Tag Archives: genome sequence

This reconstruction of another ancient modern human found in Romania 43,000 years ago gives us a glimpse of how the Siberian man might have looked like.

Humans first interbred with Neanderthals at least 50,000 Years Ago

Following the genome sequence of the oldest modern human remains outside of Africa using the most refined DNA analysis to data, scientists believe they arrived at a more price time frame when humans and Neanderthals first interbred – sometimes between 50,000 and 60,000 years ago. The findings also suggest modern humans arrived in northern Eurasia substantially earlier than some scientists thought.

A an ancient leg bone

The DNA in the man's femur shows that he had some Neanderthal ancestors. Credit: Bence Viola/Max Planck Institute for Evolutionary Anthropology

The DNA in the man’s femur shows that he had some Neanderthal ancestors. Credit: Bence Viola/Max Planck Institute for Evolutionary Anthropology

Carbon dating and DNA sequence was conducted on the shaft of a thighbone found by an artist and mammoth ivory collector on the left bank of the river Irtysh near the settlement of Ust’-Ishim in western Siberia in 2008. The remains changed several hands before they eventually reached the Max Planck Institute for Evolutionary Anthropology in Germany, where Prof Svante Paabo and colleagues pioneered methods to extract DNA from ancient human remains and read its genetic code. They found the remains belong to a person who lived some 45,000 years ago at a time when modern humans were only beginning to expand across Europe and Asia.

[ALSO SEE] Early humans interbred with Neanderthals, Denisovans, and another, mysterious species

This reconstruction of another ancient modern human found in Romania 43,000 years ago gives us a glimpse of how the Siberian man might have looked like.

This reconstruction of another ancient modern human found in Romania 43,000 years ago gives us a glimpse of how the Siberian man might have looked like.

The earliest modern human

The analysis revealed several important insights like the ancient’s diet  that included plants or plant eaters and fish or other aquatic life. Most importantly, the DNA sequence shows that the ancient human shared unshuffled chunks of DNA from a now extinct species of human, Neanderthals who evolved outside of Africa. Namely, 2.3 percent of his DNA came from Neanderthals,  a bit higher than found in modern humans living outside Africa today — a level that ranges from 1.7 to 2.1 percent — but too small a difference to be statistically significant. The new analysis of the date of human-Neanderthal mixing dramatically narrowed the likely range to between 50,000 and 60,000 years ago, a much tighter window than the previous range of between 37,000 and 86,000 years ago.

[INTERESTING] New theory suggests Neanderthals went extinct because of their larger eyes

“Our analysis shows that modern humans had already interbred with Neanderthals then and we can determine when that first happened much more precisely than we could before,” said Paabo.

Moreover, the Siberian man was equally related to West European hunter-gatherers, North Asian hunter-gatherers, East Asians, as well as to the natives of the Andaman Islands off South Asia. Previous studies suggested there was an early split of people who followed a coastal route to Australia, New Guinea and coastal Asia, however the present findings reported in Nature do not support them.

Malaria Image

Malaria genome sequence shows the disease is more challenging, yet offers opportunities

Two recently released studies by teams of international researchers sequenced the genomes of two major strains of the parasitic disease known as malaria. Their findings show that malaria is a lot more resistant than previously thought, but at the same time helps paint a broader picture which will certain aid in developing more effective treatment, which might one day lead to the eradication of the disease.

Malaria ImageMalaria is a parasitic disease that involves high fevers, shaking chills, flu-like symptoms, and anemia. The disease is caused by a parasite which is carried by mosquitoes and infect humans through bites.  After infection, the parasites (called sporozoites) travel through the bloodstream to the liver; here they mature and release another form, the merozoites. The disease is a major health problem in much of the tropics and subtropics, and an  estimate 1 million people die from it each year.

In one of the studies, the researchers examined Plasmodium vivax (P. vivax) strains from different geographic locations in West Africa, South America, and Asia – the first genome-wide perspective of global variability within this species. Their analysis rendered worrisome results; apparently P. vivax has twice as much genetic diversity as the world-wide Plasmodium falciparum (P. falciparum) strains. This means that it has a much better capability of evolving and thus avert treatment. Bad news can almost always make a turn for the better if you can read the good points that come from it. Now, armed with a better understanding of the parasitic strain, researchers can develop new strategies for battling it.

“The bad news is there is significantly more genetic variation in P. vivax than we’d thought, which could make it quite adept at evading whatever arsenal of drugs and vaccines we throw at it,” said Professor Jane Carlton, senior author on both studies and part of New York University’s Center for Genomics and Systems Biology. “However, now that we have a better understanding of the challenges we face, we can move forward with a deeper analysis of its genomic variation in pursuing more effective remedies.”

In the second study, scientists from Japan’s Osaka University sequenced three genomes of Plasmodium cynomolgi (P. cynomolgi), a close relative that infects Asian Old World monkeys, marking the first time this strain has been sequenced. The genetic make-up was then compared to P. vivax and to Plasmodium knowlesi (P. knowlesi), a previously sequenced malaria parasite that affects both monkeys and humans in parts of Southeast Asia. Since its very similar to P. vivax, their findings will aid future efforts of elaborating treatment for all forms of malaria.

“We have generated a genetic map of P. cynomolgi, the sister species to P. vivax, so we can now push forward in creating a robust model system to study P. vivax,” explained Tanabe. “This is important because we can’t grow P. vivax in the lab, and researchers desperately need a model system to circumvent this.”

The researchers’ findings were published in the journal Nature Genetics.

The skeleton of an ancient caveman dubbed Brana 1 yielded the oldest DNA found in a modern human. CREDIT: Alberto Tapia

Earliest modern human genome partially sequenced

The skeleton of an ancient caveman dubbed Brana 1 yielded the oldest DNA found in a modern human. CREDIT: Alberto Tapia

The skeleton of an ancient caveman dubbed Brana 1 yielded the oldest DNA found in a modern human. CREDIT: Alberto Tapia

Researchers have analyzed the DNA from  7,000-year-old bones of two cavemen unearthed in Spain, and have managed to sequence fragments of their genomes, making them the oldest modern human specimens ever found thus far. Ironically, the researchers found that the cavemen bear little genetic resemblance to people living in the region today, instead sharing ancestry with current populations of northern Europe.

The skeletons of two young adult males were discovered by chance in 2006 by cave explorers in a cavern high in the Cantabrian mountain range, northern Spain, at an altitude of about 1,500 meters. This made the region particularly cold, especially during that period of time, but which ultimately helped preserve the DNA in the bones. Judging by the ornament that one was found with of red-deer canines embroidered onto a cloth, also remarkably preserved, the cavemen were hunter-gatherers of the Mesolithic period, before agriculture spread to the Iberian Peninsula with Neolithic settlers from the Middle East.

“These are the oldest partial genomes from modern human prehistory,” said researcher Carles Lalueza-Fox, a paleogeneticist at the Spanish National Research Council.

The team of scientists were able to rescue the complete mitochondrial DNA, the genetic information housed in sub-cellular structures called mitochondria, from  “Braña1,” one of the two skeletons.

“Despite their geographical distance, individuals from the regions corresponding to the current England, Germany, Lithuania, Poland and Spain shared the same mitochondrial lineage,” said Lalueza-Fox in a statement. “These hunters-gatherers shared nomadic habits and had a common origin.

Previously, researchers have managed to sequence the complete genomes of our closest extinct relatives, the Neanderthals and the Denisovans. For the present study, the scientists recovered 1.34 percent and 0.5 percent, respectively, of the human genomes from the bones of these two cave men.

“There are many works that claim the Basques [of the Iberian Peninsula] could be descendants from Mesolithics that became isolated in the Basque country,” Lalueza-Fox said. “We found the modern Basques are genetically not related to these two individuals.”

The researchers now aim to complete the genomes of both cavemen. Such data could help “explore genes that have been modified with the arrival of the Neolithic in the European populations,” Lalueza-Fox said.

Findings were presented in the journal Current Biology; via LiveScience.