CRISPR isn’t just the cutting edge of genetic modification – it is re-framing our understanding of evolution.
What is CRISPR?
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The Celts, in addition to being a basketball team from Boston, were at one time a distinct cultural presence throughout much of Western Europe during the age of Antiquity, and dominant well into the early Middle Ages, even long after they converted to Christianity. While they have prominent burials and monuments that can be found throughout Europe – they have typically been associated with the culture of Ireland and Scotland, despite having encampments as far as Slavic countries such as Poland.
These people, who created Europe’s first intricate road system in what is now modern France, never actually referred to themselves as Celtic. Rather, the name “Keltoi” meaning “mysterious” was first applied to them by the ancient Greeks, who looked down on them as barbarians of the north – due to such factors as their unusual language (the third oldest in Europe, after Greek) and their pagan religion that recognized nearly 400 different gods and was rumored to involve human sacrifice.
So what set these tribes apart from the many nomadic tribes of ancient Europe? A bit less than was once imagined, as a recent DNA analysis of modern day Britons suggests that the Celts cannot be defined genetically in the United Kingdom.
The data, published in Nature this week, suggests that people of so-called “Celtic ancestry” from Scotland and Cornwall are more closely linked to English ancestry than they are to any other Celtic groups.
The study also described a few genetic differences throughout Great Britain, which indicate various regional identities.
One of the most crucial events in ancient English history is the invasion of the Anglo Saxons some 1,500 years ago, who rather than eradicate the Britons living on the island, ended up assimilating with them.
For their study, the researchers surveyed 2,000 individuals, largely middle-aged and Caucasian, who lived throughout the United Kingdom. Each participant was also required to include data of all four grandparents in the study, many who came from rural areas.
The selection method separated the population from those with long lines of British ancestry from those that immigrated to the U.K. in the early to mid-20th century.
Professor Peter Donnelly who led the study, said that the results show that while the results do not single out the existence of one genetic Celtic group, regional identities in Great Britain do have a genetic basis.
“Many of the genetic clusters we see in the west and north are similar to the tribal groupings and kingdoms around, and just after, the time of the Saxon invasion, suggesting these kingdoms maintained a regional identity for many years,” he said to BBC News.
Prof Donnelly and his team compared the genetic patterns they found against a map of the British Isles from approximately the year AD 600, shortly after the arrival of Anglo Saxons from the area that is currently southern Denmark and northern Germany in the early Middle Ages. By the seventh century, they managed to occupy most of central and southern England.
“We see striking similarities between the genetic patterns we see now and some of these regional identities and kingdoms we see in AD 600, and we think some of that may well be remnants of the groupings that existed then,” he said.
The study was funded by Wellcome Trust, which is currently involved with the People of the British Isles Research Project. The researchers had also learned that people living in northern England have more genetic similarities to people living in Scotland than to those living in southern England.
People of both North and South Wales also have a greater genetic disparity between each other than English people do from the Scots living north of them; and in Northern Ireland there are in fact two distinct genetic groupings – uncovering considerable patterns of migration throughout Late Antiquity.
Prof Mark Robinson is an archaeologist and colleague of Prof Donnelly at Oxford University, and was “very surprised” that these groups of what were culturally Celtic people living in Cornwall, Wales, Northern Ireland and Scotland had so many diverse genetic patterns.
“I had assumed at the very early stages of the project that there was going to be this uniform Celtic fringe extending from Cornwall through to Wales into Scotland. And this has very definitely not been the case,” said Robinson.
Distinct genetic groups formed in each region – but bore many differences between each other.
“Although people from Cornwall have a Celtic heritage, genetically they are much, much more similar to the people elsewhere in England than they are to the Welsh for example,” said Prof Donnelly.
“People in South Wales are also quite different genetically to people in north Wales, who are both different in turn to the Scots. We did not find a single genetic group corresponding to the Celtic traditions in the western fringes of Britain.”
The finding is the first time DNA evidence has supported an assertion that archaeologists like Robinson have long been making. The Celts were much more of a shared culture than a label that refers to a line of descent.
Robinson was happy with the results for another reason as well. They brought a little more objective evidence on what historians have long labeled as Britain’s Dark Ages, between AD 400 and 600, after which the ancient Roman Empire fell and their soldiers no longer occupied the island.
Entire towns became abandoned in the years that followed. The language spoken throughout much of what is now England changed to Anglo Saxon, which later evolved into Middle and modern English. Even the pottery styles changed, and new grains were grown, introduced to the isle from Denmark.
A long point of contention between both historians and archaeologists alike was whether the cultural changes were the result of the Saxons not only successfully occupying the island, but also fully replacing the population when they moved west. This could have been likely were the Saxons to spread disease, as one possibility.
Other evidence suggests that the Britons remaining just gave up their culture for the newly introduced Saxon ways.
The new analysis revels moderate levels of Saxon DNA, indicating that native Britons and Saxons lived alongside each other, and eventually became English. However, some evidence shows that this may not have happened quickly, but the result of eventual trade between British and Saxon communities over at least a century.
For possibly the first time, genetics has been able to give a clearer picture into a long historic controversy, where written sources are scarce.
As this all happened, the Celts likely retained their identity throughout both the western and northern regions of England when regions became occupied by Anglo Saxon conquest.
So what about all the variation between Anglo Saxons and Celtic populations? It could be as simple as a product of time, according to Donnelly.
“If groups have been separated for a period of time, they will diverge genetically so some of the differences we see genetically are the result of those kinds of effects,” he said.
Of the two genetic groupings isolated in Northern Ireland: one is closely related to their neighbors living across the sea in western Scotland and in the Highlands; while the other has been traced to individuals in both the southern portions of Scotland and England.
The former grouping is similar to patterns seen near what was once the kingdom of Dal Riata 1,500 years ago, a land divided among three brothers according to legend. The other grouping likely represents the descendants of the Ulster Plantations.
The Orkney Islands also finds some traces of Norwegian DNA, reflecting the Islands’ settlement by the Vikings. However, it occurs at levels fairly low, suggesting that a great deal of assimilation took place, casting some doubt that the Vikings were nothing but bloodthirsty warriors – they did in fact have considerable interaction with the people on the Islands. The concentrations are about the same as the traces of Anglo Saxon DNA on the mainland.
When the Vikings invaded England, they did destroy a number of villages that they marauded through, establishing a ruling council known as the Danelaw as they conquered new territory. However, these raids left little genetic evidence, if they left any at all – indicating swift military victories rather than the encroachment of large populations on the area and assimilation of culture.
By comparison, the Norman invasion in 1066, the last time that Great Britain was successfully conquered by a foreign invader, the legendary William the Conqueror, also left little genetic evidence.
Paleontologists are inching closer to the exact spot where modern day Homo sapiens first originated, and they found help through a rather unlikely clue. The fossilized skull of a whale that lived 17 million years ago is drawing them to humanity’s origins in East Africa. Here’s how:
The whale, classified as Ziphiidae, existed at a time when warm climates brought the East African plateau considerably lower than it is today. Unlike the dry grasslands it is today, this region was then hidden under dense foliage, according to the researchers. At some point it lifted far above the sea, pushing away much of the moist winds that these jungles were dependent upon – drying the land into a savannah. For scientists, it’s really been a question of when this separation between the plateau and the Indian Ocean took place.
Our distant ancestors may have swung from trees in the East African jungles, but as the trees died out in favor of grasses, our ancestors began the transition to walking upright on two legs, suggests the new research.
“It’s more or less the story about the bipedalism,” said study researcher Henry Wichura, a postdoctoral geoscience student at University of Potsdam in Germany.
The discovery of a skull belonging to a beaked whale, ziphiidae, buried in the rock layers has now allowed scientists to pinpoint the dates when the plateau began rising – sometime in the Pliocene – between approximately 17 million and 13.5 million years ago.
The whale skull was first discovered over 50 years ago – found by fossil hunters back in 1964 is one of rediscovery. Researchers originally found the fossil in 1964, but no studies were conducted on it for another decade. Then, the skull was misplaced, hidden in a museum archive at Harvard University until 2011. Surprisingly, it was discovered in the former office of the legendary paleontologist and science educator, Stephen Jay Gould. According to the study, it was placed there for safe keeping when the school’s archives were undergoing renovations.
The skull’s provenance is a bit more important than its discoverers first imagined. It is the oldest known fossil of a beaked whale, a rather puzzling discovery if you consider that these animals are actually deep sea divers. The fossil was uncovered 460 miles (740 kilometers) inland from the modern East African coast, and at 2,100 feet above sea level.
When it was alive, Wichura’s beaked whale grew to be 23-foot-long (7 m), swimming in the Indian Ocean. One day, however, he accidentally swam into a river towards present-day Kenya, where he eventually became trapped before his death.
“We came to the idea that it used a large river system, because the whale had been found in lake sediments which are [mixed with] river sediments,” Wichura said. “So we can say that it died in a kind of river-lake environment.”
The story might sound strange – a whale in a riverbed, but crazier things have happened. There are five known species of dolphin who prefer freshwater including the tucuxi, a close relative of marine dolphins that is found exclusively in the Amazon River basin. A sixth species recently became extinct. Back in 2006, a whale got stranded in the Thames River outside London, and killer whales have been found in the Columbia River near the Pacific Northwest. With the rapidly changing sea levels, incidents of this nature may have been more common.
In order to determine the depth of the prehistoric river basin, scientists took the grade of the steepest river out of the area’s case reports, applying its relative depth to the area. Were this 17 million year old river to rise 2.5 inches per mile from the coast, then the East African plateau would be somewhere between 79 feet and 121 feet high when the whale became stranded and died. They kept the difference in height as a variable – allowing that the whale may have chosen several different routes to swim along when entering the river.
Because the plateau is approximately 2,034 feet (620 m) high, the northern part of this plateau was lifted by almost 1,925 feet (590 m) within the last 17 million years.
Somewhere around 13.5 million years ago, Wichura learned that one portion of this land mass had already begun uplifting, giving the researchers a reasonable window into when the uplift started. The researchers were even able to attribute the cause of the uplift – mantle plumes – in which heated material is released from an underwater volcano from the Earth’s mantle and presses against its crust.
Had they not rediscovered the forgotten skull, this dating would have been considerably difficult.
“With the whale, everything started,” Wichura said to Live Science.
The study is a reminder to fossil hunters – both professional and amateur alike – that very often, the precise location of a fossil can sometimes be just as valuable – if not more – than the fossil itself, when it comes to understanding the prehistoric world in full context. The discovery of a single species is hardly significant on its own, but its place in time can reveal information about an entire extinct ecosystem, or even the history of a landscape that was once very different.
“Even single specimens of organisms tell us a great deal about the history of the Earth, and they sometimes appear in surprising cases,” Brown said. “This is one such case.”
This study was published on March 16 in the journal Proceedings of the National Academy of Sciences.
One of the most basic and widely-understood concepts in modern biology is Darwinian evolution, wherein DNA is inherited by offspring from the parent organism. This view of evolution, also called vertical gene transfer, is increasingly becoming too simple to explain sections of the human genome. The science journal called Genome Biology published a study last September, 2014, describing the evidence and conclusions behind an alternative mechanism of gene acquisition called horizontal gene transfer or HGT. HGT is when genetic material transfers between otherwise non-genetically-related organisms. HGT actually already evidenced in several single-celled bacteria, but this study proved higher organisms display traits and DNA evidence from outside their ancestry. Last falls Genome Biology report was able to show signature DNA in humans that did not come from the understood human lineage.
HGT is sometimes called Lateral Gene Transfer. The concept is that organisms ingest or otherwise absorb DNA from the organisms they encounter in their environment. Much of the conceptualization behind HGT originated in Seattle in 1951 Horizontal gene transfer was first described in Seattle in 1951 by Victor J Freeman in the Journal of Bacteriology. This new study is significant because it shows human genealogy may have fungal DNA through such lateral transfer.
The 2014 study shifts the conventional POV that animal evolution solely uses genes passed down from parental lineage. Because evolution is an ongoing process, this new aspect of that process is implied to be ongoing. We are still absorbing DNA from other organisms right now~!
Alastair Crisp at the University of Cambridge:
“This is the first study to show how widely horizontal gene transfer (HGT) occurs in animals, including humans, giving rise to tens or hundreds of active ‘foreign’ genes.”
There are many advantages to organisms which evolve laterally. One long-refernced example in the genetics community is quickly-evolving bacteria that can resist anti-biotics after only a few generations. In the Darwinian model, only the bacteria that had a chance mutation would resist the drug. By transfering genetic material from other related bacteria, a bacterium can adopt an immunity it did not originally have a mutation for. HGT might be an important part of the evolution of complex organisms, too, including animals. We now have evidence that nematode worms can acquired genes from the microorganisms and plants they exist in cohabitation with. Another example from the new study shows a type of beetle displayed bacterial genes which enabled them to digest coffee berries.
HGT in humans is controversial because it implies organisms in our natural – and unnatural – environments can affect our DNA, and that of our offspring. Humanity has created a planet where organisms are repeatedly exposed to organisms which would not otherwise be part of our environment.
Researchers were able to calculate the likelihood that similar genes from other species were transferred this way. Last September’s study showed the genomes of 12 species of fruit fly, four species of nematode worm, and 10 species of primates, had overwhelming evidence of HGT. The primate list included humans!
The numbers also help estimate when the genes were acquired. Most of the genes in humans that can be shown as a match to non-human organisms are blood or enzyme related. Most importantly the ABO blood group gene in humans, are confirmed to have been acquired through vertebrates using HGT. Most of the other genes were related to metabolism. This might lead to discoveries about the human diet that can change or modify metabolism.
Past studies have attempted to prove this same phenomenon but have only proven 17 genes attributed to HGT. This latest study shows 128 additional foreign genes in the human genome.
Researchers even identified which organisms the transferred genes came from. Bacteria & protists, which together comprise another class of microbes are the most common lateral gene donor. Perhaps future studies might show that the trait of HGT is one possessed by simple single celled life, rather than one controlled by the expression of multicellular organisms.
Even more strange: most of the foreign genes in primates, including humanity, seemed to come from viruses. Some genes even seemed to have originated from fungi which explains why previous studies focused on bacteria missed the most likely lateral lineage.
Despite the ongoing nature of evolution, the mutation and gradual adaptation is slow. The roots of HGT expressed in primates are ancient. Some of the DNA may have been with our species since a common ancestor was shared between Chordata & Primates.
The implications of this are far-reaching, such as rethinking the invasiveness and shared DNA in host-parasite relationships. Mistakes or incompatible DNA that is nonetheless laterally transferred could be responsible for genetic mutations that are not desirable such as a tendency for heart disease or cancer. Solid proof of HGT that can be reproduced and relied on can also mean new cures for those exact same diseases.
Most importantly HGT will change the way we discuss and teach evolution.
Yet another discovery has been brought into the growing pile of evidence that suggests Neanderthals were not quite the savage, hairy monsters we often portray them as being. Recently the fossil evidence has shown that they were attentive parents, that they had an appreciation of art – creating cave paintings of their own, and that they held elaborate burials for their dead, but a new study elaborates a bit further on their personal tastes. According to a paper published today in PLOS ONE, the Neanderthal hominids may have developed their own jewelry – necklaces fashioned from eagle talons, that until recently were attributed to modern humans.
They disappeared some 39,000 years ago, shortly after modern humans began to enter Europe – for reasons that are not quite known. For some time before their extinction, the species are believed to have interbred, and perhaps they did not so much die out as become assimilated with homo sapiens. Our DNA is 99.7% identical to theirs, and modern humans who aren’t of African descent share about 2.5% of DNA with Neanderthals. Although this lineage has recently fallen into dispute, both Neanderthals and modern humans did originate in Africa, and may have shared a common ancestor. Not only did they craft jewelry, but their hunting skills may have rivaled those of modern humans as well. In order to craft the talon necklaces which seem like a necessary ingredient in most movies featuring prehistoric cavemen – they may have also been able to fashion traps to catch more than one eagle – at that time the sky’s apex predator.
The evidence came not from a recent archaeological dig, but rather through examining some old articles from a museum collection. (as so much evidence does) from the bowels of a museum collection. At the beginning of the 20th century, Croatian paleontologist Dragutin Gorjanović-Kramberger lead an excavation of a site near the Croatian village of Krapina, which was filled with Ice Age human and animal remains. While you may have never seen Gorjanović-Kramberger’s name in print before, during his career, he used newly invented X-ray machines to look at inner bone structures from his finds and he even developed a way to determine the ages of the skeletons he found, through analyzing their fluorine content, nearly half a century before carbon dating came into existence. The site he uncovered held almost a thousand human bones, the bones of several thousand animals, several thousand animal bones, alongside at least a thousand tools, all of which dated between 120,000 to 130,000 years ago. As a result, the town is now home to a large museum dedicated specifically to Neanderthal culture and evolution.
Like most modern paleontologists, Gorjanovic-Kramberger kept a detailed record of where each skeleton was found, but when it came to discovering the necklaces, he overlooked something rather obvious.
“He found these eagle talons and sent them to a bird specialist in Budapest,” said David Frayer of the University of Kansas, one of the new study’s researchers. “But ironically, even though he was the first person to identify cut marks on human bones, he missed these really obvious signs of cut marks and manipulation on the eagle talons.”
The bird specialist in Budapest also paid little attention to the talons as did the museum curators who kept the specimens stored in their collection for well over a century.
It was not until late 2013, when one of Frayer’s colleagues became curator of the Croatian Natural History Museum and gave the talons a second look. She gave him a call after she suspected that the markings had been made by the Neanderthals they were buried with.
“When I saw them, my jaw dropped,” he said. “The talons were so complete and so beautiful, and the cut marks were so obvious.”
The single most important detail is the age of the necklaces. They are 120,000 or 130,000 years old, when Croatia was occupied solely by the Neanderthals.
Researchers have in the past suspected that Neanderthals did craft the necklaces, but may have learned their trade from what were much more sophisticated homo sapiens. The only prototypes they had for this claim, were more modern necklaces found in France, dating to about 40,000 years ago.
“People often argue that Neanderthals were mimicking modern humans instead of coming up with ornamental things on their own,” Frayer said. “In this case, there’s no doubt: There were only Neanderthals there, and only Neanderthal tools.”
The patterns of wear of the talons have led Frayer and his colleagues to believe that the claws had been strung together and were worn as necklaces. Exposure to sweat as well as other bodily fluids led to a distinct type of polishing which is often found on shell bead necklaces made in the same way.
Eagles would be rare in the mountainous terrain where the Neanderthals lived, and were also highly aggressive, two aspects indicating that these Neanderthals were highly skilled when it came to hunting.
“There are talons from three or four different eagles here, and that represents a lot of planning and skill,” he said. “They’re big birds, and they’re vicious when caught.”
These were not run-of-the-mill prey – they were targets that some of the braver Neanderthals deliberately hunted. It took about three or four birds to make one necklace. Even the decision to use eagle talons as an ornament — if it really was intended for that — may also suggest that the Neanderthals had capacity for abstract thinking.
“When you catch the most powerful aerial predator in your environment and wear it around your neck, that suggests some kind of attempt to get its power,” he said.
If you think dating is tough, it’s nothing compared to what male spiders have to go through – where getting laid can often mean getting eaten shortly after – a known practice that has given the Black Widow spider a rather fearsome reputation. Male Black Widows will sometimes catch and wrap a large insect in the web as a parting gift, a food item to distract their mate while they make their escape and avoid becoming the main course themselves. The Darwin’s Bark Spider (Caerostris darwini) has another idea for staying alive as long as it can. According to a recent report by a team of arachnologists (those who study spiders), male bark spiders may actually be providing oral sex to their female partners in order to avoid being eaten.
Simona Kralj-Fiser, a researcher at the Slovenian Academy of Sciences and Arts, led her team on a two-week field survey at the native home of this species in Madagascar, where they were able to observe the courtship of this intriguing species. The Darwin’s bark spider is already a popular interest by many in the field, considered to be one of the master artisans when it comes to web building – where they are said to build some of the most durable webs of any arachnid – spinning orb webs with anchor lines up to 82 feet in length. After limpet teeth, their silk is the second toughest known biological material, 10 times stronger than Kevlar.
Named for their resemblance to lichen, the bark spider is a rather recent discovery, found only in 2009, and so very little as actually known about this species’ ability to reproduce. This is what Kralj-Fiser and her colleagues initially came to investigate. They reported their findings last week at the annual Ethological Society’s “Causes and Consequences of Social Behavior” conference in Hamburg, Germany.
Like so many other male invertebrates, male bark spiders are significantly smaller than their female counterparts, and therefore are opportunistic maters. They were even observed mating with some of the younger females who had not yet grown fang cuticles and whose exoskeletons had not yet hardened over their bodies. For anyone who despises spiders already, this is probably the last thing you may want to read – but it is the result of an evolutionary advantage that males of this particular species are given over the females. Male bark spiders develop at faster rates, allowing them to defend their female partners as they compete against each other for rights to breed. However, this period of dominance is rather short lived.
“When a female’s cuticles harden and she can move and attack, she is able to prevent long copulations,” Kralj-Fiser explained on the New Scientist’s blog Zoo Logger.
At the conference, Krajl-Fiser explained a rather startling (although, perhaps unsurprising) statistic: When the females they observed reached their full maturity, 76 percent of them behaved aggressively towards the males. In about 35 percent of the observed cases, the females ended up cannibalizing their mates shortly after having sex. Despite the black widow spider’s reputation, females have only been shown to cannibalizes their mates only two percent of the time – quite a surprising contrast.
Recent research efforts have demonstrated that black widow males have developed the ability to sniff out their mate’s appetite for blood, allowing them to escape in time, the bark spider doesn’t appear to have adapted this useful ‘spidey-sense.’ The answer might cause you to never watch nature shows quite the same way again:
“Males nibble on female external genitals using their fangs, and then we observed that there was a liquid coming out of the fangs. We do not know what this liquid is, but it looks like digestive juices, which they usually secrete when eating,” Kralj-Fiser explained during the conference.
The researchers proposed a theory that by simply ‘going down’ on the female, the male bark spider keeps its mate calm before and after mating, a practice that helps ensure that the male won’t become dessert. Further supporting their theory is the observation that the males did not perform the same act on any of the younger, harmless females.
However, the researchers have noted that this proposal is hardly the only explanations for this ritual. For one example, female Darwin’s bark spiders will often mate with several males throughout their lives. Past research on other species of spider reveal that the males will often take measures to keep their mate content, as male black widows are known to do. However, this has been seen in non-cannibalistic species as well, as a way to be sure that they are not abandoned for another mate.
If you think the oral sex hypothesis sounds strange, females of the Leucauge mariana orb weavers seem to enjoy what arachnologists call a “hairy kiss.” A male spider who is a good ‘kisser’ has noticeably thick hairs on his mandibles which it uses to stimulate its mate. The mates of the successful ones are much more likely to stay around. For when it’s really serious, she will join him in forming a “genital plug,” in which a type of lubricant similar to that used for webs will signal that she has been claimed and prevent other males from having sex with her. As strange as it sounds, this has long been proposed as the arachnid equivalent to marriage.
Perhaps the bark spiders in performing this ritual are actually doing something similar to a genital plug rather than an oral sex act, but the research has yet to fully verify either claim.
A newly discovered fragment from an ancient jawbone may be the oldest known human fossil found yet. The bone is perhaps from a new species of human, another primate similar to us of the genus Homo, suggesting that the human family of primates may have come into existence over half a million years earlier than anthropologists once thought.
Perhaps more importantly, this new discovery has revealed the type of environment from which our closest ancestors came, said the researchers.
While modern day humans are all that’s left of the human lineage today, we were only one of a handful of human species to roam the Earth, competing against such hominids as Neanderthals for food.
When Charles Darwin first wrote about human evolution he suspected that Africa, home to several lines of large apes would likely contain the fossils of our ancestors. By the early 20th century, as paleontologists like Raymond Dart and Mary Leakey found remnants of early humans in Tanzania and South Africa, they seemed to fulfill that prediction, giving way to an “Out of Africa” hypothesis of human migration. There was plenty of evidence for tool making and walking upright, but while scientists have known for awhile that these species were tribal by nature, the question of when the concept of human families actually began.
The new find in Ethiopia is about 2.8 million years old, an important supplement to the gap in the fossil record between 2.5 and 3 million years ago. The paper describing the find was published Wednesday in the journal Science.
“There’s virtually nothing relating to the ancestors of Homo from that time period, in spite of a lot of people looking,” said the research team’s co-leader and paper co-author Brian Villmoare, a paleoanthropologist from the University of Nevada in Las Vegas, in an interview with Live Science. “Now we have a fossil of Homo from this time, the earliest evidence of Homo yet.
The jaw was discovered by their team member Chalachew Seyoum back in 2013, near the Ledi-Geraru research area of Ethiopia’s Afar region. “One hill was particularly rich in fossils — it was probably a bend in a stream, where bones tended to gather after animals died,” Villmoare said. “We found this fossil coming out of that hill.”
The fossil, labeled as LD 350-1, is a preserved left side of a hominid’s lower jaw containing five teeth. “Once we found it, we knew immediately what it was — we could tell it was a human ancestor,” Villmoare said. “We were jumping up and down the side of that hill.”
In order to determine the fossil’s age, the researchers did an analysis of the layers of volcanic ash it was buried in – both above and beneath the fossil. “When volcanoes erupt, they send out a layer of ash that contains radioactive isotopes, and these isotopes start going through radioactive decay,” Villmoare explained. “We can use this to figure out how old those layers of ash are.”
The fossil was actually found not too far from Hadar, the archaeological site that was once home to Australopithecus afarensis, our ancient ape-like ancestors that included the famous “Lucy,” who was thought to be the earliest of our ancestors to care for its young post-infancy. The original owner of LD 350-1 likely lived only 200,000 years after Lucy, and although its sloping, primeval chin is reminiscent of Australopithecus, the teeth and size of the jaw suggest that this creature was actually a member of the Homo genus. It seems like a perfect transition, with ape-like features as well as those closer to a modern human.
“It’s a mixture of more primitive traits from Australopithecus with quite a few traits only seen in later Homo. The scientists do not yet know whether this fossil belongs to a new species or to a known, extinct human species such as Homo habilis,” Villmoare said.
As exciting as the possibility of a newly discovered hominid may be, the researchers are hardly jumping to conclusions just yet – determined to know everything they can about their specimen first.
“We are holding back on that — we are hoping to find more of it, learn more about what it looked like, before we give the species a name,” Villmoare said.
Other geologic evidence at the site suggests that their location closely resembled modern African settings such as the Serengeti Plains or the Kalahari at the time that their specimen lived. It likely settled in what was a grassland with lots of shrubs. It shared a nearby lake with hippos, antelope, elephants, crocodiles and fish, in an age before the climate began to intensify dramatically, which would force its descendants northward.
“We can see the 2.8 million-year-old aridity signal in the Ledi-Geraru faunal community,” said the research team’s co-leader and study co-author Kaye Reed of Arizona State University, in a statement. “But it’s still too soon to say that this means climate change is responsible for the origin of Homo. We need a larger sample of hominin fossils and that’s why we continue to come to the Ledi-Geraru area to search.”
Looking back at the stars, with the realization that we are looking at entire worlds distant from our own like so many grains of sand, we can’t help but imagine what may be staring back. A planned flyby of the moon Titan once again has drummed up interest in the possibility of extraterrestrial life, very different from our own. While this particular moon of Saturn, a point of interest due to its vast lakes of methane, contains no water, astronomers at Cornell University have proposed a picture of what creatures from Titan might be like – very different from the carbon based life forms that exist on Earth.
Using both the power of imagination and a prominent scientific vision, in the burgeoning proto-scientific field that is astrobiology, the study of potential life processes on other planets, this team of chemical engineers proposed a way in which cells that are methane based can reproduce and acquire nutrients without the need for oxygen – carrying out the same life processes that organisms do on Earth.
They modeled a cell membrane, made up of small organic nitrogen compounds which would be capable of replicating in liquid methane temperatures as low as 292 degrees below zero, what scientists estimate to be the temperature of Titan’s lakes. Their work was published in the journal Science Advances on Feb. 27. Paulette Clancy, who specializes in molecular chemical dynamics led the effort, alongside his first author James Stevenson, who is currently a graduate student in chemical engineering. The paper’s co-author was Jonathan Lunine, who serves as the David C. Duncan Professor in the Physical Sciences in the College of Arts and Sciences’ Department of Astronomy at Cornell, where past faculty members include the legendary science educator Carl Sagan, who himself dabbled in astrobiology.
Lunine’s field of interest is the moons of Saturn. He served as an interdisciplinary scientist on the Cassini-Huygens mission, the first mission to land on Titan, and discover its methane-ethane seas back in 2004. Fascinated with the prospect of methane-based lifeforms on Titan, he received a grant from the Templeton Foundation for studying non-aqueous life. Clancy and Lunine met after the latter sought help last year with chemical modeling from Cornell faculty members.
“We’re not biologists, and we’re not astronomers, but we had the right tools,” Clancy recalled. “Perhaps it helped, because we didn’t come in with any preconceptions about what should be in a membrane and what shouldn’t. We just worked with the compounds that we knew were there and asked, ‘If this was your palette, what can you make out of that?’”
On Earth, all life is dependent on the phospholipid bilayer membrane, a strong, yet highly permeable vesicle that is water-based and shelters the organic matter that defines the makeup of every cell. Out of these vesicles come liposomes. Until now, the majority of astronomers interested in the possibility of extraterrestrial life hunted for the circumstellar habitable zone of each system, a narrow band surrounding a star where temperatures would be ideal for liquid water. The Kepler telescope has singled out several thousand of these planets throughout the universe thought to bear similarities to conditions on Earth. Rarely have they considered the possibility of lifeforms based on other elements such as methane, which contains a substantially lower freezing point than water.
The new concept is called an “azotosome,” derived from “azote,” the French word for nitrogen, and a play on “liposome” – “soma” meaning the body.
Their azotosome bears components of nitrogen as well as carbon and hydrogen molecules which exist throughout the vast cryogenic seas of Titan, regions thought to contain waves and even islands that appear and disappear under the currents. So far, the working model exhibits a similar stability and flexibility to the liposome – a surprise as neither engineers involved with the project had had much familiarity with cellular stability, building the model in the way they worked on semiconductors.
In order to commence this new application of molecular dynamics, the researchers routinely did a search on potential compounds of methane that would allow for self-assembly into membrane-like structures. The best compound they were able to find is an acrylonitrile azotosome, which maintained good stability, as well as a strong barrier to decomposition, and also had considerable flexibility, allowing for fluid molecules to enter and exit its walls – just like phospholipid membranes on Earth, therefore making it possible for organelles to develop which would later lead to living beings. Acrylonitrile – which is an organic compound that is colorless and poisonous is routinely used to manufacture acrylic fibers, resins and thermoplastics – is present in Titan’s atmosphere.
Clancy, intrigued with the launch of their concept, has said that their next step will be to simulate an environment in which their model cells would interact in the way of breathing, eating, and reproducing within a methane environment. Meanwhile, Lunine is eagerly anticipating the next mission to Titan which should kick off some time by the 2020s, soon followed by ones that will successfully sample the lake material.
We like to imagine that our distant Ice Age ancestors were hunterers by instinct, fearlessly navigating an unforgiving world, in the face of an extreme climate and unimaginable danger – nomads without a home, following only the stars and the herds through the brush. Whether it sounds romanticized or barbaric, the real picture could be very different, thanks to some new evidence brought to light by British archaeologists and published in Science this week.
While the diet of the average hunter-gatherer seems largely unpalatable today – living and dying in an age without most of the produce we take for granted, and which has also contributed to obesity epidemics, they didn’t always live off the land in the strictest sense of the term – actively trading with other tribes and even importing grains which they introduced to the British Isles from the European continent. In fact, if the ancient DNA discovered just below the British coast is any indication, it is likely that farming may have been happening in Great Britain 2,000 years earlier than what researchers once thought. Beneath the rocks of the windy coast lie the remains of what was once a prehistoric hunting camp.
“The work may be forcing archaeologists to confront the challenge of fitting this into our worldview,” said Dorian Fuller, an archaeobotanist at University College London who did not partake in the research. It may show that the evolution of agriculture was much more of a gradual and complex process than archaeologists had previously thought, affecting the transition of each adapting tribe in different ways.
For decades, the classic model held by archaeologists was that some of the earliest farmers traveled through the Middle East into Europe, first migrating some 10,500 years ago. Upon their arrival, they either began to replace or successfully converted these hunter-gatherer populations when they continued to move westward. They finally reached the British Isles somewhere around 6,000 years ago, around the time that Mesopotamia first discovered the properties of beer making. However, this worldview has undergone a number of modifications in the last several years. Back in 2013, some excavations of dwellings show that farmers and hunter-gatherers co-existed for a substantial period of time, during which they my have developed their own barter system for services, rather than everyone readily embracing the new concept of agriculture. A 2013 archaeological dig in Germany revealed that both farmers and hunter-gatherers shared a cave for burying their dead, a practice they continued for over 800 years, indicating that these groups often lived closely together on overlapping tracts of land. Another more controversial find, still not fully tested, is the claim that some hunter-gatherers living in the Baltic region of Europe 6,500 years ago may have actually eaten domesticated swine, which they were given by local farmers.
Rather than moving from east to west, this rash of new excavations could mean that these people traveled much more erratically and extensively than we once thought. Robin Allaby, a plant geneticist at the University of Warwick in the United Kingdom, led the expedition, initially in a search for evidence of the oldest domesticated plants in Great Britain, a land which was settled by people relatively later than the rest of Europe. On their travels, the researchers decided to explore an already known underwater site, the Bouldnor Cliff, about 820 feet off Britain’s southern coast in the English Channel.
Bouldnor Cliff, located 36 feet below the water’s surface, was first described as fossil rich in 1999, drawing the curiosity of researchers everywhere after the United Kingdom’s Maritime Archaeology Trust recalled, “a lobster seen throwing Stone Age worked flints from its burrow.” Archaeologists haven’t left it alone since. The hunter-gatherers who camped near the site, who we might think of as land dwellers, are suspected to have sailed wooden boats built from trees near the coast. Allaby’s team discovered some burnt hazelnut shells in the sediments, which radiocarbon dating and ancient DNA analysis revealed to be between 8,020 to 7,980 years ago, before the sea levels rose that separated Britain from France.
When comparing these DNA samples, the team was in for another pleasant surprise. They were able to isolate from the DNA samples two different kinds of domesticated wheat – one of which was of Middle Eastern origin, with no ancestors living in the wilderness of northern Europe. Therefore, the nomads who camped out on Bouldnor Cliff were somehow associated with the beginning of agriculture throughout the Middle East, which began some 10,500 years ago.
So did they farm their own wheat somewhere near the encampment? No traces of pollen were detected in further analyses, which would have implied that the plants were actually grown and underwent a flowering process in prehistoric Britain. They also ruled out any possibility that their sample was contaminated with modern grasses. If this is consistent with other findings, it is likely that farming may have begun as early as 7600 years ago, spreading to Britain from France.
However, there is the other possibility that hunter-gatherers from Britain may have gone deeper into the heart of Europe than researchers have proposed, and actually picked up products from farmers living eastward, which they then brought back to their camp. Allaby has agreed that the usage and frequency of grains in Britain at this time period is still disputable – it might have been seen as more of a rare commodity like exotic spices, than a staple of daily diets.
Perhaps one of the strangest stories of evolution is that of the whales – the descendants of wolf-like creatures who roamed the Earth eons ago. Proteins in their genomes once coded for legs, and their fins are actually shaped like hands with wrists, reminders of their long, proud mammalian lineage. It seems strange – why did animals whose long ago descendants crawl out of the sea onto dry land, return to the sea? The obvious answer is survival, adapting to an ever changing world. As to how, the short answer would be that it simply didn’t happen overnight. The modern hippopotamus, whose name literally means “water horse,” is actually a distant relative of the whale, a four-legged mammal that spends much of its life in the water. The hippo family shares a number of ancestors that adapted to living in water for the long term. Now, a recent fossil expedition in Africa has unearthed what paleontologists suspect may have been one of the first hippos to have roamed the Earth.
The first hippo, paleontologists estimate, based on the size of the newly excavated animal from a Kenya rock bed, was likely a little larger than a modern horse, just a little smaller than modern hippos, and weighing several hundred pounds.
“They are slender hippos, very thin hippos,” said Fabrice Lihoreau, a paleontologist at the University of Montpellier in France who co-authored the new paper.
This newly discovered creature, known as Epirigenys lokonensis, also had its evolutionary roots in Africa, as the study confirmed. The genetic evidence suggests that the common ancestor shared by hippos and whales existed some 53 million years ago. Epirigenys first roamed the Earth a mere 15 million years ago – with only a few known specimens found in between.
The current hypothesis is that one of the prehistoric ancestors of hippos were a family of semi-aquatic mammals, the anthrocotheres, which appeared around 40 million years ago. At one time, these ancient beasts were prevalent across the globe, with fossils found everywhere from North America to Asia. However, any ancestry it had to hippos was never identified.
The inspiration for this dig began at Kenya’s Nairobi Museum, where Lihoreau and his colleagues stumbled upon one small exhibit in the collections – a rather unusual jaw belonging to an anthrocothere. This particular jawbone had been discovered at the Turkana Basin, a fossil-rich rock formation in Kenya, where the rock layers carry a myriad of fossils dating all the way back to the Cretaceous Period and leading right up into the present day. Among the fossils in these rocks are our own recent ancestors, the Homo erectus and the Neanderthals. The exact location where the jawbone was located was a large body of water 28 million years ago, containing a plethora of crocodilian fossils. Unfortunately, the rock’s thickness made digging difficult, where they risked damaging the fossils.
While they hunted for new potential locations, the researchers took notice of a small spot called Lokone Hill with considerably softer rock that could easily be removed with acid, making the excavation much easier. The first few finds were of several uncovered teeth, which they confirmed had come from a new species of anthrocothere, previously unknown to science, and newly discovered at the Lokone Hill, found alongside sets of molars and incisors, the trademarks that this certainly belonged to a mammal. Most promising perhaps, was that the molars bore a striking similarity to the teeth found in modern-day hippos – bearing a prominent pattern that looked like a bladed three-leaf, not too different from a maple leaf shape. The new species earned its name Epirigenys lokonensis, a rough translation from Latin into “original hippo from the Lokone,” according to Lihoreau.
It was this molar pattern which linked the E. lokonensis as the hippo’s direct ancestor. (the teeth of mammals, particularly herbivorous ones, are so distinct from each other that any discovered patterns found on the molars almost act as a fingerprint for the species.) Paleontologists who are lucky enough to find one can establish a clear lineage between an extinct creature and its closest living descendants.
E. lokonensis weighed only about 220 pounds according to Lihoreau’s estimate, which is considerably smaller than the plodding two to three ton hippo that roams the African wetlands today, an aggressive creature that may or may not have earned its fearsome reputation as the most dangerous animal in Africa, known to attack if provoked. Just like their modern ancestors, however, the Lokone hippo lived primarily in the water.
“When you do a safari, you want to see a lion and you want to see an antelope, but these animals come from Asia ” Lihoreau told Live Science in an interview. “They are not really African mammals. This is really an African mammal.”
The paper describing this new species was published yesterday in the journal Nature Communications.