Early Humans in Europe Mated with Neandertals Surprisingly Frequently

    

     An article from Science News talks about how DNA analysis of some of the oldest human remains in Europe showed that inbreeding between Homo Sapiens and Neandertals was more common than previously thought. Neandertals were found to have to contributed about 3 to 4 percent of DNA found in H. Sapien remains found in Bulgaria. A skull found in the Czech Republic had 2 precent of Neandertal DNA as well. It is now believed that ancient humans actually got a large amount of DNA from the Neandertal population before it went extinct. The migration of human populations that did not have any ancestry with the Neandertals diluted the Neandertal DNA from the human gene pool.

    I find this incredibly fascinating that a species deemed "inferior" actually contributed to the gene pool of early humans, and that these species interbred with one another. I also think that it is very interesting that scientists are able to determine that these ancient DNA samples contain such a small portion of Neandertal DNA and determine roughly how many generations away the individual was from a Neandertal.

More information here

Hobbits

Research conducted at Princeton University studied if there was a possible link of modern pygmy population that lives in an Indonisian island. On this island it was found hobbit remains or scientific name Homo floresiensis fossils. (1)

H. floresiensis  were on average 3.5 feet tall, these short hobbits lived 17,000 years ago. The fossils recovered where not well preserved and scientists found it difficult to extract DNA that was viable for testing. Once DNA was sequenced they wanted to compare that to the modern pygmy population that are on average 15 inches taller then H. floresiensis, the thought that they may have similar ancestry.
They decided to develop a tool that would "help find archaic genetic sequences in modern DNA".(1)
There was this thought that since many humans share DNA from Neanderthals, and even Denisovans that just maybe these modern pygmy people have H. floresiensis DNA.
"But if you want to look for another species, like Floresiensis, we have nothing to compare, so we had to develop another method: We 'paint' chunks of the genome based on the source. We scan the genome and look for chunks that come from different species -- Neanderthal, Denisovans, or something unknown." said Serena Tucci (1)
After looking through 32 modern pygmies Tuci states " they definitely have a lot of Neanderthal, and a bit of Denisovan. We expected that, because we knew there was some migration that went from Oceania to Flores, so there was some shared ancestry of these populations."
No Homo floresiensis  was found in these people suggesting the modern pygmy population evolved independently.
"Islands are very special places for evolution, this process, insular dwarfism, resulted in smaller mammals, like hippopotamus, and elephants, and smaller humans. This is really intriguing, because it means that evolutionary, we are not that special," Tucci said. "humans are like other mammals, we are subject to the same processes."
This I believe is an important step to helping know our place in the world. We are subjected to environmental changes like any other species and adapt to survive.

resources:
1- https://www.sciencedaily.com/releases/2018/08/180802141558.htm
2- https://www.sciencedaily.com/releases/2018/08/180802141719.htm
3- https://www.sciencedaily.com/releases/2017/04/170421084917.htm
4- https://www.sciencedirect.com/science/article/pii/S0047248417300866?via%3Dihub

Neanderthals made their own jewelry, new method confirms

Neanderthals are the closest, extinct relatives to modern humans. They are either a species or a sub-species of man who were prevalent before their physical and intellectual development into Homo sapiens. Neanderthals are considered to be the first people to make tools and control fire. A new study shows that Neanderthals made their own jewelry. Archaeologists found bone tools, fossils, and make-shift necklaces in the Grotte du Renne cave in France. Scientists were unable to use DNA to link the Neanderthals to the artifacts, so they used a new method involving proteins to identify the fragments. This method delved into the new and growing field of paleo-proteomics.

Neanderthal fragments found in the Grotte du Renne cave

By examining the proteins, researchers were able to specifically compare the chemical composition of collagen in the artifacts and fossils to the collagen produced by modern people and Neanderthals. Neanderthal collagen contained a different amino acid than modern human collagen. The researchers also sequenced the mitochondrial DNA. Not only did they see that the ancestry was Neanderthal but also they noted that the fragments contained high levels of nitrogen isotopes, associated with breast-feeding. This led the team to conclude that some of the Neanderthals were infants. Through radiocarbon dating, the fragments were able to be chronologically linked with the tools and jewelry found nearby. 

This study demonstrates that Neanderthals had the ability to make their own tools and jewelry, but it also allows for more questions. Modern humans may have possibly had a social and genetic influence on Neanderthals. Through mating and socialization with Homo sapiens, the Neanderthals may have obtained enhanced cognitive abilities. I believe this is a great start to researching if enhanced cognitive skills have a genetic basis. By learning about our past and our history, we can learn more about our present selves and our future. 

Lack of Neanderthal Y Chromosome Genes in Humans

Figure 1. Neanderthal woman (left) and modern human (right)

It is not widely known, but modern humans carry up to 4% of Neanderthal DNA. This occurred because of interbreeding between the two species about 50,000 years ago when Homo sapiens were expanding to Eurasia. Of this 4% of DNA, there is none coming from the Neanderthal Y chromosome. Some scientists believe this merely due to chance that it was lost in the human gene pool, but new research presents a more likely option. Several of the Y chromosome genes of Neanderthals are a part of the immune system, so a woman's immune system would attack these genes because they see it as a threat because of the incompatibility. This would have also led to miscarriages between the two species. So far this is only a hypothesis, but the mother's immune system has been known to perform similar acts.

Before reading this article, I had no knowledge that a part of our DNA was that of the Neanderthal's. Though it is insignificant it is still fascinating to see that it is even present. It makes one wonder if there is other Homo DNA in our genomes. I also believe that the 4% will surely disappear completely within a few hundred years. If their hypothesis is correct, then mother immune systems will continue to eradicate any remaining Neanderthal Y chromosomes due to its incompatibilities.

Beneficial Contributions From Neanderthals to Modern Humans

Recent studies show that cross breeding between Homo sapiens and Neanderthals may have allowed humans to adapt to certain areas more easily. While the modern lineage of humans were still located in Africa, the Neanderthals had already migrated to Europe and Asia. Less than 100,000 years ago, humans began to leave Africa and at this point interbred with Neanderthals. Researchers speculate that the group that had already moved to Eurasia had adapted to their surroundings genetically. One specific example is the inner working of the keratinocytes that allows skin to moderate moisture loss and protect against pathogens. Other Neanderthal genes found in humans are associated with battling infections and protecting against ultraviolet radiation.

Some genes were beneficial to Homo sapiens while others researchers believe were harmful. Geneticists were led to believe this because they found "holes" in the human genomes that do not connect back to their closest extinct relatives. According to the study, the gene that is involved in human speech does not have any connections to Neanderthals. The study also indicated that the two groups were too distantly related to successfully breed. David Reich found that hybrids had issues with fertility. This information was a surprise to researchers because most animals need to be separated by a larger number of generations before they become their own species.

Researchers are constantly discovering new information about human genomes and how they relate back to our ancestors. Continuing to do research on this topic can help to make discoveries in other areas such as the medical field. It is very important and necessary that we find out as much as possible about our genes. 

Man's Genome from 45,000 Years Ago is Reconstructed

The genome of a man who lived 45,0000 years ago has now be reconstructed, from a fossil thighbone found in Siberia. Not only do the results give insight into the expansion of modern humans from Africa into Eurasia, but it is strong supportive evidence for the hypothesis that at one point, modern humans interbred with Neanderthals. This was accomplished by a team of scientists, led by geneticist Svante Pablo in Leipzig, Germany.

The team was able to do this by retrieving small parts of genes, reading the sequences and joining the fragments together to make larger pieces of the genome. They found that this man (who they deemed Ust’-Ishim man) was part of a lineage that eventually gave rise to all non-African humans, living after homo sapiens migrated from Africa, but before the species split between Europe and Asia.

The team was also able to reconstruct a Neanderthal’s genome from a single toe bone. Comparing a Neanderthal’s genome to that of Ust’-Ishim man, it was found that he had pieces of Neanderthal DNA in his genome, but with the significant difference that he had much longer pieces of Neanderthal DNA, compared to the much shorter fragments you would find in humans today. Thus showing that he was part of a lineage more closely related to Neanderthals.

From the findings, the scientists hypothesize that humans and Neanderthals interbred between 50,000 and 60,000 years ago, and that non-Africans descended from a group of people this man belonged to, who moved out of Africa, also around 60,000 years ago.

It’s very interesting to see the gaps in the history of our species slowly be reconstructed. Although we may never know everything, this is a great discovery. The hypothesis that we only just moved out of Africa, and were interbreeding with another species, just 60,000 years ago is astonishing; since that is not a long time ago in the great scheme of things, and much less than the hypothesis 100,000 years ago. I hope that more discoveries like this will not only reveal the past, but reveal how we slowly evolved into modern humans.

Link to article: http://www.nytimes.com/2014/10/23/science/research-humans-interbred-with-neanderthals.html