littor...@gmail.com wrote:
Stable isotope-based diet reconstructions of Turkana Basin hominins
Thure E Cerling cs 2013 doi org/10.1073/pnas.1222568110
Hominin fossil evidence in the Turkana Basin in Kenya from c 4.1 to 1.4 Ma samples 2 archaic early hominin genera, and records some of the early evolutionary history of Paranthropus & Homo.
Stable C isotopes in fossil tooth enamel are used to estimate the fraction of diet derived from C3 or C4 resources in these hominin taxa.
- The earliest hominin species in the Turkana Basin, Au.anamensis, derived nearly all of its diet from C3 resources.
- By c 3.3 Ma, the later Kenyanthr.platyops had a very wide dietary range—from virtually a purely C3 resource-based diet to one dominated by C4 resources.
- By c 2 Ma, hominins in the Turkana Basin had split into 2 distinct groups: -- spms attributable to the genus Homo provide evidence for a diet with a c 65/35 ratio of C3- to C4-based resources,
-- Par. boisei had a higher fraction of C4-based diet (c 25/75 ratio).
Homo sp. increased the fraction of C4-based resources in the diet through c 1.5 Ma,
P. boisei maintained its high dependency on C4-derived resources.
Isotopic evidence shows their diet was primarily C4 with rel.high δ13C values: “An apparent C4-based diet is one based on aquatic resources in which algae have elevated δ13C values because of bicarbonate uptake during photosynthesis; for this
example, algae or fish then have δ13C values with an apparent C4 component.”
IOW, only incredible imbeciles believe their ancestors ran after antelopes.
The link
https://www.pnas.org/doi/10.1073/pnas.1222568110
Stable isotope-based diet reconstructions of Turkana Basin hominins
Junbe 3, 2013
The REAL abstract:
Abstract
Hominin fossil evidence in the Turkana Basin in Kenya from ca. 4.1 to 1.4 Ma samples two archaic early hominin genera and records some of the early evolutionary history of Paranthropus and Homo. Stable carbon isotopes in
fossil tooth enamel are used to estimate the fraction of diet derived from C3 or C4 resources in these hominin taxa. The earliest hominin species in the Turkana Basin, Australopithecus anamensis, derived nearly all of its diet
from
C3 resources. Subsequently, by ca. 3.3 Ma, the later Kenyanthropus platyops
had a very wide dietary range—from virtually a purely C3 resource-based diet to one dominated by C4 resources. By ca. 2 Ma, hominins in the Turkana Basin had split into two distinct groups: specimens attributable to the genus Homo provide evidence for a diet with a ca. 65/35 ratio of C3- to C4-based resources,
whereas P. boisei had a higher fraction of C4-based diet (ca. 25/75 ratio). Homo sp. increased the fraction of C4-based resources in the diet through
ca. 1.5 Ma, whereas P. boisei maintained its high dependency on C4-derived resources.
"We use the terms C3- and C4-based resources throughout our discussion,
because our isotopic method cannot distinguish between a plant-based diet, a meat-based diet, and an omnivorous diet. Thus, based on isotopes alone, we consider that the diets of the early hominins that we have investigated could be primarily herbaceous (C3 and C4 plants), or they could be a secondary C3-
or C4-based diet, an apparent C3- or C4-based diet, or an omnivorous diet. A secondary C3- or C4-based diet could be a meat- or insect-based diet (in
which
the δ13C values are derived from the basal herbaceous diet of the prey). An apparent C4-based diet is one based on aquatic resources in which algae have elevated δ13C values because of bicarbonate uptake during photosynthesis
(40);
for this example, algae or fish then have δ13C values with an apparent C4 component (41, 42). Lastly, an omnivorous diet is a combination of the above resources: primary herbaceous diet along with secondary C3- or C4-derived components (i.e., meat or insects) or apparent components (i.e., aquatic).
"The stable carbon isotope signature of a meat-based diet depends on the
nature
of the prey: small bovid herbivores less than ca. 10 kg (e.g., dik-dik and other
neotragines) tend to be browsers and have C3-based diets (14, 32), whereas large
herbivores can have diets that are C3-based (browsers such as most tragelephines,
black rhinos, and giraffes), C4-based (grazers such as warthogs, zebra, alcelaphines,
reducines, and bovines), or mixed (e.g., impala, and some gazelles). Thus,
the size
of prey may be important in considering possible secondary diet C3 or C4 resources.
Other small mammals (e.g., hyrax, lagomorphs, or rodents) could have been an important dietary resource and would contribute to isotope mixing lines
between
C3- and C4-based end member values."
See also
http://www.pnas.org/content/early/2013/05/31/1222559110
Diet of Australopithecus afarensis from the Pliocene Hadar Formation,
Ethiopia.
Abstract:
The enhanced dietary flexibility of early hominins to include
consumption of C4/crassulacean acid metabolism (CAM) foods (i.e.,
foods derived from grasses, sedges, and succulents common in tropical
savannas and deserts) likely represents a significant ecological and
behavioral distinction from both extant great apes and the last common
ancestor that we shared with great apes. Here, we use stable carbon
isotopic data from 20 samples of Australopithecus afarensis from Hadar
and Dikika, Ethiopia (>3.4�2.9 Ma) to show that this species consumed
a diet with significant C4/CAM foods, differing from its putative
ancestor Au. anamensis. Furthermore, there is no temporal trend in the
amount of C4/CAM food consumption over the age of the samples
analyzed, and the amount of C4/CAM food intake was highly variable,
even within a single narrow stratigraphic interval. As such, Au.
afarensis was a key participant in the C4/CAM dietary expansion by
early australopiths of the middle Pliocene. The middle Pliocene
expansion of the eastern African australopith diet to include
savanna-based foods represents a shift to use of plant food resources
that were already abundant in hominin environments for at least 1
million y and sets the stage for dietary differentiation and niche specialization by subsequent hominin taxa.
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