DNA from Extinct Humans Discovered in Caves







Throughout the world, there are many different archaeological excavation sites throughout Europe and Asia that have given us tools and human made artifacts that give of us information of how the people of these periods lived. However when it comes to skeletal and other human remains left behind, the number is much lower. Recently, scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany have discovered new ways to obtain human DNA. Over four different archaeological sites including the Vindija Cave in Croatia in the picture above, these scientists have extracted the DNA of a variety of mammals, including our human ancestors. They also collected several samples of Denisovan DNA sediments from the Denisova Cave in Russia. With the collection of these DNA samples, we now know how to collect genetic affiliations of the humans that inhabited several previously found excavation sites with no yield of human remains.




The excavation as well as the analysis of the genetic composition of these emains of gives us a clearer understanding of our own evolutionary history. There are a small amount of human remains, however, a small sample of the DNA can tell us a lot. The scientists found the DNA to twelve different mammalian families that include extinct species such as the woolly mammoth, the woolly rhinoceros, the cave bear and the cave hyena. With more research done with the skeletal remains of ancient humans and other mammals, the more we will know about human evolution and the evolution of the world over the past 10 of thousands of years.


Links:

https://www.sciencedaily.com/releases/2017/04/170427141708.htm

http://www.bbc.com/news/science-environment-39747326

Why Don't Humans Have Much Neanderthal DNA in Them?

A long time ago, Neanderthal's and modern day humans diverged from a common ancestor, but only 1 of the 2 species did well.  The neanderthals did not just get wiped off the earth, since about 50,000 years ago, they interbred with modern humans as they were leaving Africa, leaving a small amount of their DNA behind.  And by small, I mean very small.  The question is, why is there such a small amount of DNA left over by the neanderthals, and why did the neanderthal human hybrids not survive well?  One answer is as simple as population size.  In smaller populations, natural selection is not as strong of a factor in the population, and so the neanderthals were subject to a lot of inbreeding, and overall the entire population developed and spread more and more mutations around within themselves.  Since these mutations did not stop them from breeding with each other, it can be assumed that all of these mutations built up, and eventually became a very large problem for  neanderthals.

This information also shows why not much neanderthal DNA remains in modern day humans.  Since the neanderthals already were so heavily mutated, when they bred with humans, they passed along their mutations to the hybrid offspring, who then either would have died from the mutations, or would have then passed them down again to their offspring, and so on.  Overtime this process makes it so that the small amount of DNA that was transferred from neanderthal to human was slowly lost, but not completely, resulting in a very small amount of their DNA found in modern humans.

I'm a little surprised that the answer to this problem is so simple.  All it really has to do with is population size, and I think that that is really interesting.  Granted the small population size does make a lot of sense, I didn't think to take into account that this means that there would be a lot of inbreeding occurring among the population, which also makes a lot of sense.  It is also pretty interesting that because of this initial inbreeding, that the major effects of it made the neanderthal human hybrids less likely to survive, and so the amount of neanderthal DNA in modern humans is so small.

http://www.nytimes.com/2016/11/09/science/neanderthal-dna-natural-selection.html?rref=collection%2Fsectioncollection%2Fscience&action=click&contentCollection=science&region=stream&module=stream_unit&version=latest&contentPlacement=58&pgtype=sectionfront 

http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1006340

Animal hybrids may hold clues to Neandertal-human interbreeding

It has long been thought that lineages between species were rigid lines that do not connect with other living species and that mating between species is impossible.  Recent studies show that human evolution may have been a river stream of  inter connected lineages that interbred rather than the conventional theory that our lineage was a tree with individual lines leading to each species.  After comparing modern day non-African human DNA with DNA from Neandertal fossils, it was found that 1.5 to 4 percent of Neandertal DNA still exists in our genome.  There is also evidence of interbreeding between humans and another ancient hominid known as the Denisovans.  Evidence of these interbreeding relationships can be found in human skulls that have been found in caves that share a resemblance to the skulls of our ancient hominid relatives.

Drawing comparing human skull to Neandertal skull.

Some scientists believe that these ancient skulls may be the evidence of hybrids that are the product of human and hominid mating.  Species that diverged from a common ancestor within a few million years still have the capacity and similar DNA to still be able to reproduce.  To further observe this, scientists have experimented with hybridizing species that exist today and comparing the results they get with those of the cave skulls they have found.  Yellow and olive baboons were interbred to see how the resultant generations would appear and what traits would be exhibited.  The results showed that hybridization blurs the lines between species and makes it harder to detect differences among the species.  Due to this, a theory has come up that Neandertals were not physically pushed to extinction by being out-competed by humans, but rather they slowly began to fade away by interbreeding with humans and leaving their mark in our DNA. 

Man's Long Lasting Friend

Dogs in the modern day and age have been called man's best friend, but many forget that they have been our friends the longest out of all bred and domesticated animals throughout the history of the human race. A grad student from the United Kingdom, Angela Perri, has been trying to identify how dogs may have been used in the hunting techniques of early human civilization. While accompanying hunters near Hiroshima, Japan, she observed how dogs were used to hunt. Through warning the hunters when the boars were close, they protected the hunters from a blindsided boar charge and shed off time during the hunt with their senses Perri then began studying the companionship and found history of 110 dog burials in Japan.

Artwork of an Ancient Japanese Hunt with Dogs

The fact that the Japanese dogs were only revered in a time and place where they would have made ideal hunting companions strongly suggests that they did indeed play this role, Perri reports this week in Antiquity. She also points to a 2500-year-old bronze bell found on the cast coast of Honshy that contains an engraving believed to depict an event from even further in the past: a boar surrounded by a hunter and his pack of dogs.

Now she, along with other scientists are looking for evidence in dog evolution over time to see how they have been domesticated to be hunting companions. In the light of genetics, one would be able to look at the fossils left behind to see certain changes in gene expression over time of the structural changes that dogs went through during their domestication over thousands of years. This question along with what truly tamed the dogs still remains uncertain today.

Some think early human hunter-gathers actively tamed and bred wolves. Others say wolves domesticated themselves, by scavenging the carcasses left by human hunters, or loitering around campfires, growing tamer with each generation until they became permanent companions.

The importance of this discovery surpasses the idea that dogs are now our friends. It is important to identify the first human and dog relationships in order to fill in the gaps in our human history and development. Our manipulation of breeding and genetics of other animals could have affected our own evolution and development and how we grew and changed as human beings.

Regardless of the missing evidence that we have in modern time, I think that it is rational to believe that humans, in order to hunt better, domesticated dogs and bred them selectively to these capabilities. Having evidence such as a systematic dog burial obviously means that dogs were very important for humans to breed and befriend. Whether they were used for nursing, hunting, protection, or friendship, the dog was the first and one of the most important domestic animals to develop our human civilization and promote our survival.