Fossils Reveal Clues on Human Ancestor (transitional fossil alert)

New York Times ^ | 20 September 2007 | John Noble Wilford

[Alter Kaker]

The discovery of four fossil skeletons of early human ancestors in Georgia, the former Soviet republic, has given scientists a revealing glimpse of a species in transition, primitive in its skull and upper body but with more advanced spines and lower limbs for greater mobility.

The findings, being reported today in the journal Nature, are considered a significant step toward understanding who were some of the first ancestors to migrate out of Africa some 1.8 million years ago. They may also yield insights into the first members of the human genus, Homo.

Until now, scientists had found only the skulls of small-brain individuals at the Georgian site of Dmanisi. They said the new evidence apparently showed the anatomical capability of this extinct population for long-distance migrations.

“We still don’t know exactly what we have got here,” David O. Lordkipanidze, the excavation leader, said Monday in an interview on a visit to New York. “We’re only beginning to describe the nature of the early Dmanisi population.”

Other paleoanthropologists said the discovery could lead to breakthroughs in the critical evolutionary period in which some members of Australopithecus, the genus made famous by the Lucy skeleton, made the transition to Homo. The step may have been taken more than two million years ago.

“The Australopithecus-Homo transition has always been murky,” said Daniel E. Lieberman, a paleoanthropologist at Harvard University. “The new discoveries further highlight the transitional and variable nature of early Homo.”

The international team led by Dr. Lordkipanidze, director of the Georgian National Museum in Tbilisi, found several skulls and stone tools at Dmanisi in the 1990s. They were dated to 1.77 million years ago and resembled Homo erectus, the immediate predecessor of Homo sapiens. The fossils were tentatively assigned to the erectus species.

[b_sharp]

"For anyone interested in human fossils, I highly recommend "Bones of Contention," by Marvin L. Lubenow. I'm about half way through it now."

Before you go recommending Lubenow's book, I suggest you read this review of it and some additional information .

[b_sharp]

"Henry Gee, the senior editor of Nature and a leading paleoanthropologist, about the newly discovered ape fossil are very noteworthy. In his article published in The Guardian, Gee refers to the debate about the fossil and writes:

"Whatever the outcome, the skull shows, once and for all, that the old idea of a 'missing link' is bunk... It should now be quite plain that the very idea of the missing link, always shaky, is now completely untenable."

This is a classic case of quote mining in an attempt to cast a shadow over the idea that hominid fossils show the evolution of man from more primitive ancestors.

Here is the link to the article by Henry Gee. His contention is not that the fossil in question, Sahelanthropus tchadensis (Toumaï) does not fit the hominid group but that the idea, pushed by creationists, that a single fossil has to fit their idea of a 'missing link' is bunk. The 'missing link' suggests hominid ancestry must follow a ladder of change. What we find is that hominid ancestry is a bush.

Why is Toumaï so important? First, it is the earliest known credible vestige of a hominid - a member of the group of creatures more closely related to human beings than to any other animals. It also doubles the antiquity of the earliest known skull: the previous recordholder, from Kenya, is around 3.3m years old.

Second, it has dropped straight into the most crucial, but least known, part of the story of human evolution. It is suspected that the last common ancestor of humans and our closest living relatives, the chimpanzees, lived around 7m years ago. We know this not from direct fossil evidence, but from studying the small differences in the otherwise similar genes of humans and chimps, and estimating the time needed for these differences to accrue.

Does the above quote sound like the author in any way thinks humans did not evolve from hominid ancestors?

If you, or the authors you quote, want to misrepresent what authorities say you should stick to publications more difficult to find.

[Coyoteman]

Before you go recommending Lubenow's book, I suggest you read this review of it and some additional information.

The latest edition has the title: Bones of Contention: A Creationist Assessment of Human Fossils.

In other words, the entire book is filtered through the ideology and religious belief that evolution is impossible, didn't happen, and causes bad breath and the heartbreak of psoriasis.

Sure sounds like creation "science" to me.

[b_sharp]

"Out of curiosity, did we have to revise any geologic dates so that the ground would magically rise just in time for these ape-men to learn to walk on too?"

Land moves all the time, up, down and laterally. We observe it happening in real time. The uplift you are referring to did not occur in order to create our ancestors, it has been proposed that the evolution of our ancestors towards current humans were triggered by the uplift. The change in dates is because of improved methods of dating uplifts.

Dating an uplift is not the same as dating the age of igneous rocks. Radiometrics are not generally affected by movement of strata in such a way that we can use them to date the move. Only if the uplift is due to intrusions of igneous rock can radiometrics be used. That is why they used river path changes to determine a new date.

You are aware I hope that you are libeling all scientists, including Christians, by positing a conspiracy to deceive.

[Sola Veritas]

“Show, for instance, that differential survival is irrelevent to the relative frequencies of different genes in a population and you’d disprove natural selection.”

Why would I want to disprove “natural selection.” It can be clearly demonstrated in “real time.” Also, I see it as a means whereby a species is preserved, not one where a new species arises from a previous one...that cannot “clearly” be demonstrated in “real time.” New genes are not “happening” per se, they are just being shuffled and expressed under the right environmental conditions.

“I’m glad you call it faith. Because faith, rather than fact, calls you to your beliefs. There’s not necessarily anything wrong in believing in something regardless of the facts, but it is important for creationists to understand that their beliefs are faith-based, not fact-based. That should inform public debates about whether creationism best belongs in a fact-based forum (a high school science class, for instance) or rather in a faith-based forum (a church or mosque).”

This all hinges on how one defines a “fact.” For instance, I cannot reproduce the resurrection of Jesus Christ. However, I can present pretty compeling evidence that it did occur. Just because a “fact” (which can also be called a truth) has its origen in religious belief, does not automatically disqualify it for consideration in science classes where origins are discussed. Now to what degree it should be considered is not something I want to be dogmatic about, but I do think it should be considered....if the majority of persons in that school district what that to be so. Materialistic “scientists” do not hold a monopoly on what is acceptable thought in “science.”

We live in a society that values free speech; especially political speech. Science has clearly become political (i.e. global warming) and is fare game for free thought and the expression of it.

I sincerely, without rancor, submit that the days of old school materialistic “scientists” being able to dictate what is or is not acceptable “science” is coming to an end. As I in good humor like to point out, one can either adapt to the change or risk becoming extinct by “natural” selection.

[A6M3]

Isn’t it ironic, how the tactics of todays materialistic science and academia have “evolved” into the tactics of the Roman Catholic Church of Galileo's’ time.

[Aquinasfan]

The 'missing link' suggests hominid ancestry must follow a ladder of change. What we find is that hominid ancestry is a bush.

Of course he believes in evolution. He's a paleoanthropologist. It's a prerequisite for those who want to survive in the profession. Evolution must be true, and we proceed from there.

Human evolution used to be a ladder. Now it's a bush. Is there any way that the theory can be falsified? As an outsider looking in, all I see is hand-waving, deceit, and manipulation of facts to fit a pre-existing theory. Arguments from authority are the weakest of all arguments, and judging from what I've read, completely useless in this field.

I have a degree in engineering. That doesn't make me an expert in paleoanthropology, but it does help me to recognize the tailoring of evidence to fit a pre-existing theory. The more I study the hard evidence, the more obvious this becomes.

[Aquinasfan]

Before you go recommending Lubenow's book, I suggest you read this review of it and some additional information .

The major theme of Bones of Contention is that the various species of hominid cannot form an evolutionary sequence because they overlap one another in time.

"In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment." --Charles Darwin

Firstly, he argues that a species cannot survive once it has given rise to a new species. Unlike many other creationists, he does at least attempt to give some justification for this. Supposedly, the newer, fitter descendant species, would, because of its superiority, drive its parent species to extinction.

To be fair, this was pretty much Darwin's theory, who was a significant figure in the development of Darwinism.

The argument is incorrect because members of the parent species may live in a separate region from the new species.

In a land far, far away. They would have to live far, far, away, because only the fittest can survive in one place.

The problem with this theory is that hominids, like neanderthal, have been discovered all over the world, as have homo sapiens. Additionally, all of these hominids existed contemporaneously, if we accept the dates given by paleoanthropologists themselves. The idea that they never encountered each other strains credulity, to be charitable.

If the species come into contact again, there may be no competition because they have diverged enough to occupy different ecological niches. (Many scientists would argue that even the requirement for a separate region is unnecessary.)

So neanderthal and homo sapiens occupied "different ecological niches"? Paleoanthropologist have a hard time distinguishing between these species' fossils (see bold sections below). The evidence indicates that they did not occupy different "ecological niches."

Additionally, it is a misunderstanding of evolutionary theory to claim that a new species is "superior", in an absolute sense, to its parent species.

"In the struggle for survival, the fittest win out at the expense of their rivals because they succeed in adapting themselves best to their environment." --Charles Darwin

Typically, both species will be "superior" at living in their own niches.

Like the various hominids that paleoanthropologist have difficulty in distinguishing (see bold section below).

This argument is so broad that it would not only disprove human evolution but all evolution; Lubenow is basically asserting that a species cannot split into two species.

Pretty much.

The argument is also contradicted by real world examples, such as that of the 13 species of finch which live on the Galapagos Islands. There is such compelling evidence that these are descended from a common ancestor...

OK, what is this compelling evidence?

Secondly, and more seriously, Lubenow claims that, in some cases, a descendant species existed before the species it supposedly descended from. Clearly, this is impossible under evolutionary theory.

For example, Lubenow claims that Homo erectus overlaps the entire time range in which Homo habilis is found. The oldest dated habilis specimen he lists is about 1.9 million years old (with a possibility that another was as much as 2.35 million years old).

Lubenow criticizes Klein (1989) for showing a graph in which habilis is shown preceding erectus in time, when none of the habilis fossils discussed by Klein are dated before 1.9 million years ago. In this case, Lubenow has not read Klein carefully enough...

And Semaw et al.(1997) have reported stone tools found in Ethiopia and dated at between 2.5 and 2.6 million years old. Since stone tools are not known to have been used by australopithecines, it is most likely that they were made by early Homo. In short, there is growing evidence of early Homo species which could have been ancestral to H. erectus.

Is he saying that some species of homo existed before australopithecines? That piece of information has not been eagerly shared with the public.

Similarly, Lubenow claims that humans are found up to 4.5 million years ago, before any australopithecines. Before 2 million years ago, the evidence for this consists of only two fossils, the Laetoli footprints and the Kanapoi Hominid (KP 271) (since dated at about 4 million years). This is Lubenow's strongest argument, because both fossils are, arguably, from humans.

Sure seems like a strong argument.

The problem is that there is not enough other evidence to exclude the possibility that both belong to australopithecines.

So paleoanthropologists can't distinguish between australopithecines and other hominids? In that case, all fossil evidence must be thrown into doubt. Either that, or homo sapiens existed alongside australopithecines. They're caught between a rock and a hard place.

There are more fossils which Lubenow considers to be sapiens, but which are as old as the earliest erectus fossils (about 2 million years). These consist of some undoubted habilis fossils such as ER 1470, and some fossils usually assigned to erectus or habilis. These fossils are all of body parts which are difficult to classify, because other Homo species are both poorly known, and not that different below the neck, as far as we know, from modern humans. Lubenow admits the difficulty but assigns them to H. sapiens anyway.

Again, scientists have a difficult time distinguishing between hominid species, that is, when the evidence doesn't fit their theory. Otherwise, they have no trouble distinguishing between hominid fossils.

I'm sorry, this is a scientific joke.

[Aquinasfan]

Isn’t it ironic, how the tactics of todays materialistic science and academia have “evolved” into the tactics of the Roman Catholic Church of Galileo's’ time.

The case of Galileo is not as simple as you suggest.

"The Roman Catholic Church of Galileo's time," specifically, a bishop and a cardinal, was also financing Copernicus' research into the theory of heliocentricity.

So why did the Church tribunal object to Galileo's theory of heliocentricity? It wasn't the theory per se, but the fact that he wanted the Church to promote his as yet unproven theory. (See link above).

[allmendream]

Yes the fossil record shows species appearing suddenly and fully formed, however this does very little to bolster the Creationist model as the fossil record clearly shows them appearing suddenly and fully formed AT DIFFERENT TIMES.

Amazing that the Creationists will accept the validity of the data only insofar as it supports their presuppositions. So the fossil record CAN be relied upon for showing the emergence of species and the time can be defined as ‘sudden’, but the time must also be contorted and distorted to fit them within the last few thousand years and have them all appear ‘suddenly’ at the same time.

If these guys were not such a threat to U.S. education in Science I would find them amusing.

[allmendream]

Actually classifying animals phylogenetic relationship based upon genetic homology is ‘easy’, ‘simple’ and ‘clear’; and it confirms the Linnean classification system based upon morphology in most cases.

Now counting those millions of species.....That can get messy as some Biologists are ‘splitters’ and would count 20 million species from the same set that a ‘lumper’ would count 15 million species from.

Species: soft definition. Reproductively isolated population. It MIGHT be able to interbreed with neighboring species in captivity and produce viable offspring, but it DOESN’T; so it is its own species. This is the ‘splitter’ definition, and you come up with a lot higher number of species than if you use the other definition.

Species: hard definition. A population that is incapable of reproducing viable offspring with a different species. According to this definition two reproductively isolated species that might mate in a different month or use different signals, CAN and WILL reproduce viable offspring when in captivity. You get a much lower species count if you use this definition.

Which one do I prefer? I like the first. Who cares if it is possible for the two populations if, in nature, it just doesn’t happen that the two different species will reproduce with each other.

[GunRunner]

So the fossil record CAN be relied upon for showing the emergence of species and the time can be defined as ‘sudden’, but the time must also be contorted and distorted to fit them within the last few thousand years and have them all appear ‘suddenly’ at the same time.

Correct; he failed to mention whether the creationist model he was referring to included a 6,000 year old Earth. Not to mention that "sudden" changes in the fossil record are usually measured in the hundreds of thousands and/or millions of years.

[Diamond]

Actually classifying animals phylogenetic relationship based upon genetic homology is ‘easy’, ‘simple’ and ‘clear’; and it confirms the Linnean classification system based upon morphology in most cases.

A facile assurance that requires for its acceptance the ability to completely ignore the long, raging conflict in systematics between molecular and morphological phylogenies.

“No consistent organismal phylogeny has emerged from the many individual protein phylogenies so far produced. Phylogenetic incongruities can be seen everywhere in the universal tree, from its root to the major branchings within and among the various taxa to the makeup of the primary groupings themselves.”
Woese, Carl. 1998. The Universal Ancestor. Proceedings of the National Academy of Sciences USA 95:6854-6859.

A"s morphologists with high hopes of molecular systematics, we end this survey with our hopes dampened. Congruence between molecular phylogenies is as elusive as it is in morphology and as it is between molecules and morphology. . . . Partly because of morphology’s long history, congruence between morphological phylogenies is the exception rather than the rule. With molecular phylogenies, all generated within the last couple of decades, the situation is little better. Many cases of incongruence between molecular phylogenies are documented above; and when a consensus of all trees within 1% of the shortest in a parsimony analysis is published (e.g. 132, 152, 170), structure or resolution tends to evaporate."
Patterson, Colin, and others. 1993. Congruence Between Molecular and Morphological Phylogenies. Annual Review of Ecology and Systematics 24:153-188.

Cordially,

[allmendream]

Woese’s paper is on the search for the universal common ancestor, not a simple phylogenetic analysis of two species.

Moore and Wilner also conclude that...

“Complementary use of molecular characters shows promise”

and that...

“combination of morphological and molecular methods has made much progress.”

It has made even more progress in the decade since 1995 when the authors made that statement.

Please refer to this and THOUSANDS of other studies done since 1995 that use this graceful, easy, clear and simple method ...

Ray DA, Xing J, Hedges DJ, Hall MA, Laborde ME, Anders BA, White BR, Stoilova N, Fowlkes JD, Landry KE, Chemnick LG, Ryder OA, Batzer MA.
Department of Biological Sciences, Biological Computation and Visualization Center, Center for Bio-Modular Multi-scale systems, Louisiana State University, 202 Life Sciences Bldg., Baton Rouge, LA 70803, USA.

Short INterspersed Elements (SINEs) make very useful phylogenetic markers because the integration of a particular element at a location in the genome is irreversible and of known polarity. These attributes make analysis of SINEs as phylogenetic characters an essentially homoplasy-free affair. Alu elements are primate-specific SINEs that make up a large portion of the human genome and are also widespread in other primates. Using a combination wet-bench and computational approach we recovered 190 Alu insertions, 183 of which are specific to the genomes of nine New World primates. We used these loci to investigate branching order and have produced a cladogram that supports a sister relationship between Atelidae (spider, woolly, and howler monkeys) and Cebidae (marmosets, tamarins, and owl monkeys) and then the joining of this two family clade to Pitheciidae (titi and saki monkeys). The data support these relationships with a homoplasy index of 0.00. In this study, we report one of the largest applications of SINE elements to phylogenetic analysis to date, and the results provide a robust molecular phylogeny for platyrrhine primates.

PMID: 15737586 [PubMed - indexed for MEDLINE]

[js1138]

Human evolution used to be a ladder. Now it's a bush. Is there any way that the theory can be falsified?

A ladder that looks like this?

[Sola Veritas]

“Isn’t it ironic, how the tactics of todays materialistic science and academia have “evolved” into the tactics of the Roman Catholic Church of Galileo’s’ time.”

Indeed, it is. That is a very astute observation on your part.

My “religious” beliefs are a part of who I am, they have a profound effect on my views and how I interpret data. Should that disqualify me to be a scientist? I don’t think so, and I would imagine most of the American public would agree. If it is an absolute essential that a person’s religious views cannot influence their take on things, then that only leaves a totally atheistic thinking person to do “science” because they lack “bias.” Besides being unrealistic, it is just plain silly. In that their aren’t that many “true” atheists.

That being said, I do understand the concern expressed by those looking for “materialistic” explanations. They are concerned, with some good reason, that the purity of scientific pursuit could be damaged by appeals to the supernatural. I agree, in principle, that this could get out of control. However, for the most part, I think their fears are unfounded. Plus, they can’t seem to understand that ID proponents and special creationists (AKA YECs) are separate groups.

All YEC Creationists believe in “intelligent design”, and even go so far as to identify the designer as the God of the Bible. However, most proponents of ID (like Professor Behe) are not identified with nor do they associate with YECs. I am firmly in the YEC group and I can tell one plainly that ID proponents are not stealth YECs as they have been accused repeatedly on Free Republic. A YEC like myself might use Behe’s work to make a point, but I think you will find that he probably would consider me a kook.

[allmendream]

Science is not atheistic because of its lack of appeal to the supernatural. Agnostic possibly. However most Scientists see no conflict between explanations for the natural world and their spiritual beliefs, and most Scientists are not Agnostic and neither are they Atheists. Scientists are in the community of believers, and many of the most famous and productive Scientists have been men and women of deep and profound faith.

[Diamond]

"combination of morphological and molecular methods has made much progress."

It has made even more progress in the decade since 1995 when the authors made that statement.

This article lists 35 different categories of assumption/problems relevant to molecular phylogenic studies. The plethora of assumptions involved make such studies anything but simple, easy, and clear. Uncounted Assumptions

There are many assumptions having to do with regularity and sample error significantly affecting the reliability of phylogenetic analysis, even purportedly Bayesian in nature, that are commonly ignored or incorrectly passed off as trivial in the speculative literature. The tree itself is a branching series of nested sets (e.g. the set of all taxa exhibiting certain state changes). A set may appear to be more definite a concept than a sample, yet it cannot be any better than the samples included in it, and a set is itself a sample.

[snip]...Below is a list of presuppositions (variously discussed in general by, among others, Avise, 1994; Felsenstein, 2004; Huelsenbeck et al., 1994; Jenner, 2004; Kolaczkowski & Thornton, 2004; Lipscomb et al., 2003; Lyons-Weiler & Milinkovitch, 1997; Maddison, 1996; Naylor & Adams, 2003; Philippe et al., 1996; Pickett & Randle, 2005; Rokas et al., 2003; Ronquist, 2004; Ruedas et al., 2000; Sites et al., 1996; Templeton, 1986; Wendel & Doyle, 1998; Wilcox, et al., 2002). These can be important but are commonly not factored in, and this is especially true in the older literature. Some are obvious and major problems, and some are cryptic to the non-adept, or merely minor, or inapplicable to particular loci.

Please refer to this and THOUSANDS of other studies done since 1995 that use this graceful, easy, clear and simple method ...

Here's a link to a working proof of the study you cited that I found for free: Alu insertion loci and platyrrhine primate phylogeny

"...Short INterspersed Elements (SINEs) make very useful phylogenetic markers because the integration of a particular element at a location in the genome is irreversible and of known polarity. These attributes make analysis of SINEs as phylogenetic characters an essentially homoplasy-free affair."

And what happens when data happens to contradict the evolutionary prediction, i.e., the "known primitive derived polarity"? If elements are periodically inserted during the course of primate evolution, generating a unique new family of interspersed repeats that create markers suitable for phylogenetic analyses, then why the need for so many ad hoc rationalizations to explain away the legions of inserted element that do not comform to nested hierarchies? How is that pseudogene studies are ballyhooed when they accomodate evolutionary predictions, but are somehow never a threat to evolutionary theory when they contradict evolutionary predictions?

Contrary to the evolutionary assumption of the study you cited above that Alu insertions are irreversible, precise deletions of Alu units can occur. In the study below, a gorilla-human shared Alu was absent at the orthologous chimp locus, and an extra 12 bp right Alu-flanking repeat, added to an empty-site sequence, marked the missing-Alu spot:

Connie M. Westhoff1 and Dwane E. Wylie1

(1) School of Biological Sciences, University of Nebraska, 325 Manter Hall, 68588 Lincoln, NE, USA

Received: 8 September 1905 Accepted: 12 January 1996

Abstract The human Rh blood-group system is encoded by two homologous genes,RhD andRhCE. TheRH genes in gorillas and chimpanzees were investigated to delineate the phylogeny of the humanRH genes. Southern blot analysis with an exon 7-specific probe suggested that gorillas have more than twoRH genes, as has recently been reported for chimpanzees. Exon 7 was well conserved between humans, gorillas, and chimpanzees, although the exon 7 nucleotide sequences from gorillas were more similar to the humanD gene, whereas the nucleotide sequences of this exon in chimpanzees were more similar to the humanCE gene. The intron between exon 4 and exon 5 is polymorphic and can be used to distinguish the humanD gene from theCE gene. Nucleotide sequencing revealed that the basis for the intron polymorphism is anAlu element inCE which is not present in theD gene. Examination of gorilla and chimpanzee genomic DNA for this intron polymorphism demonstrated that theD intron was present in all the chimpanzees and in all but one gorilla. TheCE intron was found in three of six gorillas, but in none of the seven chimpanzees. Sequence data suggested that theAlu element might have previously been present in the chimpanzeeRH genes but was eliminated by excision or recombination. Conservation of theRhD gene was also apparent from the complete identity between the 3'-noncoding region of the human D cDNA and a gorilla genomic clone, including anAlu element which is present in both species. The data suggest that at least twoRH genes were present in a common ancestor of humans, chimpanzees, and gorillas, and that additionalRH gene duplication has taken place in gorillas and chimpanzees. TheRhCE gene appears to have diverged more thanRhD among primates. In addition, theRhD gene deletion associated with the Rh-negative phenotype in humans seems to have occurred after speciation."

Cordially,

[allmendream]

Integration is of known polarity and is irreversible in SINE’s. That doesn’t mean that the sequence cannot be subsequently eliminated by excision or recombination; just that it will not ‘jump out’ using the same mechanism that allowed it to ‘jump in’.

Interesting exceptions to the overwhelming genetic similarity shared between humans and chimps such as an ALU element shared by gorillas and humans but not chimps are exactly that, interesting exceptions. The overwhelming majority of such neutral genetic changes such as ERV insertions and psuedogenes ARE shared in common to a greater degree in humans and chimps than between humans and gorillas. Anecdotes of a particular element do nothing substantial to change this overwhelming mathematical alignment that conforms to the assumption of natural selection and common ancestry.

[Sola Veritas]

“However most Scientists see no conflict between explanations for the natural world and their spiritual beliefs...”

As long as those “beliefs” are not conservative, evangelical, and protestant. These typically take scripture as literal unless clearly indicated otherwise. So if they are at ease then they are just compromising or rationalizing if they see no conflict. However, I will let God sort that out, I’m not Him and thus not qualified to do so. :-)