September 14, 2018

A fragment of bone discovered in a Siberian cave has recently revealed the first known hybrid between a Neandertal and a member of another prehistoric human group known as Denisovans. The fragment came from Denisova Cave on the Anuy River in the Altai Mountains of southern Siberia. Genetic material extracted from the bone fragment showed that a teenage girl who lived and died more than 50,000 years ago was the daughter of a Neandertal mother and Denisovan father. The finding confirms interbreeding between the prehistoric peoples that had been only hinted at in earlier genetic studies.

The bone fragment called Denisova 11 (seen here in different views) was found at Denisova Cave in 2012. DNA evidence recently showed that the bone came from the daughter of a Neandertal mother and a Denisovan father. Credit: © Thomas Higham, University of Oxford

Scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, examined a small bone fragment excavated at Denisova Cave in 2012. Proteins extracted from the bone fragment, called Denisova 11, indicated that it came from a human being. The fragment likely came from a shinbone or thighbone. The thickness of the bone suggested the fragment belonged to a female who was at least 13 years old when she died. Radiocarbon dating indicated the bone fragment was at least 50,000 years old. Analysis of the bone’s genetic material showed that Denisova 11 had approximately equal amounts of Neandertal and Denisovan ancestry.

Denisovans were prehistoric humans who lived in Asia. Scientists do not know what they looked like, because they are known only from a few skeletal remains. Scientists identified this population by analyzing ancient DNA (deoxyribonucleic acid) recovered from the bones. The scientists were able to extract and sequence entire individual genomes. The term genome refers to all the genes on a cell’s threadlike structures called chromosomes. The discovery of Denisovans was the first time that scientists identified a prehistoric human population through DNA analysis alone.

The Neandertals were prehistoric people who lived in Europe and Asia. They are mainly known from thousands of fossils that date from about 150,000 to 39,000 years ago. Neandertals were very different from people today. Their skulls were huge, with a large, projecting face; a low, sloping forehead; and a prominent browridge, a raised strip of bone across the forehead above the eyes. By 2010, scientists had sequenced the entire Neandertal genome. The Neandertal genome differs markedly from that of the Denisovans, suggesting that the populations lived apart for many thousands of years.

The young girl was a hybrid of two very distinct groups of prehistoric people. Neandertals and Denisovans differed both culturally and physically. Meetings between the two groups and the creation of hybrid children were most likely rare events. The study of human genomes shows that both Neandertals and Denisovans also occasionally interacted and interbred with modern humans, whose era was beginning as the prehistoric humans were dying out. Among modern peoples of Europe, Asia, and the Pacific islands, between 1 and 4 percent of the population’s genome comes from Neandertals. Scientists have also found that Europeans, Asians, and some aboriginal peoples of Australia, New Guinea, and islands of the western Pacific have trace amounts of Denisovan DNA.

March 28, 2018

When astronaut Scott Kelly returned to Earth from a year-long mission aboard the International Space Station (ISS) on March 1, 2016, he was a changed man. Literally. Compared to his identical twin brother, fellow astronaut Mark Kelly, there were several noticeable differences. Scott Kelly had grown about 2 inches (5 centimeters) taller in space, and his overall body mass had decreased a bit. However, National Aeronautics and Space Administration (NASA) scientists were most interested in the changes that could not be seen, changes in Kelly’s genetic makeup. And unlike his physical metamorphosis (his body soon resumed its Earthbound proportions), some changes in Kelly’s DNA seem to be permanent.

U.S. astronaut Scott Kelly poses inside the International Space Station in 2015. Kelly’s body and genetic makeup changed during his weightless year in space.

In 2015, Scott Kelly and Russian cosmonaut Mikhail Kornienko began a unique experiment to learn about the effects of long-term space travel on the human body. The pair spent 340 consecutive days on the ISS as part of a study that will help NASA scientists understand the challenges they must conquer if humans are ever to journey to Mars and beyond. Kelly and Kornienko orbited Earth more than 10,000 times speeding at 17,500 miles per hour (28,165 kilometers per hour) while floating in the weightlessness of microgravity (a condition of very low gravity). During this time, they experienced the stresses and solitude of long-term space flight and were exposed to cosmic radiation above the protective filter of Earth’s atmosphere.

NASA astronaut Scott Kelly (left) and Russian cosmonaut Mikhail Kornienko pose during training at NASA’s Johnson Space Center prior to their year in space. Credit: Bill Stafford, NASA

For experimental control, Scott’s brother Mark remained on Earth. As Scott’s identical twin brother, Mark’s genetic makeup is exactly the same as Scott’s. After Scott returned, NASA scientists studied the twin brothers. Any differences between Scott and Mark could be seen as the effects of the long-term space travel.

The growth spurt that Scott Kelly experienced in orbit turned out to be short-lived and he soon shrank back to his normal height as he returned to Earth’s gravity. But NASA scientists were surprised to find that Scott’s DNA, the genetic material that makes up his genes, was now significantly different from his twin. They found that about 7 percent of Scott’s genes, including those involved in bone formation, DNA repair, oxygen use, the immune system, and eyesight, had altered function when compared to Mark’s genes. Many of these genetic changes appear to be permanent.

NASA scientists think that Scott’s long-term mission in space altered his DNA through processes called epigenetics. Scientists have long known that environmental factors can alter how genes are expressed (how they function) in organisms through epigenetic processes. These processes are not mutations, nor are they physical changes in the DNA. Rather, the processes change how a particular gene functions. Various factors may switch a particular gene on or off or otherwise change how it is expressed. Such environmental factors include nutrition, exposure to certain chemicals, and stress. Scott and Mark remain genetically identical twins, but some of Scott’s genes are now expressed differently compared to Mark’s because of his time in space.

July 19, 2016

Late last month, paleontologists (scientists who study fossils) announced an amazing discovery. Researchers led by Lida Xing at the China University of Geosciences in Beijing had discovered two bird wings preserved in amber. They published their findings in the journal Nature Communications.

Amber preserved this 100 million-year-old wing tip featuring bones, feathers, and soft tissue.
Credit: © Ryan C. McKellar, Royal Saskatchewan Museum

Amber is a hard, yellowish-brown fossilized resin. It comes chiefly from the resins of pine trees that grew millions of years ago. These resins were gummy materials mixed with oils in the trees. When the oils oxidized (combined with oxygen), hard resins were left. These pine trees were then buried underground or underwater, and the resins slowly changed into lumps of amber. These lumps often contain insects trapped as the resins flowed from the trees. But finding larger animals such as small vertebrates (animals with backbones) is incredibly rare. In the 1993 science fiction film Jurassic Park, dinosaur DNA (deoxyriboneucleic acid) is discovered in the blood of an ancient mosquito fossilized in amber. Movie scientists then used the DNA to recreate dinosaurs—an improbable, yet intriguing, plot line.

The wing fossil subjects of last month’s report were formed about 100 million years ago, in the Cretaceous Period, in what is now Myanmar (also called Burma). Two birds apparently became stuck in the sticky resin of a tree and died. The amber preserved the three-dimensional structure of the birds’ wings, as well as the wings’ feathers, skin, and bones—even the color patterns!

Xing and his team think the wings came from a group of birds called enantiornithines, which means opposite birds in Greek. These birds had claws and teeth, and they went extinct along with the nonflying dinosaurs about 65 million years ago. The fossils showed that the wings were from young birds and that the birds hatched as miniature adults, ready to fly. This is different from modern birds, which must develop for weeks or months before they can leave the nest.

The structure of the wings and the arrangement of feathers are similar to modern bird wings. Birds evolved (developed over time) about 150 million years ago from meat-eating dinosaurs, so they must have quickly developed modern-looking wings, before enantiornithines and the ancestors of modern birds split.

Unlike science fiction, these fossils won’t resurrect the extinct enantiornithines, even if they do contain DNA. The technology to create entire animals from bits of ancient DNA does not yet—and might never—exist. The fossils do, however, offer paleontologists a treasure trove of information that will help us better understand early birds and their world.

January 29, 2015.

Prehistoric people stand side by side in this reconstruction based on fossils discovered at sites in Europe. The Neandertal man, left, is a kind of archaic human who lived in Europe and central Asia from about 150,000 to 39,000 years ago. Physically modern humans, above right, only appeared in Europe about 40,000 years ago. The two populations may have mixed and interacted with one another in many ways. Although the Neandertals died out, many humans alive today have small amounts of DNA from Neandertals and other archaic human populations. Reconstruction by Elisabeth Daynes of the Daynes Studio, Paris, France. © S. Plailly and E. Daynes, Science Source

An international team of anthropologists (scientists who study humans and their cultures), led by Israel Hershkovitz of Tel Aviv University in Israel, have published a description of a 55,000-year-old skull discovered in Manot Cave in western Galilee in the journal Nature. The fossil skull  has a mixture of features from both Neandertals and modern humans. The scientists claim that the skull provides the first fossil evidence from a critical period in human evolutionary history when early humans migrating out of Africa encountered and interbred with Neandertals.

Neandertals were a physically distinct group of archaic humans who lived in Europe and Central Asia from about 150,000 to 39,000 years ago. Unlike modern people, Neandertals had a long skull, thick skull bones, and a large face with thick browridges. Modern humans differ from archaic humans by the presence of a chin, a vertical forehead, a lack of browridges, and a smaller, less-protruding face compared with Neandertals. Anthropologists believe that physically modern humans originated in Africa and began to migrate into the Levant region (the area around the Mediterranean Sea) and beyond around 60,000 years ago. Fossil evidence shows that Neandertals also lived in the Levant when modern human beings appeared in the region. In the 1980’s, anthropologists found a complete Neandertal skeleton dating to about 60,000 years ago at Kebara, Israel, not far from Manot Cave.

The Manot skull is incomplete, missing the facial portion. However, scientists can tell from the shape of the skull and the thinner bone it is made up of that it is physically modern. Several features of the skull, however, such as a bulge at the back of the cranium (the bones that enclose the brain), called an occipital bun, are characteristic of Neandertal skulls. The scientists claim that the Manot skull demonstrates a “mosaic” of Neandertal and modern traits that likely came about from interbreeding between the two populations. They believe that the Levant may have been an important point where physically modern people moving from Africa met and interbred with Neandertals, who died out after about 35,000 years ago. Such interaction may explain the small percentage of Neandertal DNA that scientists have found persists in human populations living in Europe and Asia today.

Other World Book articles:

• Anthropology (2010-A Behind the Headline report)
• Prehistoric peoples

July 3, 2014

Recent findings are sure to disappoint people who believe that the Yeti, or Abominable Snowman, stalks the Himalaya and that Bigfoot prowls the Pacific Northwest in the United States. In a study published last week, British scientists who examined samples of “Yeti hair” sent in by museums and cryptozoologists (people who study and search for legendary creatures) reported finding no Yeti yet. The study appeared online in the Proceedings of the Royal Society B.

The Yeti is a creature said to live on Mount Everest and other mountain ranges of Asia. According to legend, the Yeti is a hairy beast with a large, apelike body and a face that resembles that of a human being. (World Book illustration by Ted Lewis).

Many people are fascinated by the idea that a large primate like the Yeti—or its American cousin, Bigfoot, or Russian relative, Almasty—could survive in remote wilderness areas unexplored by modern science. Cryptozoologists have investigated the Yeti for decades. Sensational reports of Yeti sightings have been exposed as hoaxes and fakes in the past, which has led many skeptics to dismiss the creature as pure fantasy.

The study on Yeti hair was led by Bryan Sykes, a geneticist at Oxford University. In 2012, Sykes requested samples of hair from Yeti enthusiasts,  saying, “I’m challenging and inviting the cryptozoologists to come up with the evidence instead of complaining that science is rejecting what they have to say.” Scientists on the study ended up analyzing the DNA of more than 30 of the 57 “Yeti hair” samples submitted. The remaining samples were eliminating after the scientists found that they were not hair but such substances as fiberglass. The researchers discovered that most of the 30 analyzed hair samples came from such common animals as cows, horses, raccoons, deer, and coyotes. None of the samples came from a new primate species.

Two of the samples, however, were less straightforward: one was found in Ladakh—a region in Jammu and Kashmir, the northernmost state in India; and the other came from Bhutan to the east. The tests revealed that the hair was from a mammal, but it did not match samples from known primates. Surprisingly, the DNA from the two samples matched up almost exactly with DNA from the 40,000-year-old jawbone of a Norwegian polar bear. The researchers do not believe that the “Himalayan Yeti” actually represents an isolated population of polar bears. Instead, they theorize that the region is home to a hybrid bear species unknown to science that developed from matings between polar bears and brown bears somewhere in northern Asia during the last Ice Age, when the ranges of those bears overlapped.

Sykes admits that the study does not disprove the existence of the Yeti or other large primates unknown to scientists; it only means that the samples submitted for analysis did not come from such creatures. Enthusiasts need to keep looking for evidence that stands up to scientific scrutiny.

Additional World Book articles:

• Folklore
• Hillary, Sir Edmund Percival
• Journey to the Top of the World by Sir Edmund P. Hillary (a special report)

May 21, 2014

The discovery of a nearly complete skeleton of a young girl who died nearly 13,000 years ago in what is now Mexico is providing evidence that anthropologists claim will end a decades-old debate over the origins of Native Americans. A diverse team of scientists led by anthropologist James Chatters published a description of the skeleton, which included preserved DNA, in the May 16 issue of Science. The discovery may finally end an often heated, decades-long debate among anthropologists over why Native Americans do not resemble Paleo-Indians, the first people to migrate to the Americas.

Underwater archaeologists discovered the skeleton of the young girl, perhaps only 13 years old when she died, with bones of extinct Ice Age animals. The skeleton was found while the scientists were exploring a submerged cave, called Hoyo Negro (black hole), in the Caribbean Sea, off the Yucatan Peninsula of Mexico. Scientists named her Naia, after a water nymph (maiden) in Greek mythology. The scientists speculate that Naia may have fallen into an underground cave while searching for water and died. As sea levels rose by the end of the Ice Age, the cave was submerged, creating ideal conditions to preserve Naia’s bones along with the bones of other animals that shared her fate.

Genetic studies of Native Americans indicate that their ancestors migrated into the Americas from Asia more than 12,000 years ago. The oldest known Paleo-Indian culture is the Clovis culture, identified by distinctive stone spearheads, called Clovis points. Archaeologists have discovered a only handful of Paleo-Indian skeletons, including Kennewick Man, found in Washington in 1996. However, these ancient skeletons do not physically resemble today’s Native Americans. Paleo-Indian skulls are longer and narrower, with forward projecting faces. These features are most similar to those of native people of Australia and the Ainu, an isolated native population of Japan.

The prehistoric Clovis people made distinctive stone spearheads, called Clovis points. The Clovis are the earliest known Paleo-Indian culture of the Americas (AP Photo).

Some scientists theorize that the Paleo-Indians are not the ancestors of modern Native Americans. They suggest that Native American ancestors arrived from Asia in a later migration and, over time, replaced the Paleo-Indians. Other scientists disagree. They argue that the physical features of Paleo-Indians evolved over thousands of years, giving rise to modern Native Americans.

Now, Naia may end the debate. Naia’s skull has all of the physical characteristics that confirm her identity as Paleo-Indian. However, DNA isolated from her skeleton allowed the scientists to directly link her with living Native Americans. Naia’s mitochondrial DNA—genetic material passed down from mother to child through the egg—included specific sequences of DNA that linked her with ancient populations of northeastern Asia as well as Native American peoples alive today. Similar DNA sequences were recently reported from the only known skeleton of a Paleo-Indian infant, discovered in 2001 at Anzick, a site in Montana. The DNA evidence points to Paleo-Indians as the direct ancestors of modern Native Americans. Naia indicates that the physical difference between her people and modern Native Americans results from evolutionary changes occurring over time rather than separate ancestry.

Additional World Book articles:

• Prehistoric people
• Fascinating Facts About Fossil Feces (a Special Report)
• The First Americans (a Special Report)

February 19, 2013

Scientists announced this week that for the first time they had found living bacteria beneath a glacier in Antarctica. A team of scientists from the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD), funded by the U.S. National Science Foundation, made the find. The bacteria were discovered in Lake Whillans, which is about one-half mile (800 meters) below the West Antarctic Ice Sheet. The lake is about 5-feet (1.5-meters) deep, and scientists had to drill through the entire half mile of ice to take a sample of the lake water. After running a culture of the sample, they were able to see the bacteria under a microscope. The bacteria are members of a new ecosystem of living things that is able to survive with little light, at very cold temperatures, and under large amounts of pressure.

Lake Whillans sits at the upper tip of the Ross Ice Shelf in West Antarctica. (World Book map; map data © MapQuest.com, Inc.)

DNA testing is required for scientists to be able to identify the bacteria. Once identification has occurred, it might give scientists a better idea of what the bacteria use as food.

In addition to the excitement of finding life under Antarctic ice, scientists were also very interested in the bacteria because the conditions in Lake Whillan are not unlike some of the terrains found in outer space. For example, Jupiter’s moon, Europa, and Saturn’s moon, Enceladus, both have water that exists under ice. If the bacteria discovered under Antarctica is, for example, found to consume minerals from surrounding rock as food, a similar lifeform might be able to exist elsewhere in the solar system.

Additional World Book articles:

• Jupiter
• Europa
• Saturn
• Enceladus

February 5, 2013

A facial reconstruction based on the recently discovered skull of King Richard III of England was unveiled today in London. The reconstructed face has a slightly arched nose and prominent chin, similar to features that can be seen in portraits of Richard III that were painted after his death. A skeleton found under a parking lot in Leicester during an archaeological dig in September 2012 has been confirmed to be the remains of Richard, the last English king to die in battle. DNA from the skeleton matches the DNA of two living descendants of Richard’s sister. The skeleton includes a severely curved spine and a skull clearly cleaved by a blow to the head by a some weapon. Richard, who according to legend was a hunchback, was killed at the age of 32 in the 1485 Battle of Bosworth by the forces of Henry Tudor. Tudor, the future Henry VII, was the father of Henry VIII and grandfather of Elizabeth I.

Richard III, in a portrait created after his death. (© National Portrait Gallery, London)

In Shakespeare’s historical drama Richard III, the king, stranded on foot on the field of battle, famously cries, “A horse, a horse, my kingdom for a horse” before he is struck down. Shakespeare represented Richard as one of the great villains of history who, according to legend, was responsible for the murder of his nephews, Edward V and Richard, Duke of York. After the 12-year-old Edward V succeeded his father, Edward IV, in 1483, the government was put in the care of Richard, who was named protector of the realm. However, the Woodvilles, the family of the young king’s mother, attempted to seize power. In crushing their conspiracy, Richard sought to become king himself. He was crowned early in July 1483, after Parliament had declared him king. Edward V and the Duke of York were put in the Tower of London. Some scholars believe that King Richard had the boys killed. But no proof of such a crime exists. Skeletons of two children—believed to be the young princes—were discovered in the Tower in 1674.

Officials at Leicester University state that it is beyond any reasonable doubt that the skeleton from the parking lot is that of the last Plantagenet king. The remains of Richard III are to be buried in Leicester Cathedral.

Additional World Book articles:

• Lancaster
• Tudor, House of
• War of the Roses
• York
• Analyzing Forensic Evidence (a special report)

May 25, 2012

A new search for the legendary creatures known as Bigfoot and the Yeti is being mounted by several researchers from Oxford University in the United Kingdom and the Lausanne Museum of Zoology in Switzerland–but they don’t plan to leave their laboratories. Instead of trekking through dense forests or crossing snowy mountains, the researchers plan to use sensitive DNA analysis on samples of hair, blood, and other remains that could have come from the creatures. The researchers are asking wildlife scientists, museums, and Bigfoot enthusiasts to send them written descriptions and photos of any evidence they might have of the creatures. If the descriptions look promising, the researchers will request the physical samples and then test their DNA to determine which species the samples came from. Finding DNA from an unknown primate–the group of mammals that includes monkeys, apes, and human beings–could be evidence that Bigfoot lives and would rank as one of the greatest zoological discoveries in history. “I’m challenging and inviting the cryptozoologists to come up with the evidence instead of complaining that science is rejecting what they have to say,” said geneticist Bryan Sykes of Oxford in an interview. Cryptozoology is the scientific investigation of legendary creatures.

Bigfoot, shown here in an artist's depiction, is a humanlike creature said to live in the Pacific Northwest of the United States and Canada. The creature is said to resemble a large ape--with thick fur, long arms, powerful shoulders, and a short neck--but to walk upright like a human being. (World Book illustration)

Bigfoot is a giant apelike creature said to live in forested regions of North America. Stories of this creature appear in American Indian traditions, where the creature is known as Sasquatch. Thousands of people have reported seeing Bigfoot or finding its footprints in North America, but conclusive proof of its existence has yet to be found. Reports of a similar creature come from the Himalaya range of Asia. This creature is called the Yeti or the Abominable Snowman. In 1951, the British explorer Eric Shipton took pictures of “Yeti” tracks near Mount Everest. Since then, several expeditions, including one sponsored by World Book in 1960, have searched for the creature without success.

A few scientists think it is possible that such a large primate could have survived undiscovered in the dense and remote forests of North America and Asia. One theory suggests Bigfoot and the Yeti are small relic populations of primate thought to have gone extinct. Candidates for Bigfoot include such extinct prehistoric humans as Neandertals or Denisovans, a mysterious species that died out in Siberia 40,000 years ago. Another theory suggests that Bigfoot and the Yeti may be surviving populations of Gigantopithecus, a huge ape that lived in the forests of what are now southern China, Vietnam, and northern India. Gigantopithecus, which is believed to have died out 200,000 years ago, was the largest ape to have ever lived.

The Yeti, also called the Abominable Snowman, is a creature said to live on Mount Everest and other mountain ranges of Asia. According to legend, the Yeti is a hairy beast with a large, apelike body and a face that resembles that of a human being. It has long arms that reach to its knees, and it walks erect on its thick legs. (World Book illustration)

Scientists with the Bigfoot DNA project will begin by testing an archive of remains stored at the Lausanne Museum that were assembled by cryptozoologist Bernard Heuvelmans, who investigated reported Yeti sightings from 1950 until his death in 2001. Many sensational reports of Bigfoot remains have been exposed as hoaxes and fakes in the past. The researchers in this project point out that DNA evidence cannot be faked. They expect to published their results in science journals.

Additional World Book articles:

• Shipton, Eric Earle
• Journey to the Top of the World (a Special Report)

Polar bears are more distantly related to other bears than previously thought, according to new research. Scientists have long known that polar bears share a common ancestor with brown bears. Previous research had shown that the split between the two groups occurred relatively recently, about 150,000 years ago. But in new research, scientists found that the split took place much earlier, about 600,000 years ago. Thus, polar bears are more distinct from other bears than scientists thought.

The research helps scientists to understand the history of how polar bears have evolved (developed over many generations). Polar bears have many adaptations (features) that help them to survive on Arctic sea ice. These adaptations help to make them different from brown bears. Polar bears would have had to evolve these adaptations in relatively little time if they had split from the same ancestor as brown bears only 150,000 years ago.

The new research involved studying bear DNA, which carries hereditary information. Scientists compared the DNA of black bears, brown bears, and polar bears. Comparing the DNA enabled scientists to estimate the date at which polar bears and brown bears shared a common ancestor. Earlier research into polar bear origins used DNA from a different part of the cell. Most DNA is housed in the cell’s nucleus (a body at the center of the cell). However, a small amount of DNA is housed in mitochondria (tiny bodies in the cell that burn chemical energy). The earlier research used DNA from the mitochondria to estimate the first appearance of polar bears. The new research used DNA from the nucleus. This information provided more data about polar bear origins.

The hardy polar bear lives along the frozen shores and in the icy waters of the Arctic Ocean. Polar bears have a thick, white coat that blends in with the ice and snow. They swim strongly by paddling with their front legs and stretching their head forward. (Marvin E. Newman, DPI)

Scientists suggest the different estimates for the first appearance of polar bears may have been caused by later matings between polar bears and brown bears. Such mating is known to occur, especially when polar bear populations are under stress. Thus, the mitochondria results may record breeding between polar bears and brown bears about 150,000 years ago. In fact, the research suggested that polar bears have gone through several so-called bottlenecks, periods during which relatively few polar bears survived. These bottlenecks may have corresponded to reduced sea ice or other climate changes that made it more difficult for polar bears to survive. Polar bears are currently considered vulnerable to extinction because of a loss of sea ice caused by climate change, and scientists have shown that some polar bears and brown bears have breed in recent years. The research was published online in the journal Science.

Additional World Book articles:

The Great Meltdown (a special report)