East-African apiths ate papyrus sedges ?
Isotopic evidence for an early shift to C4 resources by Pliocene hominins
Julia Lee-Thorp, Andossa Likius, Hassane Mackaye, Patrick Vignaud, Matt
Sponheimer & Michel Brunet 2012
PNAS doi 10.1073/pnas.1204209109
Foods derived from C4 plants were important in the dietary ecology of
early Pleistocene hominins in S- & E-Africa, but the origins & geographic
variability of this relationship remain unknown.
Carbon isotope data show that Au.bahrelghazali are >3 Ma, the results
extend the pattern of C4 dependence seen in Par.boisei in E.Africa by >1.5
The Koro Toro hominin fossils were found in argillaceous sandstone levels,
along with abundant grazing & aquatic faunal elements that, in
combination, indicate the presence of open to wooded grasslands & stream
channels associated with a greatly enlarged Lake Chad.
In such an environment, the most abundant C4 plant resources available to
Au.bahrelghazali were grasses & sedges, neither of which is usually
considered as standard great ape fare.
The results suggest an early & fundamental shift in hominin dietary
ecology that facilitated the exploitation of new habitats.
(Argillaceous minerals may appear silvery upon optical reflection, they
contain substantial amounts of clay-like components. Greek ἄργιλλος =
Argillaceous components are fine-grained (<2 µm) alumino-silicates, and
more particularly clay minerals such as kaolinite,
montmorillonite-smectite, illite & chlorite.
Claystone & shales are thus predom.argillaceous.
The adjective "argillaceous" is also used to define rocks in which clay
minerals are a secondary but significant component, eg, argillaceous
limestones are limestones consisting predom.of calcium carbonate, but
including 10-40 % of clay minerals: such limestones, when soft, are often
Argillaceous sandstones are sandstones consisting primarily of quartz
grains, with the interstitial spaces filled with clay minerals.)
AFAIK lowland gorillas are among the few primates that do eat sedges
Grasses are unlikely (different enamel microwear) but aquatic vegetation
(incl.sedges?) can explain the glossy polishing of afarensis etc enamel
(cf papers of P-F.Puech).
Lee-Thorp cs's findings once more corroborate my view (Hum.Evol.papers)
that most or all East-African apiths might be closer relatives of Gorilla
than of Homo or Pan, and that they lived in wetlands, bais, reedbeds,
lagoons (eg, Chesowanja) & papyrus swamps (eg, Olduvai), where they partly
fed on floating vegetation (cf AHV aquatic herbaceous vegetation in
lowland gorilla diet).
From Marc Verhaegen & Pierre-François Puech 2000
Human Evolution 15: 151-162
"Hominid Lifestyle and Diet Reconsidered:
Paleo-Environmental and Comparative Data"
Lukeino KNM-LU 335
“pre-australopithecine”: ‘The red beds seems to contain marginal
lacustrine deposits as indicated by the presence of algal mats and
lacustrine bivalves (including complete specimens with valves in the
closed position)’ (Pickford 1975).
Tabarin KNM-TH 13150
“pre-australopithecine”: ‘The fauna includes aquatic animals such as
molluscs, fish, turtles, crocodiles, and hippotami, along with others that
might be found in the vicinity of a lake of river’ (Ward & Hill 1987).
Kanapoi KNM-KP 29281 Au.anamensis: Fish, aquatic reptiles, kudus and
monkeys are prevalent. ‘A wide gallery forest would have almost certainly
been present on the large river that brought in the sediments’ (Leakey cs
Chad KT 12 A.cf.afarensis: ‘The
non-hominid fauna contains aquatic taxa (such as Siluridae, Trionyx, cf.
Tomistoma), taxa adapted to wooded habitats (such as Loxodonta, Kobus,
Kolpochoerus) and to more open areas (such as Ceratotherium, Hipparion)
[…] compatible with a lakeside environment’ (Brunet cs 1995).
Hadar, Afar Locality:
‘Generally, the sediments represent lacustrine, lake margin, and
associated fluvial deposits related to an extensive lake that periodically
filled the entire basin’ (Johanson cs 1982)
Hadar AL.333 A.afarensis: ‘The bones were found in swale-like features […]
it is very likely that they died and partially rotted at or very near this
site […] this group of hominids was buried in streamside gallery woodland’
(Radosevich cs 1992).
Hadar AL.288 gracile A.afarensis: Lucy lay in a small, slow moving stream.
‘Fossil preservation at this locality is excellent, remains of delicate
items such as crocodile and turtle eggs and crab claws being found’
(Johanson & Taieb 1976).of large perennial river and alluvial fan
deposits, amid water- and reedbucks (Walker cs 1986).
Lake Turkana: ‘The lake margins were generally swampy, with extensive
areas of mudflats […] Au.boisei was more abundant in fluvial environments,
whereas Homo habilis was rare in such environments […] Australopithecus
fossils are more common than Homo both in channel and floodplain deposits.
The gracile hominids […] seem to be more restricted ecologically to the
lake margin than are the robust forms’ (Conroy 1990).
Ileret A.boisei: ‘the fossil sample reflects climatic and ecological
environmental conditions differing significantly from those of the present
day. At Ileret, 1.5 Myr ago, climatic conditions must have been cooler and
more humid than today, and more favourable to extensive forests […] The
prominence of montane forest is particularly striking […] dominated by
Gramineae and Chenopodiaceae appropriate to the margins of a slightly
saline or alkaline lake’ (Bonnefille 1976).
Konso A.boisei: ‘The highly fossiliferous sands at the mid-section of
KGA10 are interpreted to be the middle to distal portions of an alluvial
fan, deposited adjacent to, and extending into, a lake. Fossils and
artefacts deriving from horizons of sands and silts are not abraded and
show evidence of minimal transport. A large mammalian assemblage has been
collected from the deposits, showing a striking dominance of Alcelaphini
[…] to indicate the presence of extensive dry grasslands at KGA10’ (Suwa
Chesowanja A.boisei: ‘The fossiliferous sediments were deposited in a
lagoon […] Abundant root casts […] suggest that the embayment was flanked
by reeds and the presence of calcareous algae indicates that the lagoon
was warm and shallow. Bellamya and catfish are animals tolerant of
relatively stagnant water, and such situation would also be suitable for
turtles and crocodiles’ (Carney cs 1971).
Olduvai middle Bed I: A.boisei OH.5 as well as habilis OH.7 and OH.62 were
found in the most densely vegetated, wettest condition, with the highest
lake levels (Walter cs 1991), near ostracods, freshwater snails, fish, and
aquatic birds (Conroy, 1990); ‘[…] the middle Bed-I faunas indicate a very
rich closed woodland environment, richer than any part of the present-day
savanna biome in Africa […]’ (Fernández-Jalvo cs 1998). ‘Fossilized leaves
and pollen are rare in the sediments of Beds I and II, but swamp
vegetation is indicated by abundant vertical roots channels and casts
possibly made by some kind of reed.
Fossil rhizomes of papyrus also suggest the presence of marshland and/or
shallow water’ (Conroy 1990). ‘[…] Cyperaceae fruits were common in H.
habilis habitat (Bonnefille 1984). Ancient Egyptians ate Cyperus papyrus
root which was also present at Olduvai in swamp-margins and river banks’
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