Following my previous post about an Eurasian origin of hominins, I stumbled upon a paper by Vaneechoutte, Mansfeld, Munro and Verhaegen (2024), that proposes a radical idea, that knuckle-walking chimpancees are not the ancestors of the upright-biped homo grop (that encompasses humans). It argues that chimps are the ancestors of australopithecines but not ours. Instead, they suggest that an older (6-9 million years ago) upright walking Eurasian Graecopithecus-like ape, like the one that left its footprints in Crete 6 Ma, split into two groups, one that entered Africa forming an ardipithecus-like species some 4.3-6 Ma, which led to Australopithecines, who were more hunched, and these in turn led to gorillas and pan (chimpancees) that are knuckle walkers. In the meantime, in Eurasia, through a yet unknown missing-link, Homo erectus appeared 2 Ma, later some migrated back into Africa, originating Homo sapiens there.
Homo, as a group originated in Eurasia.This is the article: Mario Vaneechoutte, Frances Mansfield, Stephen Munro, and Marc Verhaegen. (2024), Have We Been Barking up the Wrong Ancestral Tree? Australopithecines Are Probably Not Our Ancestors. Nat. Anthropol. 2024, 2(1), 10007; DOI: 10.35534/natanthropol.2023.10007 🔓
The paper is lenghty and juicy, it refutes the savannah adaptation of Australopiths (standing on two feet let them see predators from afar), and uses bones, skulls and footprint shapes to attack the chimp → Australopithecus → Homo evolution.
Bipedalism existed before Australopithecus appeared, by the way these creatures were arboreal (according to the authors), and the environment didn't pressure them to stand on two feet: "grassland savannahs had not been expanding in Africa at the time of the first australopithecines (approx. 4 Ma)... australopithecines were shown to have clear climbing adaptations, and to have lived in wetland, woodland or forest margins, they did not run long distances over open plains to chase prey or to scavenge carcasses because they were poor runners and because they were largely vegetarian"
Below is the "tree" suggested by the authors. Notice how the Australopiths evolve into chimps and gorillas.
ReplyDeleteHello Austin. It´s a very interesting research, in which the authors are proposing an audacious statement; Australopithecines, even having some “human like” features, would have been species transiting an evolutionary path in an inverse way as it was previously believed… that is; some sort of “bestialized” proto humans… where the particular adjective I deliberately chose and remarked, alludes to argentine naturalist Florentino Ameghino´s hypothesis of “bestialization”. (See Note*).
Based on my own opinion, I will try to briefly analyze what the authors are proposing in Fig. 3…
I think that their arguments “may” become feasible for Australopithecus afarensis (species that lived in East Africa between 3.9 to 2.9 Ma)… mainly due to; a) the morphology of their skull, that presents a defined sagittal crest (as Gorilla does). Although this trait is attenuated in the female individuals “Lucy” and “Selam” due of sexual dimorphism, it appears to be a feature clearly present in the body plan of this species, and b) their shoulder is very “ape like”, as the shape of their scapulae bones closely resembles that´s from extant genus Gorilla…
Also may be admitted that similar treatment of “bestialized” species could be too applied, and with less probability of error, to Paranthropus robustus and Paranthopus boisei, because they are even more “ape like” than A. afarensis… and their significantly lower age (from 2 to 1 Ma for P. robustus and from 2.3 to 1.2 Ma for P. boisei) could be indicating that they could have disposed at least 1 Ma more of evolution towards apes, than A. afarensis could eventually have had…
However (and always in my modest opinion), referring to Australopithecus africanus (species that lived in South Africa between 3.2 to 2.1 Ma), I would be somewhat reluctant to put him in the same category… because his human-like traits included a more globularly shaped skull, that virtually lacks sagittal crest…thus having strikingly more resemblance to H. habilis ´s one than the mentioned species… And I suspect that this last suggestive feature by itself would be enough to, at least, call into question the real direction of the evolutionary path this species had been following…
Amazing post…!!
Best regards
Marcelo
Note*: This is a concept developed by Ameghino more than 100 years ago, in order to help to outline his well known at the time (albeit, not accepted) Autochtonous Hypothesis of Human Evolution (origin of genus Homo in South America)…Upon his view, ”bestialization” involves evolution towards traits that are typical of ape-like species; more subnasal prognathism, hypertrophied canine teeth, more thickened bones skull bones and also the presence of a sagittal crest, among other ones… all of them derived via “backward” evolution from an older human-like ancestor. Although Ameghino´s hypothesis perished due to the lack of valid scientific proof, remaining only as a curious milestone in the history of science, some aspects of it, like the mentioned one, still have undeniable validity…
Thank you Marcelo for your comment. Very instructive. I note your point on the South African A. africanus as important and something that the theory proposed by the paper mentioned in my post, will have to address.
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