I take your point, though I think I'd take the same line as Xianghua- if our common ancestor is a bacteria, would you characterize yourself as a bacteria?
As I responded to him: yes... for a given value of 'bacteria.'
Such terms encompass much more than what we, in the casual everyday colloquial sense, realize they do.
In the same principle that I would characterize myself biologically as whatever I am descended from, I am: an ape, a primate, a mammal, a chordate, an animal, a eukaryote. I am all of these things at once.
Oh, also a human.
It's a semantic question obviously- but wouldn't all distinction break down at that point?
No, because that's not the only distinction we make.
If we refered to everything from grass, redwoods, dandelions, and pineapples as just 'plants', things might get tricky. But we have all those other names for them besides just 'plants' to rely on to differentiate.
Labels and semantics aside, objectively, we have a lot of features bacteria don't; eyes and ears and lungs and the capacity to amuse ourselves pondering them! i.e. it's not just that we represent a different configuration of a bacteria's possible variations, but that we have a vast range of emergent 'new' properties that they don't- by what process did these features emerge, do you think?
Welp... I'm not a biologist by any stretch, not especially well read on the topic, so this is just my idle speculation. But all of those attributes you mentioned are related to organs (eyes, ears, lungs, brains) and organs are essentially, broadly speaking, clusters of specialized cells.
So I think that at some point in the history of life, once multi-celluar life began to develop, different portions of multi-celluar lifeforms began to specialize at different functions, giving rise to the first primitive organs. Generalized cells became more specialized. Natural selection would have applied to these lifeforms. Lifeforms developing the best and most efficient sets of organs would thrive while less effective lifeforms would succumb and go extinct. Millimetric development, very simplified and primitive, but it would be a start.
Incidentally this would also answer a frequent creation question, namely why you don't see complex modern lifeforms like we humans suddenely developing brand new organs and features if that's what our ancient ancestors did - we are the result of like a billion years of evolution that rendered us more and more specialized. Earlier lifeforms were like lumps of clay, unformed and simple but full of morphological potential. Modern lifeforms are capable of so much more, but we're carrying around the baggage of hundreds of millions of years of evolutionary specialization.
Modern creatures no longer have mushy clusters of generalized cells, but highly developed and refined organs. Some elements of them can be changed or adapted, but entirely new functions emerging spontaneously is probably beyond biological possibility. So it's variation from here on out - we're not going to be sprouting extra pairs of arms or anything.
, I certainly don't want to tar all, or even most believers in ToE with that brush.. but it has not all been positive
