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horsehair worm

‘Mind-Controlling’ Parasitic Worms Are Missing 30% of Genes Found in All Other Animals

Parasitic worms known for their “mind controlling” abilities are missing 30% of genes that are found in all other animals, scientists say. The thread-like worms are notorious for compelling their insect hosts to jump into water and drown.

Horsehair worms, of which there are hundreds of species, hatch in water where small water-dwelling predators eventually eat their larvae. Land-dwelling predators, such as crickets and beetles that consume these smaller predators, make the ideal host for the parasite.

After spending months as larvae inside these larger predators, the adult parasites force their hosts to actively seek out and enter bodies of water. Once the insect has drowned, the horsehair worms swim out of the host’s rear orifices to begin their next generation.

The worms resemble spaghetti strings, are only a few inches long, and are found all around the world. Spending most of their lives inside other animals, they have no excretory, respiratory or circulatory systems.

According to a study published Tuesday in the journal Current Biology, horsehair worms, which belong to the phylum Nematomorpha, lost about a third of the genes found in other animals somewhere along their evolutionary history. Genome sequencing of two nematomorph species—the freshwater hairworm Acutogordius australiensis and the marine species Nectonema munidae—led researchers to find the missing genes. Beyond their unique reproductive behavior, very little was known about the worms’ genetics until now.

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Tauana Cunha, a postdoctoral research scientist at Chicago’s Field Museum of Natural History and lead author of the study, says, “One of the coolest things, maybe the thing that they are most known for, is that they can affect the behavior of their hosts and make them do things that they wouldn’t do otherwise.”

Cunha told CNN that compared with other animals, the worms seemed to be missing a group of around 200 genes.

“There’s a given set of genes that are expected to be found across animal groups. It’s used as a metric for the quality of your genome.”

The genes are known to control the development of cilia—short hairlike structures found at the cellular level, which aid in cellular movement, perform sensing functions, and remove debris and microbes.

The “tail” of a sperm cell is actually just a single, highly specialized cilium. Many microscopic organisms use cilia to swim and catch food. These structures also line our respiratory tract, retinal cells, and the surface of our lungs.

“We set out to sequence their genomes because nothing like them has ever been sequenced before at that level. The goal was to produce those genomes and eventually use them to understand the evolutionary relationships between hairworms and other kinds of animals.”

Horsehair worms seem to be thriving without cilia. “The large majority of the missing genes were exactly the same between the two species; this was just implausible by chance,” says Cunha about the marine and freshwater horsehair worm species studied.

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Biologist Keiichi Kakui, a lecturer in the Department of Biological Sciences at Hokkaido University in Japan, told CNN that the promising new research combines “genome-scale molecular data and detailed morphological observation.”

Kakui was the lead author of a separate study that identified juvenile marine horsehair worms in isopods, a type of deep-sea crustacean. It is unclear how these parasites are able to navigate the ocean without the sensory structures available to most other animals.

“It is hard for me to imagine how this species finds and enters their host in the vast deep sea.”

Scientists had previously identified five species of marine horsehair worms, joining the hundreds of species found in freshwater. Marine horsehair worms, in contrast to their freshwater counterparts, live their entire lives underwater and are not known to manipulate their hosts’ behavior. However, it appears that all species are missing the same genes, which may indicate that both lineages share a common ancestor from which the genetic deficiency was inherited.

Cunha says the new genetic information could also be used to learn about other parasitic organisms known to influence the behaviors of their hosts.

“By doing this comparative analysis across organisms in the future, we might be able to look for similarities. Or maybe these organisms evolved similar behaviors in completely different ways from each other.”

graves

Genes That Helped People Survive the Plague Linked to Autoimmune Disorders in Descendants

Scientists have discovered that the same genetic characteristics that helped people survive the Black Death more than 700 years ago are now linked to an elevated risk of developing certain autoimmune disorders.

Using the DNA of victims and survivors of the Black Death from the 14th century, scientists have discovered that Europeans with a variation of the gene called ERAP2 had a substantially better chance of surviving the disease. The mutations provided protection against the Black Death pathogen Yersinia pestis, which went on to kill off nearly half of Europe’s population.

These results, published in the Journal “Nature,” provide insight into how the Black Death influenced the development of immunity genes like ERAP2 and laid the groundwork for how some people react to disease today. For instance, inheritors of the gene have a higher risk for autoimmune diseases such as Crohn’s disease and arthritis.

Luis Barreiro, professor of genetic medicine at the University of Chicago Medical Center and co-author of the study, believes this study provides new insight into the true evolutionary impact of the plague.

“This is, to my knowledge, the first demonstration that indeed, the Black Death was an important selective pressure to the evolution of the human immune system.”

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The study was carried out on more than 500 ancient DNA samples collected from the teeth of people who had died before, during or after the plague. Some samples were taken from skeletons buried in London’s East Smithfield plague pits. According to Barreiro, the pits were used for mass burials in 1348 and 1349 when people were dying so quickly that the city’s cemeteries were running out of space.

“So the king [Edward III], at the time, bought this piece of land and started digging it. There’s basically layers and layers of bodies one on top of each other.”

Samples that contained two copies of the ERAP2 gene indicated an ability to produce functional proteins, which helped the immune system to recognize an infection. The variant also helped immune cells neutralize the virus more efficiently, making the person 40% more likely to survive the plague than their peers. However, the mutations enhanced the body’s inflammatory response, making people more susceptible to autoimmune disorders.

Hendrik Poinar, professor of anthropology at McMaster University in Canada and co-senior author of the study, said the study showed the ability of pandemics to alter genome sequences in the long-term without being detected in modern populations.

“These genes are under balancing selection – what provided tremendous protection during hundreds of years of plague epidemics has turned out to be autoimmune-related now. A hyperactive immune system may have been great in the past, but in the environment today, it might not be as helpful.”

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Evolutionary biologist David Enard from the University of Arizona said the speed of the adaptation over just a few decades had other implications. The 40% survival advantage the variant bestowed is the most significant evolutionary advantage recorded in humans.

“The evolution is faster and stronger than anything we’ve seen before in the human genome. It’s really a big deal. It shows what’s possible [for humans], in terms of adaptation in response to many different pathogens.”

According to paleogeneticist Maria Avila Arcos, the study still has its limitations by only being carried out on a narrow population. The plague also affected parts of Asia and North Africa.

“There might be way more cellular mechanisms people used to cope with this devastating outbreak, but we’re just seeing the mechanisms shared across the English and Danish.”

Evolutionary Study Shows Human Bodies Were Partially Shaped By Climate Change 

As humans evolved, it’s become common knowledge that our body’s and brain’s have both increased in size as we developed into the Homo Sapiens we are today. The original Homo genus emerged about 300,000 years ago, and today we are much larger and have a brain three times as big as our human ancestors who lived a million years ago. 

Scientists have long debated why humans evolved the way that they did. There’s a multitude of potential explanations for why our bodies and minds grew into what they are today, but one of the newer possibilities has to do with climate change, and the role it’s played in our evolution overall. 

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A research team led by Cambridge University and Tübingen University in Germany have combined data on more than 300 human fossils from the Homo genus alongside climate models to establish a direct connection between the Earth’s climate and our evolutionary journey.

The study, published in Nature Communications, explained “what temperature, precipitation and other climate conditions each of the fossils, spanning the last million years, would have experienced when it was a living human. We found a strong link between temperature and body size, showing that climate was a key driver of body size during that period.”

The colder it gets, the bigger the humans are. If you’re bigger, you have a bigger body – you are producing more heat but losing relatively less because your surface is not expanding at the same rate,” said Dr. Manuel Will, a Tübingen University researcher and author on the study.

“It’s not completely surprising, but it’s interesting to see that in this respect our evolution isn’t that different from other mammals. We face similar problems when it comes to gaining and losing heat, so we seem to have evolved in similar ways,” said Dr. Nick Longrich.

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The study also linked changes in climate to brain size among the Homo genus species, however, it found that the environment has a much greater impact on body size than brain size. 

“This phenomenon shows that body and brain size are under different selective pressures. This study really manages to detangle the fact that both brain and body size are increasing, but increasing for very different reasons.”

“The more stable [the climate] is, the larger brains are. You need a lot of energy to maintain a big brain – in stable environments, you find more stable food, so you likely have sufficient nutrition to give you that energy,” said Dr. Will.

Dr. Will also pointed out that evolution is ongoing, “but there are different drivers now to a million years ago. The past gives us clues about the future; we can learn from it. But we cannot simply extrapolate from it. While we are currently seeing that the climate is getting warmer, we cannot assume that our bodies will get smaller as a result.”

Israeli Flag

New 130,000-Year-Old Human Fossils Discovered In Israel 

Scientists have recently discovered a new kind of early human after studying pieces of a fossilized bone that was dug up at a cement plant located in central Israel. The fragments of the skull and lower jaw included teeth that suggested the fossils were about 130,000-years-old. 

The researchers were from Tel Aviv University and the Hebrew University of Jerusalem, and spoke about the discoveries this past week. The fossils are called Nesher Ramla Homo, after the location in which they were discovered. 

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The earliest humans had very large teeth and no chin, and the study suggested that they may have been ancestors of the Neanderthals, which would challenge current thinking that our evolutionary cousins originated in Europe. 

“The discovery of a new type of Homo is of great scientific importance. It enables us to make new sense of previously found human fossils, add another piece to the puzzle of human evolution, and understand the migrations of humans in the old world.”

Dr Yossi Zaidner works for Hebrew University and is the one who found the fossils while exploring a mining area of the Nesher cement plant near Ramla. The team of scientists discovered the bones about 25-feet deep along with some stone tools and the bones of horses and deer. 

The study said the Nesher Ramla “resembled pre-Neanderthal groups in Europe. This is what makes us suggest that this Nesher Ramla group is actually a large group that started very early in time and are the source of the European Neanderthal,” said Hila May, a physical anthropologist at the Dan David Center and the Shmunis Institute of Tel Aviv University.

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May explained how before this discovery experts were never able to explain how Homo sapien genes were present in earlier Neanderthal populations, but now, the Nesher Ramla group may be the reason for that.

The jaw bone of these fossils had no chin and the skull was flat. 3D shape analysis revealed that the group was not related to any known group of early humans. “What they did match were a small number of enigmatic human fossils found elsewhere in Israel, dating back even earlier, that anthropologists had never been able to place,” May said. 

“As a crossroads between Africa, Europe and Asia, the land of Israel served as a melting pot where different human populations mixed with one another, to later spread throughout the Old World,” said Dr Rachel Sarig, from Tel Aviv University.

Sheela Athreya, a Texas A&M University paleoanthropologist said the new research “gives us a lot to think about in terms of the history of population groups in this region, and how they may have interacted with populations in other regions, in Europe and North Africa.”

The Nesher Ramla fossils “look like something on a lineage heading toward Neanderthal. They seem to be categorized as fossils of an intermediate variety — this group may be predecessors to Neanderthals in this area.”

New Fossils Reveal Giant Rhinos Were Once The Largest Land Mammals To Walk The Earth 

It’s been a widely known fact in the science community that giant rhinos once roamed the Earth some 25 million years ago. While they have long been considered one of the largest land mammals that ever lived, experts were still confused as to how they were able to evolve into the rhinos we more commonly see today.

Additionally, scientists had little to no information about how these rhinos travelled throughout Asia and ended up in the parts of the world where rhinos are most commonly found now. 

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Now, paleontologists have found new fossils that are finally answering some of these questions. The fossils were specifically a part of a new, sixth species of extinct giant rhino, Paraceratherium linxiaense, and where they were discovered has given experts a greater insight into how these giants move across China, Mongolia, Kazakhstan, and Pakistan. 

The team of researchers was led by Deng Tao from the Institute of Vertebrate Paleontology and Paleoanthropology. 

The researchers uncovered one fossil of a completely preserved skull, jawbone, and teeth with their associated atlas; the part of the body where the head meets the spine. Another discovered fossil has three preserved vertebrae. 

The remains gave the team enough information to create a digital 3D model of this new species so that they can compare them to other giant rhinos. The team was able to determine this newest discovery was a newer rhino species due to its longer and more flexible neck. 

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The fossils were found in Gansu Province, China right at the northeastern border of the Tibetan Plateau. The fossils were likely from the Late Oligocene period which lasted from about 34 million years ago to about 23 million years ago. These rhinos were significantly larger than the rhinos of today, with an estimated shoulder height of 16 feet and a weight of over 40,000 pounds. These rhinos also lacked horns. 

“The Tibetan region likely hosted some areas with low elevation, possibly under 2,000 meters during Oligocene, and the lineage of giant rhinos could have dispersed freely along the eastern coast of the Tethys Ocean and perhaps through some lowlands of this region,” researchers wrote in the study

Researchers determined that, “in the Early Oligocene, the animal dispersed westward to Kazakhstan, with a descendant expanded to South Asia, then returning north to cross the Tibetan area to eventually produce P. linxiaense to the east in the Linxia Basin.”

“Late Oligocene tropical conditions allowed the giant rhino to return northward to Central Asia, implying that the Tibetan region was still not uplifted as a high-elevation plateau,” Deng said.

Melting Glacier

Climate Change May Release Ancient Viruses Trapped in Melting Glaciers

It’s common knowledge at this point that global warming is melting the world’s glaciers, leading to a rise in sea level and the destruction of habitats for life around the North and South Pole. However, scientists now have an additional concern relating to the melting of glaciers, which is that this melting may lead to the release of never-before-seen frozen viruses which have been trapped within glaciers for fifteen thousand years. As scientists have never before had an opportunity to study these mysterious viruses, they are of significant scientific interest, as not only do they offer a window into the history of the evolution of viruses, but learning about these viruses may give doctors a better chance of treating people who could potentially be affected by them. While it’s unlikely that humans will contract diseases caused by the release of these ancient viruses, the fact that so little is currently known about them leads researchers to be on high alert, as no one can say for certain what effect they might have on human beings.

Accordingly, a study, which was posted on the bioRxiv database but has not yet been peer reviewed, explores a novel method of studying these ancient viruses that minimizes the chances of contamination by modern-day bacteria. In order to prevent contamination, the researchers brought two ice core samples collected from the Guliya ice cap on the Tibetan Plateau to a cold room, where the thermometer was set to 23 degrees Farhrenheit, and cut into the ice sample with a sterilized band saw. Then, they washed the ice cores with ethanol and sterile water to expose an uncontaminated layer of ice. 

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By examining this layer of ice, the researchers found 33 groups of virus genuses, 28 of which were previously unknown to science. Between the two ice core samples, the microbes differed significantly, representing the fact that the two ice cores existed in very different climates at the time that the viruses became embedded in the ice. Researchers expect that glaciers around the world contain substantially more ancient, frozen viruses that are currently unknown to science.

One of the dangers posed by climate change is not only that these mysterious viruses could be released into the world, but that the melting of glaciers could destroy these preserved viruses, preventing scientists from learning more about the history of the evolution of viruses. Currently, glacial viruses are severely understudied, and climate change may have the effect of making study of these viruses impossible. 

Songbird

Flock of Undiscovered Songbirds Discovered Across Remote Islands

Since 1999, only an average of around five or six new bird species have been discovered across the planet each year. Therefore, it’s no surprise that the discovery of ten previously unseen songbird species has been met with a great deal of interest by ornithology and biodiversity experts the world over.

The discovery, detailed in the Jan. 10 issue of Science magazine, reveals an intriguing look at avian biodiversity. Made across several Southeast Asian islands near Sulawesi in the Wallacea region – Peleng, Taliabu and the Togian group – the discovery lists five new species alongside five new subspecies, based on the physical features, DNA and song variations of the birds. Some of these differences are visually prominent – for example, the yellow-bellied Togian jungle-flycatcher (Cyornis omissus omississimus) features a crown of iridescent blue feathers to set it apart from its cousins.

It had long been suspected that islands of Taliabu, Peleng and the Togian group may be home to a number of undiscovered bird species. The islands in question are separated from Sulawesi, the nearest landmass, by deep ocean waters; this has restricted a number of animals for intermingling throughout the region, as well as limiting access from predators. In fact, a number of tropical forest birds in the area rarely explore outside of safe, shady forest cover, meaning they are relatively undisturbed by other species.

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In recent years, the majority of new bird species have been found in South America, namely Peru and Brazil. The discovery of new species in Indonesia isn’t a total surprise though, as some researchers in the 1990s did identify what they believed to be new songbird species in the region, but neglected to collect specimens or formally describe any findings. However the fact that animals have been able to exist and survive there for so long without being documented is somewhat surprising – especially considering the number of species found.

The birds are not living without risk though – logging and severe forest fires have been threatening their habitats in recent years, and some predictions suggest the newly discovered species may not survive many more years. These elements are putting a great deal of pressure on biodiversity across the planet, and while conservation efforts are working hard to ensure the survival of such species, little can be done for those that have yet to be discovered.

So what does this discovery mean for avian biodiversity across the world as a whole? Considering North America alone has seen numbers of birds decline by 29% since 1970, the survival of these species is crucial. In the U.S., these numbers are largely due to the loss of natural habitat caused by both climate change and agricultural development, as birds are struggling to survive without the correct environment available, while seabirds are also facing the threat of marine heat waves. Living so remotely, the newly discovered songbirds have managed to largely avoid some of these factors – however this does not mean they aren’t at risk from environmental threats.

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The general consensus between researchers is that Earth is currently undergoing a sixth mass extinction, meaning for the sixth time in the life of the planet global fauna is experiencing a catastrophic collapse in numbers. The United Nations predicts up to one million species could face extinction, and this includes a large number of birds. Conservation groups are working hard to ensure that animals are protected from threats, but as we have seen with the recent wildfires in Australia, this is not always possible. Taliabu and Peleng’s own forest fires have proved that the birds are at risk, and the situation is not getting any better.

Frank Rheindt, associate professor of biological sciences at NUS and one of the researchers involved in the discovery, has been keen to encourage the importance of increased protective efforts, stating that “while most of the avifauna we described seems to tolerate some form of habitat degradation and is readily detected in secondary forest and edge, some species or subspecies are doubtless threatened by the immense levels of habitat loss on these islands. As such, urgent, long-lasting conservation action is needed for some of the new forms to survive longer than a couple of decades beyond their date of description.”

On the whole, the revelation is an overwhelmingly positive one – such a wealth of species points to positive levels of biodiversity in the region. Rheindt and his team are optimistic that the methods used in this discovery could be effectively applied in other regions and for other forms of wildlife in the future. “Going forward, the use of earth-history and bathymetric information could also be applied to other terrestrial organisms and regions beyond the Indonesian Archipelago to identify promising islands that potentially harbour new taxa to be uncovered,” stated Rheindt.

Human Genome

Scientists Sequence 5,700-Year-Old Human Genome

Despite rapid scientific advancements over the past several years, little is known about the lives of prehistoric humans, who left behind no written records and few artifacts. However, scientists were recently able to sequence a prehistoric human genome from DNA left in birch pitch, discovered in Denmark, which was used as chewing gum 5,700 years ago and was preserved in mud. This rare insight into our species’ genetic history gives scientists new information about our distant past, particularly with respect to how human beings have changed genetically over the past few millennia due to evolution. The discovery represents a breakthrough in our understanding of prehistoric human life, as the research presents insights into the diet, lifestyle, and genetic makeup of our distant ancestors.

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The results of the research were published by Nature in a paper that provides extensive detail about the methodology used to analyze the birch pitch as well as the implications of this analysis on our understanding of human history. By looking both at the complete human DNA which was found in the pitch as well as DNA from other plants and animals that the prehistoric individual may have eaten, the researchers determined information about the nearly six thousand year old person and extrapolated from this data to speculate about the larger culture she was a part of. 

The human DNA revealed that the person, whom scientists named “Lola,” was female and probably had dark skin, dark brown hair, and blue eyes. Given that the birch pitch was found in Europe, the fact that Lola had dark skin is notable, as it suggests that the spread of the trait of light skin pigmentation did not occur until later in history. Additionally, the DNA showed that Lola was lactose-intolerant, supporting the theory that tolerance to lactose evolved later in the history of human evolution after the beginning of dairy farming.

Lola, and by extension people who lived in Denmark at the time, likely lived a hunter-gatherer lifestyle, suggesting that this lifestyle persisted for longer in prehistory than scientists had previously assumed. In addition to providing a complete picture of Lola’s genome, the tree birch sample also gave scientists a snapshot of her “oral microbiome signature,” or the various species of bacteria that lived in her mouth at the time. 

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One of the species of bacteria they discovered was Streptococcus pneumoniae, suggesting Lola may have been suffering from a respiratory infection at the time. They also found evidence that Lola may have had mononucleosis, commonly known today as “mono.” Additionally, the scientists found DNA from animals and plants that were likely part of Lola’s diet, including hazelnut and mallard, supporting the opinion that Lola and the people living around her primarily found their food by hunting and gathering. While the evidence provides a genetic snapshot of a moment in Lola’s life, other details of her story, including her age and the cause of her death, will likely never be known.

 

Earth

New Research Hints at Origin of Life on Earth

While the theory of evolution is broadly accepted as fact among scientists, more controversy exists over explanations for the ultimate origin of life on Earth. However, new research published in Nature Ecology & Evolution sheds light on a potential theory for the origin of living things by attempting to recreate the conditions of the early earth and exploring how they could lead to the development of “protocells,” which are thought to be fundamental “building blocks” of all life. In an experiment, researchers successfully created conditions that led to the development of protocells by replicating the environment of underwater hydrothermal vents, whose combination of heat, alkalinity, and minerals are instrumental in the creation of protocells.

Though multiple competing theories explaining the origin of life exist, including Darwin’s assertion that life probably first evolved in shallow pools of warm water, the theory that life originally began within underwater thermal vents is supported by evidence, including the discovery of some of the world’s oldest fossils nearby these vents. Now, this explanation for the creation of life seems even more likely, as demonstrating the creation of protocells under these conditions is a key argument supporting the theory. Although the results of this research do not definitively prove that life on earth began in underwater hydrothermal vents, the researchers assert that the possibility of this explanation cannot be ruled out.

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Hydrothermal vents are located deep under the Earth’s seas, where minerals from the planet’s crust react with seawater, creating a warm, alkaline, and hydrogen-rich environment. This process leads to the creation of so-called chimneys, which are rich with alkaline and acidic fluids, enabling the formation of complex organic compounds, including, as this new research shows, protocells. These vents emerge spontaneously along fault lines as a result of geological processes, and have existed on Earth for millions, if not billions of years. Hydrothermal vents are known for being areas of the deep sea where life is relatively abundant, as they tend to be populated by shrimp, worms, and clams, who feed off of the energy and materials present around the vents.

This research has strong implications not only for the beginning of life on Earth, but for the potential for life to form elsewhere in space.

Protocells are, in essence, the most basic form of a cell, consisting of a bilayer membrane around an aqueous solution. Previous experiments succeeded in creating these cells in cool, fresh water, but only under tightly controlled conditions. Also, previous experiments attempting to replicate hydrothermal vents have failed to generate protocells which don’t fall apart. In this most recent experiment, however, the scientists identified a flaw with previous research on creating protocells in hydrothermal vents; namely, these experiments used a limited number of types of molecules, whereas in natural environments, you would expect to see a wide range of different types of molecules.

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Whereas it was previously thought that heat, alkalinity, and salt posed obstacles in the creation of protocells, this new research shows that these factors were actually beneficial in the process. This is because head allowed long carbon chains to form into a protocell structure, an alkaline solution helped protocells keep their electric charge, and saltwater helps fat molecules band together, forming more stable structures. What’s notable about this experiment is that while protocells have been created artificially in laboratory environments before, they had never been before created under conditions that match the chemistry of the early Earth.

This research has strong implications not only for the beginning of life on Earth, but for the potential for life to form elsewhere in space. This is because space missions have revealed the presence of similar hydrothermal vents on extraterrestrial bodies, including the icy moons of Jupiter and Saturn. Life on other planets or moons has not yet been discovered, of course, but research into the origins of life on Earth could give scientists a better idea of where in space to look for extraterrestrial life.