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Wednesday, June 28, 2017
Friday, June 23, 2017
Thursday, June 22, 2017
Upper/lower limb proportions across hominoids
See nice chart
http://www.pnas.org/content/
This brings out the enormous morphological changes
inherent in obligate bipedalism.
An irony to be noted is that even though bipedalism
brought about a huge relocation of muscle mass from
upper to lower limbs, the bipedal animal is far slower
on the ground than the quadrupedal ones.
It should (but it won't) provide a pause for thought
among those who believe that the transition to the
bipedal state was easy, or could have occurred
gradually. And even more so for that band who
prefer to think that gibbons were (or are) bipedal in
any significant sense, and that they were the direct
ancestors of the hominin taxon.
Note also how, in the introductory paragraph, Zihlman
and Bolter unthinkingly assume the 'savanna hypothesis'
" . . . This study presents unique quantitative data on major body components of muscle, bone, skin, and fat of 13 bonobos (Pan paniscus) for interpreting evolutionary forces that have shaped the human form for survival in a savanna mosaic environment. . . "
Thanks Paul. https://groups.google.com/forum/#!topic/sci.anthropology.paleo/0MMnDhh-8n4
http://www.pnas.org/content/
This brings out the enormous morphological changes
inherent in obligate bipedalism.
An irony to be noted is that even though bipedalism
brought about a huge relocation of muscle mass from
upper to lower limbs, the bipedal animal is far slower
on the ground than the quadrupedal ones.
It should (but it won't) provide a pause for thought
among those who believe that the transition to the
bipedal state was easy, or could have occurred
gradually. And even more so for that band who
prefer to think that gibbons were (or are) bipedal in
any significant sense, and that they were the direct
ancestors of the hominin taxon.
Note also how, in the introductory paragraph, Zihlman
and Bolter unthinkingly assume the 'savanna hypothesis'
" . . . This study presents unique quantitative data on major body components of muscle, bone, skin, and fat of 13 bonobos (Pan paniscus) for interpreting evolutionary forces that have shaped the human form for survival in a savanna mosaic environment. . . "
Thanks Paul. https://groups.google.com/forum/#!topic/sci.anthropology.paleo/0MMnDhh-8n4
New "ancestor" Aust. deyiremeda 3.5-8 ma
http://www.bbc.com/news/
The new species has been called Australopithecus deyiremeda, which means "close relative" in the language spoken by the Afar people.
The bones were found in the Afar region of Ethiopia
The remains belong to four individuals and date to between 3.3m and 3.5m years old, who would have had both ape and human-like features..
"This new species has very robust jaws. In addition, we see this new species had smaller teeth. The canine is really small - smaller than all known hominins we have documented in the past."
http://www.nature.com/nature/
The new species has been called Australopithecus deyiremeda, which means "close relative" in the language spoken by the Afar people.
The bones were found in the Afar region of Ethiopia
The remains belong to four individuals and date to between 3.3m and 3.5m years old, who would have had both ape and human-like features..
"This new species has very robust jaws. In addition, we see this new species had smaller teeth. The canine is really small - smaller than all known hominins we have documented in the past."
http://www.nature.com/nature/
Homo sapiens from Jebel Irhoud at 315 ka
New fossils from Jebel Irhoud, Morocco and the pan-African origin of
Homo sapiens.
Abstract
Fossil evidence points to an African origin of Homo sapiens from a
group called either H. heidelbergensis or H. rhodesiensis. However,
the exact place and time of emergence of H. sapiens remain obscure
because the fossil record is scarce and the chronological age of many
key specimens remains uncertain. In particular, it is unclear whether
the present day ‘modern’ morphology rapidly emerged approximately 200
thousand years ago (ka) among earlier representatives of H. sapiens or
evolved gradually over the last 400 thousand years. Here we report
newly discovered human fossils from Jebel Irhoud, Morocco, and
interpret the affinities of the hominins from this site with other
archaic and recent human groups. We identified a mosaic of features
including facial, mandibular and dental morphology that aligns the
Jebel Irhoud material with early or recent anatomically modern humans
and more primitive neurocranial and endocranial morphology. In
combination with an age of 315±34 thousand years (as determined by
thermoluminescence dating), this evidence makes Jebel Irhoud the
oldest and richest African Middle Stone Age hominin site that
documents early stages of the H. sapiens clade in which key features
of modern morphology were established. Furthermore, it shows that the
evolutionary processes behind the emergence of H. sapiens involved the
whole African continent.
http://www.nature.com/nature/
The age of the hominin fossils from Jebel Irhoud, Morocco, and the
origins of the Middle Stone Age.
Abstract
The timing and location of the emergence of our species and of
associated behavioural changes are crucial for our understanding of
human evolution. The earliest fossil attributed to a modern form of
Homo sapiens comes from eastern Africa and is approximately 195
thousand years old, therefore the emergence of modern human biology is
commonly placed at around 200 thousand years ago. The earliest Middle
Stone Age assemblages come from eastern and southern Africa but date
much earlier. Here we report the ages, determined by
thermoluminescence dating, of fire-heated flint artefacts obtained
from new excavations at the Middle Stone Age site of Jebel Irhoud,
Morocco, which are directly associated with newly discovered remains
of H. sapiens. A weighted average age places these Middle Stone Age
artefacts and fossils at 315±34 thousand years ago. Support is
obtained through the recalculated uranium series with electron spin
resonance date of 286±32 thousand years ago for a tooth from the
Irhoud 3 hominin mandible. These ages are also consistent with the
faunal and microfaunal assemblages and almost double the previous age
estimates for the lower part of the deposits. The north African site
of Jebel Irhoud contains one of the earliest directly dated Middle
Stone Age assemblages, and its associated human remains are the oldest
reported for H. sapiens. The emergence of our species and of the
Middle Stone Age appear to be close in time, and these data suggest a
larger scale, potentially pan-African, origin for both.
http://www.nature.com/nature/
Pandora
Homo sapiens.
Abstract
Fossil evidence points to an African origin of Homo sapiens from a
group called either H. heidelbergensis or H. rhodesiensis. However,
the exact place and time of emergence of H. sapiens remain obscure
because the fossil record is scarce and the chronological age of many
key specimens remains uncertain. In particular, it is unclear whether
the present day ‘modern’ morphology rapidly emerged approximately 200
thousand years ago (ka) among earlier representatives of H. sapiens or
evolved gradually over the last 400 thousand years. Here we report
newly discovered human fossils from Jebel Irhoud, Morocco, and
interpret the affinities of the hominins from this site with other
archaic and recent human groups. We identified a mosaic of features
including facial, mandibular and dental morphology that aligns the
Jebel Irhoud material with early or recent anatomically modern humans
and more primitive neurocranial and endocranial morphology. In
combination with an age of 315±34 thousand years (as determined by
thermoluminescence dating), this evidence makes Jebel Irhoud the
oldest and richest African Middle Stone Age hominin site that
documents early stages of the H. sapiens clade in which key features
of modern morphology were established. Furthermore, it shows that the
evolutionary processes behind the emergence of H. sapiens involved the
whole African continent.
http://www.nature.com/nature/
The age of the hominin fossils from Jebel Irhoud, Morocco, and the
origins of the Middle Stone Age.
Abstract
The timing and location of the emergence of our species and of
associated behavioural changes are crucial for our understanding of
human evolution. The earliest fossil attributed to a modern form of
Homo sapiens comes from eastern Africa and is approximately 195
thousand years old, therefore the emergence of modern human biology is
commonly placed at around 200 thousand years ago. The earliest Middle
Stone Age assemblages come from eastern and southern Africa but date
much earlier. Here we report the ages, determined by
thermoluminescence dating, of fire-heated flint artefacts obtained
from new excavations at the Middle Stone Age site of Jebel Irhoud,
Morocco, which are directly associated with newly discovered remains
of H. sapiens. A weighted average age places these Middle Stone Age
artefacts and fossils at 315±34 thousand years ago. Support is
obtained through the recalculated uranium series with electron spin
resonance date of 286±32 thousand years ago for a tooth from the
Irhoud 3 hominin mandible. These ages are also consistent with the
faunal and microfaunal assemblages and almost double the previous age
estimates for the lower part of the deposits. The north African site
of Jebel Irhoud contains one of the earliest directly dated Middle
Stone Age assemblages, and its associated human remains are the oldest
reported for H. sapiens. The emergence of our species and of the
Middle Stone Age appear to be close in time, and these data suggest a
larger scale, potentially pan-African, origin for both.
http://www.nature.com/nature/
Pandora
Fossils cast doubt on human lineage originating in Africa
http://www.reuters.com/
Fossils from Greece and Bulgaria of an ape-like creature that lived 7.2
million years ago may fundamentally alter the understanding of human
origins, casting doubt on the view that the evolutionary lineage that led
to people arose in Africa.
Scientists said on Monday the creature, known as Graecopithecus freybergi
and known only from a lower jawbone and an isolated tooth, may be the
oldest-known member of the human lineage that began after an evolutionary
split from the line that led to chimpanzees, our closest cousins.
The jawbone, which included teeth, was unearthed in 1944 in Athens. The
premolar was found in south-central Bulgaria in 2009. The researchers
examined them using sophisticated new techniques including CT scans and
established their age by dating the sedimentary rock in which they were
found.
They found dental root development that possessed telltale human
characteristics not seen in chimps and their ancestors, placing
Graecopithecus within the human lineage, known as hominins. Until now, the
oldest-known hominin was Sahelanthropus, which lived 6-7 million years ago
in Chad.
The scientific consensus long has been that hominins originated in Africa.
Considering the Graecopithecus fossils hail from the Balkans, the eastern
Mediterranean may have given rise to the human lineage, the researchers
said.
The findings in no way call into question that our species, Homo sapiens,
first appeared in Africa about 200,000 years ago and later migrated to
other parts of the world, the researchers said.
"Our species evolved in Africa. Our lineage may not have," said
paleoanthropologist Madelaine Böhme of Germany's University of Tübingen,
adding that the findings "may change radically our understanding of early
human/hominin origin."
Homo sapiens is only the latest in a long evolutionary hominin line that
began with overwhelmingly ape-like species, followed by a succession of
species acquiring more and more human traits over time.
University of Toronto paleoanthropologist David Begun said the possibility
that the evolutionary split occurred outside Africa is not incongruent
with later hominin species arising there.
"We know that many of the mammals of Africa did in fact originate in
Eurasia and dispersed into Africa at around the time Graecopithecus
lived," Begun said. "So why not Graecopithecus as well?"
Graecopithecus is a mysterious species because its fossils are so sparse.
It was roughly the size of a female chimp and dwelled in a relatively dry
mixed woodland-grassland environment, similar to today's African savanna,
alongside antelopes, giraffes, rhinos, elephants, hyenas and warthogs.
The findings were published in the journal PLOS ONE.
Fossils from Greece and Bulgaria of an ape-like creature that lived 7.2
million years ago may fundamentally alter the understanding of human
origins, casting doubt on the view that the evolutionary lineage that led
to people arose in Africa.
Scientists said on Monday the creature, known as Graecopithecus freybergi
and known only from a lower jawbone and an isolated tooth, may be the
oldest-known member of the human lineage that began after an evolutionary
split from the line that led to chimpanzees, our closest cousins.
The jawbone, which included teeth, was unearthed in 1944 in Athens. The
premolar was found in south-central Bulgaria in 2009. The researchers
examined them using sophisticated new techniques including CT scans and
established their age by dating the sedimentary rock in which they were
found.
They found dental root development that possessed telltale human
characteristics not seen in chimps and their ancestors, placing
Graecopithecus within the human lineage, known as hominins. Until now, the
oldest-known hominin was Sahelanthropus, which lived 6-7 million years ago
in Chad.
The scientific consensus long has been that hominins originated in Africa.
Considering the Graecopithecus fossils hail from the Balkans, the eastern
Mediterranean may have given rise to the human lineage, the researchers
said.
The findings in no way call into question that our species, Homo sapiens,
first appeared in Africa about 200,000 years ago and later migrated to
other parts of the world, the researchers said.
"Our species evolved in Africa. Our lineage may not have," said
paleoanthropologist Madelaine Böhme of Germany's University of Tübingen,
adding that the findings "may change radically our understanding of early
human/hominin origin."
Homo sapiens is only the latest in a long evolutionary hominin line that
began with overwhelmingly ape-like species, followed by a succession of
species acquiring more and more human traits over time.
University of Toronto paleoanthropologist David Begun said the possibility
that the evolutionary split occurred outside Africa is not incongruent
with later hominin species arising there.
"We know that many of the mammals of Africa did in fact originate in
Eurasia and dispersed into Africa at around the time Graecopithecus
lived," Begun said. "So why not Graecopithecus as well?"
Graecopithecus is a mysterious species because its fossils are so sparse.
It was roughly the size of a female chimp and dwelled in a relatively dry
mixed woodland-grassland environment, similar to today's African savanna,
alongside antelopes, giraffes, rhinos, elephants, hyenas and warthogs.
The findings were published in the journal PLOS ONE.
Wednesday, June 14, 2017
Sunday, June 11, 2017
Tuesday, June 6, 2017
Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees
Pliocene hominin footprints from Laetoli, Tanzania. We conducted footprint formation experiments with habitually barefoot humans and with chimpanzees to quantitatively compare their footprints to those preserved at Laetoli. Our results show that the Laetoli footprints are morphologically distinct from those of both chimpanzees and habitually barefoot modern humans. By analysing biomechanical data that were collected during the human experiments we, for the first time, directly link differences between the Laetoli and modern human footprints to specific biomechanical variables. We find that the Laetoli hominin probably used a more flexed limb posture at foot strike than modern humans when walking bipedally. The Laetoli footprints provide a clear snapshot of an early homi-nin bipedal gait that probably involved a limb posture that was slightly but significantly different from our own, and these data support the hypothesis that important evolutionary changes to hominin bipedalism occurred within the past 3.66 Myr.
Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees (PDF Download Available). Available from: https://www.researchgate.net/publication/305800105_Laetoli_footprints_reveal_bipedal_gait_biomechanics_different_from_those_of_modern_humans_and_chimpanzees [accessed Jun 6, 2017].
Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees (PDF Download Available). Available from: https://www.researchgate.net/publication/305800105_Laetoli_footprints_reveal_bipedal_gait_biomechanics_different_from_those_of_modern_humans_and_chimpanzees [accessed Jun 6, 2017].
A new Eocene archaeocete (Mammalia, Cetacea) from India and the time of origin of whales
Abstract
Himalayacetus subathuensis is a new pakicetid archaeocete from the Subathu Formation of northern India. The type dentary has a small mandibular canal indicating a lack of auditory specializations seen in more advanced cetaceans, and it has Pakicetus-like molar teeth suggesting that it fed on fish. Himalayacetus is significant because it is the oldest archaeocete known and because it was found in marine strata associated with a marine fauna. Himalayacetus extends the fossil record of whales about 3.5 million years back in geological time, to the middle part of the early Eocene [≈53.5 million years ago (Ma)]. Oxygen in the tooth-enamel phosphate has an isotopic composition intermediate between values reported for freshwater and marine archaeocetes, indicating that Himalayacetus probably spent some time in both environments. When the temporal range of Archaeoceti is calibrated radiometrically, comparison of likelihoods constrains the time of origin of Archaeoceti and hence Cetacea to about 54–55 Ma (beginning of the Eocene), whereas their divergence from extant Artiodactyla may have been as early as 64–65 Ma (beginning of the Cenozoic).
Pakicetus and contemporary archaeocetes have long been the oldest whales known as fossils (1–3). All are from red beds of the lower Kuldana Formation in Pakistan and the upper Subathu Formation in India, which are intercalated in a thicker sequence of Eocene marine sediments. All were deposited in a shallow epicontinental remnant of the Tethys Sea (Neotethys) that formerly separated the Indian subcontinent from the rest of Asia. These red beds yield essentially the same Kuldana and Kalakot freshwater fish and continental vertebrate fauna of early-middle Eocene age (4, 5). When first described, Pakicetus was interpreted as an amphibious initial stage of whale evolution that rested and reproduced on land and entered Tethys opportunistically to feed on fish (1).
We report here a new pakicetid archaeocete from marine strata of the middle Subathu Formation of India. The new pakicetid was found about 100 m lower stratigraphically and 3.5 million years older geologically than the Kuldana–Kalakot-equivalent upper Subathu red bed interval producing Pakicetus elsewhere. This not only extends the fossil record of Cetacea back in time, but also reinforces the idea that whales originated on the margin of Tethys and corroborates interpretation of pakicetids as an initial amphibious stage of cetacean evolution entering Tethys to feed on fish.
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