Study claims to identify the homeland of all modern humans
A DNA study looks for the home of the earliest modern humans.
- A DNA study traces the homeland of modern humans to the Makgadikgadi-Okavango wetland.
- The area is shared by the modern-day countries of Botswana, Namibia and Zimbabwe.
- The researchers drew conclusions from the mitochondrial DNA of humans living in that area today, but some scientists question their methodology.
Is there a specific location on Earth where humans like us originated? A new study pinpoints an area called the Makgadikgadi-Okavango wetland, shared by the modern-day countries of Botswana, Namibia and Zimbabwe in southern Africa as the birthplace of modern humans (Homo sapiens sapiens) about 200,000 years ago.
Scientists from the Garvan Institute of Medical Research discovered that the earliest ancestors of humans appeared in that area and lived there for about 70 thousand years. Eventually, they were forced to expand their domain by the climate changes in Africa.
The study lead Professor Vanessa Hayes from the Garvan Institute of Medical Research, who is also associated with the University of Sydney and the University of Pretoria, highlighted the significance of their find:
"It has been clear for some time that anatomically modern humans appeared in Africa roughly 200 thousand years ago," said Hayes. "What has been long debated is the exact location of this emergence and subsequent dispersal of our earliest ancestors."
For their study, the scientists focused on examining the mitochondrial DNA of modern-day residents of the area. Hayes explained that "Mitochondrial DNA acts like a time capsule of our ancestral mothers, accumulating changes slowly over generations." This fact allowed the researchers to compare the DNA code (or mitogenome) of different people to figure out how closely related they are.
The scientists were able to use collected blood samples to put together a much improved catalogue of the mitogenomes of early humans.
The study's first author Dr. Eva Chan from the Garvan Institute of Medical Research, who led the phylogenetic analyses, expanded on their methodology:
"We merged 198 new, rare mitogenomes to the current database of modern human's earliest known population, the L0 lineage," said Chan, adding "This allowed us to refine the evolutionary tree of our earliest ancestral branches better than ever before."
Dr Eva Chan & Professor Vanessa Hayes.
The researchers looked at the L0 lineage timeline in combination with distributions of various sublineages based on language, culture and geography. What they found is that the maternal lineage of humanity emerged in what they dubbed a "homeland' area south of the Greater Zambezi River Basin region. This "homeland" includes all of northern Botswana stretching into Namibia to the west and Zimbabwe to the east.
Why was this area so perfect for humans to develop? According to research by the geologist Andy Moore of Rhodes University, that area once contained Lake Makgadikgadi – Africa's largest-ever lake system. Once the lake started to drain due to shifts in the tectonic plates underneath, it left behind a fertile wetland, which was favorable for sustaining life.
The ecosystem was home to the early humans for 70K years until about 130 to 110 thousand years ago, when people started venturing out northeast and southwest from the area, while a group stayed in the area (with their descendants still found there today).
Why did many people leave the "homeland," which today is actually one of the largest salt flats in the world? Climate change simulations from the study's co-corresponding author Professor Axel Timmermann, Director of the IBS Center for Climate Physics at Pusan National University, point to shifts in rainfall which created "green, vegetated corridors" leading out of the area. These allowed the human ancestors to leave the homeland and look for greener pastures elsewhere.
"These first migrants left behind a homeland population," pointed out Professor Hayes. "Eventually adapting to the drying lands, maternal descendants of the homeland population can be found in the greater Kalahari region today."
Not everyone is on board with the scientists' findings. Mark Thomas, an evolutionary geneticist at the University College London, said in an email to National Geographic that "The inferences from the mtDNA data are fundamentally flawed." He also called the study "storytelling."
But others, like University of Hawaii at Manoa geneticist Rebecca Cann, who was a reviewer of the study and has carried out her own pioneering work on mitochondrial DNA, supports the study, saying while the study is "not perfect", it will move the science along and "stimulate a lot of new studies."
Check out the new study "Human origins in a southern African palaeo-wetland and first migrations" published in Nature.
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Credit: Gunawan/Nature magazine
Students who think the world is just cheat less, but they need to experience justice to feel that way.
- Students in German and Turkish universities who believed the world is just cheated less than their pessimistic peers.
- The tendency to think the world is just is related to the occurence of experiences of justice.
- The findings may prove useful in helping students adjust to college life.
The world is just? That’s news to a lot of people.<p>The study is the most recent addition to a long line of work focusing on the belief in justice, our behavior, and our reactions to evidence that might suggest injustice occasionally occurs. This study focuses on a personal belief in a just world, (PBJW) rather than a general belief in a just world (GBJW). The difference between them must be highlighted.</p><p>GBJW is the stance that justice prevails all over the world and that people tend to get what they deserve. PBJW is more focused on the individual's social environment and their belief that they tend to be treated justly. While several studies show PBJW correlates with a higher sense of well-being and a variety of other positive effects, a high GBJW is associated with less life satisfaction, negative behavior, and callousness towards the suffering of <a href="https://link.springer.com/book/10.1007%2F978-1-4939-3216-0" target="_blank">others</a>. This study controlled for GBJW, and focused on PBJW as much as possible. </p><p>To assure that culture was not a factor, the study included students at universities in both Germany and Turkey. </p><p>The researchers gave students at the four participating universities a series of questionnaires that asked if they ever cheated in class, if they perceived the world to be just, if they though that justice always prevailed everywhere, their tendencies towards socially appropriate behavior, their life satisfaction, and if they felt like they were treated justly by their teachers and fellow students. </p><p>The answers were statistically analyzed for relationships. While some of the connections seem trivially true, others were surprising. <strong></strong></p><p>PBJW turned out to only be an indirect predictor of if a student was likely to cheat. Both a belief in a just world and a lower likelihood of cheating were mediated by the justice experiences of the students, with more of these positive experiences lowering the rate of cheating and improving their belief in justice. This was also associated with higher levels of life satisfaction. </p><p>These effects existed across all demographics in both countries. </p>
What does this mean? Is a belief in justice a self-fulfilling prophecy?<iframe width="730" height="430" src="https://www.youtube.com/embed/6oMv-azHNCA" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p>In a way, it seems to be. People who have reason to think the world is just to them tend to interpret events in a way to sustain that belief and behave in a just manner. In a larger sense, the take away from this study is that experiences of justice, both from peers and instructors, is vital to student's wellbeing and understanding that the rules that exist about cheating are part of a larger, legitimate, system. </p><p>The researchers, citing previous studies on the perception of justice, note that "justice experiences (1) signal that university students are esteemed members of their social group, which in turn conveys feelings of belonging and social inclusion and (2) motivate them to accept and observe university rules and norms. These cognitive processes may thus strengthen their well-being and decrease the likelihood that they cheat."</p><p>The authors also suggest that if you want people (not only students) to act justly; consider treating them with "civility, respect, and dignity."</p><p>Sometimes, all it can take to help somebody act virtuously is to treat them well. Likewise, people treated harshly can rarely find reason to play by rules that don't protect them. The findings of this study will certainly add to the literature on how we perceive justice in the world around us, but might also help us remember that there are real consequences to our actions which can be much larger than we imagine. <strong></strong></p>
This could change how researchers approach vaccine development.
- The reason children suffer less from the novel coronavirus has remained mysterious.
- Researchers identified a cytokine, IL-17A, which appears to protect children from the ravages of COVID-19.
- This cytokine response could change how researchers approach vaccine development.
A member of staff wearing personal protective equipment (PPE) takes a child's temperature at the Harris Academy's Shortland's school on June 04, 2020 in London, England.
Photo by Dan Kitwood/Getty Images<p>Experts don't want to place kids at the back of the line, regardless of how strong their immune systems appear. At least one company, Moderna, <a href="https://www.businessinsider.com/coronavirus-vaccine-for-kids-moderna-plans-pediatric-trial-2020-9" target="_blank">hopes to begin testing</a> vaccines in pediatric volunteers by year's end.</p><p>Innate immune response is especially high during childhood (compared to adaptive immunity). This makes evolutionary sense: nature wants an animal to survive until its ready to procreate. Turns out the children in the study possessed high levels of cytokines that boost their immune response. The biggest impact is made by IL-17A, which appears to protect the youngest cohort from the ravages of the coronavirus. </p><p>While both age groups produced antibodies to fight off the infamous spike protein, adults that produce neutralizing antibodies actually suffer a <em>worse</em> fate. Herold says this "over-vigorous adaptive immune response" might promote inflammation, triggering acute respiratory distress syndrome (ARDS). </p><p>This matters for vaccine development. As Herold says, </p><p style="margin-left: 20px;">"Our adult COVID-19 patients who fared poorly had high levels of neutralizing antibodies, suggesting that convalescent plasma—which is rich in neutralizing antibodies—may not help adults who have already developed signs of ARDS. By contrast, therapies that boost innate immune responses early in the course of the disease may be especially beneficial."</p><p>Herold says current vaccine trials are focused on boosting neutralizing-antibody levels. With this new information, researchers may want to work on vaccines that boost the innate immune response instead. </p><p>With <a href="https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html" target="_blank">at least 55 vaccine trials</a> underway, every piece of data matters. </p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank" rel="noopener noreferrer">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
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