As fire light flickered on the back of the cave, a group of people ate deer, porcupine and otter. Then a man solemnly took a large bone off the fire, broke it in half and sucked the bone marrow out. He then carefully painted the broken bone with red clay and buried it in the cave.

He observed this ritual because this bone belonged to another human species. One they shared not only the forest with, but also their beds.

This is the remarkable 鈥� though so far tentative 鈥� picture emerging from controversial discoveries from two caves in south-west China. If true, some think it could overturn our understanding of what it means to be human.

Among the discoveries appears to be a primitive human species, which most closely resembles the earliest human species, Homo habilis and Homo erectus.

But while these lived about 2 million years ago, this new species lived just 14,000 years ago, says Darren Curnoe of the University of New South Wales in Sydney, Australia, who lead the team behind the discoveries. This would make it the most recent human species to have gone extinct.

鈥淚f true, this would be rather spectacular and it would make the finds of truly global importance,鈥� says at the University of Oxford, who wasn鈥檛 involved in the discoveries.

The work is excellent, he says, but is likely to leave many in the field unconvinced.

One of the most exciting pieces of evidence in the story is a hominin femur found in Muladong cave in south-west China, alongside other human and animal bones. It shows evidence of having been burned in a fire that was used for cooking other meat, and has marks consistent with it being butchered for consumption.

It has also been broken in a way that is often used to access the bone marrow.

Unusually, it had been painted with a red clay called ochre, something often associated with burial rituals. While many other bones were eaten in the cave, only the ones from human species were painted.

It鈥檚 hard to know if the bone was actually cannibalised by the H. sapiens whose remains have also been found in the area, Curnoe says, but all the evidence points towards that conclusion.

鈥淲e don鈥檛 know it was cannibalism,鈥� he says. 鈥淲e鈥檝e got cut marks that would be consistent with butchering.鈥�

But things got interesting when the team tried to identify the bone. 鈥淥ur work shows clearly that the femur resembles archaic humans,鈥� Curnoe says. Yet the sediment the bone was found in dated to just 14,000 years ago.

The shaft of the bone is very narrow and it has a thin outer layer, yet the walls are reinforced in areas of high strain. There is also a notch where muscle would have joined the bone, which is much larger than in anatomically modern humans, and it faces more towards the back of the bone (see photo, above).

鈥淭hese features suggest it walked differently,鈥� says Curnoe. And judging by the size of the bone, Curnoe estimates the adult human would have weighed about 50 kilograms 鈥� much smaller than other known Ice Age humans.

鈥淲hen you put all the evidence together the femur comes out quite clearly resembling the early members of Homo,鈥� says Curnoe.

If confirmed, says Petraglia, this would change our understanding of human evolution.

Besides Homo floresiensis, also known as 鈥渢he Hobbit鈥�, which was confined to an Indonesian island up to around 18,000 years ago, the most recent archaic humans were thought to be the Denisovans and Neanderthals, which became extinct quickly after H. sapiens came through their lands some 40,000 years ago.

鈥淭his turns that on its head,鈥� says Curnoe. 鈥淚ts young age shows that remarkably primitive-looking humans must have shared the landscape with very modern-looking people at a time when China鈥檚 earliest farming cultures were beginning to flourish.鈥�

But some in the field have doubts that such a young bone can be from something so archaic.

鈥淚t is not an archaic human,鈥� says at Washington University in St Louis. Trinkaus thinks the differences in the bone are a result of natural variation within a population, not a new species.

at the University of California, Davis, is more ambivalent. He says the femur looks very odd, but that it does seem to have similarities to very archaic humans.

The second cave

Further supporting evidence might come from Longlin cave, a few hundred kilometres north, where another stash of human bones, including an almost complete skull, were found 鈥� some as early as 1979. Curnoe and Ji Xueping at the Yunnan Institute of Cultural Relics and Archaeology in China re-analysed these bones and dug up more, describing them in 2012.

Curnoe and his colleagues they belong to a hybrid of our own species and something more archaic 鈥� quite likely the creature that once walked on the now-painted femur. They have preliminarily dated that hybrid to just 10,500 years ago.

One of the less complete bones found at Maludong cave had been cut and had holes dug near the top of it, suggesting it was used as a vessel for carrying and drinking liquid.

What all this hints at, Curnoe and colleagues say, is that H. sapiens was mating with an archaic human species, possibly eating them, and using the hybrid offspring bones as tools.

But to back up these controversial claims, we will need DNA from these bones, says Petraglia.

DNA needed

鈥淯ltimately, what we鈥檇 like is DNA evidence,鈥� agrees Curnoe, 鈥淏ut so far we鈥檝e had no luck.鈥�

The burning of many of the bones and the tropical climate have degraded the DNA. He says technology has improved, though, and they will continue trying.

DNA could answer some of the thorniest questions raised by these findings. Is the archaic human they found the mysterious Denisovan, so far only known from a finger and a tooth found in a Siberian cave? Or is it a new species, suggesting a rich array of human species existed in Asia at this time? And do we carry any of their genes?

Curnoe says the discoveries point to a profound shift in our understanding of what it means to be human.

Adding to the now well-established interbreeding that occurred with our cousins the Neanderthals and Denisovans, we can no longer consider ourselves a single lineage that emerged from Africa.

鈥淲e had particular notions of our evolution: That we found ourselves evolving in isolation in Africa and quickly replaced all the other species that were around because we thought we were superior to them. And it happened very quickly, without question, and without biological interaction,鈥� Curnoe says. 鈥淏ut the hybridisation story has turned that on its head.鈥�

Journal reference: PLoS One, DOI:

Read more: 鈥�Denisovans: The lost humans who shared our world鈥�

Image information, from top: Reproduction of Homo sapiens hunting (Enigma Man A Stone Age Mystery 漏 Vince Valitutti/Electric Pictures); Discovered femur compared with modern human femur (Darren Curnoe, Ji Xueping & Getty Images); The cave at Maludong (Ji Xueping & Darren Curnoe)

Is it hot enough for you yet? 2015 has almost certainly been the hottest year on record. And don鈥檛 stash the fans away, as there鈥檚 a good chance 2016 will be even hotter, making it three record-breaking years in a row and spelling disaster for corals.

What鈥檚 the recipe for the triple whammy? Take a generous lashing of global warming, add a half-baked El Ni帽o one year, a whopper of an El Ni帽o the next, and then let it stew for a few months. It鈥檚 an updated version of what we had when the biggest El Ni帽o then recorded hit in 1997, causing extreme weather events across the globe and making 1998 the hottest year.

This time, global warming gave everything a particularly warm head start. Even though the El Ni帽o turned out to be a near miss in 2014, it still crowned that year the new hottest on record. Now El Ni帽o has hit for real, making . But the El Ni帽o is set to last until about May or June, and air temperatures take around four months to catch up with sea surface temperatures, so next year could outdo them all.

And it鈥檚 not just about temperature. The El Ni帽o is messing with the world鈥檚 weather and hitting some ecosystems hard, in combination with other human-made effects, including pollution and overfishing. We are now seeing a global coral bleaching event that could destroy up to 5 per cent of the world鈥檚 reefs.

鈥淲e are now seeing a global coral bleaching event that could destroy 5 per cent of all reefs鈥�

Then there鈥檚 the possibility of La Ni帽a to worry about. Often just as devastating, La Ni帽a reverses her older brother鈥檚 effects, and can cool down surface air, bring drought to the west coast of the Americas and floods to Australia and Indonesia. But the reversal doesn鈥檛 always happen, and models aren鈥檛 very good at predicting a switch this far out. So stay tuned.

Read more: Click here to discover more 2016 preview articles

(Image: XL Catlin Seaview Survey)

This article appeared in print under the headline 鈥淓xtreme weather, killer heat鈥�

(Image: JAXA)

It鈥檚 a reunion of astronomical proportions. A damaged satellite that missed its rendezvous with Venus was finally sent into orbit around the planet yesterday 鈥� exactly five years late 鈥� after mission controllers came up with a successful hack to get it back on course.

On 21 May 2010, the Japanese space agency JAXA launched the Akatsuki satellite to study Venus鈥檚 atmosphere. Researchers hoped that the mission would reveal, among other things, why the planet鈥檚 surface is subject to extreme winds at up to 400 kilometres per hour.

But disaster struck on 7 December 2010, when the satellite attempted to fire its thrusters. Instead of entering into orbit around Venus, it cruised off into space and wound up travelling around the sun. Later analysis suggested the thruster nozzles had been damaged, causing a safety valve to cut in before Akatsuki had properly changed course.

Over the next few years, JAXA tested the various thrusters and found the main ones to be unusable. So the team came up with a last-ditch strategy for a second attempt on Venus.

Fuel jettisoned

In October 2011, they dumped all the fuel for the broken thrusters, making the satellite lighter. Then they used secondary attitude control thrusters, intended to orient the probe, to put Akatsuki on course to rendezvous with Venus in 2015.

On Monday, that moment arrived. After firing its secondary thrusters for a full 20 minutes, Akatsuki appears to have gone into orbit around Venus, JAXA announced. However, it will take a few days to properly pin down the orbit. JAXA expects to release an update at 6 pm Japan time (9 am GMT) tomorrow.

Concerns linger over the : it was never built to fly as close to the sun as it has, and they could have been damaged by the heat. As a result, JAXA decided to attempt the Venus rendezvous now instead of next year, even though the later date would have put the satellite into a better orbit for collecting data.

鈥淚f it is successful in getting into orbit, it will be our only opportunity to study Venus from orbit in the next few years,鈥� says from the University of New South Wales in Sydney, Australia. Since the European Venus Express orbiter ended its mission in 2014, we have not had any probes gathering data from Venus鈥檚 atmosphere, he says.

The probe鈥檚 observations could yield insights into what Earth might be like in a billion years or so, when the greenhouse effect could have run away and the sun鈥檚 output may be higher than today. 鈥淥n Earth, if you took all the carbonate rocks out and put all that carbon dioxide in the atmosphere, you鈥檇 basically get Venus,鈥� Bailey says.

The army has been deployed and tens of thousands of homes across Scotland and the north of England are without power after Storm Desmond dumped torrential rain across the area, causing major flooding.

Early figures suggest there was a record-breaking downpour of rain as 340 millimetres fell in 24 hours in the Lake District, breaking a record of 316.4mm set in 2009.

It鈥檚 too soon to know whether the storm can be attributed to climate change, but green groups point out it is just what the UK will expect to see more of as the planet warms.

Drawing a link with climate change is difficult, since the British climate has always been variable, says of HR Wallingford, a consultancy that advises the UK government on flood defences.

For example, the first half of the 20th century was much wetter than the second. 鈥淏ut the current wisdom is that storminess is increasing and therefore these types of events are likely to increase,鈥� he says.

Part of the story

鈥淚t is impossible to say that a particular flood event is or isn鈥檛 caused by climate change,鈥� says at the University of Adelaide in Australia. 鈥淏ut climate change does appear to be making the heavy rainfall events that cause floods more frequent and intense, and so should be considered to be part of the story.鈥�

Ramsbottom says the UK needs to improve its warning systems and awareness, and make sure new developments are flood resistant.

But many people in flood-prone areas won鈥檛 be protected from extreme events, even with bolstered defences.

鈥淚 guess the point will come, if this trend continues, that some places will not be liveable in,鈥� Ramsbottom says 鈥淲e know already that quite a lot of people don鈥檛 have insurance because they鈥檝e been flooded before, and therefore those people are facing a catastrophe.鈥�

This echoes messages heard after the 2013-2014 floods that affected large parts of the UK , when hydrologists and engineers told New 女生小视频 that the UK needed to consider the possibility of retreating to higher ground.

Climate campaigner Guy Shrubsole at charity Friends of the Earth has criticised the UK government for its lack of action on both climate change mitigation and adaptation.

鈥淐limate change is increasing the frequency of extreme rainfall and floods in the UK and around the world,鈥� he said . 鈥淵et the UK government is failing to protect us by not investing enough in flood defences and cutting support for the clean energy needed to tackle climate change.鈥�

Read more: 鈥�Climate known: There will be more floods and droughts鈥�

Image credit: Christopher Furlong/Getty

鈥淭ACKLING climate change is a shared mission for all mankind,鈥� said China鈥檚 president Xi Jinping. He was among nearly 150 world leaders and other representatives from 190 countries gathered in Paris to nail down a global deal to cut carbon emissions. The deal will be negotiated over the coming two weeks, including the crucial point of whether any agreements will be legally binding. But on the sidelines, other announcements are being made too.

On Monday, Indian prime minister Narendra Modi invited 120-odd nations to join a new International Agency for Solar Policy and Application, aimed at helping poorer countries in the tropics develop solar power. India is investing $30 million to set up a headquarters and aims to raise a further $400 million.

There were also pledges by 20 major economies to double investment in renewable energy research and development. The White House described Mission Innovation as 鈥渁n initiative to dramatically accelerate public and private global clean energy innovation鈥�. A similar drive by industry groups 鈥� the Breakthrough Energy Coalition, spearheaded by Bill Gates 鈥� aims to commercialise and implement the breakthroughs that Mission Innovation produces.

There is a good chance of reaching a global agreement since, instead of cuts being imposed from the top down, countries will decide their own contributions, with each offering what they think is fair.

But the exact wording on the summit鈥檚 overall aims could be tricky to agree on, such as whether to try to keep warming below 2鈥壜癈, or perhaps 1.5鈥壜癈. Some scientists believe 1.6鈥壜癈 of warming is already locked in, that 2鈥壜癈 may be inevitable, and that the current pledges will bring us to 2.7鈥壜癈. There is also likely to be debatae on the date by which the world should aim to be carbon-neutral.

Despite this, 43 countries will sign a declaration urging the UN to adopt a 1.5鈥壜癈 target, and the V20 鈥� the 20 countries most vulnerable to climate change 鈥� are expected to vote as a bloc, urging stronger global aims.

The talks follow a weekend in which people all over the world took to the streets, calling for strong action on climate change at the summit. According to campaign group Avaaz, 785,000 people joined marches in 175 countries 鈥� the largest ever climate march.

Image credit: Xinhua/Landov/Barcroft Media

The probe will scour the cosmos for protons, electrons and gamma rays. This could reveal smoking-gun signals of dark matter, the mysterious stuff which makes up 80 per cent of the mass in the universe but can鈥檛 be seen directly.

Two other space telescopes have glimpsed hints of its presence. One shows a glow from the galactic centre that may be caused by particles of dark matter colliding and then annihilating around the black hole there.

The other has detected more positrons 鈥� the antimatter sibling of electrons 鈥� than expected. This could be the result of dark matter being annihilated nearby, but might also be caused by nearby pulsars. DAMPE should be able to test which explanation is right, says team member Yizhong Fan from the Chinese Academy of Sciences in Nanjing.

The current extreme El Ni帽o is now the strongest ever recorded, smashing the previous record from 1997-8. Already wreaking havoc on weather around the world, the new figures mean those effects will probably get worse. Climate change could be to blame and is known to be making the extreme impacts of El Ni帽o on weather more likely.

The 1997-8 El Ni帽o killed 20,000 people and caused almost $97 billion of damage as floods, droughts, fires, cyclones and mudslides ravaged the world.

Now the current El Ni帽o has surpassed the 1997-8 El Ni帽o on a key measure, according to the latest figures released by the US National Oceanic and Atmospheric Agency.

El Ni帽o occurs when warm water that has piled up around Australia and Indonesia spills out east across the Pacific Ocean towards the Americas, taking the rain with it.

A key measure of its intensity is the warmth of water in the central Pacific. In 1997, at its peak on 26 November, it was 2.8鈥壜癈 above average. According to the latest measurements, it reached 2.8鈥壜癈 on 4 November this year, and went on 鈥� the highest temperatures ever seen in this region.

鈥淭he El Ni帽o community is closely watching the evolution [of this El Ni帽o] and whether the current event will surpass the 1997-8 event,鈥� says Axel Timmerman at the University of Hawaii in Honolulu. 鈥� and central Pacific temperature anomalies clearly show that this current event has surpassed it.鈥�

The temperatures in the central Pacific have the biggest impact on the global atmospheric circulation, and therefore the biggest impacts on global weather, says Timmerman, who has been warning that this El Ni帽o is likely to be a record-breaker.

The event hasn鈥檛 broken temperature records across the entire eastern Pacific, but in the central eastern Pacific. 鈥淚t鈥檚 shifted into an area where most likely the atmosphere will respond even more,鈥� Timmerman says.

Timmerman and others in 2013 that El Ni帽os have been stronger in the last few decades than in any period over the past four centuries. It is unknown whether that鈥檚 because of climate change, but Timmerman and colleagues have also shown that extreme impacts from El Ni帽o鈥檚 will double in frequency this century as a result of climate change.

, Scott Power at the Bureau of Meteorology in Australia and colleagues showed that climate change will amplify the way that El Ni帽o redistributes rainfall, making droughts and floods worse.

Record breaker

El Ni帽o has been implicated in a host of extreme weather events across the globe. Combined with global warming, it鈥檚 partly responsible for 2015 being the hottest year on record. In India, more than 2000 people died in a heatwave caused by a delayed monsoon 鈥� an effect of El Ni帽o.

Now the region is experiencing unusually heavy rains as the monsoon has finally arrived 鈥� also an expected impact of El Ni帽o. 鈥淪outhern India is having a lot of rain as it goes into winter, having come out of the dry monsoon. This is only so during extreme El Ni帽o, so it is a confirmation that the El Ni帽o is huge,鈥� says Wenju Cai at Australia鈥檚 government scientific research body, CSIRO in Melbourne.

El Ni帽o is also probably making record-breaking illegal fires in Indonesia worse, by reducing rainfall there.

And in some Pacific Islands, water levels have dropped so much that coral reefs are exposed, in a phenomenon known as Taimasa, Samoan for 鈥渟melly reef鈥�. New 女生小视频 has received photographs from Guam showing this dramatic effect (see photos above and below), only seen during extreme El Ni帽o events. Across the globe, the El Ni帽o has also begun a mass coral bleaching.

Australia has dodged some of the worst effects of El Ni帽o, as the Indian Ocean Dipole 鈥� an oscillation of sea temperatures in the Indian Ocean 鈥� which was amplifying El Ni帽o, has eased off. And because of the location of the warmest water, some regions like Peru and Ecuador are also likely to experience fewer impacts.

But overall, Timmerman suspects that the impacts of this record-breaking El Ni帽o will be record-breaking too.

Many of the effects are yet to come. For example, whether it will bring rains to California and relieve the drought 鈥� or even whether it will go too far and cause floods 鈥� isn鈥檛 yet known. Timmerman says the models are predicting a higher chance of rain for California.

And once the El Ni帽o is over, it might not be time for celebration, since it鈥檚 likely to be followed by a strong La Ni帽a, which will bring roughly opposite effects to the world鈥檚 weather. La Nina鈥檚 are also expected to be about twice as common as a result of climate change this century.

Some people may have a get-out clause when it comes to giving up cigarettes. A third of white people who smoke have gene variations that make it harder for them to kick the habit.

A gene called ANKK1 regulates the release of dopamine 鈥� a chemical involved in the brain鈥檚 reward centres. Ming Li and colleagues at the Zhejiang University School of Medicine in Hangzhou, China, wondered whether variations of this gene might affect people鈥檚 ability to give up cigarettes. So his team analysed 23 studies that have linked ANKK1 to smoking, involving more than 11,000 participants in total.

Across the board, there was no significant link between successful quitting and the gene variants. But when they looked at just the studies that analysed white people, the results were striking.

About two-thirds of white smokers carried a variation of the gene called A2/A2. These people were about 22 per cent more likely to be able to quit smoking than those who carried an alternative version of the gene, either A1/A1 or A1/A2.

The A1/A1 and A1/A2 gene variations have previously been linked to obesity and drug addiction, which suggests they may predispose people to addictive behaviours.

People carrying these versions of ANKK1 may need more aggressive strategies to fight their addiction to cigarettes, says Li. It is not clear whether the gene has the same effect for non-white people, he says. More studies that involve non-white people will be necessary to investigate this.

at the Florey Institute for Neuroscience and Mental Health, in Victoria, Australia, says these results could one day be useful for helping people quit smoking. He says the real benefit will come when the effects of these genes can be better understood, and particular treatments can be chosen for people, based on their genes. 鈥淎t the 鈥榖ig picture鈥� level it鈥檚 about matching someone鈥檚 genetics with a particular treatment option,鈥� he says.

Journal reference: Translational Psychiatry,

Image credit: Eryn Thornton/EyeEm/Getty

鈥淣othing will deter us from building the future we want for our children.鈥�

鈥淭ackling climate change is a shared mission for all mankind.鈥�

鈥淭he prosperous still have a strong carbon footprint and the world鈥檚 billions, while countries at the bottom of the development ladder are seeking space to grow.鈥�

The words, respectively, of US president Barack Obama, China鈥檚 president Xi Jinping and India鈥檚 prime minister Narendra Modi.

They were among almost 150 world leaders and representatives from more than 190 countries in Paris to nail down a global agreement to cut emissions. The final wording will be negotiated over the coming two weeks, including the crucial point on whether the agreements will be legally binding. But on the sidelines, other agreements and announcements are being made too.

On Monday, Modi officially invited 120-odd nations to join a new International Agency for Solar Policy and Application. The agency was announced earlier in the year and aims to help mostly poor countries in the tropics get connected to solar electricity.

India is investing $30 million to set up the agency鈥檚 headquarters in India, and it aims to raise $400 million from member nations and other groups.

Clean energy

The announcement followed pledges by 20 major economies to double their investment in renewable energy research and development. 鈥溾�� was described by the White House in a statement as 鈥渁n initiative to dramatically accelerate public and private global clean energy innovation鈥�. It is partnered with a similar drive by industry groups 鈥� the Breakthrough Energy Coalition spearheaded by Bill Gates 鈥� which will work to commercialise and implement the sorts of developments Mission Innovate produces.

In the negotiations, there is thought to be a good chance of reaching a global agreement, since contributions from each country are being set independently, as Intended Nationally Determined Contributions, with each country offering what they think is fair.

But wording on the summit鈥檚 overall aims 鈥� whether to keep warming below 2 掳C or perhaps 1.5 掳C 鈥� and when the world will aim to be carbon neutral could be sticking points, especially since some scientists believe 1.6 掳C of warming is already locked in, that 2 掳C may be inevitable, and that the .

Despite this, a group of 43 countries will sign a declaration urging the UN to adopt a 1.5 掳C target and the V20 鈥� the 20 countries most vulnerable to climate change 鈥� are urging stronger aims.

The talks follow a weekend in which people all over the world took to the streets, calling for strong action on climate change. According to campaigning group Avaaz, .

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