science

Ancient DNA reveals humans living 40,000 years ago in Beijing area related to present-day Asians, Native Americans

The leg of the early modern human from Tianyuan Cave was used for the genetic analysis as well as for carbon dating. Credit: MPI for Evolutionary Anthropology An international team of researchers including Svante Pääbo and Qiaomei Fu of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sequenced nuclear and mitochondrial DNA that had been extracted from the leg of an early modern human from Tianyuan Cave near Beijing, China. Analyses of this individual's DNA showed that the Tianyuan human shared a common origin with the ancestors of many present-day Asians and Native Americans. In addition, the researchers found that the proportion of Neanderthal and Denisovan-DNA in this early modern human is not higher than in people living in this region nowadays.

Humans with morphology similar to present-day humans appear in the fossil record across Eurasia between 40,000 and 50,000 years ago. The genetic relationships between these early modern humans and present-day human populations had not yet been established. Qiaomei Fu, Matthias Meyer and colleagues of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, extracted nuclear and mitochondrial DNA from a 40,000 year old leg bone found in 2003 at the Tianyuan Cave site located outside Beijing. For their study the researchers were using new techniques that can identify ancient genetic material from an archaeological find even when large quantities of DNA from soil bacteria are present.

read more: http://phys.org/news/2013-01-ancient-dna-reveals-humans-years.html

Natural cure: Scientists create stem cell contact lens

Researchers have found a better and a cheaper way to restore human sight by implanting a contact lens containing stem cells that will repair the human cornea.

Scientists from the University of Sheffield hope that the biodegradable implant disc's stem cells will multiply in the eye, thus rebuilding the transparent layer on the front of the eye, known as the cornea, the degradation of which is one of the major causes of blindness in the world, a study published in Acta Biomaterialia journal revealed.

Since stem cells have the ability to renew themselves through mitotic cell division and differentiation into a diverse range of specialized cell types, scientists hope that it will allow the eye to heal naturally as new implants are designed to form thin membranes by grafting the cells onto the eye itself.

Traditional treatment for cornea damage includes transplanting stem cells into the eye using donated human membranes. But in some cases this procedure fails, as in time the repaired eyes lose the retention of these stem cells, which are required to carry out repairs of the cornea.

read more: http://rt.com/news/eye-lens-stem-cells-489/