and treatable-enough that they cannot be selected-out in modern humans. (But almost nothing can if almost everyone is able to reproduce, and any selection effects will be driven by the number of children which is largely cultural.) If a thing hasn't been selected out, you can roughly conclude either that: 1. The selection pressure to do so isn't strong. Either few appendix bursts occur in an ancestral env, or they don't disrupt reproduction bc they happen later in life, or are treatable, or other causes of death kick in before the appendix matters. 2. Or, if the selection pressure is strong, there is "nowhere to go" in gene-space that improves this aspect of fitness, within the search-radius. (Which is really equivalent to 1: the selection pressure isn't strong enough to search widely enough) 3. Or there is a stronger selection pressure for it, even if you can't figure out what it is, like the "backup gut bacteria" thing for the appendix. (Which is actually equivalent to 1/2 also: the selection pressure isn't strong enough to find a way to separate the upside from the downside)

by pc86 2y ago

grog454 2y ago

I would think so. Who says that's not happening now? It seems reasonable that evolutionary pressure can be strong enough to have a significant impact in 1-2 generations (for example due to the introduction of a new environmental threat) or weak enough to take thousands of generations.

kjkjadksj 2y ago

Appendix is being appreciated these days as a reservoir of good gut bacteria. So there’s actually probably some pressure to keep it around. Appendicitis is a thing but of course not everyone suffers it. Maybe in the primitive world you were more likely to see your skull meet a rock before that happened in significant numbers of people in the population to the point it affected offspring counts.

4gotunameagain 2y ago

Can we be sure that we don't need the appendix ? We used to think tonsils are optional as well, and there seem to have been some studies that find a link between tonsillectomy & Crohn's, Hodgkin's or even breast cancer (from wikipedia). There surely must be vestigial parts in our organisms, like the one in the article, but more often than not we have no fucking clue how they interconnect with the whole and what their function is. I think. I'm not a doctor or anything.

evertedsphere 2y ago

for me, appendix / appendixes (organ) / appendices (to a book) too, just like index / indexes (database) / indices

sixo 2y ago

Whether a thing can be selected-out depends on the shape of the fitness landscape in the environment. For example, appendix-bursts are clearly rare enough and treatable-enough that they cannot be selected-out in modern humans. (But almost nothing can if almost everyone is able to reproduce, and any selection effects will be driven by the number of children which is largely cultural.) If a thing hasn't been selected out, you can roughly conclude either that: 1. The selection pressure to do so isn't strong. Either few appendix bursts occur in an ancestral env, or they don't disrupt reproduction bc they happen later in life, or are treatable, or other causes of death kick in before the appendix matters. 2. Or, if the selection pressure is strong, there is "nowhere to go" in gene-space that improves this aspect of fitness, within the search-radius. (Which is really equivalent to 1: the selection pressure isn't strong enough to search widely enough) 3. Or there is a stronger selection pressure for it, even if you can't figure out what it is, like the "backup gut bacteria" thing for the appendix. (Which is actually equivalent to 1/2 also: the selection pressure isn't strong enough to find a way to separate the upside from the downside)