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Darwin's hypothetical mechanism of inheritance was called pangenesis, whereby the body continually produced particles of information - gemmules - which aggregated in the gonads, and that that the offspring would be born as it was because of the information it had inherited from the gemmules.

This kind of system of heredity would be compliant with Jean-Baptiste Lamarck's theory of evolution, whereby organisms pass on characteristics to their offspring accquired during their own lifetime, seen as the body continually produces these gemmules.

My question is; Would something like pangenesis be a viable thing in alien life forms? Besides a Lamarckian mechanism of evolution, what would it entail for these organisms?

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  • $\begingroup$ Why wouldn't a RNA world occur? In animals, germline cells and somatic cells are separated very early in development, but this does not need to be the case; and it is not the case in plants, for example. All that's needed for the central dogma of molecular biology to be broken is to make a feedback mechanism from phenotype to genotype; and we already know that such mechanisms exist, e.g. reverse transcription and epigenetics. $\endgroup$ – AlexP Dec 25 '18 at 12:08
  • $\begingroup$ Lamarck basically predicted DNA methylation, where current life experiences are passed down to offspring via DNA. Why not extend that to alien DNA? $\endgroup$ – Cyn Dec 25 '18 at 16:24
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You describe epigenetic inheritance. It is real.

https://en.wikipedia.org/wiki/Transgenerational_epigenetic_inheritance

Transgenerational epigenetic inheritance is the transmission of information from one generation of an organism to the next (i.e., parent–child transmission) that affects the traits of offspring without alteration of the primary structure of DNA (i.e., the sequence of nucleotides)—in other words, epigenetically... For some epigenetically influenced traits, the epigenetic marks can be induced by the environment and some marks are heritable, leading some to view epigenetics as a relaxation of the rejection of the inheritance of acquired characteristics (Lamarckism).

It makes sense that this could be adaptive. Genomic adaptations involve a lot of luck. If you can pass down to your offspring something you have learned the hard way, it will save them a lot of grief. An example: mice who learned to associate an odor with trouble passed that on to descendants via epigenetic genome modulation.

https://www.nature.com/news/epigenetics-the-sins-of-the-father-1.14816

Dias had been exposing male mice to acetophenone — a chemical with a sweet, almond-like smell — and then giving them a mild foot shock. After being exposed to this treatment five times a day for three days, the mice became reliably fearful, freezing in the presence of acetophenone even when they received no shock.

Ten days later, Dias allowed the mice to mate with unexposed females. When their young grew up, many of the animals were more sensitive to acetophenone than to other odours, and more likely to be startled by an unexpected noise during exposure to the smell. Their offspring — the 'grandchildren' of the mice trained to fear the smell — were also jumpier in the presence of acetophenone. What's more, all three generations had larger-than-normal 'M71 glomeruli', structures where acetophenone-sensitive neurons in the nose connect with neurons in the olfactory bulb. In the January issue of Nature Neuroscience1, Dias and Ressler suggested that this hereditary transmission of environmental information was the result of epigenetics — chemical changes to the genome that affect how DNA is packaged and expressed without altering its sequence.

It would be good to keep a genome. There might be stuff in there you only need (it only needs?) every few hundred years. But how different are Darwin's cumulative "particles of information" from "chemical changes to the genome that affect how DNA is packaged and expressed without altering its sequence"?

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I suspect evolution would happen very quickly on this planet. This may be a tangent, but did you know Stalin promoted Lamarckianism because he thought he could easily reprogram his citizens into a new form of Soviet man? I suspect that once your aliens figured out how their own genetics worked it could easily form an 'arms race' (okay, a gonads race) as totalitarians and idealists sought to create environments which would generate the sort of people they wanted in their society.

EDIT: The more I think about it, the more socially stratified a society would be. If your family are farmers or miners for generations, how would you have someone strike out on their own to better themselves (and their family's prospects)? All species would be branched off into microclimate subspecies and the sentient race would have ingrained social stratification very early on.

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