Did First Placental Mammal Live Alongside Dinosaurs? Scientists Can't Agree

        

 |  By Ewen Callaway Posted: 01/15/2014 9:53 am EST

Artist's rendering of the common ancestor of placental mammals. | Carl Buell

      

 

 

 

 

 

 

 

 

 

Did the first mammal with a placenta live alongside the dinosaurs — or did it emerge after a gigantic asteroid wiped them out? This is the subject of a heated debate that pits scientists who contend that fossils are the ultimate timekeeper of life’s history against researchers who say that genetics offers more reliable dates.

Such disputes have been waging for decades, since researchers first began gleaning evolutionary detail from proteins and DNA. But the skirmish over placental mammals — animals that give birth to live offspring that are in late stages of development, including whales, mice and humans — began with a paper published early last year, arguing that the group diversified only after those dinosaurs that did not evolve into birds went extinct, 65 million years ago.

For that study, Maureen O’Leary, an evolutionary biologist at Stony Brook University in New York, and her team spent several years characterizing and analyzing thousands of traits in dozens of living and fossil mammals. The team combined those characteristics with genetic data to build a giant tree of life, showing how different placental mammals related to one another.

But to establish when the different creatures evolved, the researchers looked only at the fossil record. They concluded that the earliest placental mammals appeared only after the asteroid impact that killed the dinosaurs and marked the end of the Cretaceous period and the beginning of the Palaeogene. After this, the team said, the placentals quickly diversified, and a menagerie of mammals filled the habitat niches left by the dinosaurs.

Phil Donoghue, a palaeobiologist at the University of Bristol, UK, and his collaborators were not convinced. O'Leary's work was “an incredibly impressive study in all aspects — except the timescale in evolutionary history”, he says. “What we were really concerned about is that this stuff was going to end up in textbooks.”

Fossil boundary

Now, Donoghue and evolutionary geneticists Mario dos Reis and Ziheng Yang of University College London publish a study in Biology Letters, saying that O’Leary’s team made a fatal error in assuming that lineages of species date back no further than their oldest fossils. The fossils should instead mark the minimum age for a lineage, says Donoghue, because it is likely that animals existed before that, but were not preserved as fossils or their remains have yet to be discovered.

Using a mathematical elaboration of this concept and genome data from dozens of mammals, Donoghue’s team calculated new dates for the placental-mammal family tree. The researchers conclude that placental mammals first emerged between 108 million and 72 million years ago — well before the (non-avian) dinosaurs disappeared.

The critique follows an August 2013 technical comment on O'Leary's paper, in which an independent group also took umbrage with the suggested Palaeogene origin, because, they said, it requires a dramatic increase in the rate of evolution to explain the early diversity of placental mammals.

Hard evidence

O’Leary says that her team wanted to avoid introducing a bias by assuming that placental mammals are older than suggested by the fossil evidence. But Anne Yoder, an evolutionary geneticist at Duke University in Durham, North Carolina, prefers Donoghue, dos Reis and Yang's approach. “It’s hard to say who’s right and who’s wrong, but the weight of the data support the dos Reis conclusion,” she says.

Yoder adds that discoveries have the potential to harmonize molecular and fossil dates. A decade ago she concluded, using genetic data, that the common ancestor of bush babies and lorises lived around 40 million years ago, even though the oldest fossil was less than 20 million years old. While her paper was in press, a team reported a more than 40-million-year-old fossil that matched her predictions.

As for the current debate, “early placental mammals found in the Cretaceous will settle this once and for all”, says Yoder. O’Leary agrees that the question will be decided by fossil evidence, not mathematical models. “I don’t see this as a problem that’s going to be solved by a computer,” she says.

This story originally appeared in Nature News.

Strange Metal Asteroid Targeted in Far-Out NASA Mission Concept

By Mike Wall, Senior Writer   |   January 15, 2014 03:11pm ET 

      

Artist's concept of a spacecraft studying the metal asteroid Psyche from orbit.Credit: JPL/Corby Waste

One of the strangest objects in the solar system may get its first closeup in the coming years.
A team of scientists is mapping out a mission to the huge metallic asteroid Psyche, which is thought to be the exposed iron core of a battered and stripped protoplanet. The proposed mission would reveal insights about planet formation processes and the early days of the solar system, its designers say, and would also afford the first-ever good look at an odd class of celestial objects.

"This is the first metal world humankind will have ever seen," team member Lindy Elkins-Tanton, director of the Carnegie Institution for Science's Department of Terrestrial Magnetism, told SPACE.com last month at the American Geophysical Union's annual fall meeting in San Francisco. "I think this is an opportunity to do some fundamental science that hasn't been done before."
 

 

The huge metal asteroid Psyche may have a strong remnant magnetic field.

A protoplanet's core?

The 155-mile-wide (250 kilometers) Psyche, which lies in the main asteroid belt between Mars and Jupiter, consists largely of iron. Scientists think the object is the nearly naked core of a protoplanet whose overlying rock layers were blasted off by massive collisions long ago.

Psyche thus offers a unique opportunity to learn more about the interiors of planets and large moons, whose cores are hidden beneath many miles of rock, Elkins-Tanton said.

 

"This is absolutely the only core-like object that we know about in the entire solar system," she said.
A robotic mission to Pysche would also help astronomers take the measure of metal worlds, a type of solar system object that scientists know very little about. The project would beam home the first photos and information ever gathered at such a body.

"We know a lot about stony and icy bodies, but what about metal ones?" Elkins-Tanton said. "What does the surface of a metal world look like?"

This simulation shows a "hit-and-run" collision between two large asteroids, the kind of impact that could have stripped the rocky layers from the big metal asteroid Psyche, exposing the protoplanet's iron core.
Credit: M. Jutzi and E. Asphaug (U.Bern/ASU)

View full size image

For example, she added, it's possible that material melted and blasted out by large impacts on Psyche solidifies in a sheet before being lost to space, causing metallic curtains of ejecta to jut from the rims of impact craters.

Mission to be proposed in 2015
The researchers' Psyche probe would orbit the huge asteroid for about six months, studying the object's topography, surface features, gravity and magnetic field, among other characteristics, Elkins-Tanton said.

Data gathered by the spacecraft would shed light on how planets began coming together in the first few million years of solar system history, as well as improve scientists' understanding of the interiors of terrestrial planets such as Earth, she added.

The team has been working on the concept for about a year and a half and plans to submit it during the next call for NASA Discovery-class missions, which is expected to come in 2015. Discovery missions are lower-cost efforts capped at $425 million in 2010 dollars, excluding launch-vehicle expenses.

If selected, the Psyche mission could be ready to launch relatively quickly because it requires no new technology development, Elkins-Tanton said. The spacecraft would be based to a large degree on NASA's Dawn probe, which is currently on its way to the dwarf planet Ceres after wrapping up a 14-month campaign at another giant body in the asteroid belt, the protoplanet Vesta.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on SPACE.com.

Rebecca Morelle reports for Newsnight on the solar lull that is baffling scientists

17 January 2014 Last updated at 19:54 ET

By Rebecca Morelle Science reporter, BBC World Service

Rebecca Morelle reports for Newsnight on the solar lull that is baffling scientists
 

"I've been a solar physicist for 30 years, and I've never seen anything quite like this," says Richard Harrison, head of space physics at the Rutherford Appleton Laboratory in Oxfordshire.

He shows me recent footage captured by spacecraft that have their sights trained on our star. The Sun is revealed in exquisite detail, but its face is strangely featureless.

"If you want to go back to see when the Sun was this inactive... you've got to go back about 100 years," he says.

This solar lull is baffling scientists, because right now the Sun should be awash with activity.

The Sun's activity may be falling faster than at any time in 10,000 years

It has reached its solar maximum, the point in its 11-year cycle where activity is at a peak.

This giant ball of plasma should be peppered with sunspots, exploding with flares and spewing out huge clouds of charged particles into space in the form of coronal mass ejections.

The Sun should be at the peak of its activity - bursting with flares and coronal mass ejections

But apart from the odd event, like some recent solar flares, it has been very quiet. And this damp squib of a maximum follows a solar minimum - the period when the Sun's activity troughs - that was longer and lower than scientists expected.

"It's completely taken me and many other solar scientists by surprise," says Dr Lucie Green, from University College London's Mullard Space Science Laboratory.

The drop off in activity is happening surprisingly quickly, and scientists are now watching closely to see if it will continue to plummet.

"It could mean a very, very inactive star, it would feel like the Sun is asleep... a very dormant ball of gas at the centre of our Solar System," explains Dr Green.

This, though, would certainly not be the first time this has happened.

“Start Quote

It's an unusually rapid decline”

End Quote Prof Mike Lockwood University of Reading

During the latter half of the 17th Century, the Sun went through an extremely quiet phase - a period called the Maunder Minimum.

Historical records reveal that sunspots virtually disappeared during this time.

Dr Green says: "There is a very strong hint that the Sun is acting in the same way now as it did in the run-up to the Maunder Minimum."

Mike Lockwood, professor of space environment physics, from the University of Reading, thinks there is a significant chance that the Sun could become increasingly quiet.

An analysis of ice-cores, which hold a long-term record of solar activity, suggests the decline in activity is the fastest that has been seen in 10,000 years.

"It's an unusually rapid decline," explains Prof Lockwood.

Londoners enjoyed frost fairs on the Thames in the 17th Century

"We estimate that within about 40 years or so there is a 10% to 20% - nearer 20% - probability that we'll be back in Maunder Minimum conditions."

The era of solar inactivity in the 17th Century coincided with a period of bitterly cold winters in Europe.

Londoners enjoyed frost fairs on the Thames after it froze over, snow cover across the continent increased, the Baltic Sea iced over - the conditions were so harsh, some describe it as a mini-Ice Age.

And Prof Lockwood believes that this regional effect could have been in part driven by the dearth of activity on the Sun, and may happen again if our star continues to wane.

"It's a very active research topic at the present time, but we do think there is a mechanism in Europe where we should expect more cold winters when solar activity is low," he says.

He believes this local effect happens because the amount of ultraviolet light radiating from the Sun dips when solar activity is low.

This means that less UV radiation hits the stratosphere - the layer of air that sits high above the Earth. And this in turn feeds into the jet stream - the fast-flowing air current in the upper atmosphere that can drive the weather.

The results of this are dominantly felt above Europe, says Prof Lockwood.

Cold, snowy winters could become the norm for Europe

"These are large meanders in the jet stream, and they're called blocking events because they block off the normal moist, mild winds we get from the Atlantic, and instead we get cold air being dragged down from the Arctic and from Russia," he says.

"These are what we call a cold snap... a series of three or four cold snaps in a row adds up to a cold winter. And that's quite likely what we'll see as solar activity declines."

So could this regional change in Europe have a knock-on effect on for the rest of the world's climate? And what are the implications for global warming?

In a recent report by the UN's climate panel, scientists concluded that they were 95% certain that humans were the "dominant cause" of global warming since the 1950s, and if greenhouse gases continue to rise at their current rate, then the global mean temperature could rise by as much as 4.8C.

“Start Quote

This feels like a period where it's very strange... but also it stresses that we don't really understand the star that we live with”

End Quote Prof Richard Harrison Rutherford Appleton Laboratory

And while some have argued that ebbs and flows in the Sun's activity are driving the climate - overriding the effect of greenhouse gas emissions, the Intergovernmental Panel on Climate Change concludes that solar variation only makes a small contribution to the Earth's climate.

Prof Lockwood says that while UV light varies with solar activity, other forms of radiation from the Sun that penetrate the troposphere (the lower layer of air that sits above the Earth) do not change that much.

He explains: "If we take all the science that we know relating to how the Sun emits heat and light and how that heat and light powers our climate system, and we look at the climate system globally, the difference that it makes even going back into Maunder Minimum conditions is very small.

"I've done a number of studies that show at the very most it might buy you about five years before you reach a certain global average temperature level. But that's not to say, on a more regional basis there aren't changes to the patterns of our weather that we'll have to get used to."

Polar lights - one manifestation of solar activity in the Earth's magnetosphere - may dim

But this weather would not be the only consequence of a drawn out period of inactivity, says Dr Green.

"If the Sun were to get very quiet, one of the few things that would happen is that we'd have very few displays of the northern lights. They are driven by solar activity, and we'd miss out on this beautiful natural phenomenon," she explains.

However, there could be positive effects too.

"Solar activity drives a whole range of space weather, and these are ultimately effects on the electricity networks, on satellites, on radio communications and GPS on your sat-nav," she explains.

And while scientists cannot discount that the random bursts of activity may still occur, calmer periods of space weather would help to maintain the technological infrastructure that we rely so heavily on.

While the full consequences of a quietening Sun are not fully understood, one thing scientists are certain about is that our star is unpredictable, and anything could happen next.

"This feels like a period where it's very strange... but also it stresses that we don't really understand the star that we live with." says Prof Harrison.

"Because it's complicated - it's a complex beast."

Follow Rebecca on Twitter

"Photosynthesis is Possible on the Surface of Mars"

January 17, 2014 from the Daily Galaxy

 

"We have shown the first time, that in particular photosynthesis is possible in micro-niches on the surface of Mars," says Jean-Pierre de Vera, a scientist at the German Aerospace Center's Institute of Planetary Research in Berlin, Germany. On Earth, Antarctic lichen has shown itself capable of going beyond survival and adapting to life in simulated Martian conditions.
 

The mere feat of surviving temperatures as low as -51 degrees C and enduring a radiation bombardment during a 34-day experiment might seem like an accomplishment by itself. But the lichen, a symbiotic mass of fungi and algae, also proved it could adapt physiologically to living a normal life in such harsh Martian conditions — as long as the lichen lived under "protected" conditions shielded from much of the radiation within "micro-niches" such as cracks in the Martian soil or rocks.
"There were no studies on adaptation to Martian conditions before," said de Vera"Adaptation is very important to be investigated, because it tells you more about the interactions of life in relation to its environment."

Previous Mars simulation experiments focused on simply measuring the survival of organisms at the end of a given time period. By contrast, de Vera and his group of German and U.S. colleagues measured the lichen's activities throughout the experiment that was detailed in the Sept. issue of the journal Planetary and Space Science. They wanted to see whether the lichen had continued its normal activities rather than simply clinging to life in a dormant state.

Two groups of lichen samples were placed inside a Mars simulation chamber about the size of a big pressure cooker, which itself sat within a fridge about the size of an armoire. That allowed researchers to simulate almost everything about Martian conditions such as atmospheric chemistry, pressure, temperatures, humidity and solar radiation — the lone exceptions being Martian gravity and the added contribution of galactic radiation.

Institute of Planetary Research One of the lichen samples in the Mars chamber was exposed to the full brunt of radiation expected on the Martian surface, while the second set of samples received a radiation dose almost 24 times lower to simulate life in the "protected" condition. A third group of lichen samples sat outside the chamber as a control.

Both lichen sample groups survived their month-long period under Martian conditions. But the heavier dose of radiation from a Xenon lamp simulating the surface radiation conditions kept the unprotected sample group from doing much beyond clinging to survival.

Only the "protected" lichen carried on normal activities such as using photosynthesis to turn sunlight into chemical energy for itself. The protected lichen recovered quickly after an initial "shock" period by adapting well enough to steadily ramp up its photosynthetic activities all the way until the end of the experiment.
"We have shown the first time, that in particular photosynthesis is possible in micro-niches on the surface of Mars," de Vera explained.

The lichen chosen for the experiment, called P. chlorophanum, has proven itself a survival champion even before the Mars simulation. Researchers removed lichen samples for testing from its home atop the rocky Black Ridge in Antarctica's North Victoria Land — a frozen, dry landscape not unlike that of many places on Mars.

          
The latest Mars simulation experiment did not try to simulate the Martian dust storms that can blanket the entire planet for a month. But de Vera points out that lichen can survive in a resting state for thousands of years on Earth while covered with dust, snow or ice.

Lichen don't exist alone as possible Earth survivors on Mars. Other studies conducted by de Vera have suggested that methane-producing bacteria, known as methanogens, could also manage a Martian existence.
"There are important indices that Earth life can survive, to be metabolically active and adapt physiologically to live on Mars during the time periods which have been investigated," de Vera said.
The experiment's results have huge implications for ongoing robotic missions searching for evidence of life on Mars. First, they confirm that such missions would do well to focus on searching for possible Martian life within the "micro-niche" environments beneath the soil or within rocks protected from surface radiation. Second, they lend hope to the idea that Martian life — if at all similar to Earth life — could have indeed survived up until today.

The lichen's remarkable adaptation to Martian conditions suggests a third, equally important lesson — it justifies the ongoing caution of NASA and other space agencies in ensuring that Earth organisms don't accidentally hitchhike a ride to Mars. Such planetary protection measures seem likely to continue until the possible day that humanity decides to colonize Mars and perhaps change the planet's landscape in the process.

Because the surface of Mars today is bone-dry and frozen all year round, it’s difficult to find any place on Earth onside a lab simulation that is truly Mars-like. But two locations, Antarctica’s Upper Dry Valleys and the hyper-arid core of Chile’s Atacama Desert (below), come close. They have become prime destinations for scientists who want to understand the extreme limits of life on Earth and the prospects for life on Mars.



Jocelyne DiRuggiero, an associate professor of biology at Johns Hopkins University in Baltimore, Maryland, studies samples from both locations. She’s interested in the similarities and the differences between the microbial communities that live in these two extreme desert regions. In both places, very little liquid water is present. In the core of the Atacama, years can go by between one rainfall and the next, but it is warm, so when there is precipitation, a significant amount of liquid water is available for a very short time.

In University Valley, one of Antarctica’s Upper Dry Valleys, the availability of liquid water is limited in a different way. University Valley receives more regular precipitation than the Atacama, but it’s so cold there that any precipitation falls in the form of snow and remains frozen.

Antarctica's Dry Valley is an ideal place for scientists to study how the Earth's plumbing was formed; its current landscape was eroded in to existence millions of years ago, and has undergone very little subsequent erosion since. Researchers have labeled the Dry Valleys region a “relic landscape” as it is the only known location on Earth which is the same now as it was millions of years ago.

Johns Hopkins University geologist Bruce Marsh found the Dry Valleys in 1993, what he calls a walk-in “museum” and “the one place on earth where the plumbing system is exposed in this way. You can stand on shelves of solidified lava that were deposited by magmatic activity 180 million years ago,” he said. “It’s awe inspiring.”

“What we do in those environments is try to understand who is there, what those organisms might be doing, how they are distributed,” says DiRuggiero, and whether the organisms are “really active metabolically,” or if instead they’re “just sitting there, because they’ve been brought by the wind.”

DiRuggiero’s primary tool is DNA sequencing. Working with soil samples that weigh one- to two-tenths of a gram each (about a teaspoonful), she extracts the DNA from any microbes present in each sample. She then sends the DNA off to a lab for sequencing.

Sample preparation is a difficult process because there aren’t many microbes in her samples. Each gram of soil contains perhaps one hundred to one thousand, an extremely low number. The same size sample of ordinary soil typically contains ten million to a billion organisms.

Because the microbial populations she’s working with are so small, contamination is a serious problem. She has to be careful not to let skin cells or hair fall into her samples. Sneezing or coughing on them could pollute them. So DiRuggiero does her work under a special hood that prevents contact with outside air. And even then she has problems, because some of the silica filters she uses to extract DNA from her samples arrive from the manufacturer with microbial cells clinging to them.

Although she has had more time to work with samples from the Atacama, DiRuggiero says the University Valley samples are particularly interesting. Because University Valley is both near the South Pole and more than a mile above sea level, the ground there stays frozen even in summer. There are few places in the world where this is true. “It’s about 40 degrees Celsius colder than the Atacama soil,” she says. That’s about 70
degrees Fahrenheit colder.



That temperature difference results in a significant difference in habitability. There are more microbes in University Valley soil than in Atacama soil.

“Right now the only parameter. . .we have measured that differentiates the populations, Antarctica and the Atacama, is the temperature,” DiRuggiero says. In both locations, “the soils are very dry, the soils are very low in organics, they contain a fair amount of salt. The big difference is the temperature. We don’t really know what it means yet.”

It may seem odd that microbes are happier in sub-freezing conditions than in a warm desert. “This is counter to human experience but makes sense for microbes,” Chris McKay, a planetary scientist at NASA Ames Research Center in Moffett Field, California, wrote in an email. “Cold allows them to sleep, which is a good survival mechanism,” he explained, adding that “this result bodes well for life in the cold deserts of Mars.” McKay heads the NASA-funded IceBite team, which is testing a prototype coring drill for possible use on a future Mars mission. The IceBite team obtained the University Valley samples that DiRuggiero studies.

So far DiRuggiero has been working with University Valley samples collected during the IceBite team’s first season in the field, in 2009. She’s looking forward to getting her hands on more-extensive samples collected at the end of 2010, samples that are still making their way back from Antarctica.

Beneath the dry soil layer in University Valley is “what we call ice-cemented ground, which is basically frozen mud. And that mud has been frozen for thousands and thousands of years,” says DiRuggiero. “So the question is, Is there any water available for the micro-organisms, and do we see a difference in the microbial community between the soil above and this ice-cemented ground right underneath?”

There is some evidence, based on climate data collected last year by the IceBite team, that at the interface between the dry soil and the frozen mud, “there might be some melting in the summer,” says DiRuggiero. “There might be water available at least part of the time” and microbes might be “actively growing and metabolizing at least during a small portion of the year.”

“Melting,” in this case, doesn’t mean the soil gets soggy or muddy, or that the temperature gets above freezing. Rather, it means that thin layers of liquid water can form between the sand grains that make up the soil and the ice below it. But that’s plenty of water for microbes. They’re small. They don’t need a lot of water.

“At temperatures above -20ºC (-4ºF) there is a layer of unfrozen water between the sand grains and the ice. These layers can support microbial life at least [down] to -15ºC (5ºF),” McKay explained.
“On Mars today the temperatures of the ground ice are much too cold for this effect to be useful,” he wrote. But Mars wobbles. At present Mars is tilted on its axis at about the same angle as Earth’s.
Five million years ago, however, Mars leaned over at an angle of about 45º, and for nearly half of each martian year (equivalent to about one Earth year), the polar regions received constant sunlight. Back then “the ground ice at the polar regions,” like the site where NASA’s Phoenix spacecraft landed in 2008, “would have been much warmer. We think it would have been in the range of -15ºC to -20ºC. So liquid water layers” in the past were “a possibility.”

The question then is this: If life ever took hold on Mars, back when the planet was warmer and wetter, did a few hardy microbes evolve a survival strategy that let them go into a deep sleep, and then every 10 or 20 million years, when the ground warmed up to -20ºC or so, wake up and put on a little growth spurt?

The answer will have to wait until a follow-up mission to the martian polar regions can dig deeper than Phoenix did. It is just such deep polar drilling that McKay’s IceBite project is working to make possible.

The Daily Galaxy via NASA/Astrobio.net

Image credits: NASA/JPL and http://www.atacamaphoto.com/

The Truth Dwell in the Details

The best example of this I know is global warming, and it's relationship to carbon dioxide and other "greenhouse" gasses.  The overall facts are not disputed by scientists and anyone who has studied the issue.  Global temperatures have been rising for the last 120-130 years or so, and carbon dioxide has been steadily rising during the same period.  Now, correlation doesn't prove cause and effect, so is it just coincidence?  That carbon dioxide is a well known greenhouse gas suggests at least some cause -- this is the basic position of the "97% consensus", though I don't know if it has been proven or is just an informed hypothesis.  It is certainly reasonable.

Here is a chart that supports this conclusion:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The thick black line was added by me.  Why not just do a linear correlation and fit a straight line through the points?  One could fit a very nice line, with a correlation coefficient well above 0.9; but this fit is clearly better.  The situation with carbon dioxide concentrations is even better:

 

One could fit an even much better line through this data set; the yearly average line virtually is straight!  More, there are serious reasons to assume, if nothing drastic is not done, it will even start to become exponentially increasing in the near future.

 

 

Put the evidence of the two graphs together naively and the conclusion is stark:  over the rest of the 21st and into the 22nd centuries the globe is going to keep getting warming, even warming exponentially, until at some point the results will be calamitous for human beings and many other species as well.  Again, if nothing serious is done, starting now or soon, to abate the situation.

But notice the leveling out or even cooling, starting about 2005.  A blip, or the beginning of another cooling episode, like that of 1940-1975.  What does it mean?  I suggest we simply have insufficient data to tell yet.  And there is serious debate, with most climate scientists/organization insisting the world is still warming.  But look at this:

 

 

Starting around 1980 global temperatures and solar activity begin to diverge.  Even solar scientists didn't predict solar cooling and were completely surprised by this.  It would, however, explain the cooling (or warming abatement), and if it continues (it is probably part of a cycle) by 2100 we could find ourselves back into Little Ice Age conditions (probably not as cold because of anthropogenic warming).  Again, I emphasize that all this -- the warming abatement, the lower solar activity -- didn't come from any computer model -- but plain old observation.  Many observations will be made during the century that will be just as unpredicted.

Keep hunting.



 









 



Again: Did the Human-Chimp ancestor walk upright?

Sahelanthropus

From Wikipedia, the free encyclopedia

            

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cast of a Sahelanthropus tchadensis skull (Toumaï)

 

 

Sahelanthropus tchadensis is an extinct hominine species that is dated to about 7 million years ago, possibly very close to the time of the chimpanzee/human divergence, and so it is unclear whether it can be regarded as a member of the Hominini tribe.^[1] Few, if any, specimens are known, other than the partial skull nicknamed Toumaï ("hope of life").

 

Existing fossils include a relatively small cranium known as Toumaï ("hope of life" in the local Dazaga language of Chad in central Africa), five pieces of jaw, and some teeth, making up a head that has a mixture of derived and primitive features. The braincase, being only 320 cm³ to 380 cm³ in volume, is similar to that of extant chimpanzees and is notably less than the approximate human volume of 1350 cm³.^{[citation needed]}

 

The teeth, brow ridges, and facial structure differ markedly from those found in Homo sapiens. Cranial features show a flatter face, u-shaped dental arcade, small canines, an anterior foramen magnum, and heavy brow ridges. No postcranial remains have been recovered. The fossil suffered a large amount of distortion during the time of fossilisation and discovery.^{[citation needed]}

Because no postcranial remains (i.e., bones below the skull) have been discovered, it is not known definitively whether Sahelanthropus tchadensis was indeed bipedal or two-footed, although claims for an anteriorly placed foramen magnum suggests that this may have been the case. Some paleontologists^[who?] have disputed^[why?] this interpretation of the basicranium. Its canine wear is similar to other Miocene apes.^[2] Moreover, according to recent information, the femur of a hominid might have been discovered alongside the cranium but never published.^[3]

 

The fossils were discovered in the Djurab Desert of Chad by a team of four led by Michel Brunet; three Chadians, Adoum Mahamat, Djimdoumalbaye Ahounta and Gongdibé Fanoné, and Frenchman, Alain Beauvilain et al.^[4][5] All known material of Sahelanthropus were found between July 2001 to March 2002 at three sites (TM 247, TM 266 (which yielded most of the material), and TM 292). The discoverers claimed that S. tchadensis is the oldest known human ancestor after the split of the human line from that of chimpanzees.^[6]

 

The bones were found far from most previous hominin fossil finds, which are from Eastern and Southern Africa. However, an Australopithecus bahrelghazali mandible was found in Chad by Beauvilain A., Brunet M. and Moutaye A.H.E. as early as 1995.^[6] With the sexual dimorphism known to have existed in early hominids, the difference between Ardipithecus and Sahelanthropus may not be large enough to warrant a separate species for the latter.^[7]

 

Sahelanthropus may represent a common ancestor of humans and chimpanzees; no consensus has been reached yet by the scientific community. The original placement of this species as a human ancestor but not a chimpanzee ancestor would complicate the picture of human phylogeny. In particular, if Toumaï is a direct human ancestor, then its facial features bring into doubt the status of Australopithecus because its thickened brow ridges were reported to be similar to those of some later fossil hominids (notably Homo erectus), whereas this morphology differs from that observed in all australopithecines, most fossil hominids and extant humans.

 

Another possibility is that Toumaï is related to both humans and chimpanzees, but is the ancestor of neither. Brigitte Senut and Martin Pickford, the discoverers of Orrorin tugenensis, suggested that the features of S. tchadensis are consistent with a female proto-gorilla. Even if this claim is upheld, then the find would lose none of its significance, for at present, precious few chimpanzee or gorilla ancestors have been found anywhere in Africa. Thus if S. tchadensis is an ancestral relative of the chimpanzees (or gorillas), then it represents the first known member of their lineage. Furthermore, S. tchadensis does indicate that the last common ancestor of humans and chimpanzees is unlikely to resemble chimpanzees very much, as had been previously supposed by some paleontologists.^[8][9]

 

A further possibility, highlighted by research published in 2012, is that the human/chimpanzee split is earlier than previously thought, with a possible range of 7 to 13 million years ago (with the more recent end of this range being favoured by most researchers), based on slower than previously thought changes between generations in human DNA. Indeed, some researchers (such as Tim D. White, University of California) consider suggestions that Sahelanthropus is too early to be a human ancestor to have evaporated.^[10]

 

Sediment isotope analysis of cosmogenic atoms in the fossil yielded an age of about 7 million years.^[11] In this case, however, the fossils were found exposed in loose sand; co-discoverer Beauvilain cautions that such sediment can be easily moved by the wind, unlike packed earth.^[12]

In fact, Toumaï was probably reburied in the recent past. Taphonomic analysis reveals the likelihood of one, perhaps two, burial(s) which seemingly occurred after the introduction of Islam in the region. Two other hominid fossils (a left femur and a mandible) were in the same “grave” along with various mammal remains. The sediment surrounding the fossils might thus not be the material in which the bones were originally deposited, making it necessary to corroborate the fossil's age by some other means.^[13] The fauna found at the site – namely the anthracotheriid Libycosaurus petrochii and the suid Nyanzachoerus syrticus – suggests an age of more than 6 million years, as these species were probably already extinct by that time.

 

Orrorin

From Wikipedia, the free encyclopedia

 

Orrorin tugenensis is a postulated early species of Homininae, estimated at  .1 to 5.7 million years (Ma) and discovered in 2000. It is not confirmed how Orrorin is related to modern humans. Its discovery was an argument against the hypothesis that australopithecines are human ancestors, as much as it still remains the most prevalent hypothesis of human evolution as of 2012.^[1]

The name of genus Orrorin (plural Orroriek) means "original man" in Tugen,^[2][3] and the name of the only classified species, O. tugenensis, derives from Tugen Hills in Kenya, where the first fossil was found in 2000.^[3] As of 2007, 20 fossils of the species have been found.^[4]

The 20 specimens found as of 2007 include: the posterior part of a mandible in two pieces; a symphysis and several isolated teeth; three fragments of femora; a partial humerus; a proximal phalanx; and a distal thumb phalanx. ^[4]

Orrorin had small teeth relative to its body size. Its dentition differs from that found in Australopithecus' in that its cheek teeth are smaller and less elongated mesiodistally and from Ardipithecus in that its enamel is thicker. The dentition differs from both these species in the presence of mesial groove on the upper canines. The canines are ape-like but reduced, like those found in Miocene apes and female chimpanzees. Orrorin had small post-canines and was microdont like modern humans, whereas robust Australopithecenes were megadont. ^[4]

In the femur, the head is spherical and rotated anteriorly; the neck is elongated and oval in section and the lesser trochanter protrudes medially. While this suggest that Orrorin was bipedal, the rest of the postcranium indicates it climbed trees. While the proximal phalanx is curved, the distal pollical phalanx is of human proportions and has thus been associated with toolmaking, but should probably be associated with grasping abilities useful for tree-climbing in this context.^[4]

After the fossils were found in 2000, they were held at the Kipsaraman village community museum, but the museum was subsequently closed. Since then, according to the Community Museums of Kenya chairman Eustace Kitonga, the fossils are stored at a secret bank vault in Nairobi.^[5]

If Orrorin proves to be a direct human ancestor, then australopithecines such as Australopithecus afarensis ("Lucy") may be considered a side branch of the hominid family tree: Orrorin is both earlier, by almost 3 million years, and more similar to modern humans than is A. afarensis. The main similarity is that the Orrorin femur is morphologically closer to that of H. sapiens than is Lucy's; there is, however, some debate over this point. ^[6]

Other fossils (leaves and many mammals) found in the Lukeino Formation show that Orrorin lived in dry evergreen forest environment, not the savanna assumed by many theories of human evolution.^[6]

The team that found these fossils in 2000 was led by Brigitte Senut and Martin Pickford^[2] from the Muséum national d'histoire naturelle. The discoverers conclude that Orrorin is a hominin on the basis of its bipedal locomotion and dental anatomy; based on this, they date the split between hominins and African great apes to at least 7 million years ago, in the Messinian. This date is markedly different from those derived using the molecular clock approach, but has found general acceptance among paleoanthropologists.

The 20 fossils have been found at four sites in the Lukeino Formation: of these, the fossils at Cheboit and Aragai are the oldest (6.1 Ma), while those in Kapsomin and Kapcheberek are found in the upper levels of the formation (5.7 Ma).^[

Is a mini ice age on the way? Scientists warn the Sun has 'gone to sleep' and say it could cause temperatures to plunge

2013 was due to be year of the 'solar maximum' Researchers say solar activity is at a fraction of what they expect.  Conditions 'very similar' a time in 1645 when a mini ice age hit 

By Mark Prigg

PUBLISHED: 19:04 EST, 17 January 2014 | UPDATED: 06:47 EST, 18 January 2014

The Sun's activity is at its lowest for 100 years, scientists have warned.  They say the conditions are eerily similar to those before the Maunder Minimum, a time in 1645 when a mini ice age hit, Freezing London's River Thames.  Researcher believe the solar lull could cause major changes, and say there is a 20% chance it could lead to 'major changes' in temperatures.

Sunspot numbers are well below their values from 2011, and strong solar flares have been infrequent, as this image shows - despite Nasa forecasting major solar storms

THE SOLAR CYCLE

Conventional wisdom holds that solar activity swings back and forth like a simple pendulum.  At one end of the cycle, there is a quiet time with few sunspots and flares.  At the other end, solar max brings high sunspot numbers and frequent solar storms.  It’s a regular rhythm that repeats every 11 years.

Reality is more complicated.

Astronomers have been counting sunspots for centuries, and they have seen that the solar cycle is not perfectly regular.   'Whatever measure you use, solar peaks are coming down,' Richard Harrison of the Rutherford Appleton Laboratory in Oxfordshire told the BBC.

 

'I've been a solar physicist for 30 years, and I've never seen anything like this.'

He says the phenomenon could lead to colder winters similar to those during the Maunder Minimum.

'There were cold winters, almost a mini ice age.  'You had a period when the River Thames froze.'  Lucie Green of UCL believes that things could be different this time due to human activity.  'We have 400 years of observations, and it is in a very similar to phase as it was in the runup to the Maunder Minimum.  'The world we live in today is very different, human activity may counteract this - it is difficult to say what the consequences are.'

Mike Lockwood University of Reading says that the lower temperatures could affect the global jetstream, causing weather systems to collapse.  'We estimate within 40 years there a 10-20% probability we will be back in Maunder Minimum territory,' he said.  Last year Nasa warned 'something unexpected' is happening on the Sun'  This year was supposed to be the year of 'solar maximum,' the peak of the 11-year sunspot cycle.  But as this image reveals, solar activity is relatively low.

THE MAUNDER MINIMUM

The Maunder Minimum (also known as the prolonged sunspot minimum) is the name used for the period starting in about 1645 and continuing to about 1715 when sunspots became exceedingly rare, as noted by solar observers of the time.

It caused London's River Thames to freeze over, and 'frost fairs' became popular.

The Frozen Thames, 1677 - an oil painting by Abraham Hondius shows the old London Bridge during the Maunder Minimum

This period of solar inactivity also corresponds to a climatic period called the "Little Ice Age" when rivers that are normally ice-free froze and snow fields remained year-round at lower altitudes.

There is evidence that the Sun has had similar periods of inactivity in the more distant past, Nasa says. The connection between solar activity and terrestrial climate is an area of on-going research.

'Sunspot numbers are well below their values from 2011, and strong solar flares have been infrequent,' the space agency says.

The image above shows the Earth-facing surface of the Sun on February 28, 2013, as observed by the Helioseismic and Magnetic Imager (HMI) on NASA's Solar Dynamics Observatory.

 

It observed just a few small sunspots on an otherwise clean face, which is usually riddled with many spots during peak solar activity.  Experts have been baffled by the apparent lack of activity - with many wondering if NASA simply got it wrong.

However, Solar physicist Dean Pesnell of NASA’s Goddard Space Flight Center believes he has a different explanation.  'This is solar maximum,' he says. 'But it looks different from what we expected because it is double-peaked.'  'The last two solar maxima, around 1989 and 2001, had not one but two peaks.'

Solar activity went up, dipped, then rose again, performing a mini-cycle that lasted about two years, he said.

Researchers have recently captured massive sunspots on the solar surface - and believed we should have seen more

The same thing could be happening now, as sunspot counts jumped in 2011 and dipped in 2012, he believes.  Pesnell expects them to rebound in 2013: 'I am comfortable in saying that another peak will happen in 2013 and possibly last into 2014.'

He spotted a similarity between Solar Cycle 24 and Solar Cycle 14, which had a double-peak during the first decade of the 20th century.
If the two cycles are twins, 'it would mean one peak in late 2013 and another in 2015'.

Scientists are saying that the Sun is in a phase of "solar lull" - meaning that it has fallen asleep - and it is baffling them.

History suggests that periods of unusual "solar lull" coincide with bitterly cold winters.

Rebecca Morelle reports for BBC Newsnight on the effect this inactivity could have on our current climate, and what the implications might be for global warming.

 

David Strumfels: 

 

 

The two graphs above shows the relationship between solar activity and global temperatures from 1550-2000.  Clearly, very close.  The second graph shows the same relationship 1880-2005.  Again, strong agreement until ~1980 when the two part ways.  Solar activity and global temperatures are (as common sense dictates) closely aligned; the 1980 parting I suspect is due to CO2 build-up overcoming (temporarily?) this alignment.  If solar activity remains low for an extended period of time it should slow warming (as from ~2005-2013) or even reverse it; the 20-25 year delay is expected because warming of the oceans, which release their added heat slowly.

Read more: http://www.dailymail.co.uk/sciencetech/article-2541599/Is-mini-ice-age-way-Scientists-warn-Sun-gone-sleep-say-cause-temperatures-plunge.html#ixzz2qmAXPJ5K