A Study Suggests that Lucy Spent a Significant Amount of Time in Trees

The mystery of human ancestry has long been a topic of interest throughout the world. For years, paleontologists have made their contribution to the research of this topic by examining fossils. There are what seems like an endless amount of fossils buried beneath the Earth's surface. Some of these fossils share direct ancestry with Homo sapiens. Lucy is one of these fossils. Lucy was discovered by Donald Johanson and Tom Gray in Ethiopia in 1974. 40% of the skeleton had been preserved. The scientists decided that Lucy belonged to a new species, Australopithecus afarensis. Named after the Beatles' song "Lucy in the Sky with Diamonds," Lucy was a momentous discovery. At the time of the discovery, the fossils were to the most ancient early human ever found. Johanson found the fossils to be 3.2 million years old.

A new study suggests that Lucy probably spent a lot of time in trees. It is universally agreed that she walked on two feet and that she climbed trees, but the amount of time spent on the ground and in trees is up for debate. Researchers looked at the way bones can grow stronger through everyday use. By analyzing the structure of her arm and leg bones and comparing it to that of humans and chimpanzees, the leader of the study, Christopher Ruff, concluded that she was "stressing her limbs more like a chimpanzee than a modern human." Ruff discovered this by examining a 3-D scan of the bones. The cortical thickness of the bones was abnormally large. This indicated that she was very strong. Ruff said, "You don't develop that kind of arm strength unless you exercise your arms a lot." This study suggests that Lucy gained her strength by doing a considerable amount of climbing. However, Johanson stills believes that Lucy spent most of her time walking. It is still not clear, but this evidence supports that Lucy was more of a climber than a walker.

I think Lucy was one of the biggest paleontological discoveries of all time. I am interested in the study of human ancestry, and this article definitely taught me a lot about it. There is an almost infinite amount of fossils that are still yet to be discovered. The exact steps to human evolution remain unclear, but this discovery puts us one step closer to fully knowing human ancestry.

Evidence For Possible Unknown Human Relative Found in Modern Human DNA

     We all know that the Neanderthals and Denisovans are the closest relatives to the Homo sapiens (Modern Human) species. However, genetic evidence in Melanesians (Aboriginal Australians, and natives in New Guinea and neighboring islands) hint that there is a possible third extinct hominid relative.



     While many Neanderthal fossils were found in Europe and Asia, and the Denisovans were discovered from DNA from a finger bone and teeth found in a cave in Siberia, the third possible extinct hominid DNA may been preserved in human DNA, and not in fossil evidence, as reported by statistical geneticist Robert Bohlender on October 20 at the annual American Society of Human Genetics meeting. In 2012, a research team suggested that there were also people in Africa carrying DNA from an extinct hominid ancestor. Less than a decade ago, it was even discovered that early humans mixed with other hominid species. Bohlender and his research team concluded that a third hominid group may have bred with the human ancestors of the Melanesians.

   Eske Willerslev and his research team also came to a similar conclusion. They conducted an experiment in which they collected saliva samples from volunteers for DNA sequencing. The DNA examined was from 83 Aboriginal Australians and 25 natives from Papua New Guinea highlands. The researchers found Denisovan-like DNA, but was found to be different and possibly from another hominid species. Willerslev speculates that this DNA can be from Homo erectus or from the extinct Hobbits hominid species, but he is not a hundred percent sure.

  According to evolutionary geneticist Mattias Jakobsson, researchers don't know much about the Denisovan's genetic diversity. He believes that it was possible that a different branch of Denisovans could have been the group that mated with the Melanesians' ancestors. There geneticists like Elizabeth Blue, that believe that the genetic evidence found from Neanderthals and Denisovans is limited. Denisovans may have been spread around the world and have had genetic diversity. If they weren't however, then the genetic evidence could have come from another extinct species.

     I think that it's fascinating how evolutionary evidence could be found in modern human DNA, and not just in fossils. I hope that after further research, scientists would be able to confirm if this genetic evidence came from another distinct hominid species or just another branch of Denisovans. I also think that this evidence can help us learn more about human evolutionary history, along with that of other hominids.

Links:
https://www.sciencenews.org/article/dna-data-offer-evidence-unknown-extinct-human-relative

http://www.nature.com/nature/journal/v538/n7624/full/nature18299.html?cookies=accepted

https://ep70.eventpilot.us/web/page.php?page=IntHtml&project=ASHG16&id=160122719

Trace Your Ancient Human Ancestry with New Map

http://www.livescience.com/54217-map-traces-ancient-human-ancestry.html

A new ancestry map shows the distribution of genomes that are said to be of Denisovan decent around the world. The Denisovans are a more recent addition to the human family tree. While studies have concluded that all people of European and Asian heritage are related to Neanderthals, it is believed that people of South Asian ancestry may be more Denisovan than Neanderthal. Research found that modern interbreeding with Denisovans happened about 100 generations after the interbreeding with Neanderthals. These extinct humans ranged from Siberia to Southeast Asia and have certain classes of genes that may have helped modern humans to adapt to new environments. Scientists are able to determine which traits were better fit but studying what ancestry was removed or added through natural selection. For example, Neanderthal genes most likely contribute to tougher skin and tougher hair. The analysis of of these now extinct humans found that people from Southeast Asia and Oceania have the highest percentage of archaic ancestry while western Europeans have the least amount of Neanderthal or Denisovan genes. While there is increasing understanding of these extinct humans, it does not give enough information to confirm what they looked like, what they ate, and what diseases they were susceptible to.
I had never heard of Denisovans before reading this article, I have only heard of Neanderthals so it was interesting to read about. Reading about ancestry and genome analysis makes me want to use a website like 23andMe or Ancestry.com to learn more about my DNA and my relatives as well as my percentages of Denisovan and Neanderthal. It also makes me wonder if there are even more different types of extinct human groups that existed that we do not know about yet. Neanderthals have been researched for years, but Denisovans are relatively new to the research world. Further research of DNA would be beneficial to understand why our species survived while our close relatives died out.

Ancient Humans May Have Left Genetic Mark In Neanderthals' DNA

Scientists found the first scrap of Neanderthal DNA in a fossil in 1997. Since this discovery, they have recovered genetic material, even entire genomes, from a number of neanderthal bones. These investigations have yielded the remarkable surprise: 1 to 2 percent of the DNA in non-African people comes from Neanderthals. 

This genetic legacy is the result of interbreeding about 50,000 years ago between Neanderthals and the common ancestors of Europeans and Asians. Recent studies even suggest that human health today is influenced by Neanderthal genes, contributing to conditions from allergies to depression. 

Now, scientists have found that genes have flowed both ways. In a study published on Nature, scientists reported that another instance of interbreeding left Neanderthals in Siberia with chunks of human DNA. This exchange seems to have taken place 100,000 years ago. This is confusing, because evidence indicates the ancestors of todays non-Africans did not expand out of Africa until roughly 55,000 years ago. Thus, it is possible that these Neanderthals acquired DNA from a mysterious early migration of humans. 

Humans and Neanderthals split from a common ancestor in Africa around 600,000 years ago. At some point after this, the ancestors of Neanderthals spread to Europe, the Middle East and Central Asia. Along the way, Neanderthals took on the stocky anatomy we are all familiar with. The last Neanderthals appear to have died around 40,000 years ago. 

Scientists Dr. Siepel and Dr. Castellano found an unexpected example of so-called gene flow: the Altai Neanderthals shared some mutations with living Africans, but not Europeans or Asians. This pattern suggests that an African lineage of humans interbred with the Altai ancestors, after they split from Neanderthals. They came to the conclusion that when DNA gets passed down generation to generation, it gets shuffled into new arrangements, which can be built into some sort of timeline. Thus, scientists estimated that humans and the ancestors of Altai Neanderthals interbred about 100,000 years ago - way before people were thought to have left Africa. 

I believe this information throws a wrench in many previous findings and understandings about Neanderthal interbreeding. But, like many other scientific data, new findings alter beliefs every single day. I always believed that Neanderthals simply interbred with human ancestors to make the humans on Earth today, but I never realized that Neanderthals could possibly have human DNA. It is hard to imagine, because this must have happened before non-Africans expanded out of Africa, therefore the Neanderthals must have acquired human DNA from a mysterious early migration of humans. It is amazing how DNA mutations can serve as a timeline, and solve many genetic mysteries. 

Genes Determine the People You're Attracted to

According to a study by researchers at the University of California, San Francisco, a person tends to be attracted to people with similar DNA, specifically with specific genetic ancestry. The phenomenon known as assortative mating suggests a similar theory. According to the study, people typically select mates based on genetic ancestry, outweighing "other socioeconomic factors, such as education levels, which itself has shown to be a powerful predictor of attraction in previous research". The study further concluded that mates were often, on average, the "genetic equivalent of between third and fourth cousins". The specific statistics and collected data pool can be seen in the recent release of Proceedings of the National Academy of Sciences. In 2014, a study was conducted by the University of Colorado, Boulder, in which single-nucleotide polymorphisms were examined among a population. To their surprise, "married individuals were like to be more genetically similar than two individuals randomly selected from the same population". Lots of evidence from multiple studies around the country have confirmed that genetics play a large role in the selection of a mate.

I find this article interesting because I had always assumed that attraction was completely psychological. I hadn't imagined that genetics could be a factor in attraction to others. It is an interesting discovery that I believe needs further scientific investigation, but nonetheless is very interesting and likely an evolutionary adaptation.

Genetic Variant 7R Has Been Identified as Potential "Explorer" Gene

While humans have made many notable strides in evolutionary differences between our fellow mammals – opposable thumbs, brain size and development, advanced language, etc – one notable stride has been gaining the attention of evolutionary biologists, neurologists, anthropologists, and geneticists alike. The expansion and exploration of humanity has fallen under the microscope and the research in this area is ever-growing. As reported by none other than National Geographic (who better?), multiple fields of scientists are examining human exploration, including geneticists. In recent studies, geneticists have been examining the effects of a variation on the DRD4 gene, a gene which influences dopamine, an important neurotransmitter in regards to learning, rewards, excitement, and pleasure. The variant in question, DRD4-7R, has been linked to Attention Deficit Hyperactivity Disorder (ADHD), and is starting to get linked to the exploratory tendency of human nature. In a broad sense, human studies have correlated the presence of the 7R variation to restlessness, curiosity, and higher inclination towards adventure and change. In a larger study  conducted by the University of California, the variant 7R was found more commonly in individuals whose ancestors were highly migratory than those who hailed from more sedentary populations. Other studies have found R7 to be more common in individuals whose ancestors had longer tracks of migration, individuals in modern-day migratory groups who are more physically fit and well-nourished when migrating often as opposed to poorly-nourished individuals in settled villages, and even more common in individuals who have lived to old age and exercised well during their lifetime (both in humans and mice) . While multiple studies do come to the conclusion that there is a correlation of the variant in individuals whose ancestors travel and who benefit well from enriching environments and movement in their lifetime, most professionals agree that human exploration, while unique even among hominids (not even Neanderthals were known to move far from their established territories) , cannot be placed solely onto a single gene. Humans are the only mammal known to explore beyond established territories without the need to do so (i.e. depleted resources, following prey, etc.), but there have been a lot of physical adaptations that have led to this unique trend. The change from quadrupedal to bipedal movement allowed humans to expand their territorial range and increase their endurance; the expansion of the brain and the delay in maturation has allowed for the increase in creative thinking as well as intellect that lead to innovative tools and understanding of scenario-based potential outcomes; the rather un-matched dexterity of human hands allowed the human imagination to expand and build tools to aid in travel. While the R7 gene may correlate to hyperactivity and perhaps to the urge to move and maybe even travel, there are many factors that have led to the expansion and exploration that is inherent in humanity.

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

Modern Humans vs. Neanderthals

A new human genetics study led by Dr. Liram Carmel at the Hebrew University of Jerusalem compared limb bone DNA of a modern living human,  a Neanderthal, and a stone-age Eurasian human known as a Denisovan to better understand how well each species relates to one another. They found that the key difference in the 99.84% similarity between modern humans and Neanderthals is the presence of gene activation patterns similar to an "on/off" switch. The research team found that the remaining 0.16% difference in our DNA is merely a certain portion of gene that modern humans have activated while Neanderthals were not, and vice versa. This pattern of activation has helped contribute to the human epigenome, which differs from the regular human genome in that it is concerned only with those genes that are turned on or off even as the molecular sequence remains the same.

I think the minimal difference between modern humans and our ancestors is always interesting to think about. In thousands of years of evolution, our DNA sequence has only changed by a few tenths of a percent, and yet that has given rise to endless advancements both physically and especially mentally. More impressively, recent research on the human epigenome has helped advance knowledge in how gene silencing leads to cancer, and how twins can differ so much. To me, the epigenome seems like a solid place to turn for more answers on how we can understands and hopefully beat diseases like cancer.

Here is the original article from Chicago Tribune.
Here's a cool timeline of human evolution with some more info on major milestones.

Humans are part Neanderthal

Scientists at the University of Montreal have discovered that humans have a small part of the X chromosome that was once carried by Neanderthals. Their findings are published in the journal Molecular Biology and Evolution. Leading scientist, Damian Labuda, says that interbreeding between Neanderthals and modern humans occurred between 30,000 - 50,000 years ago. Labuda found evidence of this idea about ten years ago, but wasn't completely sure until the Neanderthal genome was released in 2010. When comparing the modern human X chromosome to the Neanderthal X chromosome Labuda found that they shared DNA in all populations except sub-Saharan African. The related gene between modern humans and Neanderthals only codes for a protein, but this could be the first step in finding more similar DNA. The most important idea to come from this research is that this is proof that not only did Homo sapiens interact with Neanderthals, but they most certainly interbred.