At Harvard University, a pair of scientists are busy studying DNA in their laboratory. But while such investigations are nothing out of the ordinary at the Ivy League institution, on this occasion the researchers uncover something truly special. Yes, during their work, the duo make a pivotal discovery – and it’s one that may lead to some incredible changes in the world of medicine.
Perhaps, then, the specialists involved in this breakthrough will ultimately see their names in history books. And if they do, they’ll be following in the footsteps of Benjamin Waterhouse, who was among the faculty at Harvard Medical School in the late 18th and early 19th centuries. Famously, Waterhouse pioneered the use of vaccination for smallpox in the U.S., and in doing so he arguably saved countless lives.
Similarly, Harvard alumnus Reginald Heber Fitz – who was also employed as a professor at the college – made his mark in the late 19th century by recording the symptoms and potential outcomes of patients with appendicitis. Fitz was also among those who promoted the removal of the affected organ as a means by which to save a sufferer of this particular ailment.
The researchers working at Harvard in 2019 were looking to make their mark, however. With assistant professor Mansi Srivastava leading the charge, the scientists were investigating a theory about DNA that, if completely realized, could be especially groundbreaking. And what they discovered may even come to revolutionize how we live our lives.
Yes, thanks to these experts and many like them, much progress in the field of medicine is still being made today. But while some diseases and medical ailments may be relatively simple to understand – especially if your health is suffering as a result of them – the intricacies of DNA are a little more complicated.
So, what exactly is DNA, and why is it so important? Well, the U.S. National Library of Medicine (NLM) has fortunately provided a thorough explanation that ought to clue you in. And if your knowledge of DNA only extends to what you’ve found out through 23andMe, then you should definitely read on.
The post on the NLM website explains, “DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. [And while] most DNA is located in the cell nucleus… a small amount of DNA can also be found in the mitochondria.”
And now you’re probably wondering, what are mitochondria? The NLM says that these are “structures within cells that convert the energy from food into a form that cells can use.” Then, the website shed light on something truly incredible. It turns out, in fact, that all humans have more in common than you may realize.
According to the NLM, “The information in DNA is stored as a code made up of four chemical bases. [These are] adenine (A), guanine (G), cytosine (C) and thymine (T).” But while, as the website explains, “human DNA consists of about three billion bases,” it turns out that “more than 99 percent of those bases are the same in all people.”
So, if every human being is so incredibly similar in this way, what accounts for all of our physical differences? That’s partly down to how that small number of bases – less than 1 percent of the total, remember – combine when we’re growing in the womb. And these so-called variants, some of which may be inherited, are what make each of us stand out from the crowd.
DNA itself, meanwhile, is often depicted in strands that seem to resemble winding staircases. And this recognizable structure is typically referred to as a “double helix.” As that name suggests, then, each double helix is made of two strands of DNA that are joined together in a distinctive spiral pattern.
The NLM’s website also states, “An important property of DNA is that it can replicate or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide, because each new cell needs to have an exact copy of the DNA present in the old cell.”
Given the many complexities of DNA, then, it’s perhaps no surprise that scientists are still trying to determine exactly how it affects our appearance, health and even our personality traits. And, of course, humans aren’t the only ones with distinctive genomes or collections of genetic material. Other members of the animal kingdom possess these, too, and their biological make-up can sometimes give them incredible abilities.
For instance, geckos use a pretty bizarre trick to help them survive in the wild. Yes, even though the lizards are often prey for other creatures, they can stop any pursuit in its tracks. Thanks to their genetics, you see, they can cleanly detach their tails – thus throwing hunters off of their scent and allowing them to get away.
But don’t worry, a gecko isn’t left tailless for long; within just a couple of months, they’ll have grown a completely new one. Salamanders have a similar regenerative ability, too, although in their case, it’s even more useful. If, for example, one of these amphibians loses a leg – entirely possible if it finds itself in the jaws of a raccoon – then it’s no problem. Yes, you’ve guessed it: eventually, the limb will simply grow back.
However, both sea anemones and planarian worms take things to a whole new level. These creatures, you see, can rebuild large portions of their bodies after they’ve succumbed to damaging attacks. The planarian worm can essentially multiply itself in those situations as well – and again, that’s all thanks to its DNA.
If a single planarian worm gets sliced in half, you see, both of those pieces can ultimately become separate living things. These incredible creatures may even multiply in greater numbers depending on the severity of the injury that the original worm has sustained. So, it’s a jaw-dropping process that shows off the intricacy of their genetics.
Jellyfish are equipped with some staggering abilities, too. Much like planarian worms and sea anemones, these aquatic lifeforms can also restore their own bodies. But that’s certainly not all. Indeed, back in the 1990s, a group of researchers uncovered a truly remarkable phenomenon when studying the Turritopsis dohrnii jellyfish.
Upon closer inspection, the team realized that this particular species of jellyfish could physically change itself from a mature adult to an undeveloped infant and vice versa. And owing to this astonishing process, these ocean-dwellers may even be able to ward off death in perpetuity. It’s no wonder, then, that Turritopsis dohrnii has been referred to as “the immortal jellyfish.”
In 2016, meanwhile, a scientist from Japan noticed something both strange and wonderful about his pet jellyfish. That’s right, months after his aquatic creature had seemingly passed away, it somehow managed to revive itself. And from there, his pet went on to age in reverse – much in the same manner as Turritopsis dohrnii.
This incredible regenerative process is understandably something that the Harvard researchers wanted to learn more about. During their work, then, the scientists were looking at the DNA of a creature known as Hofstenia miamia – or the three-banded panther worm. And as they investigated the worm’s genetic material, they made a potentially game-changing discovery.
As previously mentioned, Srivastava was in charge of this particular project, with the zoologist accompanied in her study by postdoctoral researcher Andrew Gehrke. And after the pair had made their momentous find, the details of their work went on to be published in a March 2019 edition of the journal Science.
But what exactly did Srivastava and Gehrke uncover? Well, within their DNA, animals also harbor what are known as “non-coding controls.” And while some experts have previously dismissed these sequences as being unimportant, the Harvard scientists discovered that they were, in fact, quite the opposite. In short, they realized that a particular piece of non-coding DNA may actually play a big role in regeneration.
Furthermore, through their examination of the three-banded panther worm, Srivastava and her colleague saw that the non-coding DNA kick-started a “master control gene.” This gene is otherwise known as early growth response (EGR). And when talking to The Harvard Gazette in March 2019, Gehrke explained exactly what EGR does.
Gehrke told the outlet, “What we found is that this one master gene comes on [and activates] genes that are turning on during regeneration. Basically, what’s going on is [that] the non-coding regions are telling the coding regions to turn on or off. So, a good way to think of it is as though they are switches.”
And Srivastava then revealed why the three-banded panther worm made the ideal subject for such tests. According to the assistant professor, you see, Hofstenia miamia could potentially give unparalleled insights into exactly how some animals manage to regenerate parts of themselves. This, in turn, could even have ramifications for us humans further down the line.
Speaking to The Harvard Gazette, Srivastava explained, “Previous work on other species helped us learn many things about regeneration. But there are some reasons to work with these new worms. The way they’re related to other animals allows us to make statements about evolution. [And] they’re really great lab rats.”
“I collected [three-banded panther worms] in the field in Bermuda a number of years ago during my [postdoctoral studies],” Srivastava continued. “And since we’ve brought them into the lab, they’re amenable to a lot more tools than some other systems.” But not every creature has the regenerative potential of Hofstenia miamia, as Srivastava went on to make clear.
The associate professor added, “We were able to decrease the activity of [EGR], and we found that if you don’t have [it], nothing happens. The animals just can’t regenerate.” That’s right, if you’re not biologically equipped with the master control gene, you won’t automatically be able to grow new limbs.
If you think that Homo sapiens doesn’t have the capacity for this ability, though, then the following information may just catch you off guard. Indeed, Gehrke told The Harvard Gazette, “It turns out that EGR, the master gene, and the other genes that are being turned on and off downstream are present in other species – including humans.”
Meanwhile, Srivastava explained, “The reason we called this gene in the worms EGR is because when you look at its sequence, it’s similar to a gene that’s already been studied in humans and other animals. If you have human cells in a dish and stress them, they’ll express EGR right away.”
Bearing that in mind, then, you may be wondering why the human body doesn’t simply grow back any parts that may be missing. And in an attempt to explain this, Srivastava went back to the switch comparison. She hinted that, ultimately, there may come a time when the secret is unlocked.
“If humans can turn on EGR – and not only turn it on but do it when our cells are injured – why can’t we regenerate?” Srivastava pondered. “The answer may be that if EGR is the power switch, we think [that] the wiring [in humans] is different. What EGR is talking to in human cells may be different than what it’s talking to in the three-banded panther worm.”
Srivastava added, “And what [Gehrke] has done with this study is come up with a way to get at this wiring. So, we want to figure out what those connections are and then apply that to other animals. [This would include] vertebrates that can only do more limited regeneration.”
Ultimately, then, there could be an exciting future ahead for human medicine. After all, if Srivastava, Gehrke and their peers in the field can understand our internal “wiring,” regeneration may well follow. But as you would imagine, there’s still a lot to figure out before such a process even becomes feasible.
Nonetheless, Srivastava and Gehrke are continuing their work on the subject. “Now that we know what the switches are for regeneration, we are looking at the switches involved in development and whether they are the same,” Srivastava told The Harvard Gazette. “Do you just do development over again, or is a different process involved?”
Gehrke added, “Only about 2 percent of the genome makes things like proteins. We wanted to know: what is the other 98 percent of the genome doing during whole-body regeneration? People have known for some time that many DNA changes that cause disease are in non-coding regions.”
“But [non-coding regions have] been underappreciated for a process like whole-body regeneration,” Gehrke continued. “I think we’ve only just scratched the surface.” So, what does this all mean for humans? Well, Srivastava touched on the matter – and suggested how any further studies may proceed – when talking to The Harvard Gazette.
In particular, Srivastava seemed to suggest that people would now be more inclined to think about the possibility of human regeneration. She said, “It’s a very natural question to look at the natural world and think, ‘If a gecko can do this, why can’t I?’ There are many species that can regenerate and others that can’t.”
The assistant professor concluded, “It turns out [that] if you compare genomes across all animals, most of the genes that we have are also in the three-banded panther worm. So, we think that some of these answers are probably not going to come from whether or not certain genes are present but from how they are wired together. That answer can only come from the non-coding portion of the genome.”
Of course, while it’s great to look into studies that will hopefully change the future of mankind in some way, it’s equally as fascinating when scientists can piece together events in the past. And again, DNA often plays a crucial role in this. For a long time now, you see, experts have thought that humankind originated in Africa – but new evidence now seems to prove otherwise.
A massive lake glistens beneath the sun, cutting a clear expanse across an otherwise lush wetland, some 200,000 years ago. Here, a new species – Homo sapiens – has gathered. These modern humans have evolved from their Neanderthal ancestors, and humankind has at last started its reign. Yet scientists have just now pinpointed the surprising place where it all began.
In fact, geneticist Vanessa Hayes of the Garvan Institute of Medical Research in Sydney led a study that used specific scientific data to pinpoint this exact verdant locale. In particular, Hayes and her expert team had to rely on mitochondrial DNA, which they had gathered from the cells of 1,217 samples. This battery-shaped genetic material passes from mothers to their children, so the researchers naturally had to find a population with a maternal line that stretched far into the past.
With the right DNA information gathered and analyzed, then, the research team highlighted a general area of origin. And after that came further archaeological and geological research that in turn helped Hayes and co to find something spectacular: evidence of a massive, ancient lake that broke down into wetlands. Its lush greenery was the backdrop for the first humans to walk the Earth, they say, and its modern-day location may just surprise you.
Experts have, of course, long believed that humankind traced all the way back to the African continent. But mapping evolutions and migrations has been a difficult task, to say the least. It was about seven million years ago when human beings began to evolve, after all, splitting off from primates such as the chimpanzee and the bonobo.
So it’s virtually impossible to find every link between humans and primates, since scientists simply don’t have enough fossil records to achieve this. In fact, entire species may have come and gone without leaving a trace for experts to uncover today. That’s why, in some cases, there are only bits and pieces of evidence to work with.
Yet the picture of humankind’s ancestral roots becomes clearer as scientists move nearer to the present day. They know, for example, that Neanderthals roamed Europe and even trekked into Siberia and Central Asia – although not as far as Africa. But while this population may have paved the way for modern humans, they did not actually originate the species.
Instead, it would be the evolution of Homo heidelbergensis and Homo erectus that gave way to Homo sapiens. And these new humans presented a variety of slight differences that separated them from the likes of the Neanderthal population who roamed the continent before them. For one, Homo sapiens took on a more slender build than the stockier Neanderthals up north.
In addition, modern humans mastered the art of making tools in a way that Neanderthals hadn’t. The African contingent styled their weapons to have sleek, elongated blades, for example. They also fashioned their weapons into more sophisticated throwing spears – which made their hunting more effective. The Neanderthals, by contrast, wielded clunkier weapons that had been chiseled from large stones.
But the fact that both the Homo sapien and Neanderthal populations had similar lifestyles did initially confound modern-day experts. As a result, then, scientists formulated two main theories about how and where humankind had developed. Some believed in what’s called the multi-regional hypothesis. This states that human ancestors spread across the globe – thus allowing modern humans to evolve in a handful of different places worldwide.
Then there is a single-origin concept known as the Out-Of-Africa theory. As the name suggests, this idea purports that modern humans grew and evolved on the continent for millennia before migrating to other areas of the Earth. And during the 1980s, scientists seemed to have gathered what appeared to be a clear confirmation of the Out-Of-Africa theory.
This was due to DNA testing. In fact, DNA testing completely revolutionized science in a number of ways. In terms of determining humankind’s ancestral roots, though, scientists could – using these tools – analyze the genetic information of modern populations. From there, they traced multiple subjects’ lineages back into the distant past, and these mappings seemingly always led researchers to one place of origin: Africa.
In these original studies, too, experts relied on mitochondrial DNA when tracing their subjects’ ancestral lineages. This part of the genetic code comes from people’s mothers. In addition, this section of DNA will present mutations more readily than others. So it’s therefore easier to follow how mutations have passed from mothers to children for generations.
In fact, in repeatedly tracing this mitochondrial DNA back all the way to the cradle of civilization, experts realized that one woman’s genetic code has been carried through to everyone on Earth today. She’s known to scientists as “Eve” – although she’s not the same as the biblical figure. She is not considered as the first ever human woman on Earth, after all.
Rather, this Eve lived when the entire human population consisted of a mere 10,000 people. So Eve was neither the only – nor the oldest – of our ancient predecessors. She just happened to have an unbroken line of daughters who passed her mitochondrial DNA onto their baby girls and down through the ages right through to the present day.
In short, Eve is regarded as humankind’s “most recent common ancestor,” according to Smithsonian magazine. A 2008 DNA analysis confirmed, too, that she is the only woman of that time to have an unbroken lineage of daughters. And the scientists behind the study also concluded that Eve had originated in Africa – more specifically, the eastern area of the continent.
Eve’s DNA therefore seemed to reveal the start of humankind’s story. Yet the experts had lots of other questions. If the species originated in Africa, for instance, how did they spread out to other continents? And why are such a disproportionate number of fossils from Europe? To answer these queries, then, the researchers combined the same DNA evidence with archaeological finds.
And all of this information pointed to major migrations that started between 60,000 and 80,000 years ago. At that time, then, modern humans seemingly left their African origins for Asia. By about 45,000 years ago, though, they had already moved into Australia, Indonesia and Papua New Guinea, too. Then, 5,000 years after that, bands would leave Africa for Europe.
Humans who journeyed from Africa to Europe likely took one of two pathways to get north. Some would have traced the Mediterranean coast to get onto the continent, while others probably passed through Turkey and along the Danube. Their insurgence also pushed Neanderthals into a few mountainous areas – until the species disappeared altogether about 25,000 years ago.
The final step in humankind’s journey would bring them to the Americas. This happened about 15,000 years ago and actually began in Asia. From there, you see, Homo sapiens traveled across the Pacific to reach North America. And once on land, some members of the species continued to wander until they settled in South America as well.
It’s hard to believe that all of this information comes with little fossil evidence of the first humans who started it all. And this is especially surprising considering the changes that have occurred on the African continent – where humankind is said to have originated. Today, in fact, the dry landscape easily erodes and reveals the bones of those who died there centuries ago.
Yet archaeologists have had little luck in uncovering the remains of the earliest Homo sapiens – whether they dig in Africa or in Europe. Still, the experts believe that the first humans maybe did not bury their dead like the Neanderthals, choosing instead to cremate them or leave them to decompose out in the open.
In spite of this lack of skeletal remains, though, modern science and technology has allowed researchers to pinpoint human origins. Yes, a 2019 study helmed by geneticist Vanessa Hayes of the Garvan Institute of Medical Research in Sydney relied once again on mitochondrial DNA for answers.
As previously mentioned, Hayes and her team gathered 1,217 mitochondrial DNA samples from people who currently live in southern Africa. Some of the test subjects even came from the Khosian population – an indigenous group who speak with clicking consonants and have long foraged for their sustenance.
From those samples, Hayes and the team traced what’s known as the L0 lineage in the subjects’ mitochondrial DNA. The L0 lineage goes all the way back to Eve – humankind’s common ancestor. Over time, then, Eve’s original DNA split into five main branches as people left Africa and diversified.
The L0 line, as it’s called, also has its own deviations. For instance, it branched about 130,000 years ago, when some of the human population moved from their original homes as heavy rains transformed dry lands into vegetation that could support human life. While some people followed this greenery to the southwest, though, others moved northeast to become farmers and foragers.
But the L0 mitochondrial DNA started somewhere, and Hayes and her team were able to pinpoint precisely where. Generally, they found that L0 and all of its sub-branches once again placed the earliest humans in Africa. Its territory in fact stretched from Namibia into Botswana and then on to Zimbabwe.
Then Hayes and the research team added geological, fossil and archaeological evidence into their findings. And while some of the areas of interest may seem uninhabitable in the modern era, the information gleaned about this potential point of human origin showed that it used to look very different.
The massive Lake Makgadikgadi – roughly the size of New Zealand – once covered a huge swathe of modern-day Botswana. About 200,000 years ago, though, it started to transform from lake into wetland. And according to Hayes and her team, this marshy expanse was the cradle of modern humankind.
Looking at the region today, however, it’s hard to believe that the origins of human life on Earth could have grown from this arid area. The one-time wetland sits south of the Zambezi River, and it’s nothing like it was in its water-logged past. Instead, it has dried up into sprawling salt pans, with white expanses of the mineral glistening in the sun.
According to Hayes, though, the area looked a lot different 200,000 years ago. In place of the unforgiving salt pans was a resource-laden wetland. As she told The Guardian in 2019, “It would have been very lush, and it would have provided a suitable habitat for modern humans and wildlife to have lived.”
At the time, Hayes says, the Botswana-based wetland would have served as an oasis for the arid area surrounding it. So humankind may have started there 200,000 years ago and remained in the area for 70,000 more years. But it’s believed that a shift in climate eventually pushed the founding humans from the wetlands.
As the Earth’s orbit and tilt shifted, in fact, it brought rains to new stretches of African land. Precipitation then encouraged plant growth, which sprung up in lengthy, lush corridors. These green pathways then gave humans a reason to branch out of their wetland homes and into new territories. This was a precursor to their great global migration, which began about 60,000 to 80,000 years ago.
Essentially, then, Hayes and her team reiterated the long-held origin of humankind’s roots – but they pinpointed the spot as a wetland in Botswana. Hayes said, “We have known for a long time that modern humans originated in Africa and roughly 200,000 years ago, but what we hadn’t known until this study was where exactly.”
Not all experts felt convinced by Hayes’ research, however. Chris Stringer, an expert in human origins at London’s Natural History Museum, admitted that modern DNA samples might not be entirely representative of the past. He explained, “I’m definitely cautious about using modern genetic distributions to infer exactly where ancestral populations were living 200,000 years ago – particularly in a continent as large and complex as Africa.”
Stringer also felt that Hayes and her team had been overly reliant on the mitochondrial DNA – and L0 lineage – as the main factor in their research. He cautioned, “Like so many studies that concentrate on one small bit of the genome, or one region, or one stone tool industry, or one ‘critical’ fossil, it cannot capture the full complexity of our mosaic origins once other data [is] considered.”
Other studies have also traced humankind’s ancestors back to other pockets of the African continent. In fact, Stringer highlighted a study that focused on the Y chromosomes that only men inherit. This research actually suggested that migration had commenced from west Africa – quite a distance from landlocked Botswana in the south.
Another study also found that those who left Africa for other lands carried genomes that traced back to the continent’s eastern areas. Stringer concluded, “These and many other data suggest that we are an amalgam of ancestry from different regions of Africa with, of course, the addition of interbreeding from other human groups outside the continent.”
Ultimately, Stringer called Hayes’ findings an “over-reach.” He told BBC News, “You can’t use modern mitochondrial distributions on their own to reconstruct a single location for modern human origins. I think it’s over-reaching the data because you’re only looking at one tiny part of the genome, so it cannot give you the whole story of our origins.”
Some scientists also still believe that humankind came from more than one single place. In fact, University of Cape Town archaeologist Rebecca Ackermann told The Guardian that our roots could be in Africa – and beyond. She noted, “Drawing sweeping conclusions about places of origin from analyses of this tiny part of the modern genome is deeply problematic and outdated.”
Nevertheless, Hayes’ study did pinpoint one potential origin for humankind – and many experts have long believed that the species did, indeed, evolve in Africa. Yet even with modern science and DNA testing, it still may prove an impossible question to answer definitively. For now, though, we can consider life as it may have been 200,000 years ago – with the first humans finding their way in a Botswana wetland.