Op dinsdag 28 november 2023 om 05:33:28 UTC+1 schreef JTEM is so reasonable:
Marc Verhaegen wrote:
Lucy afarensis was most likely a fossil relative of Gorilla:
Thanks, JTEM.
DNA places HP/G at 8-7 Ma = when the N-Rift began to form.
Lucy's anat.details are very gorilla-like, see list below.
You know my view now (cf my book p.299):
-early-Miocene Hominoidea = aquarboreal on archipelagoes between Arabafrica & Eurasia,
-hylobatids (even different branches?) went E along the N-Tethys-ocean coasts, -the Mesopotamian Seaway closure 15-14 Ma split hominids W (Med+Red Sea) & pongids E (Ind.ocean)
-HPG = late-Miocene hominids in Red Sea
--Gorilla 8-7 Ma followed incipient N-Rift->Afar: afarensis-anamensis-boisei... -Red Sea opened into Gulf/Aden 6-5 Ma: Homo->E=S.Asia, Pan->S=E.Africa: --H.erectus e.g. Java = shellfish-diving: brain++, POS++, nose, fossilisation amid shellfish etc.etc.
--Pan->S-Rift->Transvaal: africanus, robustus...very-chimp-like (see below) // Gorilla in N-Rift.
Simple, no? :-)
--marc
Table 2 - Quotations on gorilla-like features in large E.African australopith crania
• “Incisal dental microwear in A.afarensis is most similar to that observed in Gorilla”. Ryan & Johanson 1989.
• The composite skull reconstructed mostly from A.L.333 spms “looked very much like a small female gorilla”. Johanson & Edey 1981.
• “Other primitive [advanced gorilla-like --mv] features found in KNM-WT 17000, but not know or much discussed for A.afarensis, are: very small cranial capacity; low posterior profile of the calvaria; nasals extended far above the frontomaxillar
suture and well onto an uninflated glabella; and extremely convex inferolateral margins of the orbits such as found in some gorillas”. Walker cs 1986.
• As for the maximum parietal breadth & the biauriculare in O.H.5 & KNM-ER 406 “the robust australopithecines have values near the Gorilla mean: both the pongids and the robust australopithecines have highly pneumatized bases”. Kennedy 1991.
• In O.H.5, “the curious and characteristic features of the Paranthropus skull... parallel some of those of the gorilla”. Robinson 1960.
• The boisei “lineage has been characterized by sexual dimorphism of the degree seen in modern Gorilla for the length of its known history”. Leakey & Walker 1988.
• boisei teeth showed “a relative absence of prism decussation”; among extant hominoids, “Gorilla enamel showed relatively little decussation ...”. Beynon & Wood 1986.
Table 3 - Quotations on chimp-like features in S.African australopith crania • “Alan [Walker] has analysed a number of Australopithecus robustus teeth and they fall into the fruit-eating category ... their teeth patterns look like those of chimpanzees ... Then, when be looked at some Homo erectus teeth, he found that the
pattern changed”. Leakey 1981.
• “The ‘keystone’ nasal bone arrangement suggested as a derived diagnostic of Paranthropus [robustus] is found in an appreciable number of pongids, particularly clearly in some chimpanzees”. Eckhardt 1987.
• “P.paniscus provides a suitable comparison for Australopithecus [Sts.5]; they are similar in body size, postcranial dimensions and... even in cranial and facial features”. Zihlman cs 1978.
• “A.africanus Sts.5, which... falls well within the range of Pan troglodytes, is markedly prognathous or hyperprognathous”". Ferguson 1989.
• In Taung, “I see nothing in the orbits, nasal bones, and canine teeth definitely nearer to the human condition than the corresponding parts of the skull of a modern young chimpanzee”. Woodward 1925.
• “The Taung juvenile seems to resemble a young chimpanzee more closely than it resembles L338y-6”, a juvenile boisei. Rak & Howell 1978.
• “In addition to similarities in facial remodeling it appears that Taung and Australopithecus in general, had maturation periods similar to those of the extant chimpanzee”. Bromage 1985.
• “I estimate an adult capacity for Taung ranging from 404-420 cm2, with a mean of 412 cm2. Application of Passingham’s curve for brain development in Pan is preferable to that for humans because (a) brain size of early hominids approximates that
of chimpanzees, and (b) the curves for brain volume relative to body weight are essentially parallel in pongids and australopithecines, leading Hofman to conclude that ‘as with pongids, the australopithecines probably differed only in size, not in
design’”. Falk 1987.
• In Taung, “pneumatization has also extended into the zygoma and hard palate. This is intriguing because an intrapalatal extension of the maxillary sinus has only been reported in chimpanzees and robust australopithecines among higher primates”.
Bromage & Dean 1985.
• “That the fossil ape Australopithecus [Taung] ‘is distinguished from all living apes by the... unfused nasal bones…’ as claimed by Dart (1940), cannot be maintained in view of the very considerable number of cases of separate nasal bones
among orang-utans and chimpanzees of ages corresponding to that of Australopithecus”. Schultz 1941.
_____
You're talking end point here.
NOT where Lucy came from, but where you believe she ended up.
Regardless, Lucy shares a common ancestors with modern Homo.
Even if no modern Homo descend from Lucy, Lucy descends from
a common ancestor. And her ilk remained co fertile for a very long
time -- maybe hundreds of thousands of years, maybe a million
years...
Lucy's kind were very successful. They spread, they learned to
exploit new ecological niches. The ones closest to the starting
point? The ones occupying the areas where waterside groups
pushed inland? They kept interbreeding with the waterside
group until something stopped them.
Maybe it was the retrovirus.
The Red Sea periodically opened & closed -- maybe it was during
a period where it was open, and movement between the continents
was stopped or at least drastically slowed...
So Lucy's kind began as one and same species/population as the
Waterside population. Then Lucy's kind pushed inland and spread.
And the further they got from the point of entry to that inland
world, the less their evolution was moderated by genetic influx
(from that waterside population)....
Besides, Pliocene Homo was NOT even in Africa then:
humans & orangs & Asian animals (vs Gorilla & Pan & all Afr.mammals) lack Pliocene African retroviral DNA.
That is one way of interpreting the evidence. There are other ways.
I believe you are mostly right. That, elements of the same species
that gave rise to us were in Africa back then, but that the retrovirus
wiped them out. If they remained co fertile with Lucy and/or Ardi,
they would have been absorbed into those populations, vanishing.
The think here, and you need to understand this: You model works
either way.
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