AuthorTopic: 🐵 Geneaology of Homo Sap  (Read 174 times)

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🐵 Geneaology of Homo Sap
« on: March 03, 2018, 05:54:12 AM »
Kicking off this new official thread  for Homo Sap ancestry with this one.  :icon_sunny:


What the world’s largest family tree tells us about marriage and death in the West
13 million strong
By Angela Chen@chengela Mar 1, 2018, 1:55pm EST

Researchers used genealogical records to trace the last 500 years of Western marriage and migration patterns and show that the genetic basis of longevity is lower than many have suggested. Image: MyHeritage and Columbia University

The largest family tree to date — which includes 13 million people going back 11 generations and 500 years — provides new insights about marriage and death, and it all comes from public data.

The tree was created by a team led by Yaniv Erlich, a Columbia University computer scientist who is also chief science officer at the genealogy company MyHeritage. Erlich’s team downloaded 86 million public profiles from the ancestry site (which is owned by MyHeritage). Many small family trees emerged, along with one huge one with 13 million people; about 85 percent are from the Western world. The tree, which is available online, includes (anonymized) data on when and where everyone died. When Erlich’s team analyzed the data to find trends related to marriage and death, they found that genetics may play a smaller role in longevity than we thought, and the advent of mass transportation wasn’t the only reason why we started marrying people outside the family. The results were published today in the journal Science.

In the above 6,000-person family tree, individuals spanning seven generations are represented in green and marriage in red. Image: Columbia University

The project was possible in part because the Geni platform lets users merge trees. “So if you put your tree and I put mine, and we share an Uncle Albert, the website would offer to merge the trees together to create a much larger tree,” says Erlich. This way, his team didn’t have to start from scratch but could build on the work of people using the site. After downloading the raw data, the challenge was to clean it and make sure it didn’t include results that were biologically impossible, like people with three parents. If the data wasn’t clean, they wouldn’t be able to run algorithms to analyze the information.

For the analysis, the researchers focused on two topics: how long we live and who we choose to marry. By measuring the birth location between husbands and wives and tracking that over time, they found that, unsurprisingly, before the Industrial Revolution most Americans married someone within six miles of where they were born. This person was also likely to be a relative — a fourth cousin on average, says Erlich. After the Industrial Revolution, when transportation became more common, people started to marry those who were born farther away and were more distantly related. (By 1950, people were finding their spouses within 60 miles of where they were born.)

But the pattern shows it’s not all about transportation. Between 1800 and 1850, people were traveling more and moving to cities en masse, but the genealogical distance remained the same: in other words, people were still marrying their relatives. “This suggests that the advent of mass transportation and the train system was not the only reason that people took to marrying their cousins,” says Erlich. “There’s a lag between the two, so it’s likely that cultural factors also made people start marrying outside their group.”

Next, to look at death. The researchers analyzed the lifespans of 3 million relatives who were born between 1600 and 1910 and lived past age 30. (The data didn’t include twins and people who died in wars.) Genes obviously play a role in longevity — someone with a gene that makes them more likely to have cancer will likely have a shorter lifespan — but environmental factors matter a lot, too. By comparing each person’s lifespan to that of their relatives, they found that genes are responsible for about 16 percent of the variation in how long they lived. Peter Visscher, a quantitative geneticist at the University of Queensland who was not involved in the study, noted that he would have guessed genes were responsible for 10 to 20 percent of longevity, which is in line with the authors’ report, though some estimates have given numbers as high as 30 percent.

The results also suggest that genes that influence longevity act independently instead of interacting with each other — a question that has been a big debate in the field of genomics. If gene variants worked together, there would be a bigger correlation in lifespan between relatives who are more closely related. For example, the correlation in lifespan should increase very quickly between two first cousins compared to two identical twins. But that pattern didn’t appear in the data.

Because the data is available for free online, there are a lot of different questions it could help answer in the future, says Erlich, such as how migration affects fertility. Additionally, MyHeritage now offers DNA tests. So if users uploaded genetic data that matched the genealogy one, scientists could answer even more questions of nature and nurture, Visscher wrote in an email to The Verge.

In the meanwhile, it’s really quite beautiful to see so many lives that are spread all over the world visualized in an interlocking map.

There are 70,000 relatives shown in the above family tree, connected through marriage (in red) and shared ancestors Image: Columbia University

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🐵 Scientists excavate stone age tools at Vleesbaai in South Africa.
« Reply #1 on: March 13, 2018, 12:37:12 AM »

Scientists excavate stone age tools at Vleesbaai in South Africa.
Curtis Marean/Arizona State University

How ancient humans survived global ‘volcanic winter’ from massive eruption

By Gretchen VogelMar. 12, 2018 , 12:20 PM

About 74,000 years ago, a colossal volcano in Sumatra named Toba blew its top in the largest eruption to occur anywhere on Earth in the past 2 million years. Gas and ashes spewed into the atmosphere spread around the world within weeks, and some scientists think they triggered a global “volcanic winter” that may have lasted decades, leading to massive die-offs and the near-extinction of the human species. But others have suggested that the eruption’s effects were less dramatic.

Now, subtle traces of volcanic ash at Pinnacle Point, a famous archaeological site on the southern coast of South Africa, suggest that at least some groups of early humans survived, and even thrived, in the eruption’s aftermath. The discovery also offers archaeologists an astonishingly precise time marker for dating sites around the globe.

When Toba erupted, modern humans had already traveled out of Africa to at least the Middle East and perhaps beyond. Some researchers have proposed that Toba’s eruption was big enough to cause a reverse greenhouse effect that cooled Earth for decades, leading to ecological disaster and widespread food shortages that only a few small communities were able to survive. (Volcanoes spew sulfur dioxide into the atmosphere, which can form aerosols that reflect the sun’s rays.) But the theory is hotly debated. Sediments from Lake Malawi, in eastern Africa, for example, don’t show evidence for a dramatic change in plant life around the time of the eruption.
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Archaeologists wanted to see whether they could find evidence for effects of the volcano at Pinnacle Point, a series of caves where archaeologists have uncovered a rich trove of bones, tools, and weapons left by Stone Age humans, some dating from nearly 200,000 years ago. They also studied Vleesbaai, an open-air site 9 kilometers away where researchers have found more Stone Age tools and animal bones.

Excavations at Pinnacle Point
Curtis Marean/Arizona State University

The scientists took samples from every centimeter of sediment in a 1.5-meter vertical section of the Vleesbaai dig and also analyzed samples from key layers at Pinnacle Point. At both sites, they found a sparse sprinkling of cryptotephra, microscopic particles of glassy volcanic rock. The chemical signatures of these fragments matched Toba ash found in Malaysia and Lake Malawi. “That’s a ‘holy shit!’ result,” says archaeologist and lead author Curtis Marean of Arizona State University in Tempe, because the ash layer marks the same date—within a month—across the entire globe. Other dating techniques have about a 10% error rate, so a deposit dated as 74,000 years old could be anywhere between 66,000 and 81,000 years. Thus, the work offers a new way to correlate far-flung sites very precisely.

At Pinnacle Point, artifacts found just below and directly above the traces of ash show no gap in human use of the site, Marean and his colleagues report today in Nature. In fact, they say, the traces of human occupation intensify shortly after the volcano’s eruption, suggesting that humans living there did just fine, Marean says. The Pinnacle Point people are known to have eaten shellfish and other marine resources, and he speculates that the ocean may have been buffered from the volcano’s effect. “Hunter-gatherer economies are really resilient,” Marean says. “The impact on them is probably a lot less” than on flora and fauna.

But archaeologist Stanley Ambrose of the University of Illinois in Urbana, who proposed the idea that Toba’s eruption wiped out most early humans, isn’t convinced. Marean’s team found sandy layers just above the ash traces, which Ambrose says are indeed a sign of dramatic environmental change and a decrease in human occupation. Marean counters that those layers were part of a series of sand dunes that formed in a matter of days or weeks after the eruption and include human artifacts. “So no evidence for abandonment,” he says. Looking for volcanic traces at other sites could help settle the debate, he says.

Other researchers are impressed with the method’s potential, in part because they were able to isolate rare particles of cryptotephra, down to two particles per gram of sediment. “It’s a beautiful marker,” says Michael Petraglia, an archaeologist at the Max Planck Institute for the Science of Human History in Jena, Germany. It’s especially impressive that the team was able to find ash traces 9000 kilometers from the volcano, he says. He and his colleagues hope to use similar techniques at sites in East Africa and Arabia, he says. “When you find it, it’s fantastic.”

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🐵 Scientists Are Amazed By Stone Age Tools They Dug Up In Kenya
« Reply #2 on: March 16, 2018, 01:21:18 AM »

Scientists Are Amazed By Stone Age Tools They Dug Up In Kenya

March 15, 20183:12 PM ET

Rhitu Chatterjee

Assortment of Early and Middle Stone Age tools found in the Olorgesailie Basin, Kenya. The tool at left is a hand axe.
Jay Reed/NPR

Our ancestors in Kenya's Southern Rift Valley made some pretty innovative tools. And they made them far earlier than previously thought — over one million years ago.

The oldest innovations were axes designed to be held in the palm of the hand. They were shaped like a tear drop, with a rounded end and a pointed eye. The edges were wavy and sharp. And they look as if they were great at chopping down branches — or chopping up the carcass of a large animal.

This early Stone Age hand axe was excavated at Olorgesailie, Kenya. A chemical analysis of the stone shows it was made with locally available rocks.
Jay Reed/NPR

"I think of the hand axes as the Swiss army knife of the Stone Age," says paleoanthropologist Rick Potts, director of the Human Origins program at the Smithsonian Museum of Natural History and one of the lead scientists in a new study by a team of international scientists.

The researchers also found that the next technological revolution, marking the beginning of the Middle Stone Age happened tens of thousands of years earlier than previously thought.

And the researchers think that long periods of stress from repeated earthquakes and cycles of drought and heavy rains may have pushed these early humans to partner up with neighboring communities to come up with ways to cope.

Rick Potts, director of the National Museum of Natural History's Human Origins Program at the Smithsonian. He has been excavating in the Southern Rift Valley in Kenya since the 1980s.
Jay Reed

The team was digging in a region called Olorgesailie in southern Kenya, an area filled with layers of sediment dating back 1.2 million years. The oldest stone tools discovered there are characteristic of what's called the Acheulian culture of the Early Stone Age and consisted mostly of the hand axes.

In this Olorgesailie Basin excavation site, red ocher pigments were found with Middle Stone Age artifacts. This is the earliest evidence of the extraction and use of pigments among ancient humans.
Human Origins Program/Smithsonian

In addition to branch- and carcass-chopping, the axes were likely used to dig for water to drink or tubers to eat. The carcasses probably belonged to large animals like the giant (now extinct) ancestors of hippos, elephants and wild pigs that roamed the grasslands back then. Potts says the ancient humans of that time likely scavenged dead animals, as their heavy, clunky hand axes wouldn't have served well for hunting big game. "These are very large tools," he says. "They might have been thrown but not very accurately."

The hand axe was a multipurpose tool used by our ancestors for chopping up branches and carcasses as well as digging for tubers. They remained unchanged for several hundred thousand years.
Jay Reed/NPR

Nevertheless, these hand axes served the ancient humans well for several hundred thousand years — from 1.2 million years ago to 500,000 years ago — and the technology remained largely unchanged during the time.

But around 320,000 years ago, the ancient humans seem to have switched to an entirely new technology. The scientists found numerous smaller, flatter, sharper stone tools.

"We see a smaller technology, a more diverse series of stone tools," says Potts. These tools were designed for specific purposes — some were used as blades, some as scrapers or spear heads. The scientists report their findings in three new studies published Thursday in the journal Science.

"In Olorgesailie, you have the only record of the last million years in Africa," says Marta Mirazon Lahr, a paleoanthropologist who wasn't involved in the new study. And it's "the earliest ever documented Middle Stone Age in the whole continent."

The new studies also show that by 320,000 years ago this technology was well established in the region, suggesting that human ancestors likely started developing it even earlier, she says.

"The technology they have is not a crude, early version of the Middle Stone Age. It is the full-blown Middle Stone Age," Lahr says. "They have stone tools that are small, that are prepared and retouched, that are made with technique thought to come hundreds of thousands of years later."

Obsidian rock found at Olorgesailie was originally brought by the ancient humans from distant places, some as far away as 50 miles from the site. Scientists think this is evidence of a larger social network of groups of ancient people who stayed in touch and exchanged obsidian and other resources.
Jay Reed/NPR

The diversity of stone tools from the Middle Stone Age suggests advanced thinking and planning. "The flakes are being much more carefully prepared for a particular purpose," says Alison Brooks, an anthropologist at George Washington University and an author of the three studies.

"They are fairly small in size, compared to the technology of earlier people. And in addition, they are made with much finer grained material," which allowed them to allowed them to better control shapes and sizes of the stone tools.

"We see the ability to produce small triangular points, that look like they were projectile points," says Potts. "They were tapered at the end, so that could have been put on the shaft of something that flew through the air." In other words, a potentially lethal spear.

So our ancestors likely shifted from scavenging to hunting. An analysis of the fossilized animal bones found in the sediments show that people in that period were eating a range of mammals — which were by now much smaller, and closer in size to the animals of today — including hares, rabbits and springbok and even a couple of species of birds and fishes, says Brooks.

And they weren't just picking up nearby stones to create their weapons. Earlier hand axes were made primarily from volcanic basalt, sourced within 2 to 2.5 miles of where these humans lived. The latter weapons were made of stones like obsidian, which originated far from Olorgesailie.

A small stone point made of non-local obsidian. The chemical composition of the artifact matches obsidian sources as far as 55 miles away.
Jay Reed/NPR

"That black obsidian, that rare rock was being transported, brought in in chunks, from 15 to 30 miles away," says Potts. "We have a couple of rocks that were brought from up to 55 miles away."

These distances are far greater than what modern-day hunter gatherers travel over the course of a year, he says.

"They weren't just traveling long distances and chipping rocks as they go," he adds. "If they did that, then there would have just been small chips of obsidian left at the archaeological sites where we dig. Instead we see large pieces of raw material coming in. The rocks were shaped at Olorgesaile itself."

That kind of exchange of raw materials is a tell-tale sign of exchange between different groups of people, the scientists say. "In the Middle Stone Age, we begin to see the early stages of social networks, of being aware of another group and exchanging rocks over longer distances."

Potts and his colleagues also find evidence of exchange of brightly colored red and black rocks that were then drilled into, possibly to extract pigment. This is the earliest evidence of the extraction of pigments, says Lahr.

It's also evidence of a complex culture, where the ancient humans probably used pigments symbolically — perhaps to paint themselves, or their hides, or weapons. And where different groups exchanged raw materials (and possibly food).

Red rock found on the site. There is evidence that the rock was drilled to extract its red pigment.
Jay Reed/NPR

There's that same kind of exchange today, says Brooks, referring to hunter gatherer groups like the Hadza people of northern Tanzania.

"They deliberately maintain distant contacts with people in these other groups," she says. They have strategies to maintain these contacts — either by encouraging their children to marry into these other groups, or they take trips to visit the groups, to maintain ties by giving gifts. "It's a way of building up these distant contacts, which are extremely important for their survival."

During times of stress, when food or water is scarce, people from one group can disperse and take shelter with other groups that they've cultivated a relationship with. "So the networks are like money in the bank, or wheat in your silo or cows in your barn," says Brooks. "They don't have any other way of saving for a rainy day."

And as she and her colleagues show, the beginning of the Middle Stone Age in Kenya was preceded by a long and tumultuous phase in the region.

"Things were going haywire, in terms of the development of geological faults, earthquake activity that moved the low places high and the high places low," says Potts. "It changed the shape of the landscape." This was accompanied by repeated cycles of droughts and high rainfall.

"And it is precisely during those time periods that we expect to see hunting and gathering people to move further distances," says Potts, "and to begin to nurture relationships with groups beyond their own group."

It is no different than what humans all over the world do today, he adds. When times are tough, we look for greener pastures. The archaeological records from the Middle Stone Age at Olorgesailie reveal "the roots of that kind of migration," he says.


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