Sorry I haven't been as active as I wanted to be--blame it on the impending offspring. Apparently they require a bunch of stuff.
Jodie, after reviewing your posts I have to say you're wrong on a number of foundational assumptions.
1) Your medical training has shown you what humans are like (or at least, you say it has). You have been assuming, without substantiating this assumption in any way, that all organisms are at least similar in diversity. The problem is, humans are incredibly diverse. In fact, there's only one group of organisms that I'm aware of that has similar diversity: domesticated animals. The reason is the same in both cases: humans were, and domesticated animals are, in the initial stages of a process which, if continued for a few thousand more generations, would lead to the presence of multiple species. Species not undergoing such events tend to be far less diverse.
So no, paleontologists DON'T need to factor human diversity into our considerations--not outside of specific conditions which persist for remarkably short periods of time (on the geologic scale) and therefore tend not to appear in the fossil record. Tend to--they DO show up, but rarely, and yes, in those conditions we do have to worry about diversity.
2) You seem to have attributed some mystical quality to genetics that allows it to, with 100% accuracy, identify anything, anywhere. The issue is, it doesn't really work that way. Again, the math is identical to that used with morphological characters. More significantly, the LOGIC is identical. Essentially, geneticists look at gene sequences and say either "Yes, this is far enough apart to call it a different species" or "No, it isn't far enough apart to call it a different species". So any subjectivity you argue exists in morphological arguments about species identification--and in fact any criticism you make about the logic used--apply directly to genetic arguments about species identification as well. In fact, the use of type specimens makes morphological arguments ironically LESS subjective, as at least we have hard and fast criteria for each species.
The problem you're running into is that the concept of a species is an artificial category placed on biology. It therefore cannot be entirely without some element of subjectivity. However, and before you declare victory, there's a world of difference between what I'm saying and what you're saying. I'm saying that we can clearly know that two species are present morphologically; the subjectivity comes in the form of where, in the extremely limited region of transition, we draw the line. We know it's there, and we know it's somewhere in a certain range; the exact location within that range is somewhat arbitrary. What you are arguing is that since we have that subjectivity, the entire concept must be thrown out the window--and replaced with a concept that's exactly as arbitrary.
Think of it this way: Let's say there are two cities, with suburbs between them. The houses dwindle, but there's no real open area between them. I'm saying that we know there are two cities, and while there's some room for debate as to where to draw the boundary due to the fuzzyness of said boundary, we can still say there are two cities. You're saying that we can't, that we can NEVER know, until we take a census of the population. It's unnecessary, and won't yield any better data, and you're obviously wrong.
You're also ignoring the fact that paleontologists HAVE started using genetic data when it's available, and where the two overlap they agree. For example, there's
this paper (link goes to a discussion of the paper, with the citation). In one of the figures (not shown in the link) the authors show comparisons between phylogenies based on multiple datasets, including morphological and genetic. The result was that they agreed. What that means is that morphology is demonstrably a valid way to construct phylogenies if you accept that genetics is.
I can't wait to hear how you worm your way out of this, by the way. This paper--and many others like it--serves as direct experimental confirmation of my stance. The idea that morphology can be used to reconstruct evolutionary histories as accurate as those made via genetics is as well-established as the Higgs boson, quantum tunneling, and the structure of an atom. You want to say it isn't? Cool. I look forward to your review of that paper as the initial step.
kellyb said:
The paleos do and always have considered (and found!) deformities in Neanderthals.
There is an entire field known as paleopathology. I've looked into it, through my studies of taphonomy (gotta know premortum fractures to differentiate them from postmortum ones), but don't claim to be an expert; those who are experts are remarkably good at identifying deformities, injuries, illnesses, etc. in fossils. The issue is that bone doesn't grow properly when it's overly deformed. Even if the deformity is genetic, the bone microstructure is usually quite obviously wrong. This has allowed us to test for genetic deformities in even individual skeletons. There are also issues such as arthritis that show the presences of deformities. I have a cousin with a deformed jaw--genetic deformity, and actually all of us grandkids on that side have it, her's is just worse than most. It's nowhere near close to the deformities Jodie is hypothesizing (well, that's being too generous--speculating is more accurate, as she's provided no data that her ideas are true). Yet it would be quite obvious to any researcher studying her skeleton. Her jaw has a large amount of abnormal bone wear and arthritis in it.
Sideroxylon said:
In the observation of these nested hierarchies, there is a very powerful and potentially simple to understand argument for evolution in there, especially when tied in to biogeography.
That's how most of 'em get made, to be honest. Given that Species A lived at Place X and Species B lived at Place Y, we can expect (given a bit of knowledge about how other species in that genus/family/whatever move through time) that the ancestral species lived in Place Z.
kellyb said:
Well, if paleontology is currently being used to anticipate further human evolution, I'm not aware of it.
It's something that people toy around with, but it's not something that anyone takes seriously. The issue is that any evolutionary lineage is subject to contingent events, as Gould demonstrated a long time ago. We can make predictions of how humans will evolve given certain conditions, but they're always dependent upon those conditions.
What paleontologists predict is where to find species, and larger-scale events. We predict where to find ancestral species and what the thing should look like (remember, predictions aren't universally forward-looking; if we predict the presence of an ancestor currently unknown to science, it counts as a prediction in science). We can also say things like "During mass extinctions, smaller body size tends to be favored" (the Lilliput Effect), or "While the adaptation to new environments prompts greater diversity it does not generate truly novel bauplans" (an observation that's relevant to space exploration). Paleontology won't necessarily tell us how our food species will evolve in the future, but it CAN tell us how to set up the proper conditions for the survival of our food species.
Akri said:
If you can't demonstrate that a problem actually exists (and it seems safe to say you can't, or you'd have done so by now) then there's nothing to consider.
I want to highlight this, because it's probably the most important thing in this discussion. Jodie, your medical background should have taught you that in science it's not sufficient to say something MIGHT be true; you have to demonstrate that it IS true, or at least support it with evidence. Paleopathologists are required to present actual data on the actual bones before anyone accepts that an organism was suffering from a pathology. What that means is that we've already looked for the sort of stuff you're describing, and not found it. (It also means you haven't bothered to do the necessary background research, because you missed an entire branch of science specifically doing what you demand we do.) To counter their claims requires a great deal more than spinning "What if?" scenarios. You want us to throw out three hundred years of well-tested methods; I think it only fair to expect you to reach the level of at least the science most directly related to what you're talking about.
So, let's dig in, shall we? We're discussing paleontology; let's look at some fossils!
http://dinosaurs.about.com/od/dinosaurpictures/ig/Prehistoric-Primate-Pictures/Gigantopithecus.htm
At that link is a photo of a Gigantopithecus jaw. It's partial, but that's what we have to work with. What specific deformities do you see? What specific evidence is there of any? The potential gum disease doesn't count; the teeth are worn enough that it's equally likely that the critter is just old (based on "The Archaeology of Human Bones"
{this book}). (As an aside, my copy is a bit older; the information will be the same, but if I cite anything specific bear in mind that the page number may be different.)
http://www.uiowa.edu/~bioanth/giganto.html
Here's another site that includes photos. One shows a Gigantopithecus jaw next to a human one. What specific mutations would lead to this?
