Fossils could fill gaps in human evolution

LONDON - African fossils of one of our earliest ancestors, who lived about 4.5 million years ago, could help fill some of the gaps in early human evolution, researchers said Wednesday.
www.msnbc.msn.com...

I guess that I would have to say that I do belive in the evolution of man but I will say that I question some of the conclusions. I guess everyone has to make up their own mind. When you look at the timeline on the page I supplied there are just so many questions.

Intersting article, I think ardipithecus has been around for a while as a discovery tho no?

Originally posted by factfinder38
I guess that I would have to say that I do belive in the evolution of man but I will say that I question some of the conclusions.

Er? You accept that man evolved but not the conclusions that come from it? What conclusions?

When you look at the timeline on the page I supplied there are just so many questions.

Questions are good things tho. I'll agree that there are gaps, of course, if you have to fossils, you have one gap. If you can add a fossil into the gap, well, now you have two gaps!

It is probably my own simplicity that makes me not understand how they come to such big conclusions from just a few small bones. It seems to me that a error in one part of the model they have put together could change the outcome .

orginally from the article linked aboveA few windows are now opening in Africa to glance into the fossil evidence on the earliest hominids, though the picture we have of their anatomy and behavior is still a blur,” said Semaw. “More hominid discoveries are needed from sites such as Gona to fully understand the biological origins of our ancestors.”

Let us hope that more evidence is unearthed so that this currently blurred science can find tangible proof of our origins as a species. Unfortunately the record is so fragmented that tangible proof is hard to come by. most of the fossils are fragments and pieces. I wonder by what method they dated the fossils. Hopefully it was not by position in the fossil record since this would rely on the assumption they are trying to prove for its validity and hence becomes circular logic.

Wouldn't it be nice if media outlets like msnbc would actually provide links to the studies done and their actual data rather than just a pithy summary of it. It would allow research and hypothesis on a much broader intellectual scale and might even help Joe public to get a better understanding of the science behind these discoveries.

Originally posted by factfinder38
It is probably my own simplicity that makes me not understand how they come to such big conclusions from just a few small bones.

indeed, one has to consider if the claims match the evidence. The teeth of mammals if very specific and is widely and reasonably used to id species. The claim for upright walking must be based on the toe bones which are amoung the other few bones that they have of the specimins, so, literally, take that for what its worth. There are, tho, other ardipithecus specimins outside of this discovery.

Johannmon
Hopefully it was not by position in the fossil record since this would rely on the assumption they are trying to prove for its validity and hence becomes circular logic.

You could allways read the paper and investigate the methodology thoroughly.

Wouldn't it be nice if media outlets like msnbc would actually provide links to the studies done and their actual data rather than just a pithy summary of it

I agree 100%. In this one they don't even note what journal the research was published in. Its possible that the discoverers haven't published any research on this find yet, which would make any claims very much meaningless.
This news report contends that its reported in the latest issue of Nature.
Here is the paper in pdf format in question. Its for Nature, so I think you need a subscription to access it thru their website

a selection from the abstract
The hominid dental anatomy (occlusal enamel thickness, absolute and relative size of the first and second lower molar crowns, and premolar crown and radicular anatomy) indicates attribution to Ardipithecus ramidus. The combined radioisotopic and palaeomagnetic data suggest an age of between 4.51 and 4.32 million years for the hominid finds at As Duma. Diverse sources of data (sedimentology, faunal composition, ecomorphological variables and stable carbon isotopic evidence from the palaeosols and fossil tooth enamel) indicate that the Early Pliocene As Duma sediments sample a moderate rainfall woodland and woodland/grassland.

Here is a table of the stratigraphy of the region

Maybe its not the best image of it tho.

more on the dating from the body of the paper
Dates from two different crystal-rich tuffs (GONASH-51 and GONASH-52) found in the middle of the lower lacustrine interval 14 m below GWM-3 and from the stratigraphically higher basalt flow under GWM-5sw indicate that the deposits are Early Pliocene in age (Fig. 2a, b). The two tuffs were dated by laser fusion 40Ar/39Ar analysis of single plagioclase crystals using methods described previously8 (Supplementary Figs 1 and 2). Excluding the obvious xenocrysts, 23 of 23 (GONASH-51) and 16 of 18 (GONASH-52) plagioclase crystals yielded statistically homogeneous populations with weighted mean ages ( 2) of 4.56 0.23 Myr and 4.59 0.45 Myr, respectively. Although the individual crystal ages are relatively scattered (unweighted population means and standard deviations of 4.45 0.53 Myr (n = 23) and 4.31 0.91 Myr (n = 15) for G-51 and G-52, respectively) their intra-sample homogeneity and variable precision justify the weighted mean as the best estimate for the ages (Supplementary Figs 1 and 2; Supplementary Table 2).

Two samples of groundmass concentrate (WMASH-25 and -27) from the basalt flow beneath GWM-5 were dated by resistance-furnace incremental heating yielding plateau ages of 4.17 0.21 Myr and 4.06 0.39 Myr, with a weighted mean of 4.15 0.18 Myr (Supplementary Figs 3 and 4; Supplementary Table 3). Palaeomagnetic data (referred to the timescale in ref. 9, recalculated for conformity with the standard age used in 40Ar/39Ar dating herein) provide additional constraints on the age of the deposits. The reversed polarity sediments and flows at all sites within these densely sampled stratigraphic sections may have been deposited during a single interval of reversed geomagnetic polarity, given the strong sedimentologic similarities between the GWM-3 and GWM-5 deposits. If this proves correct, the polarity interval that simultaneously satisfies all palaeomagnetic and radioisotopic data is chron C3n.1r with age limits 4.51–4.32 Myr (Fig. 2c). An alternative—but in our view geologically less plausible—interpretation is that GWM-5 is much younger than GWM-3. In this case, the magnetically reversed sediments of GWM-3 belong to chron C3.2r (4.83–4.65 Myr) or chron C3.1r (4.51–4.32 Myr), whereas the magnetically reversed sediments of GWM-5 could conceivably belong to chron C2Ar (4.21–3.61 Myr). In this model, palaeomagnetic constraints would place the GWM-3 block between 4.83 and 4.32 Myr ago, and combined radioisotopic results would place the GWM-5 block between 4.21 and 3.61 Myr ago. Further sampling may clarify the chronological position of GWM-5. The Early Pliocene age for all of these localities is supported by the presence of biochronologically useful species recovered from the hominid sites (for example, Nyanzachoerus jaegeri10, Kolpochoerus deheinzelini11, Anancus cf. kenyensis, Pliopapio alemui12 and Kuseracolobus aramisi12. Another fossil hominid site, GWM-10, although not yet dated geochronologically, is biochronologically indistinguishable from other As Duma localities.

Notice the use of multiple methods and the recognition of the limits of the methods. Notice also the careful use of detailed stratigraphy to control what they were working with and the use of statisical methods to ensure that they weren't just looking at bizzare anomolies. Notice also the disucssion of possible alternative, unlikley, but reasonable, interpretations of the dating data ad the publication of the methods used. This is a science paper. Its claims are starkly different than the 'boiled down' news reports.

Here are some illustrations of the samples

what indicates bipedality
GWM-10/P1 is a nearly complete manual left proximal phalanx probably from ray IV. The GWM-3/P2 manual proximal phalanx, represented by the proximal 40% of the bone, is large. These phalanges are similar in overall morphology to those from Hadar, with two differences: a more transversely broad proximal articular surface and longer absolute length14. The pedal proximal phalanx fragment retains the proximal third of the bone. The transversely broad oval proximal facet is oriented dorsally, a character diagnostic of bipedality and a trait also seen in the latest Miocene hominid Ardipithecus kadabba

Here is a pdf of a paper by the researcher Semaw about a different find. Its freely available.
Hereis a corresponding 'Letter to Nature' that I was able to find, however without a perscription I think it should not be accesible.

Here is a page about the Craft Institute at IU, you could contact them for some information.

Great work Nygdan I will enjoy the reading to follow up on this. You make some good point that I did not know how to put to words myself.

Glad to see its appreciated. I thought the author was perhaps pushing the claims a bit to far myself, and figured, what the heck. A few minutes of researching, and voila!, there it is.

Man, this information superhighway totally rocks! Especially now that its one 'puters! Fer sure!