Category Archives: Evolution

When Gators Ruled The Earth: South America Was A Crocodilian Paradise Before the Amazon

You don’t have to travel far in Florida to see their iconic state reptile up close – Alligator missippiensis, the American Alligator. This apex predator has made such a successful comeback over just the last two decades. If you think finding one of them in your pool or at your door is bad news, consider yourself fortunate that you didn’t live in the South American jungles about 13 million years ago. Back then, these prehistoric beasts not only thrived in the American Southeast, but occupied a significant territory in what is now the western part of the Amazon River Basin. And they had competition, too. Peruvian paleontologists identified seven different species of crocodilians who called this region home. A great deal of diversity among each suggests that there might have even been more.

In the modern Amazon jungles, you never see more than three different types of crocodilians sharing territory – often alligators and their fairly close relatives the Central and South American caiman.

“It was a real crocodilian community,” said the study’s co-author, Rodolfo Salas-Gismondi of the Museum of Natural History in Lima, Peru. “To find seven species is just amazing.”

On the outskirts of Iquitos, Peru, Salas-Gismondi and his team stumbled across two large outcroppings of rock. Embedded in each was fossil evidence of seven different species who all co-existed in the same ecosystem. While the Amazon we know today is perhaps one of the most unique and delicate ecosystems in the world, it may have been preceded by ones that were a whole lot stranger. Salas-Gismondi suspects that such diversity among these monsters was due to the humidity and frequency of rainfall in the wetlands. 13 million years ago it was an immense swampland, offering limitless food for the crocodilians – another way to explain why some of them grew to massive proportions.

One of the prehistoric beasts that lived alongside the American Alligator and the South and Central American Caiman was Mourasuchus atopus, a behemoth that may have filtered water through its mouth to trap fish, in the way some modern birds do.

Another uncovered fossil was the already identified Purussaurus neivensis – a giant caiman the size of a stretch limousine and an apex hunter that fed off mammals and large turtles.

Perhaps most intriguing and most unlike any known living crocodilians today were three different animals that the researchers referred to as crushers, all of which were unknown to science until Salas-Gismondi published his work in the latest volume of Proceedings of the Royal Society B: Biological Sciences. The star of their paper was the creature Gnatusuchus, a name meaning “small-nosed crocodile.” Its skull was first found in a mud pile back in 2006, and was nearly destroyed by a motorboat propeller when the pilot hurried ashore to tie up his vessel.

“The thing was sitting there with the top of the skull and the eyeballs looking at us,” said one of the study’s co-authors John Flynn from the American Museum of Natural History in New York City. “It was just an incredible feeling, knowing immediately it was something so different.”

As intimidating as the name ‘crusher,’ may seem – you might think of them as the crocodilian version of Darwin’s finches – animals that adapted specifically to a diet of shellfish and mollusks which they would crush open with the use of their back teeth. A number of crushed clams have also been found in the fossil deposits.

“I didn’t really think of crocs as being clam-eaters before,” said vertebrate paleontologist David Schwimmer of Georgia’s Columbus State University, commenting on the latest research. “It’s not exactly ferocious, hunting down the giant killer clam. Just think of the image.”

While it was long suspected that the wetland’s apex predators were crocodilians of some sort, and the fossils shed valuable light about how this ecosystem may have worked, it is also an invaluable way to learn more about the diversity of crocodilians. The sixth type identified by the researchers as Caiman wannlangstoni, is believed to be one of the more recent ancestors of modern caimans.

So what happened to this forgotten link? The known crushers seem to be part of a very diverse branch of crocodilians, so how did they all disappear until now? The most likely answer is that the Amazon River itself was responsible. When it formed some 10.5 million years ago, it brought new currents of water flowing eastward into the Atlantic. When the sea levels dropped after the last Ice Ages, much of the swamplands were wiped out, along with the mollusks who specially adapted to it, killing off the crushers’ food supplies.

The Amazon also makes for poor preservation of fossils, as many minerals that are present in fossilization are recycled into the rainforest. The team was fairly fortunate to uncover these animals as well, since heavy vegetation alongside the river banks makes digging difficult.

James Sullivan
James Sullivan is the assistant editor of Brain World Magazine and a contributor to Truth Is Cool and OMNI Reboot. He can usually be found on TVTropes or RationalWiki when not exploiting life and science stories for another blog article.

Evolution Brought Kindness Before Intelligence

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All too often we imagine our hominid ancestors as hairy and primitive cavemen, living under the law of club and fang – unruly monsters that were more primate than human. The evidence, however, is painting a much different picture. Not only were other species of humans like the Neanderthals and Cro-Magnons capable of crafting tools and speaking languages, but human evolution in general likely brought about compassion and kindness some time before producing the intelligent beings of today.

Throughout history, we’ve thought of ourselves as the products of an evolutionary process grounded in intellect – only the brightest and the strongest spawned descendants, with each successive generation better than the last, the eventual outcome of lifeforms that became gradually more complex. However, according to a new study led by researcher Penny Spikins, from York University, this isn’t an entirely accurate assessment.

According to Spikins, there were at least three groups of the earliest human ancestors that exhibited altruistic behavior, developing some time before early humans showed evidence of intelligence and speech, concepts that are only about 150,000 years old.

“Human evolution is usually depicted as driven by intelligence, with empathy and deeper emotions following,” Spikins said. “However, the evidence suggests it happened the other way round. Evolution made us sociable, living in groups and looking after one another, even before we had language. Our success since then, including the evolution of intelligence, all sprang from that.”

Australopithecines, the species of ape to which Lucy belonged, were the first of our ancestors to walk upright, and lived in South Africa some three million years ago.

They had brains about one third the size of our own and were sometimes described by anthropologists as “killer apes” – a name that conjures up that scene from the beginning of 2001: A Space Odyssey. Spikins bristles at the term, reminding us of the Makapansgat pebble, found inside an African cave back in 1925 – a small stone shaped like a face that an Australopithecine did not carve, but collected and kept in its dwelling:

“What is remarkable is that this pebble was carried several miles back to its cave by an australopithecine. Did it remind them of a baby? It is impossible to tell for sure but this is not the only tantalising sign of something perhaps approaching tenderness.”

Another 1.5 million years after Lucy, and there is archaeological evidence that our close relative Homo ergaster lived in tribes that took care of their sick. There is also the Homo heidelbergensis, which lived about 450,000 years ago, and is thought to have raised disabled children to maturity.

“[Evidence suggests] early humans’ survival would have depended on co-operation,” she said, considering the difficulty that they would have had hunting alone or evading predators. “Aggressive or selfish behaviour would have been very risky.”

Spikins published her research in the new book How Compassion Made Us Human. Another piece of her evidence is a 250,000-year-old axe which was decorated with a fossilized scallop – already, humans seemed to have developed their own sense of aesthetics and beauty that they recognized in nature well before they began cave paintings of their own.

“A uniquely human feeling lies behind both the creation of such finely crafted tools and caring for the vulnerable. It suggests early humans, from two million years ago, were emotionally similar to us.”

“Compassion is perhaps the most fundamental human emotion,” she added, but hardly unique to modern homo sapiens as we might imagine. “It binds us together and can inspire us but it is also fragile and elusive. This apparent fragility makes addressing the evidence for the development of compassion in our most ancient ancestors a unique challenge, yet the archaeological record has an important story to tell about the prehistory of compassion.” Far from clouding our judgment, it made building social networks possible in a dangerous and unpredictable world.

“We have traditionally paid a lot of attention to how early humans thought about each other, but it may well be time to pay rather more attention to whether or not they ‘cared’.”

Spikins was previously involved with research on Neanderthals, published in the Oxford Journal of Archaeology.

While she does not deny that the mountains of the Neander Valley was a harsh climates to grow up in during the Ice Age, with geography that often led to isolation, the small families of Neanderthals were actually fairly close to each other. They buried their dead and their children played games which developed the skills they would later use to function as members of the tribe. Not only did parents care for sick or injured children, but child graves were marked with much more distinction than those of tribal elders.

“There is a critical distinction to be made between a harsh childhood and a childhood lived in a harsh environment,” said Spikins of her work – an important thing to consider when we imagine what our ancestors endured growing up in the Paleolithic Era.

Explaining Why We Have Such Big Brains in Just a Few Letters

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G, C, A, T to be exact. Only a slight stretch of our DNA make the difference between us and our chimpanzee cousins. When embedding the bit of genetic information into mice, scientists found that the rodents’ brains grew significantly larger than usual.

“It’s likely to be one of many DNA regions that’s critical for controlling how the human brain develops,” says Debra Silver, on the region they chose. Silver is a neurobiologist at Duke University Medical School.

It is likely that this accounts for the massive difference in brain size between humans and our closest living relative, the chimpanzee – a difference of anywhere between two and four times larger by current estimates. While also having larger brains, people also have many more neurons than their simian friends, and many more connections, or synapses, occurring between each.

Scientists have long sought to determine what genetic basis we have for abstract thought as well as valuing logic and complex emotions – our capacity to develop languages and artwork, concepts that have long been associated with larger brain size. Currently, we have a wealth of evidence that our fellow hominids the Neanderthals were also capable of artwork and tool making, presenting a rather different picture than our old stereotypes of mindless barbarians. The Human Genome Project, concluded in 2004, revealed that humans and chimpanzees have DNA approximately 95 percent identical, establishing that we have more in common with chimps than mice do with rats. Silver’s latest interest, however, is to learn more about those regions in the genome that differ. Chimps do have capacity for tool making, using straw to catch termites, but their linguistic capacity, aside from facial reading, is still being explored.

Silver and her researchers isolated a gene that aids in brain development and removed the DNA region near it, which they proceeded to plant into mice. One group received human DNA, and the other received DNA extracted from chimps.

“What we discovered is that the human DNA turned on gene activity in neural stem cells, and these are cells which produce the neurons of our cerebral cortex,” said Silver.

The mice that were born yielded brains 12 percent larger than the brains of mice who received chimp DNA. The findings were published in Current Biology.

Now, Silver’s team will begin an investigation of how differently mice with larger brains will behave as they mature, knowing that they have only begun to scratch the surface. At the same time, they are looking for other genes that are specific to humans.

Of particular interest is within a vestigial genetic region known popularly as “junk DNA,” that which evidences our common descent from other, more primitive lifeforms, but until recently was believed to serve no specific purpose of its own, since this region doesn’t code for any active proteins in the body. Currently, however, researchers suspect that this region is critical for turning on and off genes as new cells are formed. Their ultimate function, if any at all, still remains a mystery.

“We have very little scientific information about the actual functions of those regions,” said Katie Pollard, who researches human and chimp DNA from the University of California, San Francisco, in a recent interview with NPR.

Many of the ways in which we differ from chimps can be found within the junk DNA, and many researchers like Pollard are still looking to meet that gap. As impressive as the results reported in the study may have been, it is difficult to predict what effect it may have on the mice. It’s preferential to see directly how either people or chimps are affected by the region’s presence, but then the research touches on ethical grounds.

“We’re talking about humans and chimpanzees here, and you cannot experiment on either of those,” notes Pollard. “And so it’s very challenging to prove causation.”

Challenging, sure, but not necessarily impossible either. Already, Pollard and her colleagues are experimenting with lab cultivated cells from chimps and humans, raised in Petri dishes.

“We can now actually generate the equivalent of embryonic brain cells and tissues that are human or chimpanzee,” says Pollard. “And, using genome engineering techniques, we can start to study the effects of switching the human and the chimp sequences in these primate cell lines.”

As their work progresses, the team hopes that soon they may find specific sequences in the DNA that are human by their very definition – opening the gateway of questioning precisely what characteristics make us human, and how distinct we really are from our living primate relatives. The difference may be far less than we ever imagined.

Could ‘Outbreak’ Really Happen? How Climate Change Could be Behind Spread of Deadly Diseases

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As much as last summer’s Ebola outbreak was politicized after it hit American shores, it left a significant deal of damage at its epicenter in West Africa, responsible for the deaths of tens of thousands. Although several treatments have been proposed, the question is whether such an event could happen again. As climate change brings about warmer temperatures into new regions, some researchers that it may be carrying tropical diseases to new places, and ignite a series of global epidemics.

Ebola and that much unwelcome staple of summer known as the West Nile virus are only two prime examples of invasive pathogens brought to new places. Zoologist Daniel Brooks and his team propose that the rising sea levels and increased warm weather leave us much more vulnerable than we realize, in a new paper he published in a British research journal.

You might wonder why a zoologist is so concerned with global warming – but the answer is pretty apparent, and further reinforces the impact that climate change has on most bodies of science. One of the prime symptoms of climate change has been the migration of species to new regions – such as South American birds recurring in more temperate forests. These species often bring parasites with them, capable of infecting new species – either affecting humans directly or through species we may use as a food source.

“Climate change does result in species moving around, and with respect to pathogens those movements actually create an enormous number of opportunities for parasites to jump into hosts they’ve never seen before,” said Brooks in an interview with VICE News.

Prior to Brooks’ work, many researchers thought parasites were specific to only one species. The new study, however, demonstrates a number of instances in which parasites successfully transitioned themselves onto other, similar organisms. One that affects rodents could just as easily infect other kinds of rodents — and would be successful because the new host has not had the evolutionary advantage of developing resistance.

Brooks’ specialty is reconstructing genealogies of species. His work brought him to investigate the last 30 years of related research and even his previous work in identifying vector-borne diseases, some of which date back to the last Ice Age.

“These host switches don’t happen at random. They’re actually clumped at particular times,” said Brooks. The end of the last Ice Age was particularly disastrous for a number of animals after the glaciers melted, increasing sea levels and driving species to higher grounds.

The West Nile outbreaks in the early 2000s are a prime warning of what could happen – their presence being detected by songbirds as they made their way across the Western Hemisphere. Although the songbirds began developing resistance rather quickly, people have not, and the virus is now considered a chronic illness for those affected. The parasite, however, remains, continuing to evolve.

So what is the best way to avert any potential outbreaks? “As long as we think of ebola as a human-to-human problem, we’re missing the possibility that if some non-human picks up ebola we never get rid of it,” Brooks continued. “We need to pay more attention to natural history.”

At some time in the not too distant past, AIDS was a simian virus before it managed to cross species. Not much was known about phylogeny at the turn of the twentieth century, but today focusing on the pathogens in animals and their genetic history might be beneficial.

Salvatore Agosta, an assistant professor at Virginia Commonwealth’s Center for Environmental Studies, supported the paper’s claims, as parasites are a great deal more adaptive than previously thought. Another prime example is Lyme Disease – once known only in the American Midwest but in the last several decades it moved not only to the Northeast but south as well.

Ben Beard of the CDC also agrees: “The simple statement is that changes of climate will affect the environment,” he told VICE News. “What’s more difficult is to say precisely where and how.”

As critical as predicting where and how any potential outbreaks will happen is to the CDC, it often receives the least amount of attention due to its speculative nature, further complicating the problem of migrating and invasive species. Texas, in particular, has withstood several epidemics of mosquito borne illnesses – many of which, such as chikungunya, are still relatively mysterious to many health care professionals.

The CDC was hit by budget cuts last year, which significantly affected the state’s trouble with tackling the number of Ebola cases it confronted over a short period of time.

Panspermia “Alien Seed” Theory Still Unproven Despite Claims of New Evidence

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Panspermia is the (hilarious) name given to a theoretical discussion about terrestrial life originating from someplace extraterrestrial, beyond Earth. The panspermia argument began with Francis Crick, the co-discoverer of the structure of DNA molecules. If “panspermia” sounds like a science fiction idea from the 70’s you aren’t thinking too far off. While Crick is famous for the DNA thing, he actually had a more implausible idea about aliens and the origin of life. One that never stood up to scientific scrutiny but makes its way back into scientific debates from time to time.

Who knows? Maybe this guy started it all.

Over the years there have been several discoveries panspermia supporters point to excitedly, claiming they have found proof of alien life. The latest new piece of evidence comes from Milton Wainwright at The University of Buckingham. While the object was found embedded in a weather balloon designed to collect upper atmosphere debris, and it is undeniably a biosignature of some sort, it doesn’t definitively support the panspermia theory, despite recent, high-profile headlines.

Wainwright himself admits this: “Unless, of course, we can find details of the civilization that is supposed to have sent it in this respect, it is probably an unprovable theory.”

Um, yeah. So the guy quoted all over the new evidence is actually the first in line to warn against jumping to the conclusion that we are all aliens. Still, it’s a very exciting theory. Let’s take a look at other samples from various parts of Earth and beyond that have allowed dreamers to fabricate theories of life’s supposed extraterrestrial origin.

Biosignatures don’t have to be chemical. They can be magnetic, as suggested in this space.com article from 2011, or it could be described by the morphology, meaning the shape and size of fossilized evidence could indicate a living thing once left its mark. Biosignatures that support the idea of alien life or panspermic origins to terrestrial life are inconclusive but that doesn’t stop enthusiasts from pointing and claiming they have proven the theory correct. Here’s why the evidence supporting panspermia is still inconclusive:

Meteorite ALH84001

Meteorite ALH84001

Tiny, microscopic magnetite crystals were found in meteorite ALH84001. Not a lot can be proven from this undeniably interesting piece of space rock. The meteorite is likely Martian in origin. It’s famously debated because of a handful of potential biosignatures. Some scientists insisted only bacteria could have caused the crystal formations . They turned out to be wrong; similar formations can be found forming by complex physics, without life intervening.

Several other “possible biosignatures” have been investigated int he sample. There is a working hypothesis but not an empirical confirmation of life. Proof of an extraterrestrial form of life would mean these so-called biosignatures could have been formed by a living thing and only a living thing – which is clearly not the case. One such biosig was a small-pattern texture that resembled one from a known bacteria. A scientific majority ultimately decided these textures were small to be fossilized cells. Meteorite ALH84001 is a curiosity, a rare find and an amazing natural occurrence but it is not proof of the panspermia theory.

Then there is the Kerala red rain phenomenon happened in Kerala, India from 25 July to 23 September 2001. Heavy showers brought a peculiar, red-coloured liquid. The “blood rains” fell all along the southern Indian state of Kerala staining fabrics and causing alarm. Other colours were reported but the majority of reports and samples were red in color. It’s happened several times since, most recently in June 2012.

Kerala Red Rain

A photo-microscopy examination brought an initial rumor to the media: the source oft he red color was a meteor shower or explosion from asteroid particles heating up on entry to Earth’s atmosphere. Early misreports like that often cause rumors or conspiracy theories when the official story gets redacted. In this case, a detailed study commissioned by the Government of India announced the rains had been dyed by airborne spores originating from a prolific colony of terrestrial, forest algae.

It’s still a mysterious phenomenon but the genetic makeup of the cells found in red rain is far too common for the sample to be extraterrestrial.

Tardigrades

Tardigrades are so durable they seem to be able to survive for a long time when they enter a strange, dehydrated state. Tardigrades are one of the only species who can suspend their metabolism and going into a state of cryptobiosis. Several varieties of tardigrade can stay hibernating for nearly 10 years. While in this state, tardigrade metabolism falls to 0.01% and their water content goes down to 1% of normal.

Tardigrades would make excellent space travellers because they can withstand extreme environments most other lifeforms would be destroyed in, including extremes of temperature, pressure, dehydration and radiation, environmental toxins, and outer space vacuum conditions.

Wikipedia points out: tardigrades are the first known animal to survive in space. On September 2007, dehydrated tardigrades were taken into low Earth orbit on the FOTON-M3 mission carrying the BIOPAN astrobiology payload. For 10 days, groups of tardigrades were exposed to the hard vacuum of outer space, or vacuum and solar UV radiation.^[3]^[38]^[39] After being rehydrated back on Earth, over 68% of the subjects protected from high-energy UV radiation revived within 30 minutes following rehydration, but subsequent mortality was high; many of these produced viable embryos. In contrast, dehydrated samples exposed to the combined effect of vacuum and full solar UV radiation had significantly reduced survival, with only three subjects of Milnesium tardigradum surviving. In May 2011, Italian scientists sent tardigrades on board the International Space Station along with other extremophiles on STS-134, the final flight of Space Shuttle Endeavour. Their conclusion was that microgravity and cosmic radiation “did not significantly affect survival of tardigrades in flight, confirming that tardigrades represent a useful animal for space research.” In November 2011, they were among the organisms to be sent by the US-based Planetary Society on the Russian Fobos-Grunt mission’s Living Interplanetary Flight Experiment to Phobos; however, the launch failed. It remains unclear whether tardigrade specimens survived the failed launch.

Tardigrades can survive in space but that doesn’t mean they came from space. They have strong genetic ties with several other animals in the Panarthropoda group. They appear to have evolved on Earth but will likely be studied for years to come because of the adaptable nature of Earth life they represent.

Like a lot of pseudo-science, there are elements of hope and truth to tons of the details. Labeling bad science or non-science for what it is enables us to dream bigger and keep a better-informed, watchful eye on the available data. If you are feeling the sting of yet another science news story letting you down, recharge your creative side with this 90’s CGI classic that illustrates the crucial principles of panspermism:

Jonathan Howard is a skeptic and freelance writer working for Cosmoso.net

You can reach him at this email address: [email protected]

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Jonathan Howard
Jonathan is a freelance writer living in Brooklyn, NY