Re: Definitions

Posted by R. Berg on November 11, 2003

In Reply to: Re: Definitions posted by ESC on November 11, 2003

: : Is "ontogeny recapitulates phylogeny" the precise phrase? If so, what exactly does it mean? Who conined the phrase? And is it still taught as a correct principle in biology?

: : : : : : Ahem

: : : : : Meaning something like 'birds of a feather flock together' is it?

: : : : No, not that. It means that an individual goes through a succession of stages in its development that resembles the stages of development that its species went through when evolving. For example, human fetuses at one (early) stage of development have gills.

: : : : I don't know who coined the phrase or whether the principle is still thought to be correct.

: : : R.Berg's explanation is correct. The concept, however, is wrong, although it still appears in many textbooks even today. The German biologist Ernst Haeckel coined the phrase (as well as the word 'phylogeny') near the end of the 19th C. For more information, see http://www.ucmp.berkeley.edu/history/haeckel.html as a starting place. You'll find more by googling on the phrase, or on Haeckel's name; but be aware that 75% of what you'll find online is total BS; look for sites sponsored by univerities.

: : When googling use 'site:edu' as one of the required search phrases to get mostly universities and fewer BS hits.

: :
: : : : Looks like I'm a little late for the main discussion of this topic but I have a burning question: If Creationists are correct, that Ernst Haeckel's theory is BS, what explains my personal nursing experience of having cared for little newborns who exhibited gills and, yes, even little Henry who had gills, a significant tail and other birth "anomalies"? I am just asking for information here; I do not, as apparently others in the discussion have, underlying religious issues to deny or confirm.

: From Merriam-Webster online:

: Main Entry: cre.a.tion.ism
: Pronunciation: -sh&-"ni-z&m
: Function: noun
: Date: 1880
: : a doctrine or theory holding that matter, the various forms of life, and the world were created by God out of nothing and usually in the way described in Genesis -- compare EVOLUTION

: Main Entry: evo.lu.tion
: Pronunciation: "e-v&-'lü-sh&n, "E-v&-
: Function: noun
: Etymology: Latin evolution-, evolutio unrolling, from evolvere
: Date: 1622
: 4 a : the historical development of a biological group (as a race or species) : PHYLOGENY b : a theory that the various types of animals and plants have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations

: I am a Bible-thumping fundamentalist who believes that Genesis describes how God created the World and, through evolution, its creatures. Have I created a new theory? I need a name for it.

It isn't just creationists who reject Haeckel's theory, it's mainstream biologists. However, human embryos do have gills and tails, and occasionally these structures aren't completely reabsorbed before birth. Some people have extra nipples, too, a reminder that many mammal species have litters to nurse. In that way, ontogeny recapitulates phylogeny, just not in all other ways.

• Re: Definitions GPP 12/November/03