Scientists do not know what is causing the overabundance of the gas.
- A new study looked to understand the source of methane on Saturn's moon Enceladus.
- The scientists used computer models with data from the Cassini spacecraft.
- The explanation could lie in alien organisms or non-biological processes.
Something is producing an overabundance of methane in the ocean hidden under the ice of Saturn's moon Enceladus. A new study analyzed if the source could be an alien life form or some other explanation.
The study, published in Nature Astronomy, was carried out by scientists at the University of Arizona and Paris Sciences & Lettres University, who looked at composition data from the water plumes erupting on Enceladus.
The particular chemistry, discovered by the Cassini spacecraft which flew through the plumes, suggested a high concentration of molecules that have been linked to hydrothermal vents on the bottom of Earth's oceans. Such vents are potential cradles of life on Earth, according to previous studies. The data from Cassini, which has been studying Saturn after entering its orbit in 2004, revealed the presence of molecular hydrogen (dihydrogen), methane, and carbon dioxide, with the amount of methane presenting a particular interest to the scientists."We wanted to know: Could Earthlike microbes that 'eat' the dihydrogen and produce methane explain the surprisingly large amount of methane detected by Cassini?" shared one of the study's lead authors Régis Ferrière, an associate professor in the department of Ecology and Evolutionary Biology at the University of Arizona.
Earth's hydrothermal vents feature microorganisms that use dihydrogen for energy, creating methane from carbon dioxide via the process of methanogenesis.
Searching for such microorganisms known as methanogens on the seafloor of Enceladus is not yet feasible. Likely, it would require very sophisticated deep diving operations that will be the objective of future missions.
So, Ferrière's team took a more available approach to pinpointing the origins of the methane, creating mathematical models that attempted to explain the Cassini data. They wanted to calculate the likelihood that particular processes were responsible for producing the amount of methane observed. For example, is the methane more likely the result of biological or non-biological processes?
They found that the data from Cassini was consistent with either microbial activity at hydrothermal vents or processes that have nothing to do with life but could be quite different from what happens on Earth. Intriguingly, models that didn't involve biological entities didn't seem to produce enough of the gas.
"Obviously, we are not concluding that life exists in Enceladus' ocean," Ferrière stated. "Rather, we wanted to understand how likely it would be that Enceladus' hydrothermal vents could be habitable to Earthlike microorganisms. Very likely, the Cassini data tell us, according to our models."
Still, the scientists think future missions are necessary to either prove or discard the "life hypothesis." One explanation for the methane that does not involve biological organisms is that the gas is the result of a chemical breakdown of primordial organic matter within Enceladus' core. This matter could have become a part of Saturn's moon from comets rich in organic materials.
Strange underwater icicles form in the Earth's coldest regions and freeze living organisms in place.
- Spectacular brinicles form under the ice of our planet's coldest regions.
- Their formation resembles that of hydrothermal vents.
- The structures have been called "icy fingers of death" because of their ability to freeze living organisms.
Nature's grace and fury find equal measure in unique formations called brinicles or more evocatively "icy fingers of death." The strange phenomenon that forms these underwater icicles can be found in the oceans of the planet's polar regions. It's been rarely captured on camera as it occurs under floating sea ice. Brinicles are structures that resemble fingers of ice that can reach all the way down to the ocean floor, freezing everything in their paths, including creatures like starfish or sea urchins.
In an interview with Wired, professor Andrew Thurber of Oregon State University, who has seen brinicles first-hand, described them as "upside-down cacti that are blown from glass, like something from Dr. Seuss's imagination." He also said they are "incredibly delicate and can break with only the slightest touch."
The video below shows stunning footage of brinicles from BBC's Frozen Planet series:
'Brinicle' ice finger of death
How brinicles form
A study found that when sea ice in the Arctic and Antarctic regions freezes, salt and other ions normally found in seawater get left out. Brine, which is concentrated salt water, gathers in various fractures and channels in the sea ice. Brine requires much lower temperatures to freeze and stays liquid until the ice cracks and the brine leaks into the ocean below. Being heavier than water, the ultra-cold brine sinks down to the ocean floor, freezing seawater it touches on its way down. This is responsible for the finger-like shape of the brinicles.
Notably, the downward-facing brinicle ice tubes, first discovered in the 1960s, form in a way similar to hydrothermal vents, which have been theorized as cradles of life on Earth. Hydrothermal vents form when ion-rich hot water gets ejected from the seafloor, creating a porous metal tower that extends upward. Water rushes through the tower, rupturing it, and causing more metal-rich water to expand the tower.
Thousands of brinicles can be found under the ice off Little Razorback Island, Antarctica.Credit: Andrew Thurber / Oregon State University.
Could brinicles be cradles of life?
Study author Bruno Escribano of the Basque Center for Applied Mathematics in Spain explained that, like hydrothermal vents, brinicles also could have played a role in the origin of life. "Inside these compartments inside the ice, you have a high concentration of chemical compounds, and you also have lipids, fats, that coat the inside of the compartment," he shared. "These can act as a primitive membrane — one of the conditions necessary for life."
He elaborated that inside the brinicles is a mixture of acidic and basic components that may be able to supply the requisite energy for the formation of more complex molecules, potentially even DNA.
The oldest person in history lived to 122
The oldest person in history – a French woman named Jeanne Calment – lived to 122. When she was born in 1875, the average life expectancy was roughly 43.
But just how long could a human actually live? It's a question people have been asking for centuries. While average life expectancy (the number of years a person can expect to live) is relatively easy to calculate, maximum lifespan estimates (the greatest age a human could possibly reach) are much harder to make. Previous studies have placed this limit close to 140 years of age. But a more recent study proposes that the limit to human lifespan is closer to 150.
The oldest and still most widely used method for calculating life expectancy, and thus lifespan, relies on the Gompertz equation. This is the observation, first made in the 19th century, that human death rates from disease increase exponentially with time. Essentially, this means your chance of death – from cancer, heart disease and many infections, for example – roughly doubles every eight to nine years.
There are many ways the formula can be tweaked to account for how different factors (such as sex or disease) affect the lifespan within a population. Gompertz calculations are even used to calculate health insurance premiums – which is why these companies are so interested in whether you smoke, whether you are married and anything else that might allow them to more accurately judge the age at which you will die.
Another approach to figuring out how long we can live is to look at how our organs decline with age, and run that rate of decline against the age at which they stop working. For example, eye function and how much oxygen we use while exercising show a general pattern of decline with ageing, with most calculations indicating organs will only function until the average person is around 120 years old.
But these studies also unmask increasing variation between people as they grow older. For example, some peoples' kidney function declines rapidly with age while in others it hardly changes at all.
Now researchers in Singapore, Russia, and the US have taken a different approach to estimate the maximum human lifespan. Using a computer model, they estimate that the limit of human lifespan is about 150 years.
Living to 150
Intuitively, there should be a relationship between your chance of death and how rapidly and completely you recover from illness. This parameter is a measure of your ability to maintain homeostasis – your normal physiological equilibrium – and is known as resilience. In fact, ageing can be defined as the loss of ability to maintain homeostasis. Typically, the younger the person, the better they are at recovering rapidly from illness.
To conduct the modelling study, the researchers took blood samples from over 70,000 participants aged up to 85 and looked at short-term changes in their blood cell counts. The number of white blood cells a person has can indicate the level of inflammation (disease) in their body, while the volume of red blood cells can indicate a person's risk of heart disease or stroke, or cognitive impairment, such as memory loss. The researchers then simplified this data into a single parameter, which they called the dynamic organisms state indicator (Dosi).
Changes in Dosi values across the participants predicted who would get age-related diseases, how this varied from person to person, and modelled the loss of resilience with age. These calculations predicted that for everyone – regardless of their health or genetics – resilience failed completely at 150, giving a theoretical limit to human lifespan.
But estimates of this type assume that nothing new will be done to a population, such as, no new medical treatments will be found for common diseases. This is a major flaw, since significant progress occurs over a lifetime and this benefits some people more than others.
For example, a baby born today can rely on about 85 years of medical progress to enhance their life expectancy, while an 85-year-old alive now is limited by current medical technologies. As such, the calculation used by these researchers will be relatively accurate for old people but will become progressively less so the younger the person you're looking at.
The Dosi limit for maximum lifespan is about 25% longer than Jeanne Calment lived. So if you're planning to beat it (and her), you need three important things. First is good genes, which makes living to be more than a hundred unassisted a good bet. Second, an excellent diet and exercise plan, which can add up to 15 years to life expectancy. And lastly, a breakthrough in turning our knowledge of the biology of ageing into treatments and medicines that can increase healthy lifespan.
Currently, adding more than 15-20% to healthy lifespan in normal mammals is extremely difficult, partly because our understanding of the biology of ageing remains incomplete. But it's possible to increase the lifespan of much simpler organisms – such as roundworms – by up to ten times.
Even given the current pace of progress, we can confidently expect life expectancy to increase because it has been doing this since Gompertz was alive in the 1860s. In fact, if you spend half an hour reading this article average life expectancy will have increased by six minutes. Unfortunately, at that rate, the average person won't live to 150 for another three centuries.
When facing a predator, single cells sometimes unite to defend themselves, paving the way for more complex multicellular life forms to evolve.
- A new study examined the evolution of a unicellular algae species over 500 generations, roughly six months.
- The researchers subjected one of the two algae groups to a predator.
- The results showed that the algae exposed to a predator were far more likely to acquire adaptations toward multicellularity.
The transition from unicellular to multicellular life was one of the most momentous events in the evolution of life. Estimated to have first occurred more than 1.5 billion years ago, the shift to multicellularity gave rise to increasingly complex life forms on Earth, from ancient algae-like organisms to dinosaurs to human beings. Still, many of the processes underlying this biological shift have remained unclear.
One theory posits that single-celled organisms evolved multicellularity through a specific series of adaptations. First, cells began adhering to each other, creating cell groups that have a higher survival rate, partly because it's harder for predators to kill a group of cells than a single cell. But this defensive adaptation comes at the price of a lowered reproduction rate; only through adaptations acquired over generations do cell groups become better at reproducing than single cells.
A new study published in Nature Communications put that theory to the test. The researchers divided ten strains of Chlamydomonas reinhardtii, a unicellular green algae, into two groups. One group was subjected to a microscopic predator called Brachionus calyciflorus, a type of rotifer. The other group evolved without predators.
After six months, all the algae strains that faced the predator had evolved into cell groups. Meanwhile, only four of the 10 algae strains without predators evolved into groups. Surprisingly, this transition toward simple multicellularity occurred relatively quickly, over just 500 generations or six months. (The algae replicated about once every 9 hours.) The videos below show how the predator had a much harder time eating the cells when they grouped together.
RT feeding single cells www.youtube.com
RT feeding colony www.youtube.com
After cell groups boosted their defenses against predators, they were able to increase their reproductive rates. The researchers noted that these adaptations occurred on the genome level and were heritable, suggesting that with enough exposure to a selection pressure, like predation, the evolution toward multicellularity might be inevitable.
"The evolved cell groups had unique variants involved in keeping cells together after cell division, suggesting a consistent selective response on the genome level," the researchers wrote. "This fairly high degree of repeatability and the small number of generations suggest some degree of determinism for the phenotypic and genomic response in C. reinhardtii to predation pressure."
Division of labor
According to theory, once cell groups are established, cells can begin to serve specialized functions. This occurs through the differentiation of somatic and germ cells, with somatic cells being those that serve non-reproductive functions (predator avoidance, the ability to move and find resources, etc.) and germ cells being those that produce the next generation.
But this specialization process comes at a cost. The team's results showed that the shift toward multicellularity requires cell groups to first boost their survival rate, which lowers the groups' reproductive rates over the short-term. A few reasons for the lowered reproductive rate include lower resource uptake, restricted motility, and reduced photosynthetic rate.The researchers noted that other selection pressures besides predation could also lead cells to form groups, including environmental stress, more efficient nutrient usage, or salt stress, which might have been accidentally present in the experiment. The new study also wasn't the first to show that predation can spark rapid evolution toward multicellularity. But it did shed light on how even the simplest life forms can adapt through strategic trade-offs when facing hard times.
The opening of jars, while impressive and often used to illustrate octopus intelligence, is not their most remarkable ability.
So why is it that they seem to show such peculiar similarities with humans, while at the same time appearing so alien? Perhaps because despite their tentacles covered with suckers and their lack of bones, their eyes, brains and even their curiosity remind us our own thirst for knowledge.
In ethology, the study of behaviour, we explore this intelligence, which we classify as individual “cognitive abilities". These are the mechanisms through which information from the environment is perceived, processed, transformed, remembered and used to take decisions and act.
From a behavioural point of view, the flexibility with which an animal can adapt itself and adjust its behaviour to novel situations is a good indicator of its cognitive abilities. Numerous studies indicate the octopuses possess great flexibility in their behaviours, whether they express them in their natural environment or inside a tank in a laboratory.
Armed and dangerous
So what makes octopuses so smart?
Let's focus first on their defence mechanisms. Faced with multiple predators – including fish, birds and whales – octopuses are masters of camouflage. They can imitate their environment by modifying the colour and even the texture of their skin.
Without a shell, octopuses are vulnerable, and always try to remain hidden in a shelter such as a cavity or the space beneath a rock. Some species maintain their shelter by removing sand and adding pebbles and shells. Some prefer to wrap themselves in shells and pebbles, while others transport their shelter in their arms. This is the case for the coconut octopus, which, true to its name, has been observed carrying coconut shells around to hide within in case of danger.
Octopuses are also formidable predators themselves, and their attack mechanisms are suited to the wide variety of prey they consume, including seashells, crustaceans, fish and even other cephalopods. They can use their vision and camouflage skills to hunt, and their arms to explore, touch and taste their environment to seize every bit of food within reach.
The octopus is a thoughtful hunter. It can cooperate with other species such as groupers to hunt hidden prey. It can learn to avoid crabs bearing poisonous anemones or find a way to cautiously attack them while avoiding being stung.
Octopuses use different techniques to consume seashells and molluscs, either pulling apart the shell by force and placing a small stone inside to keep it open, or drilling into the shell to inject a paralysing toxin which will make the prey open up. This toxin is injected into a very precise muscle under the shell, and octopuses learn and remember the drilling site of each seashell they consume.
Boneless, not brainless
We can test the cognitive abilities of octopuses in the lab. In our EthoS laboratory, we are currently working on the memory and future planning abilities of the common octopus. They are complex animals to study, because of their astonishing abilities.
Their incredible strength allows them to easily destroy our lab tools: be careful with underwater cameras, they can open the waterproof box to drown them! And because octopuses are boneless, they can easily escape their tanks through the smallest of openings. They are also extremely curious and will spend their time catching hands, nets or any other object introduced to their tank. From there, it is up to them to decide when to release their catch.
The opening of jars, while impressive and often used to illustrate octopus intelligence, is not their most remarkable ability. This is mostly a matter of dexterity and gripping, and octopuses are quite slow when executing this task: even when over-trained, an octopus always takes more than a minute to open a jar. A better example of their impressive intelligence is their ability to manipulate an L-shaped object so it can pass through a small square opening in a wall.
Octopuses also excel in discriminative learning: confronted with two objects, they learn to attack one of them in exchange for a reward, basing their choice on characteristics such as colour, shape, texture or taste, and they can retain this information for several months. They can also generalise, a complex thought process in which they need to spontaneously apply a previously learned rule to new objects. For example, octopuses who have previously learnt to attack a real ball can go on to attack a virtual ball on a screen.
Octopuses can also use conditional discrimination, that is, they can modify their choice depending on the context. For example, they can learn to attack an object only in the presence of bubbles. They can also use spatial learning, and find an hidden shelter by remembering its position, or use visual cues to know how to orient their arm inside an opaque T-shaped apparatus.
Last but not least, octopuses can learn by watching other octopuses carry out tasks, such as choosing one specific object over another. This is surprising, because they are mainly solitary creatures.
Grade: sea minus
Octopuses meet every criteria for the definition of intelligence: they show a great flexibility in obtaining information (using several senses and learning socially), in processing it (through discriminative and conditional learning), in storing it (through long-term memory) and in applying it toward both predators and prey.
Despite their obvious abilities, octopuses are oddly erratic in their responses, especially in visual discrimination tasks, in which they carry out the correct response around 80% of the time, while other animals succeed almost perfectly.
And do not be mistaken: octopuses may be clever, but in the classroom of cephalopods they would be the bright but unruly pupil, and the cuttlefish would be top of the class.
The humble cuttlefish is less familiar, but is the subject of numerous research projects worldwide. Less disruptive than octopuses, they possess exceptional learning abilities, can pick up complex rules in no time and apply them perfectly.