Hackers are not terrorists, hands off Red Hack!

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Category: Science & Technology

Created on Monday, 08 October 2012 11:34

Written by Hurriyet Daily

Red Hack, an infamous Turkish Maoist hacker group that predates Anonymous is being declared a terrorist cell by the Turkish state. Thanks to Joe for sharing this.

Egypt: Website as an organizer #RevSoc

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Category: Science & Technology

Created on Friday, 14 September 2012 03:10

Written by Jadaliyya

Egypt: Website as an organizer #RevSoc

Posted by Mike E on September 14, 2012

Brick factory worker in Meit Ghamr has his mobile phonehanging from his turban during the work shift. Some falsely argue that online resources are inaccessible to the poor — but even in a country like Egypt online access has deeply penetrated. Photo by Mohamed Ali Eddin

“The lack of interest that comrades in the movement had in acting as correspondents for the site did not only reflect the fact that the site was badly-designed or difficult to browse, but it also had political roots, which can be summarized in the lack of political awareness of the political task that a website must play in a revolutionary movement—that of an organizer.“

The following appeared on Jadaliyya. Thanks to Enaa.

What is to be Done:

The Website as an Organizer #RevSoc

The Revolutionary Socialists Movement launched its new website on 7 August. The site represents a qualitative change in our propaganda work, but it also presents some major challenges to the membership of the movement as a whole and not only to the comrades in the media committee alone.

It is a necessity to provide content on an organized basis for publication, for comrades to continue to act as correspondents for the site, and to extend this correspondence with written reports, pictures, videos, and artistic works (cartoons, stencils, comics). Correspondence with the site is not a luxury or only the responsibility of the small number of comrades who run the site, but it should continue to be the task of the largest possible number of comrades in the movement, if not all of them.

The site is still in an experimental stage, and there are a number of technical problems and tasks which are not finished. The technical team is working on solving or completing them and developing the site to move to the next phase of the project, which includes the establishment of a special multimedia section and a discussion forum for members of the movement.

The transition to the next phase of the site may take several months, as the challenge before us is not just technical, but also political and organizational, as the site will not be able to raise its performance and take on the role it should play without reorganizing the ranks of the movement to serve this new approach to revolutionary work. To clarify this, let us go back a little and give some background on this issue.

A number of well-known comrades from the movement have ben present in the citizen-journalism (blogging) movement since 2005 and the youth of the Revolutionary Socialists (RS) have made increasing use of “alternative media” tools since 2008. However, they generally took individual initiatives and the movement did not have a general strategy for dealing with the internet and social networks which were spreading, although there was a degree of organizational coordination between the RS labor organizers and the movement’s bloggers over the Mahalla strike of September 2007, the Mahalla uprising of April 2008, and the tax-collectors’ sit-in in December 2007, a battle which led to their formation of the first independent union in Egypt since 1957.

The launch of the old site (www.e-socialists.net) on 6 April 2009, the first anniversary of the Mahalla uprising, was a step forward, because for the first time in the movement’s history, a committee was formed to manage the site and organize propaganda work on the internet. At the time, the site provided a good opportunity, to the extent available at the time, to spread our ideas on the internet, provide an archive of literature, win a number of young people to the movement and its ideas, and develop some initiatives and activities which were happening on an individual level and link them to the general orientation of the movement.

Problems

However, there were many problems and shortcomings in the work of the group, such as:

• The site was often an isolated island and the members of the site team had to “hunt down” comrades in order to get reports from them, which often appeared late or did not even make it onto the site.
• The old site was not able to highlight audiovisual content such as photos and videos.
• Despite the rich content of the site, it was difficult for the visitor to browse or find the desired material because of its complexity and the poor organization of its sections.
• The site suffered a number of technical problems because of its irregular maintenance and development, and it kept collapsing under the volume of visits.
• The focus was on the official website, and there was no clear plan for propaganda on the social networks such as Twitter, Facebook, Flickr, Scribd, Diigo, and YouTube, despite the establishment of official accounts for the movement on them.

These problems also had a political nature:

• The design of the site with a single large photo in the center with no other visual content highlighted in the form of images, videos, and the design highlighted written content in the form of columns; this reflected the traditional political outlook on the nature of the site, which was that it was no more than an online companion for the content of the print edition of the Socialist newspaper, which at that time appeared monthly.
• The lack of interest that comrades in the movement had in acting as correspondents for the site did not only reflect the fact that the site was badly-designed or difficult to browse, but it also had political roots, which can be summarized in the lack of political awareness of the political task that a website must play in a revolutionary movement—that of an organizer.

Lenin’s book What is to be done? represents the theoretical basis for building Marxist organizations from the last century. In this book, Lenin tries to answer the question that was facing revolutionaries in Russia at the time, and that faces revolutionaries in Egypt today and at any time: how can we build our organization? How can we transform coordination between groups of geographically-dispersed revolutionaries? How can we ensure unity and centralism in reality, and at the same time, create channels of democratic debate between revolutionaries?

Lenin’s answer at the time was a revolutionary newspaper. Every member of the revolutionary organization was also a reporter for the revolutionary newspaper, and their job was to supply the newspaper with reports. But how were these reports produced? The revolutionary correspondent would get involved in any struggle or activity where he lived or worked, and follow these with reports sent to the newspaper, so that this experience would be generalized to all the comrades who read them in other sectors and areas, and the newspaper would create an opportunity for him to connect with this audience and to engage them in his issue.

When you read a report about a factory in an issue of The Socialist, it means that a comrade went to the factory, interacted with the workers and created links with them, and then returned with the report. The process of journalism is a process of organization. It is easy for anyone to sit in the office, browse the net, and write a news story about the factory, but this is not the kind of journalism we want. Sending a report to the paper means that you are engaged on the ground at the same time as you are connected to the rest of the members of the movement, and that you are engaged through the channel which is open between you and the editorial board of the newspaper.

The revolutionary correspondent is not “impartial” and does not pretend to be. The revolutionary correspondent is biased—in favor of the workers in their struggle with management and in favor of the masses in any battle with the authorities. But this does not mean biased in the sense of lies and exaggeration. That is the task of the bourgeois media, not the revolutionary. Sometimes, unfortunately, we see some activist journalists who exaggerate the size of demonstrations so that a demonstration of twenty workers suddenly becomes two thousand, or a defeat of workers in a strike is reported as a victory. The people who do this think mistakenly that they are helping the workers and that this will raise their spirits. But in reality, they are misinforming their audience and their exaggerations could be easily debunked, leading to a loss of credibility.

The organizing revolutionary newspaper, as Lenin explains, plays a role in unifying the stances of the members of the movement in different parts of the country. So a revolutionary socialist, in any place in Egypt, from Alexandria to Aswan, can see through the newspaper the official position of the movement on this issue or that.

But when Lenin wrote these words at the beginning of the twentieth century, news traveled from city to city by postmen on horseback. Even in 1917, when the Russian Revolution broke out, news of the revolution in Petrograd and Moscow could take weeks or sometimes months to reach the rest of the Russian empire.

The situation is different today. News travels at lightning speed, not only inside the country, but even between the five continents of the world. Over the internet and satellite channels it is possible to sit in Cairo and follow news of the Tunisian revolution minute by minute. You can be in Alexandria and connect with British clerical workers having a sit-in at their office in a small town in Scotland over Twitter and Facebook. You can be in Assuit and follow the demonstrations of the Spanish miners via live-streaming over the internet.

The development of the communications sector in Egypt is a glaring example of the “uneven and combined development” of capitalism that Trotsky talked about.

In a country that has a population of around ninety million, in which forty percent of them live below the poverty line, the number of mobile phone subscribers in Egypt has reached ninety-two million—saturation surpassing one-hundred percent of the population, according to the latest report from the Ministry of Communications this May.

According to the same report, the number of internet users has risen to roughly thirty-one million.

It is very interesting to observe the relative distribution of internet users, for we find that the lion’s share of them get online via mobile phones and USB modems, which are constantly falling in price.

The spread of this method of access is progressively enabling social classes beyond the bourgeoisie and the middle class to get online. It is this segment of users that is most likely to increase at a rate surpassing the other sectors.

The tempo of work in every revolutionary movement is set to a large extent by the central organizer. In the 1990s, the newspaper Revolutionary Socialism was the organizer for the movement, and it appeared monthly. This was appropriate to the low level of class struggle, and was also reflected in the small size of the Revolutionary Socialists movement. Today, if we consider the website as the organizer, it means that we must update this site minute by minute, and follow political events and activities that occur in Egypt before any traditional source of expertise. The arrival of reports and updates for the site around the clock translates organizationally into the presence of revolutionary correspondents on the ground getting involved with events and then sending a report to the “center,” which is the site editorial board that establishes, in turn, a faster rhythm of organizational work.

For example, if Al-Masry Al-Youm publishes a news story about a strike in a factory in Mansoura and this does not appear on our site, then we need to ask ourselves why not? If the Revolutionary Socialists have any presence there or connection with the factory, then why did they not send the news immediately to the site? It is just as critical for a worker (who is, in these circumstances, a revolutionary correspondent), to contact the site to spread the vital news of the strike as it is to build barricades to defend the sit-in. Contacting the site at this moment means that the revolutionary worker correspondent is included in a communication network, and the experience of what he does in Mansoura is disseminated immediately to the rest of the members of the movement, as well as all militants interested workers’ struggle. This means they are always ready to offer solidarity and coordinate what they are doing in their own areas with what their comrades are doing in Mansoura.

This once again gives a tremendous push to the acceleration of the rhythm of communication between the different sections of the movement. The presence of revolutionary correspondents on the ground in every province, tasked with supplying the site with constant reports, and accountable when we hear news from their areas via the traditional media rather than from them, means that there are activists on the ground, assigned at all times to throw themselves into events that are happening, and under constant pressure to expand the network of revolutionary correspondents in their provinces, which translates into gains for the membership of the movement.

Suppose a military coup took place today. Would revolutionary socialist cadres across Egypt wait for two or three weeks until the paper appeared to know our position? Or would the leadership of the movement phone and travel to meet each comrade to tell them the line? Here we return to the role of the site as organizer. It is obvious that the site will offer a quick way to connect and announce the official position to members of the movement in different provinces on this or that issue, which requires a rapid, unified reaction.

Newspaper journalists care about written content, but comrades who are correspondents for the site should pay special attention to audio-visual content alongside written reports about the events they are involved in. Photographs and videos are not a luxury, as it is the duty of every comrade involved in a event to make efforts to take photographs or film on a mobile phone. In general, the movement must pay special attention to passing on skills in photography and training in the secure use of email and social networks, such as Facebook and Twitter, to as much of the membership as possible.

The site will not be a substitute for the paper, and comrades must continue in the hard work of distributing the paper at events, to the network of members, and to sympathizers. Despite the increasing numbers of workers using the internet (whether via mobile, a link at home, or in cyber-cafés), the paper will continue to be an essential means to interact with them. We must do our best to ensure that it is published regularly, but the paper will be a complementary, rather than a central, organizing publication. It may be that the adoption of the website as an organizer is the first step towards the modern answer to the same question posed by Lenin in the last century: what is to be done?

[This article was originally published on 3arabawy.]

Genetics & Fossils: Tracking human origins, two entwined tales

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Category: Science & Technology

Created on Tuesday, 07 August 2012 11:10

Written by Nicholas Wade

For two hundreds years, we humans studied our ancestors by digging up bones, studying their location, their change over time, and the cultural artifacts that accompanied them. In the last fifty years a quite independent way of exploring that same story of descent has emerged: DNA. The interplay of fossil evidence and DNA have generally "filled in the picture" for each other, confirming or refining timelines.

Recently, DNA studies have uncovered growing evidence of interbreeding among early hominids, and pieces of modern DNA strands (among living people) that are traceable back to different earlier species of humans.

In other words, while  our main ancestors came from that  pool of people call Homo heidelbergensis (which then gave rise to Homo sapians), there is among different modern Homo sapians DNA strands shared from the Neanderthal humans and from a still-little-known species of archaic humans called Denisovans.

The following first appeared in the New York Times.

Genetic Data & Fossil Evidence Tell Differing Tales of Human Origins

By NICHOLAS WADE

After decades of digging, paleoanthropologists looking for fossilized human bones have established a reasonably clear picture: Modern humans arose in Africa some 200,000 years ago and all archaic species of humans then disappeared, surviving only outside Africa, as did the Neanderthals in Europe. Geneticists studying DNA now say that, to the contrary, a previously unknown archaic species of human, a cousin of the Neanderthals, may have lingered in Africa until perhaps 25,000 years ago, coexisting with the modern humans and on occasion interbreeding with them.

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Sudden melting in Greenland: New concerns about global warming

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Category: Science & Technology

Created on Wednesday, 25 July 2012 15:56

Written by KELLY SLIVKA

(click for larger image) The extent of Greenland's ice sheet surface, in white, on July 8, left, and July 12, right, based on measurements from three satellites, which pass over at different times and whose data are combined and analyzed. The deepest pink areas reflect maximal certainty that the ice has melted.

This has been a summer of rare heat -- including (obviously) in the U.S. The following report appeared in the New York Times (July 24, 2012) and describes a troubling development in Greenland, the giant frozen island in between Canada and Europe.

Within four days, the virtually entire surface of Greenland's famous ice sheet has turned to slush.

Just to be clear, this is not the disappearance of the whole thick sice sheet itself, but the unusually widespread "melt" of its surface. 

Rare Burst of Melting Seen in Greenland's Ice Sheet

 By KELLY SLIVKA

In a scant four days this month, the surface of Greenland's ice sheet melted to an extent not witnessed in 30 years of satellite observations, NASA reported on Tuesday.

On average, about half of the surface of the ice sheet melts during the summer. But from July 8 to July 12, the ice melt expanded from 40 percent of the ice sheet to 97 percent, according to scientists who analyzed the data from satellites deployed by NASA and India's space research institute.

"I started looking at the satellite imagery and saw something that was really unprecedented" since the advent of satellite imaging of the earth's frozen surface, or cryosphere, said Thomas L. Mote, a climate scientist at the University of Georgia who for 20 years has been studying ice changes on Greenland detected by satellite.

While scientists described it as an "extreme event" not previously recorded from space, they hastened to add that it was normal in a broader historical context.

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Glimpsing Higgs Boson: tracing subatomic particle amid the debris

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Category: Science & Technology

Created on Wednesday, 04 July 2012 15:11

Written by Adam Mann

The shimmering trails of shattered particles reveals evidence of a massive particle that matches the predicted profile of Higgs Boson. Scientists are already eagerly looking for ways that it may diverge from expectations and therefore help unravel elements of their previous theories. This is how knowledge and theory develop. Theoretical proposals, testing in practice, confirmation and new problems, new theoretical reaching and controversies, new practice.

“I would be delighted if this new state is a Higgs boson, but perhaps not the Standard Model Higgs boson,” physicist Fabiola Gianotti of the LHC’s ATLAS experiment said after the announcement, with an apology aside to Peter Higgs. “Because this will open the road to something else.”

This first appeared in Wired Science.

Newly Discovered Particle Appears to Be Long-Awaited Higgs Boson

by Adam Mann

Prepare the fireworks: The discovery of the Higgs boson is finally here. Early in the morning on July 4, physicists with the Large Hadron Collider at CERN announced they have found a new particle that behaves similarly to what is expected from the Higgs.

“As a layman, I would now say, I think we have it,” said CERN director-general Rolf-Dieter Heuer. “It’s a historic milestone today. I think we can all be proud, all be happy.” Both CMS and ATLAS, the two main LHC Higgs-hunting experiments, are reporting a boson that has Higgs-like properties at a mass of 125 gigaelectronvolts (GeV) with a 5-sigma significance, meaning they are 99.999 percent confident of its existence.

At the first mention of 5-sigma by physicist Joe Incandela, who presented results from one of the main Higgs-searching efforts at the LHC, the audience burst into applause. “It was really a magnificent moment to see the reaction from the community,” he said later in a question and answer session. “Emotionally it didn’t really hit me until today because we have had to be so focused, and so much work to do.”

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Richard Lewontin: Biology as ideology

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Category: Science & Technology

Created on Friday, 04 May 2012 07:08

Written by Richard Lewontin

A far-ranging discussion of science under capitalism by the evolutionary biologist (and revolutionary activist) Richard Lewontin.

Ian Tattersall: How we became so uniquely human

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Category: Science & Technology

Created on Sunday, 22 April 2012 09:08

Written by Laurence A. Marschall

Intro by Mike Ely

I am halfway through Ian Tattersall's new book, Masters of the Planet: The Search for Our Human Origins-- and I find myself slowing down, to enjoy the new information and insight shared on almost every page.

This is not a work written with those breathtakingly encyclopaedic interconnections of a Stephen Jay Gould. It is a focused, almost workman-like overview of what we know of human evolution.

But that is a fascinating story told by someone with expert knowledge and razor-edged opinions.

There are many times when you sense that Ian is laboring hard to keep his sharp tongue in its sheath (or perhaps his editors were helping him do that) -- but that obvious restraint only serves to highlight (for the careful reader) the sharp polemical frontlines of evolutionary debate, taking place over small mounds of teeth, bone fragments, and a few wonderful almost-complete skeletons.

Tattersall is a partisan of the bushiness of human evolution. He points out that for most of the history of this science, the practitioners were experts in human anatomy, with little training in identifying diverse species of human existing at the same time. In fact, the idea that there were several human (or proto-human) species existing for almost all of our emergence is an idea that was stubbornly resisted by many, for a long time, even as  the evidence itself made it harder and harder to turn away.

Tattersall is also a partisan of human specialness. He zooms in on that remarkable uniqueness of the human mind (with its symbolic thinking, special self-consciousness and speech), and asks how that emerged from the world of interconnected species (especially apes and early hominids) that could think, communicate, and create tools but who (somehow) lacked those particular faculties that made humans so dominant and powerful on this planet. This is not the nineteenth century view of the "ascent" or perfecting of humanity, or of some Bible based view right to human "dominion" over the planet. But there is a drama here of the evolutionary process taking a "prey" species (of juicy, slowmoving, weak, upright-walking apes in Africa) and make them capable of building cities and inventing art. It is a story of continuity (i.e. of descent) and major ruptures -- including some happening rather late (rather recently) in the history of our own specific species (modern Homo sapiens) itself.

And so, Tattersall, a scientist trained in the riotously diverse species world of lemurs, bring an edgy sensibility to the last decades of debate.

Quietly, in my own mind, Tattersall has emerged (over several years and several books) as "my guy" on human evolution -- I respect his candor and insight, I enjoy his partisan engagement in the great debates of his field, and I have felt there is much for us all to learn from how evolutionary science (and especially human evolution) is being constantly reimagined as practice deepens and inherited assumptions become exhausted. (His chapter on the errors of Ernest Mayr, and the negative impact of the Great Synthesis assumptions of the inter-war period, is fascinating -- especially since we all understand well the tremendous creative leap involved in that fusion of evolutionary theory and new genetic breakthroughs. That chapter alone....)

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Science vs. Lies: Imagining a "clean break" with Israel over Iran

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Category: Science & Technology

Created on Friday, 03 February 2012 10:14

Written by Gary Leupp

This piece also appears on Dissident Voice and Cold Warfare.

by Gary Leupp

A recent column by the always insightful Ray McGovern succinctly demonstrates the problem.

The world of science acknowledges matter-of-factly that Iran is not pursuing a nuclear weapons program. There is simply no evidence for one. The UN’s International Atomic Energy Agency, staffed by specialists on nuclear power and maintaining a tight watch on Iran’s civilian facilities, finds no evidence of a military program. Two successive reports (National Intelligence Estimates) produced (in 2007 and 2010) by all 16 U.S. intelligence agencies have declared with confidence that there is no operative weapons program. U.S. Defense Secretary Leon Panetta and (even) Israel’s Defense Minister Ehud Barak have both recently stated (or let it slip) that Iran is not currently attempting to build nuclear weapons.

But then there is the political world of systematic disinformation. The world of big, bold lies which, as they are constantly repeated, acquire a certain life of their own. Thus the mainstream press and the entire political class in this country refer routinely to “Iran’s nuclear weapons program” as though there obviously were one. As though any questioning of the charge were thoroughly naive.

(By the way: try doing an advanced Google search for the exact phrase “Iran’s nuclear weapons program” and you will call up 4,640,000 results. Try “Israel’s nuclear weapons program”—which we know exists—and you’ll get 533,000. What does this tell you?)

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From a Siberian girl's pinkie: Traces of humanity's hybrid past

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Category: Science & Technology

Created on Wednesday, 01 February 2012 15:29

Written by Alanna Mitchell

A view above the Denisova cave, where clues to prehistoric interbreeding were found. photo: Johannes Krause

Parts of this story have been told before (including here on Kasama):

DNA study of a single human finger bone found in Siberia’s Denisova cave reveals that we include genetic material from two other human species, the Neanderthals and a previously unknown species now called the Denisovians.

Still there is much to learn and enjoy in this  exploration unfolds:

It reveals how remarkably curious and clever we humans are — that our tireless and skilled investigators are able to extract such insights from a bone fragment!

And their work contains of a promise of how much more will be revealed, in the years ahead, as we explore our own past with two independent yet parallel methods: archeology and genetics.

Just the details from this cave alone are fascinating: There are over 20 cultural levels found there — left by humans over tens of thousands of years (and presumably by humans of different and overlapping species!).

The cave contains  remnants of 27 species of large and middle-sized mammals, 39 species of small mammals and remnants of other vertebrates — including the tusk of mammoth, ostrich egg shell, remnants of small cave bear, cave hyaena, cave lion, and wooly rhinoceros. That’s just the archeology side of it.

And now a sliver from a finger (and one tooth!) gives up startling new information about our common past.

For a couple hundred years, we have developed our trove fossil and tool discoveries, but did not have a sure way of knowing which humans left them. In this case, we have the reverse! We have the remarkable evidence of Denisovians who (as Dr. Reich says below) are currently “a genome in search of an archaeology.”

Quite possibly these Denisovians form a major part of human history (despite the fact that we know almost nothing about them yet). This article includes early speculation of their range and importance.  But the simple fact is that this cave is in the far north and the genetic remnant of their line appears strongest among some humans in the far South (Oceania) — suggesting (possibly, tentatively) a wide Asian range over long periods.

Human remains (of all previous hominid species) are remarkably rare, and more rare the further we go back in time. This is especially so in warmer climates where the dead bodies were quickly dispersed and decomposed. We have rather extensive knowledge (and over a hundred skeletons) of the recent, cold climate hominids called Neanderthal, compared to their contemporaries in Africa and the larger tropical band.

Also remarkable in this report is this statement:

“Dr. Parham’s analysis, which shows that some archaic immune alleles are widespread among modern humans, concludes that as few as six couplings all those tens of thousands of years ago might have led to the current level of ancient immune alleles.”

Reports on these developments have appeared in many places, this particular article is from the New York Times (Jan 30).

DNA Turning Human Story Into a Tell-All

By ALANNA MITCHELL

The tip of a girl’s 40,000-year-old pinky finger found in a cold Siberian cave, paired with faster and cheaper genetic sequencing technology, is helping scientists draw a surprisingly complex new picture of human origins.

The new view is fast supplanting the traditional idea that modern humans triumphantly marched out of Africa about 50,000 years ago, replacing all other types that had gone before.

Instead, the genetic analysis shows, modern humans encountered and bred with at least two groups of ancient humans in relatively recent times: the Neanderthals, who lived in Europe and Asia, dying out roughly 30,000 years ago, and a mysterious group known as the Denisovans, who lived in Asia and most likely vanished around the same time.

Their DNA lives on in us even though they are extinct. “In a sense, we are a hybrid species,” Chris Stringer, a paleoanthropologist who is the research leader in human origins at the Natural History Museum in London, said in an interview.

The Denisovans (pronounced dun-EE-suh-vinz) were first described a year ago in a groundbreaking paper in the journal Nature made possible by genetic sequencing of the girl’s pinky bone and of an oddly shaped molar from a young adult.

Those findings have unleashed a spate of new analyses.

Scientists are trying to envision the ancient couplings and their consequences: when and where they took place, how they happened, how many produced offspring and what effect the archaic genes have on humans today.

Other scientists are trying to learn more about the Denisovans: who they were, where they lived and how they became extinct.

A revolutionary increase in the speed and a decline in the cost of gene-sequencing technology have enabled scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, to map the genomes of both the Neanderthals and the Denisovans.

Comparing genomes, scientists concluded that today’s humans outside Africa carry an average of 2.5 percent Neanderthal DNA, and that people from parts of Oceania also carry about 5 percent Denisovan DNA. A study published in November found that Southeast Asians carry about 1 percent Denisovan DNA in addition to their Neanderthal genes. It is unclear whether Denisovans and Neanderthals also interbred.

A third group of extinct humans, Homo floresiensis, nicknamed “the hobbits” because they were so small, also walked the earth until about 17,000 years ago. It is not known whether modern humans bred with them because the hot, humid climate of the Indonesian island of Flores, where their remains were found, impairs the preservation of DNA.

This means that our modern era, since H. floresiensis died out, is the only time in the four-million-year human history that just one type of human has been alive, said David Reich, a geneticist at Harvard Medical School who was the lead author of the Nature paper on the Denisovans.

For many scientists, the epicenter of the emerging story on human origins is the Denisova cave in the Altai Mountains of Siberia, where the girl’s finger bone was discovered. It is the only known place on the planet where three types of humans — Denisovan, Neanderthal and modern — lived, probably not all at once.

John Hawks, a paleoanthropologist at the University of Wisconsin-Madison, whose lab is examining the archaic genomes, visited the cave in July. It has a high arched roof like a Gothic cathedral and a chimney to the sky, he said, adding that being there was like walking in the footsteps of our ancestors.

The cave has been open to the elements for a quarter of a million years and is rich with layers of sediments that may contain other surprises. Some of its chambers are unexplored, and excavators are still finding human remains that are not yet identified. The average temperature for a year, 32 degrees Fahrenheit, bodes well for the preservation of archaic DNA.

Could this cave have been one of the spots where the ancient mating took place? Dr. Hawks said it was possible.

But Dr. Reich and his team have determined through the patterns of archaic DNA replications that a small number of half-Neanderthal, half-modern human hybrids walked the earth between 46,000 and 67,000 years ago, he said in an interview. The half-Denisovan, half-modern humans that contributed to our DNA were more recent.

And Peter Parham, an immunologist at the Stanford University School of Medicine, has used an analysis of modern and ancient immune-system genetic components — alleles — to figure out that one of the Denisovan-modern couplings most likely took place in what is now southeastern China. He has also found some evidence that a Neanderthal-modern pair mated in west Asia.

He stressed, however, that his study was just the first step in trying to reconstruct where the mating took place.

Dr. Parham’s analysis, which shows that some archaic immune alleles are widespread among modern humans, concludes that as few as six couplings all those tens of thousands of years ago might have led to the current level of ancient immune alleles.

Another paper, by Mathias Currat and Laurent Excoffier, two Swiss geneticists, suggests that breeding between Neanderthals and modern humans was rare. Otherwise, they say, modern humans would have far more Neanderthal DNA.

Were they romantic couplings? More likely they were aggressive acts between competing human groups, Dr. Stringer said. For a model, he pointed to modern hunter-gatherer groups that display aggressive behavior among tribes.

The value of the interbreeding shows up in the immune system, Dr. Parham’s analysis suggests. The Neanderthals and Denisovans had lived in Europe and Asia for many thousands of years before modern humans showed up and had developed ways to fight the diseases there, he said in an interview.

When modern humans mated with them, they got an injection of helpful genetic immune material, so useful that it remains in the genome today. This suggests that modern humans needed the archaic DNA to survive.

The downside of archaic immune material is that it may be responsible for autoimmune diseases like diabetes, arthritis and multiple sclerosis, Dr. Parham said, stressing that these are preliminary results.

Although little is known about the Denisovans — the only remains so far are the pinky bone and the tooth, and there are no artifacts like tools. Dr. Reich and others suggest that they were once scattered widely across Asia, from the cold northern cave to the tropical south. The evidence is that modern populations in Oceania, including aboriginal Australians, carry Denisovan genes.

Dr. Reich and others suggest that the interbreeding that led to this phenomenon probably occurred in the south, rather than in Siberia. If so, the Denisovans were more widely dispersed than Neanderthals, and possibly more successful.

But the questions of how many Denisovans there were and how they became extinct have yet to be answered. Right now, as Dr. Reich put it, they are “a genome in search of an archaeology.”