AP Biology class blog for discussing current research in Biology

Tag: chimpanzee

Your Inner Chimpanzee



What is the closest living relative we have (evolutionary speaking)? That’s right, chimpanzees!! Our evolutionary paths separated us about five to six million years ago leading to the chimpanzee of today, and us humans of the 21st century, but we still have much in common. Like humans, Chimpanzees use body language to communicate. They often kiss, hug, pat each other on the back, hold hands and shake their fists. They even laugh when they get tickled. At the same time, a lot has also changed. Not only do we stand on two legs and are relatively hairless, but we also have brains that function differently. 


Recent research from Lund University has found the answer to what in our DNA makes our brains different. Created by Shinya Yamanaka, the study used a revolutionary stem cell technique. Yamanaka discovered that if reprogrammed specialized cells can be developed into all types of body tissue. It was even recognized by the 2012 Nobel Prize in Physiology or Medicine. 


The researchers used stem cells grown in a lab. Their partners in Germany, the US, and Japan reprogrammed the skin cells. Then Johan Jakobsson, professor of neuroscience at Lund University, and his partners examined the stem cells that they had developed into brain cells. Using the stem cells, the researchers specifically grew brain cells from humans and chimpanzees and compared the two cell types. The researchers then found that humans and chimpanzees use a part of their DNA in different ways. This appears to play a significant role in the development of our brains.


What the researchers learned was different in part of our DNA they and I found so unexpected. Unlike previous research in the part of the DNA where the protein-producing genes are — about roughly two percent of our entire DNA, the difference that was found indicated that the differences between chimpanzees and humans appear to lie outside the protein-coding genes. The research found that it is actually located a so-called structural variant of DNA in what has been labeled as “junk DNA,” a long repetitive DNA string that has long been deemed to have no function. This was thought to have no function. 


This data suggests that the basis for the human brain’s evolution is a lot more complex than previously throughout genetic mechanisms, as it was supposed that the answer was in that 2 percent of the genetic DNA. These results indicate that the overlooked 98 percent is what has been significant for the brain’s development is instead perhaps hidden in, which appears to be important. 


Researchers hope to answer that question one day. But there is a long way to go before they reach that point. The question that now remains is instead of carrying out further research on the two percent of coded DNA should they delve deeper into all 100 percent. Even though exploring the missed ninety-eight percent is a considerably more complicated task for research. 


One question that also definitely still remains is why did the researchers want to investigate the difference between humans and chimpanzees in the first place?  


Well, Johan Jakobsson believes that in the future the new findings will prove his belief that the brain is the key to understanding what it is that makes humans human. How did it come about that humans can use their brains in such a way that they can build societies, educate their children and develop advanced technology? It is fascinating!” (Lund University). He hopes that this research will contribute to answers about things like genetically-based questions about psychiatric disorders, such as schizophrenia. As for me, I wonder if this continued research will tell us anything about how Chimpanzees will evolve. 



The Human Brain vs. Chimpanzee Brains – The TH Gene

Well let’s start off with, what is the TH gene? The TH gene is a “protein encoded by this gene is involved in the conversion of tyrosine to dopamine. It is the rate-limiting enzyme in the synthesis of catecholamines, hence plays a key role in the physiology of adrenergic neurons.” How does this even relate to human and chimpanzee brains?

However, here’s a little background to the dimensions of the human brain compared to the chimpanzee brain. Modern humans share about 95% of their genetic code with chimpanzees.  Yet, human brains are three times larger, have many more cells, and would therefore have more processing power than a chimpanzee. Does this mean chimpanzees do not function as efficiently as the human brain or are there just some areas a human brain can be efficient on better as for the chimpanzee brain as well ?

According to two researchers from Yale University, Ying Zhu and André Sousa, TH was found highly expressed in human neocortex, but absent from chimpanzee neocortex. Sousa states, “The neocortical expression of this gene was most likely lost in a common ancestor and reappeared in the human lineage.” Since the gene is absent from the chimpanzee cortex, does this mean that they do not produce any dopamine? Do chimpanzees produce dopamine in a different way?

At the end of the day, we can conclude that human and chimpanzee brains do have a vast majority of similarities. Alternatively, there are certain aspects to the chimpanzee and human brain that allow us to differentiate the two and continue to allow for extensive research in such fields. I challenge you to discover something specific about the human brain and chimpanzee brain that are both extremely similar and different. What will you discover next?

Violent Chimpanzees


Scientists had wondered whether chimpanzees were naturally violent to one another or if human influence made the animals more aggressive. A recent study disproved the theory that chimpanzee violence was caused by human impact. Researchers analyzed chimpanzees and bonobos (pygmy chimpanzee) in Africa and noticed that the mammals killed other members of their species to provide themselves with more resources and territory, ultimately becoming a more dominant primate.

The argument was supported by Dr. Michael L. Wilson, an anthropologist at the University of Minnesota and the study organizer for the research. Wilson led the 54-year study with 29 other authors and collected data on 18 chimpanzee groups in Africa. According to the researchers, there were 152 chimpanzee killings, the scientists observed 58, they inferred 41, and suspected 53 killings in 15 communities. Wilson contributed data from the Ngogo group of chimpanzees in Uganda and found that they were “the most violent group of chimpanzees there is,” even though their habitat is little disturbed by humans. The chimps just “go around and kill their neighbors.”

Other anthropologists from different universities wanted more data on the subject. Robert Sussman at Washington University continues to support the idea that humans pressure chimpanzees to act in violent ways because the statistics from Wilson’s paper did not tell him enough. “They haven’t established lack of human interference.” Humans are too involved in chimpanzee societies and the animals then reflect that human behavior. Brian Fergusan at Rutgers University held a similar view to Sussman and claimed that the impact humans have on the chimps “can’t be assessed by simple factors” organized by Wilson.

The new data changed this solid theory that human interference in chimpanzee society made the primates more violent. While some scientists remain dismissive on the paper, the data offers a new view on the argument.





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