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Humanity's Earliest-Known Ancestors Have Been Discovered in Southern England

This is the oldest fossil ever found belonging to the line that leads to us.

The ancestors to modern humans scouting for food. Credit: Mark Witton, Acta Palaeontologica Polonica.

Phylogeny is the biological development and history of an organism or its class. Paleontologists have been researching the class Mammalia’s phylogeny for some time, particularly its trajectory from tiny rodent-like creatures in the late Triassic 200 million years ago, to modern-day humans. There are currently around 5,000 mammals on the planet, and it's a very diverse group at that.


Mammals are split into three subgroups. The first are the monotremes (Prototheria) who still lay eggs; among them only the duck-billed platypus and the spiny anteater. The second are the marsupials (Metatheria) among them kangaroos, wallabies, and the lowly possum. The last, latest, and most common type are placental mammals (Eutheria, Placentalia). These are mammals kept in a placenta in a mother’s womb before being born live and fully formed. This group comprises over 4,000 species with fantastic diversity, from mice and horses to whales and humans, and so many others.

Unfortunately, we don’t know much about the origins of placental mammals. But now, fossils of the earliest placental mammal—and as such our first ancestor—have been found. They are two teeth belonging to two rat-like creatures who lived 145 million years ago, during the Mesozoic era. Researchers at the University of Portsmouth in the UK found the teeth, belonging to creatures who probably scurried around the feet of dinosaurs. Their findings were published in the journal, Acta Palaeontologica Polonica.

There’s been conflicting evidence until now of when placental mammals first emerged. Other findings have pointed to the Cretaceous or Jurassic periods. This discovery puts their emergence squarely in the Cretaceous. This is the oldest fossil ever found belonging to the line that leads to us.


Electron microscope scans of the fossilized teeth. Credit: Acta Palaeontologica Polonica.

The fossils were found on the Jurassic Coast of Dorset in Southern England, near the city of Swanage. There, undergraduate student Grant Smith was sifting through some rocks from the early Cretaceous when he came across them. This is a rich location. Thousands of fossils have been unearthed in the area. Smith said he knew he’d found mammalian teeth, but never expected them to be so important.

He brought the teeth to Dave Martill, a professor of palaeobiology at the university. Prof. Martrill confirmed they were in fact mammalian. Martill said in a press release, “We looked at them with a microscope but despite over 30 years’ experience, these teeth looked very different and we decided we needed to bring in a third pair of eyes and more expertise in the field in the form of our colleague.”

Dr. Steve Sweetman is a research fellow at the university. He specializes in prehistoric rodents. “Quite unexpectedly,” Dr. Sweetman said, “he found not one but two quite remarkable teeth of a type never before seen from rocks of this age… even at first glance my jaw dropped!”


Dr. Steve Sweetman. Credit: The University of Portsmouth, England.

Dr. Sweetman further explained:

The teeth are of a type so highly evolved that I realized straight away I was looking at remains of Early Cretaceous mammals that more closely resembled those that lived during the latest Cretaceous – some 60 million years later in geological history.

In the world of paleontology there has been a lot of debate around a specimen found in China, which is approximately 160 million years old. This was originally said to be of the same type as ours but recent studies have ruled this out. That being the case, our 145 million year old teeth are undoubtedly the earliest yet known from the line of mammals that lead to our own species.

He believes the rodents were nocturnal. One burrowed into the ground and most likely ate insects, while the larger one may have included plants in its diet. “The teeth are of a highly advanced type that can pierce, cut and crush food,” Sweetman said. “They are also very worn which suggests the animals to which they belonged lived to a good age for their species. No mean feat when you’re sharing your habitat with predatory dinosaurs!”

One final note of these newly found species: one has been named Durlstotherium newmani. That’s after Charlie Newman, the landlord of the Square and Compass pub, the closest watering hole to where the teeth were discovered.

To learn more about this discovery, click here:

Hulu's original movie "Palm Springs" is the comedy we needed this summer

Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.

Gear
  • Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
  • As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
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Two MIT students just solved Richard Feynman’s famed physics puzzle

Richard Feynman once asked a silly question. Two MIT students just answered it.

Surprising Science

Here's a fun experiment to try. Go to your pantry and see if you have a box of spaghetti. If you do, take out a noodle. Grab both ends of it and bend it until it breaks in half. How many pieces did it break into? If you got two large pieces and at least one small piece you're not alone.

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Our ‘little brain’ turns out to be pretty big

The multifaceted cerebellum is large — it's just tightly folded.

Image source: Sereno, et al
Mind & Brain
  • A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
  • The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
  • This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.

Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).

A neural crêpe

A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.

So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.

The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."

Study's cross-sections of a folded cerebellum

Image source: Sereno, et al.

A complicated map

Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."

That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.

It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."

This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."

Bigger and bigger

The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.

"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."

As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."

Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."

Economists show how welfare programs can turn a "profit"

What happens if we consider welfare programs as investments?

A homeless man faces Wall Street

Spencer Platt/Getty Images
Politics & Current Affairs
  • A recently published study suggests that some welfare programs more than pay for themselves.
  • It is one of the first major reviews of welfare programs to measure so many by a single metric.
  • The findings will likely inform future welfare reform and encourage debate on how to grade success.
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