Author Topic: Homo sapiens and Their Cousins  (Read 9485 times)

Recusant

  • Miscreant Erendrake
  • Administrator
  • Wears a Colander Hat for Special Occasions
  • *****
  • Posts: 6159
  • Gender: Male
  • infidel barbarian
Re: Homo sapiens and Their Cousins
« Reply #60 on: November 27, 2018, 07:39:12 PM »
I've personally never thought that the 'just the once' hypothesis (in which anatomically modern humans only interbred with Neanderthal on a single occasion) made any sense.

"Study suggests multiple instances of inter-breeding between Neanderthal and early humans" | PhysOrg

Quote
A pair of researchers at Temple University has found evidence that suggests Neanderthals mated and produced offspring with anatomically modern humans multiple times—not just once, as has been suggested by prior research. In their paper published in the journal Nature Ecology and Evolution, Fernando Villanea and Joshua Schraiber describe their genetic analysis of East Asian and European people and how they compared to people from other places. Fabrizio Mafessoni with the Max Planck Institute for Evolutionary Anthropology offers a News and Views piece on the work done by the pair in the same journal issue.

In recent years, scientists have discovered that early humans moving out of Africa encountered Neanderthals living in parts of what is now Europe and Eastern Asia. In comparing Neanderthal DNA with modern humans, researchers have found that there was a least one pairing that led to offspring, which is reflected in the DNA of humans—approximately 2 percent of the DNA in non-African humans today is Neanderthal. In this new effort, the researchers have found evidence that suggests there was more than one such encounter.

[Continues . . .]

A full pre-print version of the paper is available: "Spectrum of Neandertal introgression across modern-day humans indicates multiple episodes of human-Neandertal interbreeding" | BioRxiv

Quote
Abstract:

Neandertals and anatomically modern humans overlapped geographically for a period of over 30,000 years following human migration out of Africa. During this period, Neandertals and humans interbred, as evidenced by Neandertal portions of the genome carried by non-African individuals today. A key observation is that the proportion of Neandertal ancestry is ∼12-20% higher in East Asian individuals relative to European individuals.

Here, we explore various demographic models that could explain this observation. These include distinguishing between a single admixture event and multiple Neandertal contributions to either population, and the hypothesis that reduced Neandertal ancestry in modern Europeans resulted from more recent admixture with a ghost population that lacked a Neandertal ancestry component (the “dilution” hypothesis). In order to summarize the asymmetric pattern of Neandertal allele frequencies, we compile the joint fragment frequency spectrum (FFS) of European and East Asian Neandertal fragments and compare it to both analytical theory and data simulated under various models of admixture.

Using maximum likelihood and machine learning, we found that a simple model of a single admixture does not fit the empirical data, and instead favor a model of multiple episodes of gene flow into both European and East Asian populations. These findings indicate more long-term, complex interaction between humans and Neandertals than previously appreciated.
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Icarus

  • The wise one.
  • Guardian of Reason
  • *****
  • Posts: 5598
Re: Homo sapiens and Their Cousins
« Reply #61 on: November 27, 2018, 11:10:26 PM »
That interbreeding may have occurred is not the least surprising. Not improbable either.  Sex drives are powerful enough to cause males to attempt interbreeding with sheep and whatever else is at hand. (Hand: no pun intended)

Ecurb Noselrub

  • No Wall in my name!!!
  • Wears a Colander Hat for Special Occasions
  • *****
  • Posts: 6531
  • Gender: Male
Re: Homo sapiens and Their Cousins
« Reply #62 on: November 29, 2018, 12:58:04 AM »
That interbreeding may have occurred is not the least surprising. Not improbable either.  Sex drives are powerful enough to cause males to attempt interbreeding with sheep and whatever else is at hand. (Hand: no pun intended)

I did NOT have sex with that sheep!

It seems more and more that they were not really all that different from us.  Maybe no more different than modern races, which aren't that different at all.  I suspect there was a whole lot of shakin' going on.   

Tank

  • Administrator
  • Excellent and Indefatigable Guardian of Reason
  • *****
  • Posts: 31272
  • Gender: Male
Re: Homo sapiens and Their Cousins
« Reply #63 on: November 29, 2018, 12:03:57 PM »

I did NOT have sex with that sheep!

Really? I was sure it was ewe!
If religions were TV channels atheism is turning the TV off.
“Religion is a culture of faith; science is a culture of doubt.” ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

Ecurb Noselrub

  • No Wall in my name!!!
  • Wears a Colander Hat for Special Occasions
  • *****
  • Posts: 6531
  • Gender: Male
Re: Homo sapiens and Their Cousins
« Reply #64 on: November 30, 2018, 01:08:14 AM »

I did NOT have sex with that sheep!

Really? I was sure it was ewe!

Ewe just had to ram that one through, didn’t you?

Tank

  • Administrator
  • Excellent and Indefatigable Guardian of Reason
  • *****
  • Posts: 31272
  • Gender: Male
Re: Homo sapiens and Their Cousins
« Reply #65 on: November 30, 2018, 06:34:15 AM »

I did NOT have sex with that sheep!

Really? I was sure it was ewe!

Ewe just had to ram that one through, didn’t you?

I felt I should Shepard that train of thought.
If religions were TV channels atheism is turning the TV off.
“Religion is a culture of faith; science is a culture of doubt.” ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

Recusant

  • Miscreant Erendrake
  • Administrator
  • Wears a Colander Hat for Special Occasions
  • *****
  • Posts: 6159
  • Gender: Male
  • infidel barbarian
Re: Homo sapiens and Their Cousins
« Reply #66 on: January 17, 2019, 04:52:18 PM »
Interesting story about a study which appears to show that there was a fairly widespread hybrid of Neandethals and Denisovans that contributed to the modern human genome.

"Artificial intelligence applied to the genome identifies an unknown human ancestor" | ScienceDaily

Quote
By combining deep learning algorithms and statistical methods, investigators from the Institute of Evolutionary Biology (IBE), the Centro Nacional de Análisis Genómico (CNAG-CRG) of the Centre for Genomic Regulation (CRG) and the Institute of Genomics at the University of Tartu have identified, in the genome of Asian individuals, the footprint of a new hominid who cross bred with its ancestors tens of thousands of years ago.

Modern human DNA computational analysis suggests that the extinct species was a hybrid of Neanderthals and Denisovans and cross bred with Out of Africa modern humans in Asia. This finding would explain that the hybrid found this summer in the caves of Denisova -- the offspring of a Neanderthal mother and a Denisovan father -- was not an isolated case, but rather was part of a more general introgression process.

The study, published in Nature Communications, uses deep learning for the first time ever to account for human evolution, paving the way for the application of this technology in other questions in biology, genomics and evolution.

[Continues . . .]

Full paper available: "Approximate Bayesian computation with deep learning supports a third archaic introgression in Asia and Oceania" | Nature Communications

Quote
Abstract:

Since anatomically modern humans dispersed Out of Africa, the evolutionary history of Eurasian populations has been marked by introgressions from presently extinct hominins. Some of these introgressions have been identified using sequenced ancient genomes (Neanderthal and Denisova).

Other introgressions have been proposed for still unidentified groups using the genetic diversity present in current human populations. We built a demographic model based on deep learning in an Approximate Bayesian Computation framework to infer the evolutionary history of Eurasian populations including past introgression events in Out of Africa populations fitting the current genetic evidence.

In addition to the reported Neanderthal and Denisovan introgressions, our results support a third introgression in all Asian and Oceanian populations from an archaic population. This population is either related to the Neanderthal-Denisova clade or diverged early from the Denisova lineage. We propose the use of deep learning methods for clarifying situations with high complexity in evolutionary genomics.
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Recusant

  • Miscreant Erendrake
  • Administrator
  • Wears a Colander Hat for Special Occasions
  • *****
  • Posts: 6159
  • Gender: Male
  • infidel barbarian
Re: Homo sapiens and Their Cousins
« Reply #67 on: April 11, 2019, 04:04:39 PM »
An ancient hominin found in a cave in the Philippines is potentially a new species, being called Homo luzonensis. Some of its traits appear related to the australopithecines, just as some traits of Homo florensis do. This may point to an earlier spread of hominins from Africa, before the known migrations of Homo erectus.

"New species of ancient human discovered in the Philippines" | National Geographic

Quote
Humankind's tangled shrub of ancestry now has a new branch: Researchers in the Philippines announced today that they have discovered a species of ancient human previously unknown to science.

The small-bodied hominin, named Homo luzonensis, lived on the island of Luzon at least 50,000 to 67,000 years ago. The hominin—identified from a total of seven teeth and six small bones—hosts a patchwork of ancient and more advanced features. The landmark discovery, announced in Nature on Wednesday, makes Luzon the third Southeast Asian island in the last 15 years to bear signs of unexpectedly ancient human activity.

[. . .]

While evolution sculpted H. luzonensis into a small form similar to that of H. floresiensis, we don't know which island conditions drove the differences between the two species. Also, while a barrage of studies makes clear that interspecies unions happened regularly, we don't know whether H. luzonensis ancestors interacted or bred with other hominin species that lived in Asia at the time, such as the enigmatic Denisovans.

“You could see this as kind of a natural experiment in human evolution,” says Gerrit van den Bergh of the University of Wollongong, an expert on H. floresiensis.

Another major unknown is how the ancestors of H. luzonensis even reached the Philippines. In 2016, researchers unveiled stone tools on the Indonesian island of Sulawesi that date to between 118,000 and 194,000 years old—or at least 60,000 years older than the island's oldest known modern humans. Taken alongside the remains from Flores and Luzon, the sites suggest that ancient hominin dispersal throughout the region wasn't necessarily as rare—or as accidental—as researchers once thought.

[Continues . . .]

"Homo luzonensis: New human species found in Philippines" | BBC

Quote
The Indonesian island of Flores was home to a species called Homo floresiensis, nicknamed The Hobbits because of their small stature. They are thought to have survived there from at least 100,000 years ago until 50,000 years ago - potentially overlapping with the arrival of modern humans.

Interestingly, scientists have also argued that Homo floresiensis shows physical features that are reminiscent of those found in australopithecines. But other researchers have argued that the Hobbits were descended from Homo erectus but that some of their anatomy reverted to a more primitive state.

In an article published in Nature, Matthew Tocheri from Lakehead University in Canada, who was not involved with the research, commented: "Explaining the many similarities that H. floresiensis and H. luzonensis share with early Homo species and australopiths as independently acquired reversals to a more ancestral-like hominin anatomy, owing to evolution in isolated island settings, seems like a stretch of coincidence too far."

[Full article]
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Recusant

  • Miscreant Erendrake
  • Administrator
  • Wears a Colander Hat for Special Occasions
  • *****
  • Posts: 6159
  • Gender: Male
  • infidel barbarian
Re: Homo sapiens and Their Cousins
« Reply #68 on: May 02, 2019, 05:14:43 AM »
Denisovan remains apparently found in Tibet at a high altitude. The first example found other than those from the Denisova cave.

"Major discovery suggests Denisovans lived in Tibet 160,000 years ago" | NewScientist

Quote
The first fossil of our cousins the Denisovans ever to be discovered outside Siberia has been identified in Tibet. It hints that fossils from these extinct humans are more widespread than we thought, and may help settle a long-running debate about our origins.

Denisovans were discovered in 2010, when the DNA from an ancient bone fragment found in Denisova cave in Siberia was sequenced. Since then, a few other fossil fragments have been uncovered in the cave, and genetic analysis has discovered that many people in China and South-East Asia carry a little Denisovan DNA. This reveals that our ancestors must once have lived alongside and interbred with our cousins.

Studies like these also found that people in Tibet carry a specific Denisovan gene that allows red blood cells to cope with low oxygen levels, helping people to live at high altitude.

Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, wondered if any human remains previously found in Tibet might really be Denisovan.

He and his colleagues examined a jawbone discovered in 1980 in Baishiya Karst cave, in Tibet’s Jiangla river valley. They found that the shape of the jaw and large size of the teeth are different to those of modern humans.

Radioisotope dating suggested that the fossil is 160,000 years old at least, which is tens of thousands of years before our own species is thought to have reached the Tibetan Plateau.

No DNA could be extracted from the fossil, but analysing collagen protein in its teeth confirmed the jawbone came from a Denisovan, because modern humans and our other extinct cousins the Neanderthals have different genes for collagen.

[Continues . . .]

The BBC has a story on this paper as well. "Denisovans: Primitive humans lived at high altitudes".
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Recusant

  • Miscreant Erendrake
  • Administrator
  • Wears a Colander Hat for Special Occasions
  • *****
  • Posts: 6159
  • Gender: Male
  • infidel barbarian
Re: Homo sapiens and Their Cousins
« Reply #69 on: July 10, 2019, 06:58:44 PM »
A very early anatomically modern human (AMH) skull has been identified. It was found decades ago in Greece, but was previously believed to be a Neanderthal. It provides evidence that AMH were coming out of Africa much earlier than previously believed (though they--we may not have gained a successful foothold at that time). The press release below is good, but I'm hoping for more in-depth articles about this soon.

"'Oldest remains' outside Africa reset human migration clock" | Agence France Presse

Quote
A 210,000-year-old skull has been identified as the earliest modern human remains found outside Africa, putting the clock back on mankind's arrival in Europe by more than 150,000 years, researchers said Wednesday.

In a startling discovery that changes our understanding of how modern man populated Eurasia, the findings support the idea that Homo sapiens made several, sometimes unsuccessful migrations from Africa over tens of thousands of years.

Southeast Europe has long been considered a major transport corridor for modern humans from Africa. But until now the earliest evidence of Homo sapiens on the continent dated back only around 50,000 years.

There has however been a number of discoveries indicating the ancient presence of Neanderthals -- an early human cousin -- across the continent.

Two fossilised but badly damaged skulls unearthed in a Greek cave in the 1970s were identified as Neanderthal at the time.

In findings presented in the journal Nature, an international team of researchers used state-of-the art computer modelling and uranium dating to re-examine the two skulls.

One of them, named Apidima 2 after the cave in which the pair were found, proved to be 170,000 years old and did indeed belong to a Neanderthal.

But, to the shock of scientists, the skull named Apidima 1 pre-dated Apidima 2 by as much as 40,000 years, and was determined to be that of a Homo sapiens.

That makes the skull by far the oldest modern human remains ever discovered on the continent, and older than any known Homo sapiens specimen outside of Africa.

[Continues]

"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


xSilverPhinx

  • Non Dvcor
  • Administrator
  • Luxembourg Trembles!
  • *****
  • Posts: 16231
  • Gender: Female
  • I Spy With My Googly Eyes...
Re: Homo sapiens and Their Cousins
« Reply #70 on: July 13, 2019, 01:08:53 AM »
^ That's very interesting! 8)
Give no mercy to your fear.



Dark Lightning

  • Has Actually Read the Bible!
  • **
  • Posts: 611
  • Gender: Male
  • Curmudgeon
Re: Homo sapiens and Their Cousins
« Reply #71 on: July 13, 2019, 03:06:09 AM »
False. I have this one book reprinted in the millions of copies that completely does not cover any of this "evolution" stuff. It MUST be correct! What!?  :P

[drops god hat] I truly love seeing this sort of information! It's so neat to see all the little pieces of the puzzle getting put together.

Icarus

  • The wise one.
  • Guardian of Reason
  • *****
  • Posts: 5598
Re: Homo sapiens and Their Cousins
« Reply #72 on: July 13, 2019, 03:14:25 AM »
I have one of those books too DL.   I also have a few other books that do not entirely agree with the first one or the third one....or any of the several others.   

xSilverPhinx

  • Non Dvcor
  • Administrator
  • Luxembourg Trembles!
  • *****
  • Posts: 16231
  • Gender: Female
  • I Spy With My Googly Eyes...
Re: Homo sapiens and Their Cousins
« Reply #73 on: July 13, 2019, 03:29:11 PM »
False. I have this one book reprinted in the millions of copies that completely does not cover any of this "evolution" stuff. It MUST be correct! What!?  :P

[drops god hat] I truly love seeing this sort of information! It's so neat to see all the little pieces of the puzzle getting put together.

Peer-reviewed by other sheepherders. Must be right.
Give no mercy to your fear.



Dark Lightning

  • Has Actually Read the Bible!
  • **
  • Posts: 611
  • Gender: Male
  • Curmudgeon
Re: Homo sapiens and Their Cousins
« Reply #74 on: July 13, 2019, 09:12:52 PM »
False. I have this one book reprinted in the millions of copies that completely does not cover any of this "evolution" stuff. It MUST be correct! What!?  :P

[drops god hat] I truly love seeing this sort of information! It's so neat to see all the little pieces of the puzzle getting put together.

Peer-reviewed by other sheepherders. Must be right.

:lol: Got me there! Must be.