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Comment by thaumasiotes | Hacker News Reader

This is the well-known fallacy known as "ontogeny recapitulates phylogeny".

https://en.wikipedia.org/w/index.php?title=Ontogeny_recapitu...

There is a difference between (a) observing what happens for some organisms, and then saying it is "as if" X were the case, and (b) asserting that X must necessarily be the case.

The parent comment is similar to the fallacy you mention, but as phrased is not an endorsement nor assertion of the fallacy.

This idea is explored heavily by Steven J. Gould in his book Ontogeny and Phylogeny. I highly recommend anyone interested in this idea to check it out. As far as I remember the "fallacy" is not that these stages exist, but that evolution works by adding new stages on top and pushing the previous stages down into development.

Surely that is one of the ways evolution works?

No actually it's not a fallacy, taken from your own link:

"Embryos do reflect the course of evolution"

Try quoting more than the first half of a sentence intended to placate people who learned to believe in the fallacy.

the shortcomings of the theory had been recognized by the early 20th century, and it had been relegated to "biological mythology" by the mid-20th century

The Haeckelian form of recapitulation theory is considered defunct.

the Biogenetic Law was abandoned, and its fall freed scientists to appreciate the full range of embryonic changes that evolution can produce

The cited book is 1963. I'd feel more comfortable with something more recent. It seems to be a debate of degree. Earlier forms do tend to be preserved in the embryo, but it's only a tendency, not a "rule".

Mentioned in my other comment above: https://en.wikipedia.org/wiki/Ontogeny_and_Phylogeny_(book)

>> it had been relegated to "biological mythology" by the mid-20th century

> The cited book is [from] 1963.

Sorry, when would you expect a citation for "it had been relegated to 'biological mythology' by the mid-20th century" to date from?

As a hard and fast rule, yes, it has been deprecated, but not as a tendency or influence.

AFAICT the comment you first responded to is consistent with the modern form of the idea. There's no reason to assume they were specifically thinking of Haeckellian recapitulation.

It is a fact that many embryos go through stages similar to portions of that organism's evolutionary history. This fact alone justifies the cautious phrasing of the great-grandparents comment, in my opinion. Since this fact is also indicated in the excerpted quote you criticize, I think the quote served it purpose. (Though I would agree the 'reflect' can be misinterpreted).

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