News

Neanderthal Mother, Denisovan Father! Concrete Proof that Hybrid Hominin Families Did Exist

Neanderthal Mother, Denisovan Father! Concrete Proof that Hybrid Hominin Families Did Exist


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

Together with their sister group the Neanderthals, Denisovans are the closest extinct relatives of currently living humans. "We knew from previous studies that Neanderthals and Denisovans must have occasionally had children together," says Viviane Slon, researcher at the MPI-EVA and one of three first authors of the study. "But I never thought we would be so lucky as to find an actual offspring of the two groups."

The ancient individual is only represented by a single small bone fragment. "The fragment is part of a long bone, and we can estimate that this individual was at least 13 years old," says Bence Viola of the University of Toronto. The bone fragment was found in 2012 at Denisova Cave (Russia) by Russian archaeologists. It was brought to Leipzig for genetic analyses after it was identified as a hominin bone based on its protein composition.

  • Research Confirms that Neanderthal DNA Makes Up About 20% of the Modern Human Genome
  • Extinct Denisovans from Siberia Made Stunning Jewelry. Did They Also Discover Australia?
  • A world map of Neanderthal and Denisovan ancestry in modern humans

This bone fragment ('Denisova 11') was found in 2012 at Denisova Cave in Russia by Russian archaeologists and represents the daughter of a Neanderthal mother and a Denisovan father. ( T. Higham/ University of Oxford )

"An interesting aspect of this genome is that it allows us to learn things about two populations -- the Neanderthals from the mother's side, and the Denisovans from the father's side," explains Fabrizio Mafessoni from the MPI-EVA who co-authored the study. The researchers determined that the mother was genetically closer to Neanderthals who lived in western Europe than to a Neanderthal individual that lived earlier in Denisova Cave. This shows that Neanderthals migrated between western and eastern Eurasia tens of thousands of years before their disappearance.

View of the entrance to the Denisova Cave archaeological site, Russia. ( Bence Viola/ Max Planck Institute for Evolutionary Anthropology )

Analyses of the genome also revealed that the Denisovan father had at least one Neanderthal ancestor further back in his family tree. "So from this single genome, we are able to detect multiple instances of interactions between Neanderthals and Denisovans," says Benjamin Vernot from the MPI-EVA, the third co-author of the study.

  • Did light-skinned, redheaded Neanderthal women hunt with the men?
  • DNA Evidence Suggests Captured Russian Ape Woman Might Have been Subspecies of Modern Human
  • The Coming of the Thunder People: Denisovan Hybrids, Shamanism and the American Genesis

"It is striking that we find this Neanderthal/Denisovan child among the handful of ancient individuals whose genomes have been sequenced," adds Svante Pääbo, Director of the Department of Evolutionary Genetics at the MPI-EVA and lead author of the study. "Neanderthals and Denisovans may not have had many opportunities to meet. But when they did, they must have mated frequently -- much more so than we previously thought."

Male and female Homo neanderthalensis in the Neanderthal Museum, Mettmann, Germany. (UNiesert/Frank Vincentz/Abuk SABUK/ CC BY SA 3.0 )


    How Many Human Species?

    The recent publication of the Neandertal/Denisovan hybrid from Denisova Cave has inspired a number of really interesting reactions from scientists quoted in the popular press. People are openly speculating that humans, Neandertals, and Denisovans are really all part of our species, Homo sapiens, because we can (or could) all interbreed. The Atlantic quotes John Hawks saying,

    When you find a needle in a haystack, you have to start wondering if what you’re really looking at is a needlestack … This genome shows that hybrids were nowhere near as rare as people have been assuming. They must have been really common.

    I can see his point. As I mentioned, there have been 23 genomes of ancient humans sequenced, and two of them turned out to be recent hybrids. That’s a frequency of 8.7%, which is no small number when it comes to poulation genetics. Add to that the observation that the Denisova girl’s Denisovan father carried bits of Neandertal DNA, and you realize that the intermingling of these different humans must have been fairly easy wherever they met.

    Does that mean we’re all one species? In a Nature news article, Matthew Warren writes,

    With a Neanderthal mother and a Denisovan father, what should we call the new specimen? “We shy away a little from the word ‘hybrid’,” says [ancient DNA expert Svante] Pääbo. The term implies that the two groups are discrete species of human, whereas in reality the boundaries between them are blurry — as the new study shows. Defining a species in the natural world is not always clear-cut, says [population geneticist Kelley] Harris, and it’s interesting to see long-running debates about how to categorize organisms start to be applied to humans.

    This is very consistent with Pääbo’s previous comments on Neandertals and Denisovans, where he has avoided calling them separate species from modern Homo sapiens. This is also of great interest to creationists, since young-age creationists have often insisted that Neandertals are just a variety of modern humans and within the range of variation found in modern humans (this is erroneous, by the way, but they say it anyway). In contrast, the old-age creationists at Reasons to Believe have insisted that Neandertals must be a separate animal species and not human.

    I’ve commented on this before over on my blog back in 2011, but this new discovery raises the question again, and I think it’s worth discussing. I continue to maintain (as I always have) that Neandertals and Denisovans are separate human species that are not the same as Homo sapiens, regardless of the evidence of interbreeding between them or the frequency of that interbreeding.

    First of all, we can see from the bones of Neandertals and humans distinct morphological differences. Neandertals posses a protruding face, a low forehead, and a bulging occipital bone that modern Homo sapiens do not have. Modern Homo sapiens have chins that Neandertals do not have. We are morphological distinct.

    Second, since we have skeletal remains of Neandertal juveniles, we can see that these distinguishing features do show up early in development. These are not merely aberrant or extremely old Homo sapiens remains. They have distinguishing characteristics from the moment they’re born. They also grow and develop differently from modern Homo sapiens.

    The skull of a Neandertal toddler found at Pech de l’Azé, France. Image from humangenesis.org.

    Third, their genomes are genetically distinct, quite outside the range of modern Homo sapiens. If you compared DNA from the most distinct forms of Homo sapiens living today, you’d still find only about a fourth of the differences you’d find if you compared the DNA of any living human to the DNA of a Neandertal. That applies just as much to Denisovans. They are also genetically distinct.

    In fact, it is the genetic distinction that allows us to recognize Neandertal/Denisovan hybrids in the first place. If they were all within the range of modern human genetic differences, we would simply conclude that they were funny-looking Homo sapiens. That would be a far more startling discovery. Instead what we have are genetically distinct lineages, which means they are not interbreeding very frequently, despite what these fossils seem to indicate.

    Along the way, apparently, they freely spread their genes to outsiders. That highlights the question, [ancient DNA expert Johannes] Krause says, of why Denisovans and Neanderthals nevertheless remained genetically distinct groups. “Why don’t they come together as one population if they come together from time to time?”

    Precisely. If these populations were so capable of interbreeding, why aren’t we modern human beings carrying around more Neandertal or Denisovan DNA? Why aren’t Neandertals or Denisovans well within the range of modern human DNA diversity?

    Svante Pääbo thinks it has something to do with geographic isolation. According to Warren’s Nature piece,

    Pääbo agrees that Neanderthals and Denisovans would have readily bred with each other when they met – but he thinks that those encounters were rare.

    That’s one possible explanation, but I still don’t think viewing Neandertals, Denisovans, and modern humans as geographically isolated varieties or subspecies does justice to the differences between them.

    My final point in favor of recognizing Neandertals and Denisovans as separate species is the patchy distribution of Neandertal and Denisovan DNA in modern people. Instead of finding DNA of ancient origin scattered randomly through modern human genomes, Neandertal and Denisovan DNA tend to show up in particular parts of our chromosomes but not in other parts. This is not what we would expect from random variability of inheritance. This pattern would more likely arise if certain parts of the Neandertal or Denisovan genomes were somehow poorly compatible with the genomes of modern Homo sapiens. Those pieces would tend to be eliminated over time.

    DNA of mixed compatibility is precisely what I would expect when two species hybridize. It’s also not a bit surprising that two species could produce hybrids. This is common in the world of biology. Introgression – the passing of genes from one species to another – is a well-known phenomenon and the subject of many studies. In fact, hybridization is so easy, I often wonder how we keep species separate in the first place.

    The reality of multiple human species has nothing to say about their origin, of course. As I’ve stated before, I view Neandertals, Denisovans, and modern Homo sapiens as human descendants of Adam and Eve, despite their status as separate species. What remains here is an interesting puzzle, however. How is it that Neandertals, Denisovans, and Homo sapiens could readily interbreed, and did so often enough that we’ve found two hybrid individuals already, but not so frequently that we all just merged into one large, variable species? The conventional model, exemplified here by Pääbo, offers geographic isolation as the solution. These people could interbreed readily enough, but it was rare because they didn’t meet that often.

    As a young-age creationist, I see two related questions: How did we get such genetic differences in the first place and why didn’t the populations merge? I suspect the answer to the second question has to do with the confusion at Babel. These peoples didn’t merge for the same reason other peoples didn’t merge: They couldn’t understand each other. How we got these genetic differences in the first place is a more interesting question that still remains to be answered.


    Ten interesting things we read this week

    Image: Shutterstock

    At Ambit, we spend a lot of time reading articles that cover a wide gamut of topics, including investment analysis, psychology, science, technology, philosophy, etc. We have been sharing our favourite reads with clients under our weekly &lsquoTen Interesting Things&rsquo product. Some of the most interesting topics covered in this week&rsquos iteration are related to &lsquoMusical chairs in Private Equity&rsquo, &lsquoWhy complaining alters our brain&rsquo and &lsquofirst generation hybrid hominin specimen&rsquo

    1) Private equity plays risky game of musical chairs [Source: Financial Times ]
    Gala Bingo Hall, which merged with rival Coral in 2005, was at the epicentre of one of Europe&rsquos least successful and controversial leveraged buyouts as it was passed around private equity firms in a financial game of pass the parcel that lasted over a decade. Successive owners would pay themselves high dividends, aided by easy financing, before selling to the next private equity house. Through the whole process, the levels of debt the business carried, measured as a multiple of its earnings, kept creeping up. As business condition toughened post 2008 crisis, the debt burden became unsustainable and Gala Coral nearly went bust, before the business was eventually acquired by rival Ladbrokes in 2016. While the Gala Coral story might have proved a salutary experience about the risks of such pass-the-parcel dealmaking, the opposite has been the case. Last year, the industry did a record 576 so-called secondary deals, when a company or a stake in a company is sold by one private equity firm to another compared to 394 such transactions in the peak of the deal boom in 2007, just before the financial crisis.

    Private equity advisers are increasingly worried that the sector could see a repeat of Gala Coral&rsquos experience as interest rates start to rise, increasing debt payments and raising the chance of a recession. A recent analysis of the performance of 2,137 companies owned by 121 PE firms by Saïd Business School at Oxford University showed that secondary transactions have lower returns than other deals when done by a firm that is under pressure to deploy capital. &ldquoEvery time a company is sold between private equity funds there is a risk that you are taking off some of the potential upside as the business may have been optimized through acquisitions or operational improvements,&rdquo says Neel Sachdev, a leveraged finance partner at the law firm Kirkland & Ellis, which advised Apollo in acquiring the debt of Gala Coral in 2009. &ldquoSo there may be less potential upside every time you pass it on.&rdquo

    Recent examples of pass-the-parcel deals include Cinven&rsquos acquisition this year of laundry services business JLA from peer HG Capital, and KKR&rsquos sale of roses supplier AfriFlora to Sun European Partners last year. &ldquoBuyout groups like secondaries because they are buying an asset from a peer and it feels like there is not much work to do,&rdquo says Per Stromberg, a professor of finance and private equity at the Swedish House of Finance, a research centre. &ldquoBut often this leads to them paying too much.&rdquo Secondary deals often increase the incentives for private equity owners to load more debt on to a business. &ldquoIf you buy a company that has been improved by one or two previous private equity owners and if there is not much to do to improve it, then one way to get returns up is to add more leverage to it,&rdquo he says.

    Defenders of pass-the-parcel deals argue that the key is to work out why the house is selling &ndash due to pressure to return the money back to investors or unfavourable market conditions ahead. They argue that buyout groups bring much-needed injections of capital to fund the growth of a business through acquisitions or expansion. Secondary buyouts, they argue, are part of the evolution of an industry that owns more and more companies and is awash with cash to deploy on deals. Buying the businesses already owned by other private equity firms has become an attractive way to invest their funds, especially as these firms also face growing competition from corporations hungry to find new assets.

    In the case of Gala-Coral, the high debt levels were key to the company&rsquos travails. Sebastien Canderle, author of The Debt Trap, a book on how leverage affects the performance of private equity deals, writes that &ldquowhat brought Gala to the brink of bankruptcy was.&thinsp.&thinsp.&thinsp[that it was] absurdly overleveraged compared to its peers&rdquo. While the other large companies in the sector suffered in the period after the financial crisis, none faced the risk of default or administration. &ldquoAs Gala&rsquos competitors demonstrated, without that much debt laden on the balance sheet the business would not have needed a financial restructuring.&rdquo The private equity industry is now in overdrive, buoyed by record fundraisings. However, some senior figures in the industry say they are shying away from secondary transactions. Lionel Assant, the European head of private equity at Blackstone, said only 1% of his firm&rsquos global deals represent secondary transactions because of concerns that they may deliver meager returns.

    2) Science explains what happens to someone&rsquos brain from complaining every day [Source: educateinspirechange.org ]
    Within the last 20 years, thanks to rapid development in the spheres of brain imaging and neuroscience, we can now say for certain that the brain is capable of re-engineering. In many ways, neuroplasticity &ndash an umbrella term describing lasting change to the brain throughout a person&rsquos life &ndash is a wonderful thing. So why is it so helpful? Because we can: 1) increase our intelligence (IQ) 2) recover from certain types of brain damage and 3) &ldquounlearn&rdquo harmful behaviors, beliefs and habits. Also, on the other side of the coin, we can redesign our brain for the worse! Neuroplasticity can be both the problem and the solution. The topic of this post &ndash complaining is one such behavior. We all know that one person who is continually negative. The person who never seems to be satisfied with anything or anyone. Negative people are almost always complainers, without fail. Worse, complainers are not satisfied in keeping their thoughts and feelings to themselves instead, they&rsquoll seek out some unwilling participant and vent.

    Complainers generally fall into one of these three groups: 1) Attention-seeking Complainers: People who seek attention through complaining always dwelling on about how they&rsquove got it worse than everyone else. 2) Chronic Complainers: These folks live in a constant state of complaint. If they&rsquore not voicing about their &ldquowoe is me&rdquo attitude, they&rsquore probably thinking about it. 3) Low-E.Q. Complainers: &lsquoE.Q.&rsquo is short for emotional quotient, and constituents within this group are short on E.Q. What I.Q. is to intelligence, E.Q. is to emotional understanding. These people aren&rsquot interested in your perspective, thoughts, or feelings. So, is the brain to be blamed? Mostly, it is, yes. Most negative people don&rsquot want to feel this way. Harmful behaviours such as complaining, if allowed to loop within the brain continually, will inevitably alter thought processes. Altered thoughts lead to altered beliefs which in turn lead to a change in behavior.

    Our brain possesses something called the negativity bias. In simple terms, negativity bias is the brain&rsquos tendency to focus more on negative circumstances than positive. Dr. Rick Hanson, a neuroscientist and author of Buddha&rsquos Brain, explains negativity bias: &ldquoNegative stimuli produce more neural activity than do equally intensive positive ones. They are also perceived more easily and quickly.&rdquo Repetition is the mother of all learning. When we repeatedly focus on the negative by complaining, we&rsquore firing and re-firing the neurons responsible for the negativity bias. It&rsquos not possible to be &ldquohappy-go-lucky&rdquo all of the time. We should, however, take concrete steps to counteract negative thinking.

    Research has repeatedly shown that meditation and mindfulness are perhaps the most powerful tools for combating negativity. Positive psychology researcher, Barbara Fredrickson, and her colleagues at the University of North Carolina, showed that people who meditate daily display more positive emotions than those who do not. Following a three-month experiment, Fredrickson&rsquos team noted that &ldquopeople who meditated daily continued to display increased mindfulness, purpose in life, social support, and decreased illness symptoms.&rdquo After learning the basics of meditation, which involves focus on the breath, it&rsquos advisable to create a daily meditation schedule that works for you. 15-20 minutes of daily meditation may just make a huge difference in your life &ndash and your brain!

    3) One big problem with how Jeff and MacKenzie Bezos are spending a small share of their fortune [Source: The Conversation ]
    What happens when someone perceived as not so generous suddenly donates a huge amount for good cause? Yes, people question the decision. And here it&rsquos Jeff Bezos, founder of Amazon. Jeff Bezos and his wife, MacKenzie Bezos, recently announced a plan to spend US$2 billion of their $164 billion fortune on homeless shelters and preschools. But as a political theorist who studies the ethics of philanthropy, Ted Lechterman, the author of this piece, thinks Bezos&rsquos charitable turn raises grave concerns about the pervasive power of business moguls. The Bezos family&rsquos philanthropy is following an unsettling pattern in terms of its timing. Amazon&rsquos market value had recently topped $1 trillion, raising more questions than ever around Amazon&rsquos overwhelming size and power.

    This wasn&rsquot the first time that Bezos effectively redirected attention from Amazon&rsquos immense clout with a big announcement about philanthropy. When news broke in 2017 that Amazon was acquiring Whole Foods, raising new concerns about the company&rsquos retail domination, Bezos made a dramatic public appeal through Twitter for advice on how to focus his giving. The timing may have been coincidental both times, but the suspicion that philanthropy distracts the public from questionable conduct or economic injustice is a familiar worry. Since the days of robber barons like Andrew Carnegie and John D. Rockefeller, social critics have charged that philanthropy is a wolf in sheep&rsquos clothing. This cynical view holds that magnificent acts of generosity are nothing more than cunning attempts to consolidate power. Like dictators who use &ldquobread and circuses&rdquo to pacify the masses, the super-rich give away chunks of their fortunes to shield themselves from public scrutiny and defuse calls for eliminating tax breaks or raising taxes on the wealthiest Americans.

    Dramatic acts of charity by the ultra-wealthy may reduce pressure on governments to tackle poverty and inequality comprehensively. Depending on private benefactors for access to basic necessities can reinforce social hierarchies. And when the elite spend their own money on essential public services like housing, the homeless and education for low-income children, it lets the rich mold social policy to their own preferences or even whims. In other words, even if Bezos has great ideas, no one elected him or hired him to house the homeless and educate kids before they enter kindergarten. The tax deductibility of the donations made by the richest Americans can exacerbate these concerns because it effectively subsidizes their giving. Some scholars argue that the point of tax incentives is to encourage donations for things the government can&rsquot or shouldn&rsquot support directly &ndash like maintaining a church property. Observers, including MarketWatch reporter Kari Paul and Guardian columnist Marina Hyde, have noted that if people like Bezos and the businesses they lead were to stop fighting for low tax rates, democratically elected officials would have more money to spend tackling big problems like homelessness and other urgent priorities.

    Bezos&rsquos behaviour as a businessman has raised other questions about his generosity and respect for democracy. When Amazon&rsquos hometown of Seattle proposed to tackle runaway housing costs with a tax on the city&rsquos largest employers, Amazon resisted. The city backed off after the company threatened to scale down its Seattle operations if the bill passed. It may seem odd that someone who opposed a tax intended to help cover housing costs for his low-income neighbours would want to spend part of his fortune on housing. But to Ted it makes sense, because in his view, Jeff Bezos&rsquos beef isn&rsquot with his duties to help the least fortunate, but with the limits on economic power that democracy requires.

    4) JP Morgan widens blockchain payments to more than 75 banks [Source: Financial Times ]
    More than 75 of the world&rsquos biggest banks are turning to the blockchain to fight the threat of new payments rivals in what will be the regulated banking industry&rsquos largest application of the distributed ledger technology underpinning cryptocurrencies. More than 70 additional banks, including Société Générale and Santander, are joining the Interbank Information Network (IIN) which JPMorgan, Royal Bank of Canada and ANZ have been trialing for 11 months to see if blockchain technology can speed up payments that have errors or require additional compliance checks. The idea is that a mutually-accessible ledger across banks would allow them to quickly resolve issues such as compliance checks, faulty addresses or missing data, which can lead to payments being held up for weeks. The banks expect to put about 14,500 US dollar-denominated payments a day through the enlarged network. &ldquoPayment is one of the segments banks worry most about in terms of ceding to non-bank competition,&rdquo said Jason Goldberg, banks analyst at JP Morgan. &ldquoBlockchain is a way to keep more of that (payments business) in-house.&rdquo

    There is no comprehensive data on how much market share has been won by payments start-ups leveraging technology to offer cheaper services, but individual players have achieved significant scale, including UK-based TransferWise, which processes more than £3bn every month. Emma Loftus, global head of global payments and receivables at JPMorgan Treasury Services, said the IIN would help protect their businesses. &ldquoOne of the complaints that the non-banks have been pointing out [relates to] these frictional processes in the existing cross-border payment mechanism,&rdquo she said. &ldquoGiven that things like blockchain are addressing some of these age-old problems, we&rsquore able to solve the problems ourselves.&rdquo Ms Loftus said only a &ldquosmall percentage&rdquo of total payments instructions get held up but it can take up to two weeks to resolve any issues, making it a &ldquosignificant pain point&rdquo for clients.

    Apart from facilitating seamless payments ecosystem, the IIN also facilitates secure peer-to-peer messaging. The number of transactions put through the IIN will likely expand exponentially as the number of participating banks increases. JP Morgan plans to continue adding banks, and also hopes to expand the IIN offering into other payments in non-US currencies.

    5) Sex and the village: The sexual lives of rural Indian women. [Source: Livemint ]
    This article throws light on how the women in rural villages deal with their sexual desires. The women in villages are known to live a routine life. A life circled around family, kitchen and house. But, in this article, the author shows how the rural women go out of their way to satisfy their desires. Sex, sexuality, desire and sexual needs, particularly those of woman, are not topics that make for easy conversation in a country that seems to believe in sexually regulating one half of its population more than the other. Yet behind the closed doors of homes in the heart of our rural idyll lie undiscovered stories of female desire. This is backed by the Union Government&rsquos National Family Health Survey (NFHS-4), published in December. The survey has a number of findings. Compared to urban women, rural women have sex earlier in life (urban women begin having sex almost two years later than rural women) the frequency of sex is higher and they have more sexual partners in their lifetime.

    While researching for this article, the author came across a village, Charan, where women discuss about using brinjals and other things to pleasure themselves. There was a woman who tried to pleasure herself by inserting a stone pestle used to ground spices into her vagina. Conversations around desire are so normalised in these villages that people discuss what someone did, rather than why they did it. &ldquoIt is very deeply understood in rural areas that sex is a basic need,&rdquo says Archana Dwivedi, director of Delhi-based non-profit Nirantar: A Centre for Gender and Education. &ldquoFrom wherever they are getting or providing it, no one makes a big deal about it.&rdquo Nirantar conducted a workshop for three years, beginning 2005-06, where they brought together four organisations and tried to explore how rural women in north India perceive sexuality. One of their findings was that rural women are much more open about sexuality than urban women, despite differences across caste, class and religion. In one workshop, a group of rural women were asked to list sexual acts. Some 64 acts were listed, including fisting, inserting the penis in the armpit, or even something as simple as playing with the hair.

    Researchers have even found that village life, in some settings, allows for freedom from boundaries and definitions concerning sexuality. Maya Sharma, a Vadodara-based feminist activist, found two women living together in a village. The people of the village referred to the couple as a miya-biwi-ki-jodi (husband and wife couple). While such associations in rural India are often ignored or forgiven, there are cases where too many people find out, or when certain lines are crossed. Punishment can then turn harsher than it would be in a city. Penalties include age-old forms of rural justice: parading women naked, or exiling them from their village. It is inevitable that in a hierarchical society like India, the way sexuality is expressed by women is also dependent on the caste, religion, and class they belong to.

    A great deal of Dalit literature points to how upper-caste men have for centuries exercised a sexual &ldquoright&rdquo over Dalit women when male members of these women&rsquos families are in their employ. Yet only some of these relationships find high caste sanction. For example, an upper-caste married man can have a physical relationship with a Dalit woman, but an unmarried upper-caste man cannot, because he could potentially marry her. Hunger and sexual desire are universal, visceral, and primal. Perhaps this is why hunger has long been used as a metaphor for sex across cultures. These villages in the heart of India are no exception. With hardly any access to sex education, navigating desire is a fraught enterprise. A lot of the women this reporter met spoke about watching porn after marriage mostly because their husbands wanted them to watch it along with them&mdashas a way to legitimize desire.

    6) The blob that tells a story about the origins of life [Source: Financial Times ]
    In 1946, a geologist rummaging in the Ediacara Hills in Australia found curious pancake-shaped, finely ribbed imprints on the underside of rocks. Reginald Sprigg named the fossils medusoids because they resembled jellyfish. These fossils, and similar specimens found nearly all over the world, have puzzled palaeontologists ever since. They look vaguely animal-like but predate the Cambrian Explosion, an abrupt event 541m years ago that heralded the rise of the major animal groups. Taxonomic guesses for so-called Ediacaran fossils, which feature palmlike fronds and spindles as well as ridged discs, have varied wildly: were they fungi, giant single-celled organisms, marine worms or maybe even category-defying life forms lying somewhere between plant and animal? Now, a chemical analysis has offered clues. Scientists in Australia have found ancient traces of cholesterol in Dickinsonia, one such species. Cholesteroid, which is left behind as cholesterol decays, is a biomarker thought to be unique to animals.

    This makes Dickinsonia, which lived between about 570m and 540m years ago, officially the oldest macroscopic animal in the rock record &mdash in other words, the oldest animal that can be seen with the naked eye. The research, led by Ilya Bobrovskiy at the Australian National University, was published in the journal Science. The animal has been imagined as a &ldquoflat, inflated bag&rdquo with the consistency of a thick jellyfish it is likely to have clung to the sea floor, grazing on microbes and absorbing food through its quilted skin. It was, basically, a living blob. It has no recognisable surviving descendants. The latest finding adds to previous research suggesting Dickinsonia, with its ribbed pattern, was an animal.

    A team of researchers, led by Renee Hoekzema at Oxford University, looked at specimens of different sizes and wondered if Dickinsonia grew like a worm, which adds segments as it develops. Larger specimens, presumed to represent older organisms, seemed to have more &ldquoribs&rdquo than smaller examples, with the ribs appearing fatter. In other words, Dickinsonia seemed to grow just like animals do, unfurling to a developmental template still common today. The facts feed into an intriguing picture: creatures, even if only bloblike, existed close to 570m years ago and then seemingly vanished. It was the Cambrian explosion 30m years later that marked the beginning of animal life as we know it. Along came skeletons, shells, legs and other mobility-boosting appendages, compound eyes and teeth. Humans belong among the chordates, which include vertebrates (animals with backbones). Arthropods include insects and crustaceans.

    The trigger for such frenetic evolutionary activity in the Cambrian period has long been debated, but one possibility is a sudden abundance of oxygen. Such an environmental change could have fuelled the development of energy-intensive adaptations such as muscles and nervous systems. This fresh revelation of the world&rsquos oldest macroscopic animal provokes new thinking on the evolution of life. There could be more archaic beasts to come: animals may have been languishing in the seas 700m years ago.

    7) Can Mark Zuckerberg fix Facebook before it breaks democracy? [Source: New Yorker ]
    If Facebook were a country, it would have the largest population on earth. More than 2.2 billion people, about a third of humanity, log in at least once a month. That user base has no precedent in the history of American enterprise. Fourteen years after it was founded, in Zuckerberg&rsquos dorm room, Facebook has as many adherents as Christianity. A couple of years ago, the company was still reveling in its power. By collecting vast quantities of information about its users, it allows advertisers to target people with precision&mdasha business model that earns Facebook more ad revenue in a year than all American newspapers combined. Zuckerberg was spending much of his time conferring with heads of state and unveiling plans of fantastical ambition, such as building giant drones that would beam free Internet (including Facebook) into developing countries. He enjoyed extraordinary control over his company in addition to his positions as chairman and C.E.O., he controlled about 60% of shareholder votes. His personal fortune had grown to more than $60bn. Facebook was one of four companies (along with Google, Amazon, and Apple) that dominated the Internet the combined value of their stock is larger than the G.D.P. of France.

    For years, Facebook had been pulled into issues concerning its privacy and its ability to shape people&rsquos behavior. The company&rsquos troubles came to a head during the US Presidential election of 2016, when propagandists used the site to spread misinformation that helped turn society against itself. Some of the culprits were profiteers who gamed Facebook&rsquos automated systems with toxic political clickbait known as &ldquofake news.&rdquo In a prime example, at least a hundred Web sites were traced to Veles, Macedonia, a small city where entrepreneurs, some still in high school, discovered that posting fabrications to pro-Donald Trump Facebook groups unleashed geysers of traffic. Fake-news sources also paid Facebook to &ldquomicrotarget&rdquo ads at users who had proved susceptible in the past. At the same time, former Facebook executives, echoing a growing body of research, began to voice misgivings about the company&rsquos role in exacerbating isolation, outrage, and addictive behaviors. One of the largest studies, published last year in the American Journal of Epidemiology, followed the Facebook use of more than 5,000 people over three years and found that higher use correlated with self-reported declines in physical health, mental health, and life satisfaction.

    Later, Facebook was confronted with an even larger scandal: the Times and the British newspaper the Observer reported that a researcher had gained access to the personal information of Facebook users and sold it to Cambridge Analytica, a consultancy hired by Trump and other Republicans which advertised using &ldquopsychographic&rdquo techniques to manipulate voter behaviour. In all, the personal data of eighty-seven million people had been harvested. Moreover, Facebook had known of the problem since December of 2015 but had said nothing to users or regulators. The company acknowledged the breach only after the press discovered it. On July 25th, Facebook&rsquos stock price dropped 19%, cutting its market value by $119bn, the largest one-day drop in Wall Street history. Nick Bilton, a technology writer at Vanity Fair, tweeted that Zuckerberg was losing $2.7 million per second, &ldquodouble what the average American makes in an entire lifetime.&rdquo

    While privacy is an important issue, Facebook and Mark have been involved in other issues where they took a beating. Zuckerberg is not yet 35, and the ambition with which he built his empire could well be directed toward shoring up his company, his country, and his name. The question is not whether Zuckerberg has the power to fix Facebook but whether he has the will whether he will kick people out of his office&mdashwith the gusto that he once mustered for the pivot to mobile&mdashif they don&rsquot bring him ideas for preventing violence in Myanmar, or protecting privacy, or mitigating the toxicity of social media. He succeeded, long ago, in making Facebook great. The challenge before him now is to make it good.

    8) Prehistoric girl had parents belonging to different human species [Source: newscientist.com ]
    A sliver of bone from a cave in Russia is at the centre of what may be the biggest archaeological story of the year. The bone belonged to an ancient human who had a Neanderthal mother and a Denisovan father. &ldquoDenny&rdquo is the only first-generation hybrid hominin ever found. &ldquoMy first reaction was disbelief,&rdquo says Viviane Slon of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The find is either a stunning stroke of luck or a hint that hominins interbred more often than we thought. It may even suggest that extinct groups like Neanderthals did not die out, but were absorbed by our species. In prehistory, members of our species interbred with at least two other ancient humans: the Neanderthals and the mysterious Denisovans, who are known only from fragments of bone and teeth discovered in Denisova cave, Russia. Neanderthals and Denisovans interbred too, and Denisovans carried genes from unidentified hominins. These interbreeding events were thought to be rare.

    &ldquoThe likelihood of actually finding a [first-generation] hybrid has always been considered infinitesimally low,&rdquo says Katerina Harvati-Papatheodorou at the University of Tübingen, Germany. A few years ago, archaeologists found a 90,000-year-old bone fragment in Denisova cave. Samantha Brown, then at the University of Oxford, discovered that it came from a hominin by examining the proteins preserved inside it. Her team nicknamed the hominin &ldquoDenny&rdquo. Based on the structure of the bone, Denny died at about 13 years of age. Slon and her colleagues have now examined Denny&rsquos DNA, discovering that Denny was female &ndash and that she had astonishing parentage. Her DNA was almost 50:50 Neanderthal and Denisovan, arranged in a tell‑tale way. Our DNA comes in paired strands called chromosomes, one from each parent. In Denny&rsquos case, each pair had one Neanderthal and one Denisovan chromosome, with very little mixing. She was the daughter of parents from different species.

    Denny&rsquos mitochondrial DNA, which is inherited only from mothers, is Neanderthal. Therefore, her mother was Neanderthal and her father Denisovan. Experts contacted by New Scientist all accept the finding. &ldquoThey nail it,&rdquo says Pontus Skoglund of the Francis Crick Institute in London, UK. &ldquoThere seems to be no uncertainty at all.&rdquo Denny is an enigma, says Harvati-Papatheodorou. &ldquoSince her known remains consist of an unidentifiable bone fragment, it is very difficult to say anything about her daily life, activities, health or subsistence.&rdquo Only 23 ancient hominins have had their genomes sequenced. Yet Denny is not the first with recent shared ancestry. There is also &ldquoOase 1&rdquo, a member of our species who lived 37,000 years ago in what is now Romania. They had a Neanderthal ancestor just four to six generations earlier. If interbreeding were rare, we should not have found these individuals so easily, says Svante Pääbo, also of the Max Planck Institute for Evolutionary Anthropology. &ldquoIt suggests that these groups, when they met, mixed quite freely with each other.&rdquo

    This doesn&rsquot mean Neanderthals and Denisovans were constantly interbreeding. Their genomes show they were &ldquoquite distinct populations&rdquo, says Pääbo. They controlled separate territories &ndash the Neanderthals in Europe, the Denisovans in east Asia &ndash and occasionally met at the boundaries. He says the Denisova cave was &ldquoa unique area where they met, and then they had no prejudices against each other&rdquo. &ldquoThe evidence is growing that interbreeding among different human lineages was more common than previously thought,&rdquo agrees Harvati-Papatheodorou. They had good reason. &ldquoHuman groups were very small and vulnerable to drastic mortality,&rdquo she says. Interbreeding may have been a good way to find a mate. Pääbo argues that when modern humans expanded from Africa into Europe and Asia, they often interbred with Neanderthals and Denisovans. This could be why these groups vanished. &ldquoNeanderthals and Denisovans may not have become violently extinct, but may have become absorbed into modern human populations.&rdquo

    9) Perplexing side effects of xEVs proliferation: Underappreciated risks [Source: Inc42 ]
    Under the new &lsquoelectrification&rsquo theme, there seems an entry of flurry of new players of foreign origin and homegrown start-ups specially in 2Ws and 3Ws segment busy developing and launching products, aspiring consumers to queue up to buy digital feature enabled automobiles, while several established automotive firms have chosen calibrated wait-n-watch approach. However, in the backdrop most of the incumbent players have their cards ready to jump on to EV bandwagon. The Indian government plans to help the renaissance of xEVs and help it gain a market foothold, with a subsidy outlay of Rs5,500 crore under FAME II which just got cleared. While the government is doing quite a bit to enable electric mobility, when it comes to entire xEVs ecosystem, there seem uncoordinated efforts at several fronts including: 1) CAFÉ & BS-VI norms 2) Vehicle scrap policy at the cabinet 3) March 2018 E-waste regulations and 4) FAME- II Rs5,500-crore subsidy outlay, none of which talks about what to do with batteries when they retire and have completely overlooked repurposing and recycling of depleted xEV batteries.

    The risk associated with &ldquoRepurposing or Recycling of Batteries&rdquo, get further exacerbated by lack of limited availability of natural resources for LiB battery manufacturing in India in a deterrent to growth of xEVs. This might not seem pressing today- the industry itself is in the infancy and most of xEVs still have young and healthy batteries. However, it&rsquos likely that first batch of batteries from India&rsquos first electric car Mahindra Reva NXR M1 (aka Mahindra e2O) launched sometime early 2013 will soon hit the retirement age and in absence of any appropriate policy framework in the country for repurposing or recycling of batteries, it&rsquos bound for landfills. Left unattended, it will turn out to be a huge problem for the industry. The dilemma of what to do with those batteries, once they are discarded will only grow with time.

    As of today, EV battery recycling barely exists as an industry. However, according to the author, beyond 2025 the techno-commercial economics is likely to improve significantly with the emergence of several factors (e.g., high volume of used batteries, decline in cost, new battery compositions). There are some signs of progress with global players like Belgian Umicore, US-Retriev & Tesla planning to have an onsite recycling facility in Nevada, USA. In the short term, used lithium-ion batteries can be used for lower cyclic requirement of stationary applications in which diminished capacity matters less. The economics and business viability of second life use cases is compelling. China is precisely encouraging the same and has issued new guidelines to become the Detroit of depleted car batteries in the world. A recent article by Bloomberg also mentions Chinese refurbishers paying $4.0 per kilogram for batteries with reuse potential a battery more suited for recycling will go for as little as $1.50 per kilogram.

    10) This is your brain on the internet [Source: Medium ]
    In this piece, the author talks about how the Internet has changed the functioning of our brain. Humans have always been good at learning and adapting to new environments. So given the internet&rsquos dramatic impact on life in the developed world, it is no surprise that we have adjusted our thinking and behavior. The biggest impact has perhaps come from companies like Google, which make all knowledge available to us at a few keystrokes. Our internet usage has &ldquoGooglified&rdquo our brains, making us more dependent on knowing where to access facts and less able to remember the facts themselves. This might sound a little depressing, but it makes perfect sense if we are making the most of the tools and resources available to us. Who needs to waste their mental resources on remembering that an &ldquoostrich&rsquos eye is bigger than its brain,&rdquo when the internet can tell us at a moment&rsquos notice? Let&rsquos save our brains for more important problems.

    Photographs also have transformative effects on the way our memories work. Photographs can be a great way to physically save a moment into your collection, and cameras may help visual memory if used as a tool to enhance how you engage with an experience. But don&rsquot let them come at the expense of your own enjoyment and natural memory of the real thing in front you. It&rsquos counterproductive and a little bizarre to take photos of the world&rsquos wonders, but forget to look at them while they&rsquore actually there. A 2009 study showed that people who heavily engage in multiple forms of media at the same time (e.g., talking on the phone, while working on an essay, while listening to music, while watching TV), perform worse in standardized cognitive tests that measure memory, attention, and task-switching. A 2013 study suggested the opposite effect for task-switching.

    Recent studies even suggest that children who use the internet excessively may develop less gray and white matter volume in certain brain areas, and may harm their verbal intelligence. It is not yet clear if internet usage directly causes these effects or if children who are predisposed to the effects are just more likely to overuse the internet. For now, the evidence provides notes of caution and attention rather than conclusive insights.

    The advantages of using the internet correctly are enormous, so we need to be careful about making any concrete recommendations on usage limits. However, as with practically everything in the world, moderation and thoughtful consumption are likely to go a long way. When we pay careful attention to what the internet is doing to us in our own lives &mdash how happy or sad it is making us, and how much it is helping or hindering our progress &mdash we can make better decisions about optimizing our well-being. The internet is amazing, but the beautiful world outside is also waiting for us to directly experience, learn from, and appreciate it. The whole wide world and the world wide web may well compete for our time and attention. It is up to us to maximize the benefits in our own lives by choosing the right &ldquowww&rdquo when it matters.


    RELATED ARTICLES

    They found that alone they were not, but that adding a single extra episode of interbreeding around 700,000 years ago, involving a shared ancestor of both Denisovans and Neanderthals, was enough to make sense out of the data.

    This shared ancestor came from after the split with the human branch of the hominin family tree and is believed to have bred with a mystery population of 'super-archaic' hominins — the same one that the Denisovans would later mate with.

    'This is the only model I’ve come up with that fits well,' Professor Rogers told New Scientist.

    'No one else has come up with a model that explains these data this well,' he added.

    The existence of this ancient group is suggested by the genetic analysis of Denisovan (pictured, artist's impression) and Neanderthal remains, along with modern human genomes

    Anthropologists believe that hominins evolved in Africa around 13 million years ago.

    The first hominin species to migrate out into other continents was likely Homo erectus , which emerged from Africa around 2 million years ago and had migrated eastwards to reach Dmanisi in Georgia about 1.8 million years ago.

    H. erectus ultimately migrated at least as far as Indonesia, where it is thought they survived until around 550,000 years ago.

    'My results are consistent with the view that these super-archaics are descendants of that original out-of-Africa migration,' Professor Rogers said.

    It is possible, then, that the mysterious 'super-archaic' hominin population may have been H. erectus, whose emergence 2 million years ago matches the researchers' estimated dating of the split between the super-archaics and other hominins.

    Researchers believe that these ancient hominins emerged around 2 million years ago — suggesting that they could be Homo erectus (pictured, in an artist's reconstruction)

    Back in Africa, it is thought that the shared ancestors of Denisovans and Neanderthals, which are unknown in the fossil record, likely split from the ancestors of modern humans around 800,000 years ago.

    The Neanderthal/Denisovans ancestors, which Professor Rogers has dubbed 'Neandersovans', would later have migrated out of Africa, eventually meeting up with the super-archaics — possibly H. erectus — with whom they mated.

    It was only around 200,000 years ago that modern humans first migrated out of Africa and, in doing so, encountered both the Neanderthals and the Denisovans.

    Modern humans likely never met any H. erectus , whom it is thought would have become extinct before the arrival of our direct ancestors.

    When humans mated with Neanderthals, they had only been evolving apart for a maximum of 750,000 years.

    In contrast, the Neandersovans and the mysterious super-archaics had been evolving in isolation from each other for around 1.3 million years.

    This would make the mingling of the two groups the most extreme example of hominin interbreeding that we are aware of.

    As a consequence of their differences, it is likely that the hybrids born of this extreme interbreeding had health issues, Professor Rogers noted.

    'There’s good evidence that hybrids between either Neanderthals or Denisovans and modern humans seem to have been less healthy,' he said, explaining that evolution appears to have since weeded out many genes introduced by such interbreeding.

    'Since the super-archaics had been separated even longer from Neandersovans, you might expect that that would have been a greater problem for them,' Professor Rogers added.

    It is thought that the shared ancestors of Denisovans and Neanderthals, which are unknown in the fossil record, likely split from the ancestors of modern humans around 800,000 years ago

    Professor Rogers and his colleagues' findings also suggest that fragments of DNA from the super-archaic populations might be preserved in Neanderthal genomes — and, by extension, potentially even in modern humans.

    Any such remnants will be dispersed throughout the genome, however, making finding them difficult.

    'I’m not going to say it’s impossible,' Professor Rogers said.

    But, he added, such would certainly be more of a challenge than finding the Neanderthal DNA many of us carry in small amounts.

    Evolutionary biologist Serena Tucci of Princeton University, New Jersey, who was not involved in the present study, is sceptical about the findings.

    The results will need to be validated using other research methods, she told New Scientist.

    It is also possible, Dr Tucci noted, that the super-archaic group is not H. erectus , but in fact an entirely different group not presently known to us from the fossil record.

    'I would be very cautious here,' she said.

    A pre-print version of the article, which has not yet been peer-reviewed, can be read on the bioRxiv repository .

    WHO WERE THE DENISOVANS?

    The Denisovans are an extinct species of human that appear to have lived in Siberia and even down as far as southeast Asia.

    Although remains of these mysterious early humans have only been discovered at one site - the Denisova Cave in the Altai Mountains in Siberia, DNA analysis has shown they were widespread.

    Scientists were able to analyse DNA from a tooth and from a finger bone excavated in the Denisova cave in southern Siberia.

    The discovery was described as 'nothing short of sensational.'

    The individuals belonged to a genetically distinct group of humans that were distantly related to Neanderthals but even more distantly related to us.

    Researchers are now beginning to find out just how big a part they played in our history.

    DNA from these early humans has been found in the genomes of modern humans over a wide area of Asia, suggesting they once covered a vast range.

    They are thought to have been a sister species of the Neanderthals, who lived in western Asia and Europe at around the same time.

    The two species appear to have separated from a common ancestor around 200,000 years ago, while they split from the modern human Homo sapien lineage around 600,000 years ago.

    Last year researchers even claimed they could have been the first to reach Australia.

    Aboriginal people in Australia contain both Neanderthal DNA, as do most humans, and Denisovan DNA.

    This latter genetic trace is present in Aboriginal people at the present day in much greater quantities than any other people around the world.

    Bone and ivory beads found in the Denisova Cave were discovered in the same sediment layers as the Denisovan fossils, leading to suggestions they had sophisticated tools and jewellery.

    Professor Chris Stringer, an anthropologist at the Natural History Museum in London, said: 'Layer 11 in the cave contained a Denisovan girl's fingerbone near the bottom but worked bone and ivory artefacts higher up, suggesting that the Denisovans could have made the kind of tools normally associated with modern humans.

    'However, direct dating work by the Oxford Radiocarbon Unit reported at the ESHE meeting suggests the Denisovan fossil is more than 50,000 years old, while the oldest 'advanced' artefacts are about 45,000 years old, a date which matches the appearance of modern humans elsewhere in Siberia.'

    Did they breed with other species?

    Yes. Today, around 5 per cent of the DNA of some Australasians – particularly people from Papua New Guinea – is Denisovans.

    Now, researchers have found two distinct modern human genomes - one from Oceania and another from East Asia - both have distinct Denisovan ancestry.

    The genomes are also completely different, suggesting there were at least two separate waves of prehistoric intermingling between 200,000 and 50,000 years ago.

    Researchers already knew people living today on islands in the South Pacific have Denisovan ancestry.

    But what they did not expect to find was individuals from East Asia carry a uniquely different type.


    Oldest Human DNA Reveals Mysterious Branch of Humanity

    The oldest known human DNA found yet reveals human evolution was even more confusing than thought, researchers say.

    The DNA, which dates back some 400,000 years, may belong to an unknown human ancestor, say scientists. These new findings could shed light on a mysterious extinct branch of humanity known as Denisovans, who were close relatives of Neanderthals, scientists added.

    Although modern humans are the only surviving human lineage, others once strode the Earth. These included Neanderthals, the closest extinct relatives of modern humans, and the relatively newfound Denisovans, who are thought to have lived in a vast expanse from Siberia to Southeast Asia. Research shows that the Denisovans shared a common origin with Neanderthals but were genetically distinct, with both apparently descending from a common ancestral group that had diverged earlier from the forerunners of modern humans. [See Images of Excavation & Mysterious 'New Hominid']

    Genetic analysis suggests the ancestors of modern humans interbred with both these extinct lineages. Neanderthal DNA makes up 1 to 4 percent of modern Eurasian genomes, and Denisovan DNA makes up 4 to 6 percent of modern New Guinean and Bougainville Islander genomes in the Melanesian islands.

    Pit of Bones

    To discover more about human origins, researchers investigated a human thighbone unearthed in the Sima de los Huesos, or "Pit of Bones," an underground cave in the Atapuerca Mountains in northern Spain. The bone is apparently 400,000 years old.

    "This is the oldest human genetic material that has been sequenced so far," said study lead author Matthias Meyer, a molecular biologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "This is really a breakthrough &mdash we'd never have thought it possible two years ago that we could study the genetics of human fossils of this age." Until now, the previous oldest human DNA known came from a 100,000-year-old Neanderthal from a cave in Belgium.

    The Sima de los Huesos is about 100 feet (30 meters) below the surface at the bottom of a 42-foot (13-meter) vertical shaft. Archaeologists suggest the bones may have been washed down it by rain or floods, or that the bones were even intentionally buried there.

    This Pit of Bones has yielded fossils of at least 28 individuals, the world's largest collection of human fossils dating from the Middle Pleistocene, about 125,000 to 780,000 years ago.

    "This is a very interesting time range," Meyer told LiveScience. "We think the ancestors of modern humans and Neanderthals diverged maybe some 500,000 years ago." The oldest fossils of modern humans found yet date back to about 200,000 years ago.

    Denisovan relative?

    The researchers reconstructed a nearly complete genome of this fossil's mitochondria &mdash the powerhouses of the cell, which possess their own DNA and get passed down from the mother. The fossils unearthed at the site resembled Neanderthals, so researchers expected this mitochondrial DNA to be Neanderthal.

    Surprisingly, the mitochondrial DNA reveals this fossil shared a common ancestor not with Neanderthals, but with Denisovans, splitting from them about 700,000 years ago. This is odd, since research currently suggests the Denisovans lived in eastern Asia, not in western Europe, where this fossil was uncovered. The only known Denisovan fossils so far are a finger bone and a molar found in Siberia. [Denisovan Gallery: Tracing the Genetics of Human Ancestors]

    "This opens up completely new possibilities in our understanding of the evolution of modern humans, Neanderthals and Denisovans," Meyer said.

    The researchers suggest a number of possible explanations for these findings. First, this specimen may have been closely related to the ancestors of Denisovans. However, this seems unlikely, since the presence of Denisovans in western Europe would suggest an extensive overlap of territory with Neanderthal ancestors, raising the question of how both groups could diverge genetically while overlapping in range. Moreover, the one known Denisovan tooth is significantly different from teeth seen at the Pit of Bones.

    Second, the Sima de los Huesos humans may be related to the ancestors of both Neanderthals and Denisovans. The researchers consider this plausible given the fossil's age, but they would then have to explain how two very different mitochondrial DNA lineages stemmed from one group, one leading to Denisovans, the other to Neanderthals.

    Third, the humans found at the Sima de los Huesos may be a lineage distinct from both Neanderthals and Denisovans that later perhaps contributed mitochondrial DNA to Denisovans. However, this suggests this group was somehow both distinct from Neanderthals but also independently evolved several Neanderthal-like skeletal features.

    Fourth, the investigators suggest a currently unknown human lineage brought Denisovan-like mitochondrial DNA into the Pit of Bones region, and possibly also to the Denisovans in Asia.

    "The story of human evolution is not as simple as we would have liked to think," Meyer said. "This result is a big question mark. In some sense, we know less about the origins of Neanderthals and Denisovans than we knew before."

    The scientists now hope to learn more about these fossils by retrieving DNA from their cell nuclei, not their mitochondria. However, this will be a huge challenge &mdash the researchers needed almost 2 grams of bone to analyze mitochondrial DNA, which outnumbers nuclear DNA by several hundred times within the cell.

    The scientists detailed their findings in the Dec. 5 issue of the journal Nature.


    Artificial Intelligence Detects Unknown Human Ancestor

    Can the minds of machines teach us something new about what it means to be human? When it comes to the intricate story of our species’ complex origins and evolution, it appears that they can.

    A recent study used machine learning technology to analyze eight leading models of human origins and evolution, and the program identified evidence in the human genome of a “ghost population” of human ancestors.

    The analysis suggests that a previously unknown and long-extinct group of hominins interbred with Homo sapiens in Asia and Oceania somewhere along the long, winding road of human evolutionary history, leaving behind only fragmented traces in modern human DNA.

    The study, published in Nature Communications, is one of the first examples of how machine learning can help reveal clues to our own origins. By poring through vast amounts of genomic data left behind in fossilized bones and comparing it with DNA in modern humans, scientists can begin to fill in some of the gaps of our species’ evolutionary history.

    In this case, the results seem to match paleoanthropology theories that were developed from studying human ancestor fossils found in the ground. The new data suggest that the mysterious hominin was likely descended from an admixture of Neanderthals and Denisovans (who were only identified as a unique species on the human family tree in 2010).

    Such a species in our evolutionary past would look a lot like the fossil of a 90,000-year-old teenage girl from Siberia’s Denisova cave. Her remains were described last summer as the only known example of a first-generation hybrid between the two species, with a Neanderthal mother and a Denisovan father.

    “It’s exactly the kind of individual we expect to find at the origin of this population, however this should not be just a single individual but a whole population,”

    says study co-author Jaume Bertranpetit, an evolutionary biologist at Barcelona’s Pompeu Fabra University.

    Previous human genome studies have revealed that after modern humans left Africa, perhaps 180,000 years ago, they subsequently interbred with species like Neanderthals and Denisovans, who coexisted with early modern humans before going extinct. But redrawing our family tree to include these divergent branches has been difficult. Evidence for “ghost” species can be sparse, and many competing theories exist to explain when, where, and how often Homo sapiens might have interbred with other species.

    Traces of these ancient interspecies liaisons, called introgressions, can be identified as places of divergence in the human genome. Scientists observe more separation between two chromosomes than you’d expect if both of the chromosomes came from the same human species. When scientists sequenced the Neanderthal genome in 2010, they realized that some of these divergences represented fractions of our genome that came from Neanderthals. Studies have also revealed that some living humans can trace as much as 5 percent of their ancestry to Denisovans.

    “So, we thought we’d try to find these places of high divergence in the genome, see which are Neanderthal and which are Denisovan, and then see whether these explain the whole picture,” Bertranpetit says. “As it happens, if you subtract the Neanderthal and Denisovan parts, there is still something in the genome that is highly divergent.”

    Identifying and analyzing the many divergent places throughout the genome, and computing the countless genetic combinations that could have produced them, is too big a job for humans to tackle on their own—but it’s a task that may be tailor made for deep learning algorithms.

    Deep learning is a type of artificial intelligence in which algorithms are designed to work as an artificial neural network, or a program that can process information the same way a mammalian brain would.

    These machine learning systems can detect patterns and account for previous information to “learn,” allowing them to perform new tasks or look for new information after analyzing enormous amounts of data. (A common example is Google DeepMind’s AlphaZero, which can teach itself to master board games.)

    “Deep learning is fitting a more complicated shaped thing to a set of points in a bigger space,” says Joshua Schraiber, an evolutionary genomics expert at Temple University. “Instead of fitting a line between Y and X, you’re fitting some squiggly thing to a set of points in much bigger, thousand-dimensional space. Deep learning says, ‘I don’t know what squiggly shape should fit to these points, but let’s see what happens.’”

    In this case, machines were set to work analyzing the human genome and predicting human demographics by simulating how our DNA might have evolved over many thousands of possible scenarios of ancient evolution.

    The program accounted for the structure and evolution of DNA as well as models of human migration and interbreeding to try to fit some of the pieces together in an incredibly complex puzzle.

    The researchers trained the computer to analyze eight different models of the most plausible theories of early human evolution across Eurasia. The models came from previous studies that attempted to come up with a scenario that would result in the current picture of the human genome, including its known Neanderthal and Denisovan components.

    “There could be other models, of course, but these models are the ones that other people have been proposing in the scientific literature,” Bertranpetit says. Each model begins with the accepted out-of-Africa event, then features a different set of the most likely splits between human lineages, including various interbreedings with both known species and possible “ghost” species.

    “With each of these eight models, we calculate over weeks of computations how well they are able to reach the actual, present genetic composition of humans,” Bertranpetit says. “Every time we do a simulation, it’s a simulation of a possible path of human evolution, and we have run those simulations thousands of times, and the deep learning algorithms are able to recognize which of the models best suit the data.”

    The machine’s conclusion? An ancestor species is present in our lineage that we have yet to identify. “By far, the only models we tested that really are backed by the data are the ones having this ghost population introgression,” Bertranpetit says.

    The intriguing study and others like it may help redraw the map of how humans migrated and evolved though what appears to be an increasingly complicated ancient world in Eurasia and Oceania.

    “It’s certainly interesting and consistent with the emerging picture of a complex reticulated phylogeny in human evolution,” Iain Mathieson, a University of Pennsylvania population geneticist, says via email.

    “I’m not even sure it makes sense to talk about ‘introgression events’ when that seems to be the norm.” In fact, because only eight models were tested and many others could be possible, Mathieson adds that the new findings are “certainly a plausible scenario, but the reality is likely even more complex.”

    As new fossil discoveries are made in the field, updated models can now be tested against the human genome using these types of programs. Schraiber says the power of deep learning for studying human origins lies precisely in its capability to analyze complex models.

    “If you want to do an extremely detailed model because you’re an anthropologist, and you want to know if this introgression happened 80,000 years ago or 40,000 years ago, that’s the power of a deep learning approach like this.”

    Complex as they are, the interbreedings of ancient Eurasia are still only one part of our human story. Bertranpetit believes that future advances in deep learning can help uncover other new chapters.

    “This kind of method of analysis is going to have all kinds of new results,” he says. “I am sure that people working in Africa will find extinct groups that are not recognized yet. No doubt Africa is going to show us surprising things in the future.”


    RELATED ARTICLES

    The researchers used the algorithm to look at genomes from two Neanderthals, a Denisovan and two African humans.

    Alongside finding that a small proportion of the Neanderthal genome came from ancient humans, the team also determined that one per cent of the Denisovan genome appears to have come from an unknown and more distant species.

    Moreover, up to 15 per cent of this 'super-archaic' genetic material has likely been passed down into modern humans who are alive today, the researchers said.

    While it is not clear exactly from which species these fragments of DNA originated, the team suspect that they may have come from Homo Erectus, an ancient hominin species that first emerged around two million years ago.

    'This new algorithm that Melissa has developed — ARGweaver-D — is able to reach back further in time than any other computational method I've seen,' commented Professor Siepel.

    'It seems to be especially powerful for detecting ancient introgression.'

    Alongside finding that a small proportion of the Neanderthal genome (red) came from ancient humans, the team also determined that one per cent of the Denisovan genome (blue) appears to have come from an unknown and more distant species (orange). Moreover, up to 15 per cent of this 'super-archaic' genetic material has likely been passed down into modern humans who are alive today (green), the researchers said

    The findings add to the many previously known cases of gene flow between ancient humans and their relatives.

    Moreover, given the number of introgression events, it seems likely that interbreeding occurred whenever two groups overlapped in time and space, the researchers commented.

    The ARGweaver-D algorithm may also prove a useful tool to study other species which have undergone significant interbreeding episodes — such as occurs among wolves and dogs.

    The full findings of the study were published in the journal PLOS Genetics.

    WHO WERE THE DENISOVANS?

    The Denisovans are an extinct species of human that appear to have lived in Siberia and even down as far as southeast Asia.

    Although remains of these mysterious early humans have only been discovered at one site - the Denisova Cave in the Altai Mountains in Siberia, DNA analysis has shown they were widespread.

    DNA from these early humans has been found in the genomes of modern humans over a wide area of Asia, suggesting they once covered a vast range.

    DNA analysis of a fragment of pinky finger bone in 2010, (pictured) which belonged to a young girl, revealed the Denisovans were a species related to, but different from, Neanderthals.

    They are thought to have been a sister species of the Neanderthals, who lived in western Asia and Europe at around the same time.

    The two species appear to have separated from a common ancestor around 200,000 years ago, while they split from the modern human Homo sapien lineage around 600,000 years ago.

    Bone and ivory beads found in the Denisova Cave were discovered in the same sediment layers as the Denisovan fossils, leading to suggestions they had sophisticated tools and jewellery.

    DNA analysis of a fragment of a fifth digit finger bone in 2010, which belonged to a young girl, revealed they were a species related to, but different from, Neanderthals.

    Later genetic studies suggested that the ancient human species split away from the Neanderthals sometime between 470,000 and 190,000 years ago.

    Anthropologists have since puzzled over whether the cave had been a temporary shelter for a group of these Denisovans or it had formed a more permanent settlement.

    DNA from molar teeth belonging to two other individuals, one adult male and one young female, showed they died in the cave at least 65,000 years earlier.

    Other tests have suggested the tooth of the young female could be as old as 170,000 years.

    A third molar is thought to have belonged to an adult male who died around 7,500 years before the girl whose pinky was discovered.



    Comments:

    1. Peverell

      Gotta try everything

    2. Cadmus

      You are not right. I can defend my position. Email me at PM, we will discuss.

    3. Zoloshakar

      That he projects?



    Write a message