LC11C. Stay Current—Climate and Human Evolution

2024-01-08. Strong monsoons may have carved a path for early humans out of Africa. [https://www.science.org/content/article/strong-monsoons-may-have-carved-path-early-humans-out-africa] By BRIDGET ALEX, Science. Excerpt: More than 140,000 years ago, East Asia was a much colder, drier place than today—a landscape that likely deterred many African creatures, humans among them, from venturing into the region. Then, some 100,000 years ago, roving members of our species may have reached East Asia and found a rain-soaked, verdant landscape. What changed? According to a new study published today in the Proceedings of the National Academy of Sciences, a strengthening monsoon—and the lushness it lent—helped attract the region’s first Homo sapiens. …Evidence from fossils, artifacts, and DNA has established that H. sapiens evolved in Africa by roughly 300,000 years ago. About 60,000 years ago, the lineage that led to people alive today began to disperse across all of Earth’s habitable lands. …One climatic phenomenon that would have impacted early migrants is the Asian monsoon. Today, this seasonal shift in winds dumps torrential summer rain that nourishes forests and farms across Asia. In winter, Siberian winds bring dry, cold conditions. Paleoclimate records …indicate the monsoon’s intensity has waxed and waned over the millennia, but …. How wet Asia gets, the researchers learned, varies with multiple factors, including greenhouse gas concentrations, the amount of ice covering the Northern Hemisphere, and the intensity of sunlight reaching Earth, ultimately governed by the planet’s tilt, wobble, and solar orbit. Between 125,000 and 70,000 years ago, …East Asia had spells of 27.5°C summers with more rain than the present day—an enticing environment for mammals and the hunter-gatherers tracking them. …Meanwhile, over the same time span, climate in southeastern Africa worsened, the authors found, perhaps pushing humans to find new homelands.

2023-08-31. Human ancestors may have survived a brush with extinction 900,000 years ago. [https://www.science.org/content/article/human-ancestors-may-have-survived-brush-extinction-900-000-years-ago] By ELIZABETH PENNISI, Science. Excerpt: About 1 million years ago, our distant ancestors hunted in small bands and gathered their food with sophisticated stone tools. Then, about 900,000 years ago, something happened: The number of breeding individuals dwindled to only about 1300, according to a new study modeling ancient population sizes. Our ancestors came within a hair’s breadth of extinction, and populations remained that low for the next 100,000 years or more, researchers argue today in Science. …Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology, is skeptical. She notes that the genetic signal for the bottleneck is strongest only in present-day African populations, and not in people who today live outside Africa…. The conclusions, “though intriguing, should probably be taken with some caution and explored further,” she says…..

2023-08-10. Using climate to model ancient human migration. [https://www.science.org/doi/10.1126/science.adj4631] By Emily J. Beverly. Excerpt: …Although there is now consensus that all modern humans originated from a population in Africa, there is considerable disagreement as to how, when, and why they migrated to Europe and what happened once they arrived. Therefore, the focus of research has shifted to the identification of when humans could feasibly have migrated out of Africa. For example, a climate model was used to identify windows of time over the past 300,000 years in which humans could have migrated across difficult terrain in northern Africa and the Arabian Peninsula…. Other researchers took a different approach, determining whether freshwater springs would persist through major climate swings in Africa related to long-term changes in Earth’s orbit around the Sun. This was combined with mapping the maximum distance that a human could travel from these perennial sources of water (∼3 days, 150 km) to determine potential migration pathways during different wet and dry scenarios from the Pleistocene (∼2.58 million to 11,700 years ago)…. …The model showed that around 1.1 million years ago, habitats in Europe would likely have been unsuitable for permanent hominin occupation. This is because glacial conditions were so strong that it would have been too cold for hominins to survive without adaptations such as fire or clothing, for which there is currently no evidence. This suggests that hominins might not have permanently settled in Europe at this time and may have instead repeatedly repopulated from Asia, but additional hominin sites with better age control are needed to further test this hypothesis….

2023-07-10. Humans Adapted to Diverse Habitats as Climate and Landscapes Changed. [https://eos.org/articles/humans-adapted-to-diverse-habitats-as-climate-and-landscapes-changed] By Deepa Padmanaban, Eos/AGU. Excerpt: Our genus, Homo, evolved over 3 million years by adapting to increasingly diverse environments. Now, a new study published in Science deeply explores how six species of Homo(H. ergaster, H. habilis, H. erectus, H. heidelbergensis, H. neanderthalensis, and early H. sapiens) adapted to habitats across Africa and Eurasia. In its analysis, the team of scientists from South Korea and Italy used data from more than 3,000 human fossil specimens and archaeological sites. They then combined those data with climate and vegetation models of the past 3 million years. …during the early to middle Pleistocene (about 2.6 million years ago to 0.5 million years ago), massive changes in Earth’s climate played a role in the distribution of vegetation, as well as the evolutionary development of the Homo species studied. …the climate has cooled considerably over the past 3 million years. Reasons for this pattern of climate change include a gradual decrease in atmospheric carbon dioxide levels, glacial cycles brought on by long-term changes in Earth’s orbit and axis, and, after the Mid-Pleistocene Transition (MPT) about 1 million years ago, a lengthening of glacial cycles from about 41,000 years to about 100,000 years. …“Because cold air holds less water, planetary cooling was accompanied by an overall drying.” This global cooling resulted in a shrinking of warm tropical forests in central Africa and southern Europe—habitats to which the early hominins H. ergaster and H. habilis were adapted. Forests were replaced by more open environments such as grassland and dry shrubland….

2023-02-03. Centuries-Old Archive Reveals Far-Flung Impacts of Major Eruptions. [https://eos.org/articles/centuries-old-archive-reveals-far-flung-impacts-of-major-eruptions] By Shannon Banks, Eos/AGU. Excerpt: In 1815, an Earth-shattering explosion sent roughly 130 cubic kilometers of gaseous fumes, ash, and rocks high into the atmosphere above the Indonesian island of Sumbawa. Mount Tambora had blown its top. Temperatures tanked worldwide as sooty debris circulated in the skies of the Northern Hemisphere, blocking the Sun’s rays. The chilling effects lasted through 1816—later dubbed the “Year Without a Summer.” …Alice Bradley and her team of undergraduate researchers at Williams College are studying how Tambora and other major volcanic eruptions affected the climate in New England. Their source material is a weather data set that dates back more than 2 centuries to the Tambora eruption. It has been updated daily by Williams staff and students ever since. …According to the team’s analysis, daily low temperatures after the Tambora and Pinatubo eruptions were often more than 5°C below baseline….

2022-11-07. Did a Chaotic Climate Drive Human Evolution? [https://eos.org/articles/did-a-chaotic-climate-drive-human-evolution] By Elise Cutts, Eos/AGU. Excerpt: A new 620,000-year climate record from East Africa reveals dramatic swings between wet and dry conditions that may have influenced human evolution. We owe much of our understanding of the human family tree to decades of fossil finds in East Africa. But whereas researchers know quite a lot about hominin bones, the environments our ancestors and evolutionary cousins inhabited are a different story—despite East Africa’s anthropological significance, climate records for the region have remained stubbornly sparse. Now, researchers have produced what they say is one of the first-ever continuous climate records from a proven habitat of ancient Homo sapiens. The new 620,000-year history of hydroclimate at Chew Bahir, a playa lake in southern Ethiopia, showed that the local climate swung dramatically between wet and dry extremes. Shifts in the intensity and frequency of those swings seem to have occurred alongside, and perhaps even driven, major events in hominin evolution. The results were published in Nature Geoscience.…

2022-06-28. Early human ancestors one million years older than earlier thought. [https://www.theguardian.com/science/2022/jun/28/early-human-ancestors-one-million-years-older-than-earlier-thought] By AFP, The Guardian. Excerpt: The fossils of our earliest ancestors found in South Africa are a million years older than previously thought, meaning they walked the Earth around the same time as their east African relatives like the famous “Lucy”, according to new research. The Sterkfontein caves at the Cradle of Humankind world heritage site northwest of Johannesburg have yielded more Australopithecus fossils than any other site in the world. Among them was “Mrs Ples”, the most complete skull of an Australopithecus africanus found in South Africa in 1947. Based on previous measurements, Mrs Ples and other fossils found at a similar depth of the cave were estimated to be between 2.1 and 2.6m years old. But “chronologically that didn’t fit,” said French scientist Laurent Bruxelles, one of the authors of a study published Monday in the PNAS science journal. “It was bizarre to see some Australopithecus lasting for such a long time,” the geologist told AFP. …casting doubt on Mrs Ples’s age was recent research showing that the almost-complete skeleton of an Australopithecus known as “Little Foot” was 3.67m years old. Such a big gap in ages between Mrs Ples and Little Foot seemed unlikely given they were separated by so few sedimentary layers. …The previous dates underestimated the age of the fossils because they measured calcite flowstone mineral deposits, which were younger than the rest of that cave section, the study said. For the latest study, the researchers used a technique called cosmogenic nuclide dating, which looked at levels of rare isotopes created when rocks containing quartz were hit by high-speed particles that arrived from outer space. “Their radioactive decay dates when the rocks were buried in the cave when they fell in the entrance together with the fossils,” said the study’s lead author, Darryl Granger of Purdue University in the US. The researchers found that Mrs Ples and other fossils near her were between 3.4 and 3.7m years old.…

2021-09-01. Lush wetlands in Arabia lured waves of early humans out of Africa. Source: By Michael Price, Science Magazine. Excerpt: If you know what to look for in dappled satellite images of desert…the dried-up ghosts of prehistoric lakes pop out against the sand fields of the Arabian Peninsula. Eight years ago, one ancient multihued lake in the Nefud Desert caught the eye of researchers. When scientists excavated its ancient shorelines, a new study reports, they found thousands of stone tools—and evidence that multiple waves of Homo sapiens and their relatives have been migrating across the Arabian interior for at least the past 400,000 years. The results bolster the idea that the periodic greening of this typically harsh desert played a pivotal role in humans’ dispersals out of Africa—and provide the best evidence yet that different groups of humans pulsed out of the continent through the Sinai Peninsula…. digging revealed that the paleolakes at Khall Amayshan 4 had formed and dried up six different times; stone tools were associated with five of those long-lost lakes, dating to 400,000, 300,000, 200,000, 100,000, and 55,000 years ago, the researchers report today in Nature. At another paleolake about 150 kilometers to the east, the Jubbah oasis, they found stone tools in layers dating to 200,000 and 75,000 years ago. …researchers found fossilized animal bones at many of the dry lakes, suggesting large African animals like hippopotamuses, elephants, and ostriches also followed this green route out of Africa, at least in the wet season.… [https://www.science.org/content/article/lush-wetlands-arabia-lured-waves-early-humans-out-africa]

2018-07-11. Our ancestors may have left Africa hundreds of thousands of years earlier than thought. By Ann Gibbons, Science Magazine. Excerpt: More than 2 million years ago, our ancestors were already world travelers, trekking all the way from Africa to Asia, according to stone tools found on a cliff face in north-central China. The age of the tools suggests that the forebears of modern humans left Africa at least 250,000 years earlier than thought; it also supports a minority view that a key human ancestor, Homo erectus, may have originated in Asia, not in Africa. Until now, the oldest evidence of human ancestors outside of Africa was in Dmanisi, Georgia. Here, fossils of short people thought to be early H. erectus date back to about 1.85 million years—just after the species appears in Africa. The oldest evidence of early human activity in China and Indonesia has been fossils and stone tools that date to 1.5 million to 1.7 million years ago…. Now, evidence from the site of Shangchen, …is shaking up that view. On the steep cliff faces of a gully at Shangchen, a Chinese team unearthed 96 stone points, flakes, and cores that were probably used to carve up animal bones or to smash them open for marrow. …led by geologist Zhaoyu Zhu of the Guangzhou Institute of Geochemistry…the researchers used paleomagnetic dating—which detects known reversals in Earth’s magnetic field that are recorded in ancient rock—and found that the stone tools range in age from 1.6 million to 2.1 million years ago. This indicates hominins—the family that includes humans and our ancestors—got out of Africa at least a quarter of a million years earlier than thought, and occupied Shangchen on and off for more than 850,000 years, the team reports today in Nature…. http://www.sciencemag.org/news/2018/07/our-ancestors-may-have-left-africa-hundreds-thousands-years-earlier-thought

2018-03-12. After a Volcano’s Ancient Supereruption, Humanity May Have Thrived. By Shannon Hall, The New York Times.  Excerpt: About 74,000 years ago, a supervolcano at the site of present-day Lake Toba on the Indonesian island of Sumatra rocked our world. But while it was the largest volcanic eruption of the last two million years, a new study published Monday in Nature suggests that humans not only survived the event — they thrived. The study counters previous hypotheses, which suggested that the behemoth was so disastrous it caused the human species to teeter on the brink of extinction. … Climate models suggest that temperatures may have plummeted by as much as 30 degrees Fahrenheit. And in such a cold world, plants may have ceased growing, glaciers may have advanced, sea-levels may have dropped and rainfall may have slowed. Then in 1998, Stanley Ambrose, an anthropologist, linked the proposed disaster to genetic evidence that suggested a population bottleneck had occurred around the same time. He was certain that the Toba supereruption had caused the human population to decline to some 10,000 people — a close call for our ancestors. …The latest study, however, suggests that those theories are incorrect, Dr. Petraglia said. “We’re not seeing all the drama.”…. https://www.nytimes.com/2018/03/12/science/toba-supervolcano-supereruption.html

2014-12-04. Dwindling African tribe may have been most populous group on planet. By Ann Gibbons, Science. Excerpt: The famous Kalahari Bushmen of southern Africa have long been in decline. For more than a century, the people, who speak Khoisan languages, have been pushed off their land by farmers and brutalized by colonialists. Yet for tens of thousands of years, the Khoisan’s ancestors were members of “the largest population” on the planet, according to a new study. …The Khoisan have long stood apart from other groups within Africa. They look distinct, speak in “click” languages, and have also maintained the greatest genetic diversity known among human populations. …the 100,000 Khoisan speakers in Africa today are far outnumbered by other groups, such as the 45 million Bantu speakers and their 180 million descendants who now speak Swahili and other languages.  …In the new study, published online today in Nature Communications, biochemist Stephan Schuster of Nanyang Technological University in Singapore and colleagues sequenced the complete genomes of five Khoisan hunter-gatherers from Namibia and compared them with the DNA from 1462 genomes of people from around the world.  …population sizes for the ancestors of the Khoisan, as well as for Europeans, Asians, and another African group, the Yoruba… declined … between 120,000 and 30,000 years ago. …The researchers uncovered declines in population in all four groups, likely tied into periods of dry climate in Africa. But the Khoisan suffered the least, perhaps because their huge ancestral population was buffered from droughts that winnowed other groups, such as the Yoruba and the African ancestors of Europeans and Asians, because the Khoisan lived farther south in Africa where rainfall actually increased. The Khoisan then began a more drastic decline in the past 20,000 years or so, with a major blow when the Bantu farmers spread through Africa 4000 years ago. “This shows us how much climate can influence populations,” says genomicist Webb Miller of Pennsylvania State University, University Park, a co-author….  http://news.sciencemag.org/africa/2014/12/dwindling-african-tribe-may-have-been-most-populous-group-planet *.

2010 March 1. Human Culture, an Evolutionary Force. By Nicolas Wade, NY Times. Excerpt: As with any other species, human populations are shaped by the usual forces of natural selection, like famine, disease or climate. A new force is now coming into focus. It is one with a surprising implication — that for the last 20,000 years or so, people have inadvertently been shaping their own evolution.
…Although it does shield people from other forces, culture itself seems to be a powerful force of natural selection. People adapt genetically to sustained cultural changes, like new diets. And this interaction works more quickly than other selective forces, “leading some practitioners to argue that gene-culture co-evolution could be the dominant mode of human evolution,” Kevin N. Laland and colleagues wrote in the February issue of Nature Reviews Genetics. Dr. Laland is an evolutionary biologist at the University of St. Andrews in Scotland….

2009 October 4. Ardipithecus: We Meet At Last. By Carl Zimmer, Discover. Excerpt: Meet Ardipithecus.
This introduction has been a long time coming. Some 4.4 million years ago, a hominid now known as Ardipithecus ramidus lived in what were then forests in Ethiopia. Fifteen years ago, Tim White of Berkeley and a team of Ethiopian and American scientists published the first account of Ardipithecus, which they had just discovered. But it was just a preliminary report, and White promised more details later, once he and his colleagues had carefully prepared and analyzed all the fossils they had unearthed. “Later,” it turned out, meant 15 years.
…Today, the journal Science has handed many of its pages over to White and his colleagues, who have filled them with lots of details about Ardipithecus…. Ardipithecus has gone from being an enigmatic collection of bones to a new touchstone for our early hominid ancestors….
C. Owen Lovejoy of Kent State University spearheaded the studies on how Ardipithecus moved. He and his colleagues argue that its pelvis could support its upper body during bipedal walking. It wasn’t a fabulous walker, and was probably a terrible runner. Nevertheless, it had some of the same anchors for muscles that we have on our pelvis, and which chimpanzees and other apes lack….
…Ardipithecus’s feet…were adapted for walking on the ground. Yet the big toe was still opposable, much like our thumbs. This sort of big toe helped Ardipithecus move through the trees much more adeptly…. Ardipithecus probably moved carefully through the trees, using its hands and feet all at once to grip branches…. 

2008 November 27. Did Neanderthal cells cook as the climate warmed? By Ewen Callaway, New Scientist. Excerpt: Neanderthals may have gone extinct because their cells couldn’t cope with climate change, according to a new hypothesis…
Metabolic adaptations to Ice Age Europe may have proved costly to Neanderthals after the continent’s climate started to change, says Patrick Chinnery, a molecular biologist at Newcastle University, UK.
He and colleague Gavin Hudson identified potentially harmful mutations in the newly sequenced Neanderthal mitochondrial genome. In particular, the researchers found genes that are associated with neurodegenerative diseases and deafness. “If they were found in modern humans they would be bad news,” Chinnery says.
The extinction of Neanderthals, close relatives of modern humans, some 25,000 years ago remains unexplained.
…Chinnery and Hudson suggest that mutations in mitochondria helped Neanderthals cope with the cold weather, but that when the climate started fluctuating between warm and cold periods, they were at a disadvantage.
In all cells, from yeast to human, a mitochondrion’s main job is to produce the energy that powers cells… Our mitochondria do this quite efficiently under ideal conditions…
Mutations that sap this efficiency would generate heat instead – a potentially useful trick for Neanderthals who are known to have had adaptations to cold weather, Chinnery says. However, a warmer and less climatically stable habitat could have spelled trouble for Neanderthals with such mutations….

2008 August 14. Graves Found From Sahara’s Green Period. By JOHN NOBLE WILFORD, The New York Times. Excerpt: When Paul C. Sereno went hunting for dinosaur bones in the Sahara, his career took a sharp turn from paleontology to archaeology. The expedition found what has proved to be the largest known graveyard of Stone Age people who lived there when the desert was green.
The first traces of pottery, stone tools and human skeletons were discovered eight years ago at a site in the southern Sahara, in Niger. After preliminary research, Dr. Sereno, a University of Chicago scientist who had previously uncovered remains of the dinosaur Nigersaurus there, organized an international team of archaeologists to investigate what had been a lakeside hunting and fishing settlement for the better part of 5,000 years, originating some 10,000 years ago.
…the team described finding about 200 graves belonging to two successive populations. Some burials were accompanied by pottery and ivory ornaments….
…The sun-baked dunes at the site, known as Gobero, preserve the earliest and largest Stone Age cemetery in the Sahara, Dr. Sereno’s group reported…
Other scientists said the discovery appeared to provide spectacular evidence that nothing, not even the arid expanse of the Sahara, was changeless. About 100 million years ago, this land was forested and occupied by dinosaurs and enormous crocodiles. Around 50,000 years ago, people moved in and left stone tools and mounds of shells, fish bones and other refuse. The lakes dried up in the last Ice Age.
Then the rains and lakes of a fecund Sahara returned about 12,000 years ago, and remained, except for one 1,000-year interval, until about 4,500 years ago. Geologists have long known that the region’s basins retained mineral residue of former lakes, and other explorers have found scatterings of human artifacts from that time, as Dr. Sereno did at Gobero in 2000.
“Everywhere you turned, there were bones belonging to animals that don’t live in the desert,” he said. “I realized we were in the green Sahara.”… 

2008 May 9. How the Sahara Became Dry & Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years. Jonathan A. Holmes. Science 9 May 2008: Vol. 320. no. 5877, pp. 752 – 753 DOI: 10.1126/science.1158105. Excerpt: Around 14,800 years ago, a strengthening of the summer monsoons led to a dramatic increase in North African lakes and wetlands and an extension of grassland and shrubland into areas that are now desert, creating a “green Sahara” (see the first figure). …a lake sediment record … sheds light on how this “African Humid Period” came to an end. 

2008 May 9. Climate-Driven Ecosystem Succession in the Sahara: The Past 6000 Years. S. Kropelin, et al. Science: Vol. 320. no. 5877, pp. 765 – 768 DOI: 10.1126/science.1154913.Excerpt: Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a “green Sahara” to the present hyperarid desert. Our continuous 6000-year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site-specific thresholds. Strong reductions in tropical trees and then Sahelian grassland cover allowed large-scale dust mobilization from 4300 calendar years before the present (cal yr B.P.). Today’s desert ecosystem and regional wind regime were established around 2700 cal yr B.P. This gradual rather than abrupt termination of the African Humid Period in the eastern Sahara suggests a relatively weak biogeophysical feedback on climate. …One of the most prominent environmental changes of the past 10,000 years is the transition of northern Africa from a “green Sahara” during the early Holocene “African Humid Period” to the world’slargest warm desert today. Detailed knowledge of the tempo and mode of this transition is crucial for understanding the interaction between tropical and mid-latitude weather systems and the multiple impacts of mineral aerosols exported from the Sahara on global climate and distant ecosystems….

2007 November 13. Jawbone Sheds Light on Divergence of Humans and Apes. By HENRY FOUNTAIN, NY Times. Excerpt: Scientists who study the divergence of humans from the other great apes have been stymied by a lack of evidence. It is thought that humans and chimpanzees split 6 million to 7 million years ago, and humans and gorillas a couple of million years before that. But almost no ape fossils from this period – the Late Miocene – have been found in Africa.
So some scientists suggest that an interloper of sorts, an ancient ape from Eurasia, returned 10 or 11 million years ago to Africa and became the last common ancestor of humans and the African great apes.
The discovery of a 10-million-year-old jawbone with teeth, in deposits of volcanic mud in Nakali, Kenya, may help put such thoughts to rest.
Yutaka Kunimatsu of Kyoto University in Japan and colleagues report in The Proceedings of the National Academy of Sciences that the fossil, the first of such vintage to be found in the region since 1982, represents a new genus of great ape…. 

2007 October 2. Fossil DNA Expands Neanderthal Range. By NICHOLAS WADE. NY Times. Excerpt:
In the Treaty of Tordesillas, Spain and Portugal divided the world outside Europe between them. That was not the first time that two rival groups carved up the globe. More than 50,000 years ago, all the world outside Africa was divided between two archaic human species.
The Neanderthals held sway in Europe and the Near East, bottling up the troublesome ancestors of modern humans in Africa, and Homo erectus dominated East Asia. But a new discovery suggests that this division of the world may not have been quite so clear-cut.
…Svante Paabo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany… has shown that Neanderthal DNA can be picked out and identified. So far, he and others have identified DNA from 13 European Neanderthals.
He and colleagues have now identified Neanderthal mitochondrial DNA in bones at two new sites, they say in an article published electronically in Nature this week. One is Teshik Tash, in Uzbekistan, some 750 miles east of the Caspian Sea and, until now, the easternmost known limit of Neanderthal territory. The other bones are from the Okladnikov cave in the Altai mountains, some 1,250 miles farther east.
This huge extension of the Neanderthal’s known range puts them well into southern Siberia.
Because the mitochondrial DNA sequence of the new finds differs only slightly from that of the European Neanderthals, Dr. Paabo believes that they may have moved into Siberia relatively late in the Neanderthal period, perhaps as recently as 127,000 years ago, when a warm period made Siberia more accessible.
If Neanderthals penetrated as far as Siberia, might they have reached ever farther east, trespassing far into the assumed domain of Homo erectus? “We now know that they are on the doorstep to Mongolia and even China, so I would not be surprised if we one day find a Marco Polo Neanderthal,” ….

2007 June 26. Humans Have Spread Globally, and Evolved Locally. The New York Times. By NICHOLAS WADE. Excerpt: Historians often assume that they need pay no attention to human evolution because the process ground to a halt in the distant past. That assumption is looking less and less secure in light of new findings based on decoding human DNA. People have continued to evolve since leaving the ancestral homeland in northeastern Africa some 50,000 years ago, both through the random process known as genetic drift and through natural selection. A striking feature of many of these changes is that they are local. The genes under selective pressure found in one continent-based population or race are mostly different from those that occur in the others. These genes so far make up a small fraction of all human genes. The new scans for selection show so far that the populations on each continent have evolved independently in some ways as they responded to local climates, diseases and, perhaps, behavioral situations. The concept of race as having a biological basis is controversial, and most geneticists are reluctant to describe it that way. But some say the genetic clustering into continent-based groups does correspond roughly to the popular conception of racial groups.

2006 September 21. Little Girl, 3 Million Years Old, Offers New Hints on Evolution. By JOHN NOBLE WILFORD. NY Times. Excerpt: If the fossil Lucy, the most famous woman from out of the deep human past, had a child, it might have looked a lot like the bundle of skull and bones uncovered by scientists digging in the badlands of Ethiopia. The paleontologists who are announcing the discovery in the journal Nature today said the 3.3-million-year-old fossils were of the earliest well-preserved child ever found in the human lineage. It was … a member of the Australopithecus afarensis species, the same as Lucy’s.
An analysis of the skeleton revealed evidence of a species in transition, …afarensis walked upright, like modern humans. But gorillalike arms and shoulders suggested that it possibly retained an ancestral ability to climb and swing through the trees. …The Dikika girl’s brain size …was about the same as that of a similarly aged chimpanzee, but a comparison with adult afarensis skulls indicates a relatively slow brain growth slightly closer to that of humans. …hyoid bone …a rarely preserved bone in the larynx, or voice box, that supports muscles of the throat and tongue. … appeared to be primitive and more similar to those found in apes than in humans, the scientists said, but is the first hyoid found in such an early human-related species and thus important in research about the origins of human speech.
The first relatively complete shoulder blades to be found in an australopithecine individual was one of the most puzzling aspects of the discovery, several scientists said. The lower body appeared to be adapted for upright walking by afarensis. But the shoulders and long arms were more apelike.

15 November 2005. A Conversation with Carel Van Schaik: Revealing Behavior in ‘Orangutan Heaven and Human Hell’. By CONNIE ROGERS, NY Times. Excerpt: People keep asking Carel van Schaik if there is anything left to discover in fieldwork. “I tell them, ‘A lot,’ ” said Dr. van Schaik, the Dutch primatologist. “Look at gorillas. We’ve been studying them for decades, and we just now have discovered that they use tools. The same is true for orangutans.” In 1992, when Dr. van Schaik began his research in Suaq, a swamp forest in northern Sumatra, orangutans were believed to be the only great ape that lived a largely solitary life foraging for hard-to-find fruit thinly distributed over a large area. Researchers thought they were slow-moving creatures – some even called them boring – that didn’t have time to do much but eat. But the orangutans Dr. van Schaik found in Suaq turned all that on its head. More than 100 were gathered together doing things the researchers had never seen in the wild.

January 2005. Popular Science, Evolution’s Small Wonder. By TABITHA M. POWLEDGE. Excerpt: A three-foot-tall “hobbit” who lived in Indonesia up to 12,000 years ago is changing the way we think about the human family. She was only three feet tall? And her brain was smaller than your average chimp’s. Yet she and her relatives apparently lived fully human lives. They seem to have made sophisticated tools, cooperated to find food and cook it, and perhaps even buried their dead with ceremony. The startling discovery of bones from hobbit-size humans who lived on the Indonesian island of Flores as recently as 12,000 years ago-a time when our own species had already populated the Americas-has scientists revising their ideas about the skills of other humans in our growing family tree and about the importance of brain size. Peter Brown of the University of New England in Australia, who leads the team that’s examining the bones, says it was a major surprise to find tools, including points and hafted microblades, associated with Homofloresiensis, as the new human family member has been named. The tools are like those previously seen only with European fossils from our own species, Homo sapiens, Brovn notes, and the oldest of them were made 94,000 years ago. Homo sapiens is thought to have arrived in the region a mere 40,000 years ago, much too late to be responsible for the implements. If this tiny human made the tools, then the internal structure of its brain must have been more like our own than a chimps despite being just a third the size of ours. Of the six species of humans known, all extinct except ours, this is by far the smallest-brained human scientists have ever seen. The researchers suspect that H. floresiensis is a dwarfed descendant of H. erectus, to which it is anatomically similar. This is not so strange as it might at first sound. When organisms are isolated in regions with scarce resources but few predators, being big is a disadvantage and evolution tends to shrink them, a process known as island dwarfing. There are other examples on Flores, notably an extinct dwarf elephant, Stegodon…. 

15 February 2005. For Neanderthals and Homo Sapiens, Was It De-Lovely? By JOHN NOBLE WILFORD, NY Times. The scientists did not get around to the nitty-gritty question until the fourth hour of a two-and-a-half-day symposium on Neanderthals, held recently at New York University. A strong consensus was emerging, they agreed, that the now-extinct Neanderthals were a distinct evolutionary entity from modern humans, presumably a different species. They were archaic members of the human family, robust with heavy brow ridges and forward-projecting faces, who lived in Europe and western Asia from at least 250,000 years ago until they vanished from the fossil record about 28,000 years ago. Neanderthals may have seen their first modern Homo sapiens some 100,000 years ago in what is now Israel. The two people almost certainly came in contact in Europe in the last centuries before the dwindling Neanderthal population was replaced forever by the intruding modern humans. >

February 2005. Boning Up On Human Evolution By David Pescovitz, Science Matters @ Berkeley. Tim White, a UC Berkeley professor of Integrative Biology, is on what he calls “a planetary mission,” but the planet he’s exploring is Earth, albeit a very long time ago. White and an international team of scientists are digging deep into the geological record of remote Ethiopia to find clues about this planet as it existed 6 million years ago. What was the weather like? What kinds of plants thrived? What animals roamed the terrain? And, of particular interest to paleoanthropologists like White, what did our ancestors look like before evolution transformed them into us? 

26 August 2004. Scientists warn of new Anthropocene age — Should we recognize new epoch of human influence? By Clive Cookson, Financial Times. STOCKHOLM, Sweden – Scientists are beginning to accept that Earth has entered a new geological epoch, the “Anthropocene”, so named because humans have come to rival nature in their impact on the global environment. The EuroScience forum in Stockholm heard on Thursday that climate change was the most obvious of a complex range of man-made effects that is rapidly changing the physics, chemistry and biology of the planet. Paul Crutzen, the Nobel Prize-winning atmospheric chemist who first proposed the term Anthropocene four years ago, said the concept was winning wide acceptance from colleagues in other fields.

April 2004. Human Evolution: Interpreting Evidence. An approach to teaching human evolution in the classroom–article by Jerry DeSilva, Boston Museum of Science. Perhaps the best topic teachers can use to exemplify the nature of science is paleoanthropology, the study of human evolution through the fossil record. Science educators have an opportunity to tackle ‘How do we know?’ questions by examining evidences of our past and accurately defining the terms “hypothesis,” “fact,” “theory” and “belief.” They can use recent discoveries to demonstrate that science is a self-correcting mechanism of understanding the world. By examining different hypotheses, they can encourage the skepticism, debate and challenge to authority on which science thrives. …In this paper, we present an updated approach to teaching human evolution, and a model for explaining what science is and how it is done.

4 March 2004. New Ethiopian fossils are from 6-million-year-old hominid living just after split from chimpanzees. By Robert Sanders. BERKELEY – Paleoanthropologists from the University of California, Berkeley, and the Cleveland Museum of Natural History have found more fossils of a nearly 6-million-year-old human ancestor first reported three years ago, cementing its importance as the earliest hominid to appear after the human line diverged from the line leading to modern chimpanzees.

11 June 2003. 160,000-year-old fossilized skulls uncovered in Ethiopia are oldest anatomically modern humans. Robert Sanders, UC Berkeley News. BERKELEY – The fossilized skulls of two adults and one child discovered in the Afar region of eastern Ethiopia have been dated at 160,000 years, making them the oldest known fossils of modern humans, or Homo sapiens.

11 July 2001. UC Berkeley/ Paleoanthropologists find oldest human ancestor in Ethiopia. By Robert Sanders, Media Relations, Berkeley. Scouring the dry washes encircling an Ethiopian site where scientists seven years ago found fossils of 4.4 million-year-old human ancestors, University of California, Berkeley, graduate student Yohannes Haile-Selassie has found even older fossils that show human ancestors walked on two legs as early as 5.2 million years ago. The fossils are the earliest hominid known, and date from close to the time when human ancestors are believed to have split off from the chimpanzees on the first steps of their evolutionary trip to modern Homo sapiens. The fragmentary fossils, which include teeth, a jawbone, hand, arm and collar bones, and one toe bone, appear to be from family members of the species discovered in 1994 by an international team led by UC Berkeley paleoanthropologist Tim White. They named that species Ardipithicus ramidus, and concluded that it was the earliest known human ancestor. Haile-Selassie, for now, has designated the new fossils as a subspecies of this earlier find: Ardipithicus ramidus kadabba.

RIFT VALLEY FEVER. Scientists are learning that the key to predicting certain epidemics –like Rift Valley fever in Africa or Hanta virus in the U.S. — lies in an unexpected place: the ocean. Researchers at NASA Goddard Space Flight Center and at the Walter Reed Army Institute of Research have discovered that outbreaks of Rift Valley fever follow sudden floods triggered by El Niño and a similar (yet lesser-known) climate disturbance called the “Indian Ocean Dipole.” Using weather satellites to track sea surface temperature patterns in the Indian and Pacific oceans, they now believe they have found a way to predict outbreaks up to five months in advance.