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blood test that detects Large mammals

A team of scientists developed a test that can estimate the age of an individual with only a blood sample.

The method can be used, for example, forensic investigators who need information related to age of a suspect or dead.

The technique is based on the identification of a characteristic of a type of immune cells called T cells, which are transported in the blood.

These cells play a key role in the recognition of "invading" foreign to the body, such as bacteria, viruses, parasites or cancer cells.

As part of the process that cells use to recognize these invaders produce small circular DNA molecules.

The number of these molecules, known as excision circles of T cell receptor (sjTREC) decreases steadily with age.

According to scientists, the study shows that this biological phenomenon can be used to calculate "with precision and reliability," the age of a human individual. Strangers



This approach, say the researchers, will locate an individual in a category that extends generational in 20 years.

Predicting the "phenotypes" humans, the external characteristics of a person as hair and eye color-from the information in DNA is a new emerging field of forensic science.

But now, with the DNA information can be identified only a few features phenotypes with sufficient precision to have practical implications.

As explained by Dr. Manfred Kayser, who led the study, the new test has proved the most accurate of all tests that are designed to calculate a human characteristic phenotype from DNA information.

"The conventional DNA profiling to forensic science applied can only identify people who are already known to the investigating agencies," explains the scientist.

"Therefore, every forensic laboratory has found cases in which the DNA profile obtained from material evidence did not match any of the suspects tested no one in the database of criminal DNA.

"In those cases, it is expected that the information is clear evidence of material help find strangers," he adds.

Experts expect the new test, along with the methods currently used to reconstruct the appearance of strangers from a biological sample found at the scene of the crime, eventually help to solve more cases.

The details of the investigation carried out in Medical Center of Erasmus University in Holland, are published in the journal Current Biology. (BBC)

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age filled the void left by dinosaurs

disappearance of the dinosaurs 65 million years ago allowed the mammals to increase their size, according to a new study published in the journal Science.

After carefully reviewing a number of fossils, the researchers concluded that the extinction of the dinosaurs helped mammals weighing between one and ten kilograms reached, in some cases, the 17 tons.

specialist scientific topics of the BBC, Neil Bowden explained that all this happened for 25 million years, a relatively short period in geological terms.

"There was a time when the hornless rhinoceros and called protoelefantes Deinotherium Indrucotherium and dominated the world, "says the study.

Scientists say that during that time, the ecosystem was able to" reprogram "quickly to meet the needs of these animals, whose size increased dramatically.

Brake However

growth stopped there, because warm-blooded mammals are not able to maintain a constant body temperature.

may, while the animals occupied the continent, the area of \u200b\u200bland and food have become scarce also, say researchers in Science.

giant mammals lived only until few thousand years ago in the form of woolly mammoths.

These creatures could be gone by the existence of other mammals are much smaller than the hunted: humans. (BBC)