Modern humans have crossed paths with at least five groups of archaic humans

A new study published in the Proceedings of the National Academy of Sciences (PNAS) gives us some details on the so-called blending events that have seen modern men join different groups of archaic humans in the course of their history following their departure from Africa.

It is thought that modern human beings crossed with at least five different archaic human groups in the course of their history that saw them move from Africa through Eurasia to Southeast Asia and beyond. Two of these archaic groups are known: the Neanderthals and the Denisovans group. The others remain unknown although DNA analysis shows the union of our ancestors with other different populations.

In particular, according to the researchers, it was the area of ​​South-East Asia that was a “hotbed of diversity.” As João Teixeira, a researcher at the University of Adelaide, specifies the first author of the study, “These archaic groups were widespread and genetically different and survive in each of us. Their story is an integral part of what we have become.”

An example is given by the fact that today’s populations show in their DNA about 2% of the DNA of the Neanderthals. This, and other genetic data, shows that mixing with Neanderthals must have taken place almost immediately after our ancestors left Africa, in a period between about 50,000 and 55,000 years ago somewhere in the Middle Orient. However, our ancestors, traveling further east, met and mixed with other different groups of humans.

Using various information regarding these migratory routes, the researchers concluded that an important mixing event must have occurred in the areas of southern Asia, in Southeast Asia, with a group that was named “Hominino Estinto 1.” Other crossings, probably of lesser incidence, must then have taken place in East Asia, in the Philippines and near the island of Flores, Indonesia, with another group that the same researchers called “Hominino Estinto 2.”

This information shows that the history of our ancestors once they left Africa seems to be much more complex than I previously deduced and that the South East Asian region played a very important role in the mixing events that led to modern men thanks also to a relative geographical isolation of these populations for hundreds of thousands of years.

Furthermore, this information also suggests that the disappearance of these archaic human populations occurred substantially coinciding with the arrival of modern humans.


Cortisol levels in hair indicative of depression or mental illness in adolescents

According to a group of researchers from Ohio State University, one day it may be possible to diagnose depression or mental illness in adolescents by analyzing their hair.

Analyzing the concentration of cortisol, a stress hormone, in the hair as well as the same symptoms of depression in 432 adolescents aged between 11 and 17 years, the researchers have in fact found what was defined in the press release appeared on the website of the University as a “surprising connection.”

In fact, higher cortisol levels seemed to correspond to a greater probability of depression while lower levels could be linked to mental problems. Few types of research in the past have considered this hormone as a possible predictor of depression and in this sense, this research provides fairly new data in this sense.

In the scientific article, which appeared in Psychoneuroendocrinology, we describe the experiments and analyzes carried out by researchers who suggest, as specified by Jodi Ford, a nursing professor at the aforementioned university and the principal author of the study, that there may be an average level of cortisol which can be considered as “normal”: a level that is too low or too high could therefore indicate bad things.

This discovery leads to an important connection whose demonstration requires further research though, as Ford itself points out, “it is possible for some people to experience a reduction in the stress response that reduces cortisol production or changes the way in which is processed. Maybe the body isn’t using cortisol the way it should in some cases.”


New sauropodomorphic dinosaur species identified in South Africa

A fossil dinosaur specimen preserved at the University of Witwatersrand, Johannesburg, was analyzed again following an erroneous identification made years ago.
Paleontologist Paul Barrett, along with several South African colleagues, aided in particular by student Paul Barrett, has identified a new species of sauropodomorph, as well as a new genus.

The new dinosaur has been named Ngwevu intloko, which can be translated as “gray skull” in the Xhosa language. As Barrett also specifies, the samples of this dinosaur were collected in the areas of Johannesburg some thirty years ago and have been examined by other scientists and paleontologists. Eventually, it was concluded that it was a specimen of Massospondylus, a sauropodomorph and one of the first dinosaurs to appear at the beginning of the Jurassic.

By analyzing the fossil remains more closely, Barrett and Chapelle understood that it is a new species. The differentiation was possible thanks to the fact that there are various dead Massospondylus specimens at various stages of growth, from the embryo to the adult specimens. The remains were represented by “extraordinarily well preserved” pieces of the skull. It was a bipedal dinosaur, quite large, with a long, slender neck but a small square head.

It measured about three meters from the tip of the snout to the end of the tail and was probably omnivorous. This specimen must have lived around 200 million years ago, on the border between the Triassic and the Jurassic, a period characterized by a mass extinction phase.

The discovery is important because until a few years ago it was thought that there was only one type of sauropodomorph with regard to the area of ​​today’s South Africa. With recent discoveries, including this one, “we now know that there were actually six or seven of these dinosaurs in this area, as well as varieties of other dinosaurs from less common groups. It means that their ecology was much more complex than we thought. Some of these other sauropodomorphs were like the Massospondylus, but some were close to the origins of true sauropods, if not true sauropods themselves,” as Professor Barrett points out.

The study was published in PeerJ.