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Comment by vharuck | Hacker News Reader

For the biologists out there: what parts of this theory are limited by actual phenomena? What parts just push the bounds of a mental model used by scientists to help understand biology? As a non-biologist, it's sometimes hard to know the difference.

Also, what are the arguments for not saying transmissible cancers are parasites?

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It's helpful to see how there are fundamental precedents for externally mediated genomic change, which may then give rise to phenotypic ("what we see") or genomic ("the source code of what we see") differences:

Transposons or "jumping genes" [1] are segments of DNA code which can move around within a genome by themselves (autonomously).

Presumably though, over time, enough of these moving in the right place - in combination with some other mutation - might confer some benefit that leads to speciation [2].

edit: length / clarity

[1] - https://en.wikipedia.org/wiki/Transposable_element

[2] - https://www.scientificamerican.com/article/wandering-fly-gen...

DNA is nothing like source code. Why do people keep repeating this analogy.

At any rate, cell differentiation/compartmentation within a tumor has been observed, so things do get blurry indeed. It's also worth noting that there isn't a single definition of 'species' and it's all just semantics that changes depending on your field. (The traditional 'inter-fertile over two generations' you learn in high school is helpful but doesn't stand up to many observations.) Ultimately a species is what biologists say is a species.

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