Eideard

Our species may have bred with a now extinct lineage of humanity before leaving Africa, scientists say.

Although we modern humans are now the only surviving lineage of humanity, others once roamed the Earth, making their way out of Africa before our species did, including the familiar Neanderthals in West Asia and Europe and the newfound Denisovans in East Asia. Genetic analysis of fossils of these extinct lineages has revealed they once interbred with modern humans, unions that may have endowed our lineage with mutations that protected them as we began expanding across the world about 65,000 years ago.

Now researchers analyzing the human genome find evidence that our species hybridized with a hitherto unknown human lineage even before leaving Africa, with approximately 2 percent of contemporary African DNA perhaps coming from this lineage. In comparison, recent estimates suggest that Neanderthal DNA makes up 1 percent to 4 percent of modern Eurasian genomes and Denisovan DNA makes up 4 percent to 6 percent of modern Melanesian genomes.

“We need to modify the standard model of human origins in which a single population transitioned to the anatomically modern state in isolation — a garden of Eden somewhere in Africa — and replaced all other archaic forms both within Africa and outside Africa without interbreeding,” researcher Michael Hammer, a population geneticist at the University of Arizona in Tucson, told LiveScience. “We now need to consider models in which gene flow occurred over time…”

“We think there were probably thousands of interbreeding events,” Hammer said. “It happened relatively extensively and regularly.”

I don’t think the “extensive and regular” part is a surprise either. It may upset some boring, straight-laced and narrow-minded pundits; but, evolution doesn’t pay any attention to ideology.

Bees do it, humans do it – move genes among crop plants, that is. But until now, researchers and growers had a hard time getting a grip on the factors that determine how much of this gene flow happens in an agricultural landscape.

A new data-driven statistical model that incorporates the surrounding landscape in unprecedented detail describes the transfer of an inserted bacterial gene via pollen and seed dispersal in cotton plants more accurately than previously available methods…

The transfer of genes from genetically modified crop plants is a hotly debated issue. Many consumers are concerned about the possibility of genetic material from transgenic plants mixing with non-transgenic plants on nearby fields. Producers, on the other side, have a strong interest in knowing whether the varieties they are growing are free from unwanted genetic traits.

Up until now, realistic models were lacking that could help growers and legislators assess and predict gene flow between genetically modified and non-genetically modified crops with satisfactory detail.

This study is the first to analyze gene flow of a genetically modified trait at such a comprehensive level. The new approach is likely to improve assessment of the transfer of genes between plants other than cotton as well.

“The most important finding was that gene flow in an agricultural landscape is complex and influenced by many factors that previous field studies have not measured,” said Heuberger. “Our goal was to put a tool in the hands of growers, managers and legislators that allows them to realistically assess the factors that affect gene flow rates and then be able to extrapolate from that and decide how they can manage gene flow.”

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Farmers growing conventional corn next to GM crops can benefit from the reduction in crop-destroying pests without paying the premium for GM seeds, a new study has shown.

The research, published today in the journal Science, examined 14 years of records in the top US corn-producing states of Minnesota, Illinois, Iowa, Nebraska and Wisconsin, looking at the prevalence of the European corn borer, a moth whose caterpillars eat into corn stalks and topple the plants.

The so-called Bt GM corn varieties were first planted in 1996 and produce toxins taken from a soil bacterium called Bacillus thuringiensis, which is deadly to the pest. In GM fields, the pest is eradicated, but the data showed that in neighbouring non-GMO fields the pest populations shrank by 28-78%, depending on how much GM corn was being grown in the surrounding area.

The study also found that the caterpillar-killing GM varieties grown in the vast US corn belt had retained their potency 14 years after being first sown, showing the pests had not developed resistance.

Scientists said the demonstration of the “halo effect” was a triumph for genetically modified crops. Prof Bruce Tabashnik, an entomologist from the University of Arizona, who was not part of the research team, said: “It’s a wonderful success story. It’s a great example of a technology working how it should…”

The researchers, led by Prof Bill Hutchison at the University of Minnesota, also calculated the economic benefits over the 14 years of the GM corn-growing. They valued the extra corn harvested because of the reduction in corn borer numbers and took into account the extra $1.7bn farmers had paid for the GM seeds, equivalent to $10-20 per hectare. The total benefit was $6.8bn but they found it was not evenly distributed: non-GM fields gained two-thirds of the total benefit, despite making up only one-third of the land.

Another hundred years or so and there will be sufficient testing and records to show everyone whether or not GM food crops are a step forward. Probably enough to satisfy most.

And the naysayers will not change their objections one iota.

Test larvae have flourescent marker tied to gene

For years, researchers worldwide have attempted to create genetically altered mosquitoes that cannot infect humans with malaria. Those efforts fell short because the mosquitoes still were capable of transmitting the disease-causing pathogen, only in lower numbers.

Now for the first time, University of Arizona entomologists have succeeded in genetically altering mosquitoes in a way that renders them completely immune to the parasite, a single-celled organism called Plasmodium. Someday researchers hope to replace wild mosquitoes with lab-bred populations unable to act as vectors, i.e. transmit the malaria-causing parasite.

“If you want to effectively stop the spreading of the malaria parasite, you need mosquitoes that are no less than 100 percent resistant to it. If a single parasite slips through and infects a human, the whole approach will be doomed to fail,” said Michael Riehle, who led the research effort…

Riehle’s team used molecular biology techniques to design a piece of genetic information capable of inserting itself into a mosquito’s genome. This construct was then injected into the eggs of the mosquitoes. The emerging generation carries the altered genetic information and passes it on to future generations…

When Riehle and his co-workers studied the genetically modified mosquitoes after feeding them malaria-infested blood, they noticed that the Plasmodium parasites did not infect a single study animal.

“We were surprised how well this works,” said Riehle. “We were just hoping to see some effect on the mosquitoes’ growth rate, lifespan or their susceptibility to the parasite, but it was great to see that our construct blocked the infection process completely…”

“The eradication scenario requires three things: A gene that disrupts the development of the parasite inside the mosquito, a genetic technique to bring that gene into the mosquito genome and a mechanism that gives the modified mosquito an edge over the natural populations so they can displace them over time.”

“The third requirement is going to be the most difficult of the three to realize,” he added, which is why his team decided to tackle the other two first…

At this point, the modified mosquitoes exist in a highly secured lab environment with no chance of escape. Once researchers find a way to replace wild mosquito populations with lab-bred ones, breakthroughs like the one achieved by Riehle’s group could pave the way toward a world in which malaria is all but history.

Bravo!

Tons of detail in the article. Sooner or later the study will be published somewhere with free access.

Experiments by a UA anthropologist and his colleagues show that fossil footprints made 3.6 million years ago are the earliest direct evidence of early hominins using the kind of efficient, upright posture and gait now seen in modern humans.
More than three million years ago, the ancestors of modern humans were still spending a considerable amount of their lives in trees, but something new was happening.

David Raichlen…and his colleagues…have developed new experimental evidence indicating that these early hominins were walking with a human-like striding gait as long as 3.6 million years ago.

A trackway of fossil footprints preserved in volcanic ash deposited 3.6 million years ago was uncovered in Laetoli, Tanzania, more than 30 years ago. The significance of those prints for human evolution has been debated ever since.

The most likely individuals to have produced these footprints, which show clear evidence of bipedalism, or walking on two legs, would have been members of the only bipedal species alive in the area at that time, Australopithecus afarensis. That species includes “Lucy,” whose skeletal remains are the most complete of any individual A. afarensis found to date…

Since the Laetoli tracks were discovered, scientists have debated whether they indicate a modern human-like mode of striding bipedalism, or a less-efficient type of crouched bipedalism more characteristic of chimpanzees whose knees and hips are bent when walking on two legs.

To resolve this, Raichlen and his colleagues devised the first biomechanical experiment explicitly designed to address this question…

“Based on previous analyses of the skeletons of Australopithecus afarensis, we expected that the Laetoli footprints would resemble those of someone walking with a bent knee, bent hip gait typical of chimpanzees, and not the striding gait normally used by modern humans,” Raichlen said. “But to our surprise, the Laetoli footprints fall completely within the range of normal human footprints…”

“What is fascinating about this study is that it suggests that, at a time when our ancestors had an anatomy well-suited to spending a significant amount of time in the trees, they had already developed a highly efficient, modern human-like mode of bipedalism,” said Gordon.

True Believers may ignore this entire post and the linked article. Of course.

You may now return to jiggling your beads or whatever it is that you fondle on a Sunday evening after all televised sports have ended.