Tag Archives: anthropology

Europeans’ white skin developed later than thought

Europeans' white skin developed later than thought

Sweden’s Crown Princess Victoria and Prince Daniel in 2011. Traits of white skin emerged more recently than thought in Europe. (AP Photo/Lehtikuva/Vesa Moilanen)

Science notes that Europe is often thought of as the “ancestral home of white people.” But a new DNA study suggests that pale skin and other traits we associate with the continent may have emerged only within the last 8,000 years—a “relatively recent” occurrence.

The study—published last month on the bioRxiv.com server and presented last week at the American Association of Physical Anthropologists’ annual meeting—compared genome DNA across three populations of farmers and hunter-gatherers who crossed over into Europe in discrete migrations within the past eight millennia, Science notes.

What scientists found: a handful of genes tied to diet and skin pigmentation that withstood natural selection and thrived in the northern regions. The data indicates hunter-gatherers who settled in Spain, Hungary, and Luxembourg about 8,500 years ago lacked two specific genes—SLC24A5 and SLC45A2—and had darker skin, Science notes.

But hunter-gatherers hunkered down further north in Sweden had both those light-skin genes and also a third gene that leads to blue eyes (and possibly fair skin and blond hair).

When the third demographic, the Near East farmers, arrived, they also carried the SLC24A5 and SLC45A2 genes, so paler skin started emerging throughout the continent as the populations interbred.

Although researchers don’t offer a definitive answer as to why natural selection picked those genes to thrive in the north, one paleoanthropologist speculated at the meeting that the lack of sun in the northern parts of Europe required people to adapt by developing lighter skin to better absorb more vitamin D, as well as the LCT gene that allowed them to digest the sugars their ancestors couldn’t in milk, also filled with vitamin D.

(This one infant could tell us where the first Americans came from.)

This article originally appeared on Newser: Europeans’ White Skin Came Later Than Thought

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Ancient skeleton of teenage girl sheds new light on first Americans

firstamericans.jpg

FILE: Diver Susan Bird, working at the bottom of Hoyo Negro, a large dome-shaped underwater cave in Mexico’s Yucatan Peninsula, brushes a human skull found at the site while her team members take detailed photographs.AP

Thousands of years ago, a teenage girl toppled into a deep hole in a Mexican cave and died. Now, her skeleton and her DNA are bolstering the long-held theory that humans arrived in the Americas by way of a land bridge from Asia, scientists say.

The girl’s nearly complete skeleton was discovered by chance in 2007 by expert divers who were mapping water-filled caves north of the city of Tulum, in the eastern part of the Yucatan Peninsula. One day, they came across a huge chamber deep underground.

“The moment we entered inside, we knew it was an incredible place,” one of the divers, Alberto Nava, told reporters. “The floor disappeared under us and we could not see across to the other side.”

They named it Hoyo Negro, or black hole.

Months later, they returned and reached the floor of the 100-foot tall chamber, which was littered with animal bones. They came across the girl’s skull on a ledge, lying upside down “with a perfect set of teeth and dark eye sockets looking back at us,” Nava said.

The divers named the skeleton Naia, after a water nymph of Greek mythology, and joined up with a team of scientists to research the find.

The girl was 15 or 16 when she met her fate in a cave, which at that time was dry, researchers said. She may have been looking for water when she tumbled into the chamber some 12,000 or 13,000 years ago, said lead study author James Chatters of Applied Paleoscience, a consulting firm in Bothell, Washington. Her pelvis was broken, suggesting she had fallen a long distance, he said.

The analysis of her remains, reported Thursday in the journal Science by researchers from the United States, Canada, Mexico and Denmark, addresses a puzzle about the settling of the Americas.

Most scientists say the first Americans came from Siberian ancestors who lived on an ancient land bridge, now submerged, that connected Asia to Alaska across the Bering Strait. They are thought to have entered the Americas sometime after 17,000 years ago from that land mass, called Beringia.  And genetic evidence indicates that today’s native peoples of the Americas are related to these pioneers.

But the oldest skeletons from the Americas — including Naia’s — have skulls that look much different from those of today’s native peoples. To some researchers, that suggests the first Americans came from a different place.

Naia provides a crucial link. DNA recovered from a molar contains a distinctive marker found in today’s native peoples, especially those in Chile and Argentina. The genetic signature is thought to have arisen among people living in Beringia, researchers said.

That suggests that the early Americans and contemporary native populations both came from the same ancestral roots in Beringia — not different places, the researchers concluded. The anatomical differences apparently reflect evolution over time in Beringia or the Americas, they said.

The finding does not rule out the idea that some ancient settlers came from another place, noted Deborah Bolnick, a study author from the University of Texas at Austin.

Dennis O’Rourke, an expert in ancient DNA at the University of Utah who didn’t participate in the work, said the finding is the first to show a genetic link to Beringia in an individual who clearly had the anatomical signs of a very early American.  He said he considered the notion of multiple migrations from different places to be “quite unlikely.”

Last February, other researchers reported that DNA from a baby buried in Montana more than 12,000 years ago showed a close genetic relationship to modern-day native peoples, especially those in Central and South America. An author of that study, Mike Waters of Texas A&M University, said the Mexican finding fits with the one in Montana.

There are so few such early skeletons from the Americas, he said, that “every single one of them is important.”

However, Richard Jantz, a retired professor of forensic anthropology at the University of Tennessee in Knoxville, said he still believes early settlers arrived by boat from east Asia before any migration occurred via Beringia. That’s based on anatomical evidence, he said. The argument in the new paper “leaves a lot of unanswered questions,” he said in an email.

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What we learned about human origins in 2013

What we learned about human origins in 2013

By Charles Q. Choi

Published December 30, 2013

LiveScience
  • dmanisi-human-skull-1

    The 1.8-million-year-old skull unearthed in Dmanisi, Georgia, suggests the earliest members of the Homo genus belonged to the same species, say scientists in a paper published Oct. 18, 2013 in the journal Science. (PHOTO COURTESY OF GEORGIAN NATIONAL MUSEUM)

The existence of a mysterious ancient human lineage and the possibility that the earliest humans were actually all one species were among the human-evolution-related discoveries of 2013. Other breakthroughs include the sequencing of the oldest human DNA yet.

Here’s a look at what scientists learned about humanity and human origins this year:

Mystery lineage
Recent analyses of fossil DNA have revealed that modern humans occasionally had sex and produced offspring not only with Neanderthals but also with Denisovans, a relatively newfound lineage whose genetic signature apparently extended from Siberia to the Pacific islands of Oceania.

This year, hints began emerging that another mystery human lineage was part of this genetic mix as well. Now, the first high-quality genome sequence from a Neanderthal has confirmed those suspicions.

These findings come from Denisova Cave in southern Siberia, where the first evidence of Denisovans was discovered in 2008. To learn more about the Denisovans, scientists examined DNA from a toe bone unearthed there in 2010.

The researchers found that the fossil belonged to a Neanderthal woman. Her DNA helped refine the human family tree, as it revealed that about 1.5 to 2.1 percent of the DNA of modern people outside Africa is Neanderthal in origin, whereas about 0.2 percent of DNA of mainland Asians and Native Americans is Denisovan in origin. [Top 10 Mysteries of the First Humans]

The scientists also discovered that the Denisovans interbred with an unknown human lineage, getting as much as 2.7 to 5.8 percent of their genomes from it. This newfound relative apparently split from the ancestors of all modern humans, Neanderthals and Denisovans between 4 million and 900,000 years ago, before these latter groups started diverging from each other. It’s possible that this mysterious lineage could even be Homo erectus, the earliest known undisputed predecessor of modern humans. However, there are no signs that this unknown group interbred with modern humans or Neanderthals.

Genetic analysis also revealed that the parents of this Neanderthal woman were closely related possibly half-siblings, or another close relative. (Inbreeding may have been common among early humans it remains uncertain as to whether it was some kind of cultural practice or whether it was unavoidable due to small community populations at the time.)

Were earliest humans all one species?
Modern humans, Homo sapiens, are the only living member of the human lineage, Homo, which is thought to have arisen in Africa about 2 million years ago at the beginning of the Ice Age. Many now-extinct human species were thought to once roam the planet, such as Homo habilis, which is suspected to be among the first stone-tool makers; the relatively larger-brained Homo rudolfensis; the relatively slenderHomo ergaster; and Homo erectus, the first to regularly keep the tools it made.

The level of variation seen in Homo fossils is typically used to define separate species. However, analysis of 1.8-million-year-old skulls excavated from the Republic of Georgia revealed the level of variation seen among those skulls was about the same as that seen among ancient African Homo fossils. As such, researchers suggest the earliest Homo fossils may not be multiple human species, but rather variants of a single lineage that emerged from Africa. In other words, instead of Africa once being home to multiple human species such asHomo erectusHomo habilisHomo ergaster and Homo rudolfensis, all of these specimens may actually simply be Homo erectus.

Oldest human DNA
The testing of the oldest known human DNA added more evidence that human evolution was complex.

The genetic material, some 400,000 years old, came from a human thighbone unearthed in the Sima de los Huesos, or “Pit of Bones,” an underground cave in northern Spain. Until now, the previous oldest known human DNA had come from a 100,000-year-old Neanderthal from a Belgian cave.

The fossils unearthed at the site resembled those of Neanderthals, so researchers expected the ancient DNA they analyzed to be Neanderthal as well. Surprisingly, the DNA revealed that this fossil’s closest known relatives were not Neanderthals but Denisovans. This finding is strange, scientists said, because studies to date currently suggest the Denisovans lived in eastern Asia, not in western Europe, where this fossil was uncovered. One possible explanation is that a currently unknown human lineage brought Denisovan-like DNA into the Pit of Bones region, and possibly also to the Denisovans in Asia.

Evolution of tool use
The capability to make and use complex tools is a critical trait distinguishing modern humans from all other species alive today. Now, scientists have found an ancient hand-bone fossil that reveals that the modern human ability to make and use complex tools may have originated far earlier than previously thought.

A key anatomical feature of the modern human hand is the third metacarpal, a bone in the palm that connects the middle finger to the wrist. A little projection of bone known as a styloid process in this bone helps the thumb and fingers apply greater amounts of pressure to the wrist and palm. Researchers had thought the styloid process was a relatively recent feature, perhaps evolving close to the origin of modern humans. However, scientists have discovered a 1.4-million-year-old fossil that possesses this vital anatomical feature, meaning it existed more than 500,000 years earlier than it was previously known to have existed and was perhaps fundamental to the evolution of the whole genus Homo, not just modern humans.

This hand bone may not be the only key trait for tool use that evolved near the origin of the human lineage. Humans are the only species that can throw with great speed and precision, and scientists found this ability first evolved nearly 2 million years ago with anatomical changes to the shoulder, arm and torso. This advance likely boosted the hunting prowess of now-extinct human ancestors, helping them effectively and safely kill big game.

Neanderthal discoveries
In 2013, researchers also made important discoveries about Neanderthals, modern humans’ closest extinct relatives. For instance, analysis of a Neanderthal tomb in France suggests that, like modern humans, Neanderthals may have intentionally buried their dead. The new findings are further evidence that Neanderthals might have possessed complex forms of thought, enough for special treatment of the dead.

In addition, a cache of Neanderthal fossils discovered in a cave in Greece suggests the area may have been a key crossroad for ancient humans. The age of these fossils suggests Neanderthals and other humans may have had the opportunity to cross paths there, and even interact, the researchers added.

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Human hand fossil turns back clock 500,000 years on complex tool use

Human hand fossil turns back clock 500,000 years on complex tool use

By Charles Q. Choi

Published December 17, 2013

LiveScience
  • human-hand-fossil

The discovery of a 1.4-million-year-old hand-bone fossil reveals that the modern human ability to make and use complex tools may have originated far earlier than scientists previously thought, researchers say.

A critical trait that distinguishes modern humans from all other species alive today is the ability to make complex tools. It’s not just the extraordinarily powerful human brain, but also the human hand, that gives humans this unique ability. In contrast, apes humans’ closest living relatives lack a powerful and precise enough grip to create and use complex tools effectively.

A key anatomical feature of the modern human hand is the third metacarpal, a bone in the palm that connects the middle finger to the wrist.

“There’s a little projection of bone in the third metacarpal known as a “styloid process” that we need for tools,” said study lead author Carol Ward, an anatomist and paleoanthropologist at the University of Missouri.”This tiny bit of bone in the palm of the hand helps the metacarpal lock into the wrist, helping the thumb and fingers apply greater amounts of pressure to the wrist and palm. It’s part of a whole complex of features that allows us the dexterity and strength to make and use complex tools.” [In Images: The Oddities of Human Anatomy]

Until now, this styloid process was found only in modern humans, Neanderthals and other archaic humans. Scientists were unsure when this bone first appeared during the course of human evolution. (The human lineage, the genus Homo, first evolved about 2.5 million years ago in Africa.)

“We had thought the modern human hand was something relatively recent, maybe something that appeared as a recent addition near the origin of our species,” Ward told LiveScience.

Now, researchers have discovered a fossil almost 1.5 million years old that possesses this vital anatomical feature, meaning it existed more than 500,000 years earlier than it was previously known to have existed.

“This suggests this feature might be fundamental to the origin of the genus Homo,” Ward said.

The scientists discovered a third metacarpal bone in northern Kenya, west of Lake Turkana. The fossil was found near the sites where the earliest Acheulean tools named for St. Acheul in France where tools from this culture were first discovered in 1847 were unearthed. The Acheulean artifacts were the first known complex stone tools, rough hand axes and cleavers that first appeared some 1.8 million years ago.

“It’s an arid badlands desert area now,” Ward said. “There’s not much vegetation to cover up fossils there’s cobble and rock everywhere, and we try and find fossils by going out and looking under all that cobble and rock on the surface.”

The hand-bone fossil is about 1.42 million years old. The researchers suspect it belonged to the extinct human species Homo erectus, the earliest undisputed predecessor of modern humans.

“Back then, this area was an open woodland area much more lush than today, probably with some trees and some areas of grassland,” Ward said. “The fossil was found near a winding river, which often deposits things like fossils.”

By revealing the early human lineage had a modern handlike anatomy, the fossil “suggests this feature may have [been] a pre-adaptation that helped set the stage for all the technology that came later,” Ward said.

Intriguingly, “at this time, in addition to early members of Homo, there were some late-surviving members of Australopithecus still around close relatives of humans that don’t seem to have this adaptation,” Ward said. “This raises the question of how important our hands were in the success of our lineage and the extinction of their lineage (Australopithecus).”

The researchers now want to find older hand bones “to see when this feature evolved,” Ward said. “We want to get closer to 2 million years ago to find out when this transition to modern hand anatomy took place.”

Ward and her colleagues detailed their findings online Dec. 16 in the journal Proceedings of the National Academy of Sciences.

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