Transitional forms in human evolution

You’re probably right, it says Australopithecus species unknown. Can you post a similarly complete fossil for A. afarensis?

The first sentence:

Australopithecus afarensis is one of the longest-lived and best-known early human species—paleoanthropologists have uncovered remains from more than 300 individuals!

As for your other questions, I would recommend doing a Google scholar search of the species and see the types of studies that were done on many of the different specimen we have.

The very first sentence eh? Well fancy that.
Let me answer the other questions for you.
Many of those individuals are represented by a single bone or tooth.
There are zero skeletons at least 50% complete. Lucy is 40% complete and has no hands or feet. (So how did they “know” they made the Laetoli tracks?)
None were found articulated.
There is one foot fossil complete to the level of Little Foot and that shows evidence of an abducted great toe.
We can be certain that at least one of the fossil skeletons contains foreign bones; Lucy. Recently it was realised that the skeleton actually contained a baboon vertebra.

They could and they did. One of the people making the footprints was stepping in the footprints of the person in front of them. Whether the one with the “weird big toe” is one of those is not stated. Actually that one is a cast so it is a negative of the footprint which might affect its appearance.

The article referenced seemed to state that maybe it is or maybe it isn’t, depending on opinion despite the headline. It also states they confirmed the other 88 fragments of bones were Lucy’s so it really is not an issue.

You say this as if that is a bad thing? Also do you know if this is the case or not? What kinds of sources are you looking at for both the claim that this is a bad thing and that we just have single bones or teeth.

Also, how would one go about identifying Australopithecus afarensis specimen? That’s an important question as well.

Here for an example is a fairly recent paper titled: Laetoli footprints reveal bipedal gaitbiomechanics different from those ofmodern humans and chimpanzees. Some key highlights:

  • The only hominin taxon recognized from fossils that lived around the same time as the Laetoli footprints were made is Australopithecus afarensis
  • The post-cranial anatomy of AA is well known thanks to fossil discoveries at Hadar, Ethiopia
  • It is challenging to determine via skeletal morphology habitual locomotor patterns, especially with rare or fragmentary fossils and those that lack modern functional analogues
  • The Laetoli hominin is morphologically distinct from both chimpanzees and habitually barefoot modern humans

Why does this matter? You can reconstruct specimen without articulation.

But if that’s true that means we have even greater confidence in the authenticity of the rest of her skeleton! I hope that you are not insinuating we can dismiss evidence now, just claiming foreign bones are likely mixed up in all these hominin fossils. A little writeup on this can be seen here:

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HUMAN-like footprints have been found stamped into an ancient sea shore fossilised beneath the Mediterranean island of Crete.

They shouldn’t be there.

Testing puts the rock’s age at 5.7 million years.

That’s a time when palaeontologists believe our human ancestors had only apelike feet.

And they lived in Africa.

So, is this changing the subject your way of conceding you have no real argument when it comes to disputing the Laetoli footprints were made by A. afarensis?

image

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Just like the Laetoli prints, “human-like” is not at all identical with “H. Sapiens”

You are quoting from a journalism lede designed to attract readers and advertising dollars. Contrast that with the actual paper:

Morphometric analysis shows the footprints to have outlines that are distinct from modern non-hominin primates and resemble those of hominins. The interpretation of these footprints is potentially controversial. The print morphology suggests that the trackmaker was a basal member of the clade Hominini. [emphases mine]

Being an intelligent man, Chris, you have no doubt noticed by now the enormous gap between the journalism teaser and the actual science.

The reason this paper is controversial is that it suggests that the earliest hominins appeared 5.7mya, whereas the previous earliest fossils dated to about 4.5mya. It (possibly) changes a few of the fine details in our understanding of human lineage. However, it is entirely consistent with the strong evidence of common ancestral population between H. Sapiens and chimpanzees 6 - 8mya.

I found the actual research paper linked in the clickbait article. I clicked the link. I found the name of the original paper, then googled for it to get the link to a site from which I could download the PDF. I downloaded the PDF.

You could have done this, too, Chris. It’s not that hard.

I heartily recommend the practice of relying on the original research instead of clickbait journalism.

My $.02,
Chris

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Sorry to drop out pf the conversation; I’ve been busy. I expect to be back next week.

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Now I posted this last week in the wrong thread so I am re-posting here.

The story so far…
Australopithecus afarensis (Lucy) has been proposed as a transitional species between apes and humans based on the assertion that it was an obligate biped. This claim was made by Johanson following the find of a knee bone in the Afar region of Ethopia which he believed came from an Australopithecus species and which showed an angled knee joint. Johanson was not a knee expert and went to the extent of raiding a local Afar burial mound to get a human knee bone for comparison.

This conclusion is however dubious since some apes do have angled knee joints (Orangutan and Spider monkey) and the sample size of known obligate bipeds is too small (one) to conclude that this is actually a requirement of bipeds.

Following this Johanson made the leap that the Laetoli tracks were made by A. afarensis even though he lacked foot bones to support that conclusion. We still have very few Australopithecus foot remains but the few we do have, Little Foot and Dikka Child, show a splayed (abducted) great toe which does not match the Laetoli Tracks.

The only Hominid known to leave footprints matching those at Laetoli are Homo sapiens. But “since they are dated at millions of years prior to when evolutionists believe modern humans arrived, they are regarded as australopithecine prints, by definition, even though australopithecine foot bones are substantially different from human ones. And then in an amazing twist, the same prints are held up as evidence that australopithecines walked upright like humans—regardless of the fact that other aspects of their anatomy indicate otherwise.” Sarfati & Matthews

Thus far the evidence used to propose A afarensis as a transitional species between apes and humans is decidedly weak.

@Chris_Falter, yes I did read the paper by Hatala, et al. I think it is far from conclusive.

First off, Lucy is not transitional because she was bipedal since ostriches are bipedal and are obviously not transitional between us and common ancestor shared with apes. The best evidence, IMHO, is not found in the knee but in the hips.

image
https://www.researchgate.net/figure/The-Ar-ramidus-pelvis-has-a-mosaic-of-characters-for-both-bipedality-and-climbing-Left_fig2_276926358

It is quite obvious that both Lucy and Ardy (Ardipithecus ramidus) have a pelvis like ours and very different from chimps (i.e. P. troglodytes). Whether Lucy was an obligate biped or not, she had the adaptions for bipedalism in her pelvis.

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Hi Chris,

You have vastly misrepresented the evidence, and Safarti, a physicist, has badly misrepresented it as well. Not out of malice, but out of lack of expertise and lack of careful consideration of the peer-reviewed research.

For example, Safarti asserts the following about the Laetoli prints:

Dr Russell Tuttle has shown that these are the same sorts of prints as made by habitually barefoot humans.

Nothing of the sort! Tuttle said the prints are “very similar to” modern human footprints. He did not say they are “identical to” modern human footprints. The difference is very, very important.

Much research has shown that the Laetoli prints were made by A. Afarensis, whose bio-mechanics are distinguishable from those of modern humans. Consider, for example, the peer-reviewed research by Hatala, et al. (2016):

We find that the Laetoli hominin probably used a more flexed limb posture at foot strike than modern humans when walking bipedally. The Laetoli footprints provide a clear snapshot of an early hominin bipedal gait that probably involved a limb posture that was slightly but significantly different from our own, and these data support the hypothesis that important evolutionary changes to hominin bipedalism occurred within the past 3.66 Myr. [emphasis added]

Source: Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees

For the sake of readers who are inquisitive enough to delve into the actual research being done by anthropologists, I cite another key study of Laetoli footprint bio-mechanics–Crompton, et al. (2012):

Pixel-wise topographical statistical analysis of Laetoli footprint morphology, compared with results from experimental studies of footprint formation; foot-pressure measurements in bipedalism of humans and non-human great apes; and computer simulation techniques, indicate that most of these functional features were already present, albeit less strongly expressed than in ourselves, in the maker of the Laetoli G-1 footprint trail, 3.66 Mya. [emphasis added]

You ascribe no value to the peer-reviewed literature, even though you are unable to point to any flaws in it.

<Irony_warning>That’s a really convincing critique. Devastating, even.</Irony_warning>

Best,
Chris

P.S. The fact that the original discoverer had no expertise in hominin gait bio-mechanics is utterly irrelevant. It is no more relevant than Darwin’s ignorance of DNA. A lot of good peer-reviewed research has since been conducted and published on the Laetoli discoveries. Rather than snipe at the relative ignorance of the original discoverer, wouldn’t it be better and more noble to take on the hard but enjoyable work of reading the peer-reviewed research that has been conducted since?

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Partly true, but both Lucy and Ardi (Ardipithecus ramidus) have a pelvis like a gorilla. If you go to Bone Clones and look at non-human primate pelvises you will see that there is quite a lot of variety; enough to say that both Lucy and Ardi fit within the ape group. Like the angle of the knee the evidence only looks convincing if you don’t consider the full range of variability within apes.

From what I can see, the ilium of the gorilla pelvis is rotated towards the dorsal side like it is in chimps and unlike the human and australopithecine pelvis where the ilium is rotated to the side of the body. Australopithecines fit in better with humans than with other apes. There is also the bony attachment for the glutes which is the same in human and australopithecines but different in other apes (the solide white arrow in the photo above).

All of this begs the question of what features a fossil would need in order for you to accept it as being transitional.

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According to Linnaeus, who lived and worked a century before the theory of evolution even existed, the species Homo Sapiens fits within the Homo genus alongside orangutans and chimpanzees.

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Indeed. His reasoning was rather straightforward.

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I’ve got another explanation for “transitionals”:

I haven’t met you before, Henry. Welcome.

It’s clear that you’ve put some effort into this analysis. I’d like to give you something to think about. How would your “kinds with overlap” hypothesis predict the following classes of evidence?

Chronological stratification of biological orders by age.

Your analysis contends that genotypic kinds have always existed at every point in history (after the creation week), but that overlapping phenotypes might show up in a more unpredictable fashion. What the fossil record shows is that what you would call “kinds” did not appear more or less simultaneously. Instead, some “kinds” like the trilobites appeared fairly early then died out eons later, while others like primates do not appear until very late in geological history. In other words, the fossil evidence shows widespread presence of certain features in a narrow time band, such as the Cambrian, then their subsidence or disappearance when other features appear.

For example, trilobites disappeared in the Permian extinction event, and you can’t find them anywhere subsequently. Fish did not appear until the Devonian. Amphibians did not appear until the late Carboniferous. Dinosaurs did not appear until the Triassic. I could list dozens more examples, especially if we were to look at the plant kingdom as well.

Close alignment observed between genotype and phenotype

We do not find worms with feathers, primates with beaks, or bipedal ruminants. You rely on an analogy (synthesized music) which does not actually mimic the close relationship observed in biology between genotype and phenotype.

Nested hierarchy in genomes

Mathematical studies of genomes find that ancestral relationships are most accurately described as a nested hierarchy, rather than as independent "kind" lineages with overlap.

Nested hierarchy in characters (phenotypes)

Mathematical studies of what biologists call characters show that ancestral relationships are best described as a nested hierarchy, rather than as independent “kind” lineages with overlap.

Nested hierarchy in fossil lineages

The fossil record, though incomplete, provides strong evidence of nested hierarchy. For example, just a few kinds of proto-mammals showed up in the Triassic, but then they diversified relatively rapidly in the Cenozoic. The diversification from an ancestral root is well depicted by the descent from Pakicetus in the Paleocene, to early whales in the Eocene, to today’s broad array of cetaceans (dolphins and whales).

Consilience of nested hierarchies

The three kinds of nested hierarchy patterns – genomic, phenotypic, and fossil record – point in the same direction. For example, mathematical studies of cetacean genotypes, of cetacean phenotypes, and of cetacean fossils all point to a nested hierarchy relationship.

Evolution is the theory that predicts these classes of evidence

The theory of evolution predicts that nested hierarchies will be the mathematical pattern that describes ancestral relationships between today’s species.

The theory of evolution predicts the chronological stratification of biological orders by age.

The theory of evolution predicts the strong relationship between genotype and phenotype.

“Kinds with overlap” does not predict these observations; therefore, “kinds with overlap” is not scientifically viable, in my opinion.

Peace,
Chris

P.S. You can maintain a strong faith in Biblical revelation while also upholding the work of the scientific community. But since you focused on the scientific analysis, that was my focus as well.

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Hello Sir, thanks. It may take me some time to respond, but I can make sense of these classes of evidence, actually.
First thing to notice here,is, that evolution is merely a >forensic interpretation< of observable data. It’s not a scientific hard fact, but an explanation of how the observable data got here. Let’s keep that in the back of our heads, when discussing my points. I’ll be back soon.