Författare Ämne: Intelligent Homo erectus?  (läst 175445 gånger)

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« Svar #180 skrivet: november 01, 2011, 20:47 »
"Raser" inom H. erectus? Skiljd evolutionär linje?

Craniofacial morphology of Homo floresiensis: Description, taxonomic affinities, and evolutionary implication

This paper describes in detail the external morphology of LB1/1, the nearly complete and only known cranium of Homo floresiensis. Comparisons were made with a large sample of early groups of the genus Homo to assess primitive, derived, and unique craniofacial traits of LB1 and discuss its evolution. Principal cranial shape differences between H. floresiensis and Homo sapiens are also explored metrically.

The LB1 specimen exhibits a marked reductive trend in its facial skeleton, which is comparable to the H. sapiens condition and is probably associated with reduced masticatory stresses. However, LB1 is craniometrically different from H. sapiens showing an extremely small overall cranial size, and the combination of a primitive low and anteriorly narrow vault shape, a relatively prognathic face, a rounded oval foramen that is greatly separated anteriorly from the carotid canal/jugular foramen, and a unique, tall orbital shape. Whereas the neurocranium of LB1 is as small as that of some Homo habilis specimens, it exhibits laterally expanded parietals, a weak suprameatal crest, a moderately flexed occipital, a marked facial reduction, and many other derived features that characterize post-habilis Homo. Other craniofacial characteristics of LB1 include, for example, a relatively narrow frontal squama with flattened right and left sides, a marked frontal keel, posteriorly divergent temporal lines, a posteriorly flexed anteromedial corner of the mandibular fossa, a bulbous lateral end of the supraorbital torus, and a forward protruding maxillary body with a distinct infraorbital sulcus. LB1 is most similar to early Javanese Homo erectus from Sangiran and Trinil in these and other aspects. We conclude that the craniofacial morphology of LB1 is consistent with the hypothesis that H. floresiensis evolved from early Javanese H. erectus with dramatic island dwarfism. However, further field discoveries of early hominin skeletal remains from Flores and detailed analyses of the finds are needed to understand the evolutionary history of this endemic hominin
species.


http://www.sciencedirect.com/science/article/pii/S0047248411001941

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« Svar #181 skrivet: november 01, 2011, 22:48 »
Kan 'moderna människor' helt enkelt vara 'arkaiska kaukasoider' som levt i norra Eurasien under paleolitikum, varifrån små grupper utvandrat när klimatet gjort det möjligt att vandra genom centrla Eurasien - som t.ex. under Eem-perioden?

Det äldsta 'moderna' skelett från Kina råkar också vara 110.000 år gammalt:
http://www.youtube.com/watch?v=LpsKbyyI7iE&feature=relmfu 
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Intelligent Homo erectus.
« Svar #182 skrivet: februari 07, 2012, 23:44 »
Chris Stringer har undertiden blivit skeptisk till den konforma "Ut-ur-Afrika-teorin".

http://edge.org/conversation/rethinking-out-of-africa

Dags för ännu en ny vända.
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« Svar #183 skrivet: mars 12, 2012, 08:10 »
Stenyxor från erectus-människor:

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Hand axes unearthed in Kenya are oldest advanced stone tools ever found

Researchers dated the sediments where the tools were found to 1.76m years old. Until now, the earliest stone tools of this kind were estimated to be 1.4m years old and came from a haul in Konso, Ethiopia. Others found in India are dated more vaguely, between 1m and 1.5m years old.

Older, cruder stone tools have been found. The most ancient evidence of toolmaking by early humans and their relatives dates to 2.6m years ago and includes simple pebble-choppers for hacking and crushing. These Oldowan tools, named after the Olduvai gorge in Tanzania, were wielded by our predecessors for around a million years.

But the latest collection of stone tools from Kenya belong to a second, more advanced generation of toolmaking. Known as Acheulian tools after a prominent archaeological site in France, they are larger, heavier and have sharp cutting edges that are chipped from opposite sides into the familiar teardrop shape.

Most Acheulian stone tools have been recovered from sites alongside fossilised bones of Homo erectus, leading many archaeologists to believe our ancestors developed the technology as an improvement on the Oldowan toolmaking skills they inherited.


http://www.guardian.co.uk/science/2011/aug/31/hand-axes-oldest-advanced-stone-tools?INTCMP=ILCNETTXT3487
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« Svar #184 skrivet: mars 15, 2012, 00:25 »
Nya erectus-människa hittat i Kina?

I Guangxi- respektive Yunnan-provinsen har man hittat två likartade skelett från arkaiska människor - som inte är mer än 11.500-14.000 år gamla. Nu undrar man på om att erectus-ättlingarna; cro-magnon, neander, denisovan och flores - inte haft ett eget gäng kusiner till - i Kina...

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Our analysis suggests two plausible explanations for the morphology sampled at Longlin Cave and Maludong. First, it may represent a late-surviving archaic population, perhaps paralleling the situation seen in North Africa as indicated by remains from Dar-es-Soltane and Temara, and maybe also in southern China at Zhirendong. Alternatively, East Asia may have been colonised during multiple waves during the Pleistocene, with the Longlin-Maludong morphology possibly reflecting deep population substructure in Africa prior to modern humans dispersing into Eurasia. 

http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031918?__utma=240918044.1160836565.1325370711.1331334024.13317


http://news.nationalgeographic.com/news/2012/03/120314-new-human-species-chinese-plos-science-red-deer-cave/
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« Svar #185 skrivet: mars 17, 2012, 23:18 »
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Researchers are divided over whether the skulls, which date back more than 11,000 years, could constitute a completely new species of human.


http://www.bbc.co.uk/news/science-environment-17378498
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« Svar #186 skrivet: mars 18, 2012, 10:38 »
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New fossils provide more questions than answers

The origin of the human species remains one of the most fascinating and difficult topics of modern science. One of the main reasons for this is a continuing lack of agreement about how we should define ourselves. In other words, what is it that makes us human or, scientifically, Homo sapiens?

The father of biological classification, 18th century Swede Carl Linnaeus, wrote in his Systema Naturae the words “nosce te ipsum”, or “know thy self”: a statement at once prescient and frustratingly uninformative.

Defining Human

More annoying, the issue of how we define “human” seems to get more complicated the more fossils we unearth.
A new study published today by a team of Australian and Chinese scientists – led by my colleague Ji Xueping and I – opens a new chapter in the story of human evolution in East Asia.


http://www.pasthorizonspr.com/index.php/archives/03/2012/defining-human-new-fossils-provide-more-questions-than-answers
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« Svar #187 skrivet: mars 18, 2012, 12:39 »
Jag har inte hunnit sätta mig i de nya fynden än, men jag tycker man är alldeles för generös när det kommer till artklassifikation av utdöda "arter" (där var jag allt rolig!).

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« Svar #188 skrivet: mars 28, 2012, 22:20 »
Nu har det dykt upp ännu en hominid - från Afar-regionen - jämngammal med Lucy...

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Surprising 2nd hominin lineage

He said the new discovery shows hominin evolution didn't follow a single lineage, contrary to what many scientists previously thought.

Like A. afarensis, the new species has characteristic features in two of its joints adapted to walking on two legs – features unique to hominins and not found in apes or monkeys.


http://www.cbc.ca/news/technology/story/2012/03/28/science-new-hominin-ethiopia.html
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« Svar #189 skrivet: mars 28, 2012, 22:54 »
Gorillans genom är nu kartlagd och det visar sej att gorillor och människor har några gener gemensamt - som inte finns hos schimpanserna...

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DNA Mutations Show Great Ape Splits

"Although [70 percent] of the human genome is indeed closer to chimpanzees, on average, a sizable minority of 15 percent is in fact closer to gorillas, and another 15 percent is where chimpanzees and gorillas are closest," said geneticist Aylwyn Scally, a study co-author also at the Wellcome Trust.

Primatologists know from fossils that humans, chimps, and gorillas shared an ancient ancestor. Tracing exactly when these lineages diverged, however, is tricky.

According to the new genetic research—when combined with known fossils—the lineage that led to humans, chimps, and gorillas evolved from a common ancestor about 10 million years ago.

Humans and chimps then popped off of that lineage some 6 million years ago, according to the new study.

Gorilla DNA Shows Surprises

Another surprising result is that part of the gorilla genome is at odds with the current structure of the great ape evolutionary tree.

For example, instead of gorillas being most similar to chimps and then humans in that portion of the DNA, the branches flip to humans being most similar to gorillas and then chimps.

"This doesn't change the overall view of evolution, and the overall tree is still the same. What this does show is that each branch has it own complexities and challenges," said Richard Gibbs, a geneticist at Baylor College of Medicine's Human Genome Sequencing Center, who wasn't involved in the study.

"It means within each branch things can happen. We can't just conform to a simple tree on a gene-by-gene basis."
The gene discoveries also offer new riddles in primate—and human—evolution.

"The big picture is that we're perhaps 98 percent identical in our sequences to gorillas. So that means most of our genes are very similar, or even identical to, the gorilla version of the same gene," said Chris Tyler-Smith, a geneticist at Wellcome Trust.

"But it's the few that differ that are of particular interest here."


Annars har man upptäckt andra märkvärdigheter också...

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Genetic Differences Revealed

One difference the researchers discovered is a gorilla gene that probably helps the animal's skin grow a tough layer of keratin—a protein that makes up fingernails—on their knuckles, which aids in the animal's distinctive knuckle walk. Humans seem to lack this genetic variant.

Another is in sperm genes—in humans, a specific gene enables sperm to compete with those of other males. In gorillas, those genes are inactive or scaled back.

"Gorillas live in groups with one male and lots of females, so there's not much opportunity for sperm competition," said Tyler-Smith, another co-author of the study, which appears this week in the journal Nature.

Some genes tied to dementia and heart failure in humans appeared roughly the same in both humans and gorillas, but are not harmful to gorillas.

http://news.nationalgeographic.com/news/2012/03/120306-gorilla-genome-apes-humans-evolution-science/




För övrigt har man redan en diskussion om orangutangen är vår allra närmaste släkting bland nutida apor:
http://news.nationalgeographic.com/news/2009/06/090623-humans-chimps-related.html
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« Svar #190 skrivet: mars 28, 2012, 23:19 »
Studie av delfiner har hittat en ny modell för sociala strukturer och könsroller bland högre primater:

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Model search

Past attempts to find an appropriate model from the animal kingdom to describe the social structure of male dolphins have failed, says Sherwin.

In the most recent attempt, he and colleagues checked two different previously untested models to see if they applied to dolphins.

One model, taken from the social structure of chimps, involves a small number of male gangs defending the boundaries of the community. These gangs cover the territory of all other individuals.

The other model is one where gangs defend small groups of females during the mating season, by covering a smaller territory.

Dolphin tracking

In one of the most extensive studies of its kind, the researchers tracked the movements of dolphin gangs in Western Australia's Shark Bay.

They followed the movements of hundred of dolphins, all of which had been tagged and given names, such as 'Captain Hook' and 'Flat Fin' based on the shape of their fins.

But much to their disappointment, Sherwin and colleagues found no evidence to support the "community defence" or the "mating season defence" models.

It appears that dolphins have an open social network with fluid boundaries as well as a complex hierarchy of groups, says Sherwin.

"You can't just draw a bound a boundary around the edge and say this is where everyone interacts and outside that they don't interact very much," he says.

Sherwin says humans are the only other creatures that have the same kind of social structure.

They interact most often within families and less often within communities and nations but there is free flow between different groupings.


http://www.abc.net.au/science/articles/2012/03/28/3464065.htm?topic=enviro

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A novel mammalian social structure in Indo-Pacific bottlenose dolphins (Tursiops sp.): complex male alliances in an open social network;

Terrestrial mammals with differentiated social relationships live in ‘semi-closed groups’ that occasionally accept new members emigrating from other groups. Bottlenose dolphins (Tursiops sp.) in Shark Bay, Western Australia, exhibit a fission–fusion grouping pattern with strongly differentiated relationships, including nested male alliances. Previous studies failed to detect a group membership ‘boundary’, suggesting that the dolphins live in an open social network.

The Shark Bay dolphins, therefore, present a combination of traits that is unique among mammals: complex male alliances in an open social network. The open social network of dolphins is linked to their relatively low costs of locomotion. This reveals a surprising and previously unrecognized convergence between adaptations reducing travel costs and complex intergroup–alliance relationships in dolphins, elephants and humans.


http://rspb.royalsocietypublishing.org/content/early/2012/03/20/rspb.2012.0264.abstract
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« Svar #191 skrivet: juni 28, 2012, 21:12 »
"Raser" inom H. erectus? Skiljd evolutionär linje?

Craniofacial morphology of Homo floresiensis: Description, taxonomic affinities, and evolutionary implication

The LB1 specimen exhibits a marked reductive trend in its facial skeleton, which is comparable to the H. sapiens condition and is probably associated with reduced masticatory stresses. However, LB1 is craniometrically different from H. sapiens showing an extremely small overall cranial size, and the combination of a primitive low and anteriorly narrow vault shape, a relatively prognathic face, a rounded oval foramen that is greatly separated anteriorly from the carotid canal/jugular foramen, and a unique, tall orbital shape. Whereas the neurocranium of LB1 is as small as that of some Homo habilis specimens, it exhibits laterally expanded parietals, a weak suprameatal crest, a moderately flexed occipital, a marked facial reduction, and many other derived features that characterize post-habilis Homo. Other craniofacial characteristics of LB1 include, for example, a relatively narrow frontal squama with flattened right and left sides, a marked frontal keel, posteriorly divergent temporal lines, a posteriorly flexed anteromedial corner of the mandibular fossa, a bulbous lateral end of the supraorbital torus, and a forward protruding maxillary body with a distinct infraorbital sulcus. LB1 is most similar to early Javanese Homo erectus from Sangiran and Trinil in these and other aspects. We conclude that the craniofacial morphology of LB1 is consistent with the hypothesis that H. floresiensis evolved from early Javanese H. erectus with dramatic island dwarfism. However, further field discoveries of early hominin skeletal remains from Flores and detailed analyses of the finds are needed to understand the evolutionary history of this endemic hominin
species.


http://www.sciencedirect.com/science/article/pii/S0047248411001941

I N-Europa fryser man - sen 2. världskriget - på ryggen så fort man nämner 'skallmätning' som verktyg inom biologi och etnologi. Märkligt nog fortsatte denna forskning i USA, utan att häftas av politisk stigmatisering - under namn som "Fysisk Antropologi" och "Kraniometri".   

Genom dom senare decenniers forskning på 'arkaiska' människotyper har "kraniometri" återkommit för fullt - och den används numer som referens till genetiska studier.

Det var därför mycket upplysande att läsa vad amerikanska antropologer och palentologer tagit reda på gällande vårt teoretiska ursprung som art och underarter. Märkligt nog håller fältets stora auktoritet, Charleton S. Coon, med om denna tråds huvudanliggande - genom att påstå att dom olika underarter (raser) av Homo Sapiens har ett gemensamt ursrpung - som Homo Erectus...  :P

Coon's vetenskapliga testamente - "The Origin of Races" (1962) - beskriver faktisk en evolution som grundas på vårt homo-erectus-nivå - och en historisk modell som ligger näst intill den "multi-regionala tesen" - där diversiteten bland världens människotyper förklaras med en historik utveckling sedan erectus-stadiet.  8)

http://en.wikipedia.org/wiki/Carleton_S._Coon
http://en.wikipedia.org/wiki/Multi-regional_origin
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Ny människotyp upptäckt
« Svar #192 skrivet: augusti 08, 2012, 22:47 »
En ny typ av arkaiska människor - drygt 1,5 mill. år gamla, är upptäckt i Afrika. Det innebär att minst TRE olika människotyper har levt samtidigt å den afrikanska kontinenten under tiden i fråga.

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Fossils from Northern Kenya show that a new species of human lived two million years ago, researchers say.

The discoveries suggests that at least three distinct species of humans co-existed in Africa.

The research adds to a growing body of evidence that runs counter to the popular perception that there was a linear evolution from monkey to ape to modern human.

The research has been published in the journal Nature.


http://www.bbc.co.uk/news/science-environment-19184370
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« Svar #193 skrivet: augusti 09, 2012, 16:49 »
Även tidliga hominider var påtagligt hemkära.

Nu kan modern teknologi bidra till en ganska så fantastisk insikt i våra tidiga förfäders levnadssätt. En laser-studie av tänder från Afrikas tidiga homnider kan bl.a. berätta om deras diet, samt att också Afrikas arkaiska  människor alla varit bundna vid sin hemort, livet ut:

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Apart from the dietary differences, the new results indicate that the home-range area was of similar size for species of the three hominin genera.

The scientists have also measured the strontium isotope composition of dental enamel. Strontium isotope compositions are free of dietary effects but are characteristic of the geological substrate on which the animals lived.

According to the results all the hominids lived in the same general area, not far from the caves where their bones and teeth are found today.


http://www.heritagedaily.com/2012/08/early-human-ancestors-had-more-variable-diet/
 
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3,4 millioner år gamla stenredskap.
« Svar #194 skrivet: september 15, 2012, 00:55 »
Det verkar som om Homo erectus tillverkade handkilar något tidigare än man hittills trott.
 
http://www.sciencedaily.com/releases/2011/08/110831205942.htm

Nu påstår man ha säkra bevis för att arkaiska människor använde redskap för att slakta arkaiska getter och kor - redan för 3,4 millioner år sen.

Om rapporterna från UCLA håller vatten är väl grundfrågan i tråden rett tydligt besvarad. I så fall var inte bara Homo erectus utrustade med rationalitet och kreativ intelligens, män även deras förfäder...  :o

Fynden från Dikika i Etiopien innebär i så fall att man får göra "en allvarlig re-värdering" av "den intelligenta människans" ålder - och historia.

http://www.youtube.com/watch?v=V2YMfzhm8ao&feature=share
http://news.discovery.com/history/early-human-tool-use.html

 

   
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« Svar #195 skrivet: september 16, 2012, 08:04 »
Det beror litet på vad man menar med intelligens. Våra förfäder jagade säkert långt före den här tidpunkten.

http://www-bcf.usc.edu/~stanford/chimphunt.html

De här fynden flyttar däremot tilbaka den tidpunkt då man började använda stenverktyg för att stycka köttet och för att komma åt benmärgen (troligen oftast då stora djur som urprungligen dödats av andra predatorer).

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« Svar #196 skrivet: oktober 06, 2012, 12:06 »
Man kan ju fråga sig om de ett till fyra procent av vårt DNA som är gemensamt med neandertalaren härrör sig från korsning mellan arterna eller om det är äldre DNA som på något sätt hängt med från en gemensam anfader?

http://news.nationalgeographic.com/news/2010/05/100506-science-neanderthals-humans-mated-interbred-dna-gene/

Nu är frågan troligen avklarad:

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Dr. Sriram Sankararaman and colleagues measured the length of DNA pieces in the genomes of Europeans that are similar to Neanderthals. Since recombination between chromosomes when egg and sperm cells are formed reduces the size of such pieces in each succeeding generation, the Neanderthal-related pieces will be smaller the longer they have spent in the genomes of present-day people. In this way, they function as a "genetic clock".

The team estimate that Neanderthals and modern humans last exchanged genes between 37,000 and 86,000 years ago, well after modern humans appeared outside Africa but potentially before they started spreading across Eurasia. This suggests that Neanderthals (or their close relatives) had children with the direct ancestors of present-day people outside Africa.


http://popular-archaeology.com/issue/september-2012/article/scientists-estimate-date-when-neanderthals-and-modern-hu
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« Svar #197 skrivet: oktober 07, 2012, 21:17 »
Nu är det ju så att man främst identifierar "neandertalgener" som sådana gener som fanns hos neandertalarna och som finns i moderna populationer i Eurasien, men saknas i Afrika.

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« Svar #198 skrivet: oktober 07, 2012, 22:39 »
Utgångspunkten är väl ändock gener från tandrötterna av fastställda neandertaler?

Att man sen inte hittar samma gen i Afrika är i grund och botten en något annan skiva. Poängen är väl att man här ville utreda hur vida våra europeiska neander-gener var en relikt från vårt gemensamma ursprung - eller om det var ett resultat av en senare korsning. Vilket man nu anser bevisad, eller hur? 

http://www.sciencedaily.com/releases/2012/10/121004201046.htm
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« Svar #199 skrivet: oktober 10, 2012, 10:22 »
Ny studie beskriver "flera emmigrationer" och "mulitregional påverknad" i utvecklingen av nutidens olika populationer:

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The dispersal of Homo sapiens across southern Asia: how early, how often, how complex?

...we cannot exclude the possibility that several dispersal events occurred, from both North and East Africa, nor the likelihood that early populations of H. sapiens in southern Asia interbred with indigenous populations of Neanderthals, Denisovans and Homo erectus. The population history of southern Asia during the Upper Pleistocene is likely far more complex than currently envisaged.

► Homo sapiens likely exited Africa from 125 ka onwards rather than after 60 ka.
► H. sapiens dispersals from Africa likely from several donor populations.
► H. sapiens likely entered Asia several times and from several entry points.
► Inter-breeding likely between H. sapiens, Neanderthals and Denisovans.


http://www.sciencedirect.com/science/article/pii/S0277379112001758
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