On the path of evolution from chimpanzees and bonobos on one hand, and the genus Homo on the other, in between is Australopithecus, about 3.5 million years ago. Analysis of tooth enamel from Australopithecus remains in South Africa shows that this human ancestor ate very little meat and relied predominantly on plant based food.
The underlying paper is: Tina Lüdecke, Jennifer N. Leichliter, Dominic Stratford, Daniel M. Sigman, Hubert Vonhof, Gerald H. Haug, Marion K. Bamford, Alfredo Martínez-García. "Australopithecus at Sterkfontein did not consume substantial mammalian meat." 387 (6731) Science 309 (January 2025). DOI: 10.1126/science.adq7315
8 comments:
A. afarensis (Lucy, Dik-1) had laryngeal air sacs as seen in chimps, gorillas, orangs, siamangs. Humans and gibbons don't. Australopiths are not direct ancestors of Homo, were probably closer to Pan, whose ancestors were more bipedal than today's extant chimps & bonobos. So I would expect mainly vegetation/fruit, with some insect larvae, eggs, small primates in their diet.
DDeden
A. afarensis (Lucy, Dik-1) had laryngeal air sacs as seen in chimps, gorillas, orangs, siamangs
reference ?
https://en.m.wikipedia.org/wiki/Selam_(Australopithecus)
"Here we describe a well-preserved 3.3-million-year-old juvenile partial skeleton of Australopithecus afarensis discovered in the Dikika research area of Ethiopia. The skull of the approximately three-year-old presumed female shows that most features diagnostic of the species are evident even at this early stage of development. The find includes many previously unknown skeletal elements from the Pliocene hominin record, including a hyoid bone that has a typical African ape [hominid] morphology."
Unlike all Homo fossil hyoid bones known, A. afarensis hyoid resembles chimp hyoid.
laryngeal air sacs= hyoid ?
They are attached, except in gibbons & humans. https://www.researchgate.net/figure/MR-images-of-the-laryngeal-air-sac-for-the-same-female-chimpanzee-Pal-a-At-4-mo-a_fig2_225148707
https://www.sciencedirect.com/science/article/abs/pii/S0047248411002004
I've shown many times, gibbons & humans share many unique traits exclusively, which arboreal great apes have lost. This is due to a change from lateral locomotion to vertical, and adaptation of arboreal bowl nesting, and resulting qpal knucklewalking.
This article confirms this change from lateral to vertical locomotion in great apes but not gibbons or humans:
https://www.nature.com/articles/srep11528
Humans and gibbons have (eye) orbits which are significantly less convergent than those of chimpanzees / bonobos, gorillas and orangutans (p < 0.001). These elements suggest a morphology favoring lateral vision in humans. More specifically, the human orbit has a uniquely rearward temporal orbital margin (107.1°; p < 0.001), suitable for avoiding visual obstruction and promoting lateral visual field expansion through eye motion. Such an orbital morphology may have evolved mainly as an adaptation to ... bipedal locomotion.
The 2nd cite refers to linguistic reduction of airsacs in Homo to enable complex speech, but that is a teleology which is unparsimonious. Airsacs allow repeated loud calls, used air returns to the lungs to prevent hyperventilation, in chimps, gorillas, orangutans and siamangs. Gibbons and humans have continuous song, all used air is exhaled directly, and the calls are shorter. There are no indications in gibbons or humans of ancestral large airsacs comparable to arboreal great apes.
"Because the presence or absence of air sacs is correlated with the anatomy of the hyoid bone, a probable minimum and maximum date of the loss of air sacs can be estimated from fossil hyoid bones. Australopithecus afarensis still had air sacs about 3.3 Ma, while Homo heidelbergensis, some 600 000 years ago and Homo neandethalensis some 60 000 years ago, did no longer".
https://pubmed.ncbi.nlm.nih.gov/19149203/ No laryngeal airsacs in Homo erectus, nor in Homo sapiens (except pathologically).
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