8 ms·
> It seems to me that it can only accumulate errors and mutations. Except some of those mutations can be useful – some deadly, but some could be selected for a
by incongruity 10y ago
> It seems to me that it can only accumulate errors and mutations.
Except some of those mutations can be useful – some deadly, but some could be selected for as one's environment/niche shifts. That's evolution and selection in a nutshell. Not all mutations are bad and not all bad mutations are always bad.
- coredog64 10y agoConcrete example: Sickle cell anemia is bad, but sickle cell carriers also have protection against malaria.
- EdSharkey 10y agoYes, truly over the long haul, the fittest survive - helpful mutations account for all survival thus far. I just envy what I interpret as an intragenerational bolstering of genetic traits that females have, assuming the EXITS thing is truly what's going on. They don't have to wait a generation to perhaps select out the bad, they get to do it on the fly.
- incongruity 10y agoIt's a conservative strategy -change from one generation to another will likely be moderated/averaged by the influence of the second X chromosome for female offspring. Alternatively, single copy governed traits (as in males) mean greater ability to adapt (at a higher mortality rate) and those successful remaining males can propagate their single X chromosome (new and improved, thank you) to their daughters. It's a cool pattern of balances, IMHO.
- EdSharkey 10y agoHmm. Are you saying that men's imputing of adaptations to their one X chromosome is somehow more concentrated/effectual than the adaptations a woman imputes to her 2 X chromosomes? What is the mechanism and how did you draw that conclusion? Because she only passes one along? It seems to me that chiefly the non-suppressed X chromosome in females would see action by its workings and thus accumulate adaptations.
- echelon 10y agoFemales have both X chromosomes active, but only one copy per cell due to Barr body deactivation. Some female cells have one copy active, others utilize the other copy. This scheme can lessen certain X-linked genetic disorders in women since not all cells will be affected.
- Godel_unicode 10y agoAh, but how do you define helpful? Sickle cell (as cited up-thread) is a selected-for mutation.
- james_pm 10y agoAs a parent of a daughter with Fragile X Syndrome, I'm glad she has two X chromosomes. The "good" one in her case helps reduce the severity of her symptoms. Males with the Syndrome face far more difficulties as their lone X chromosome is the one with the mutations.