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The University of Texas at Austin. Illustration by Jenna Luecke.
The University of Texas at Austin. Illustration by Jenna Luecke.

Our Gut Microbiome Evolved Alongside Us, Study Finds

The University of Texas at Austin. Illustration by Jenna Luecke.
The University of Texas at Austin. Illustration by Jenna Luecke.

A new study in the journal Science examining the genetics of the bacteria living in the guts of African great apes and people from Connecticut supports the idea that our microbiome has been evolving with us, despite bacteria-affecting changes in environment, diet, geography, and for humans, medicine usage.

Using fecal samples, an international team of scientists led by researchers from the University of Texas at Austin created evolutionary trees for three different groups of bacteria that make up one-fifth of the human gut microbiome, tracing bacterial species back millions of years. They found that our gut microbiome can be traced all the way back to before the human species existed, to the common ancestor that both humans and great apes evolved from millions of years ago. Gut microbes have evolved in parallel with the different species, they say, with genetic splits in bacteria occurring at the same time as gorillas diverged from other hominids about 15.6 million years ago (which is much earlier than some previous estimates) and humans split from chimps and bonobos roughly 5.3 million years ago.

This means that though our environment does affect our microbiome (eating less fiber, for instance, has been shown to alter the bacterial makeup, as has using deodorant), genetics play a major role in the types of species we play host to.

There’s potential that some of our bacterial lineage may be shared with species even farther back in the evolutionary tree, the researchers say. “Maybe we can trace our gut microbes back to our common ancestors with all mammals, all reptiles, all amphibians, maybe even all vertebrates,” study author Andrew Moeller postulates. This research doesn’t dive quite so deep, but future studies might explore those issues.

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AFP, Stringer, Getty Images
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Stones, Bones, and Wrecks
The Most Complete Fossil of an Early Human Relative Goes on Display
AFP, Stringer, Getty Images
AFP, Stringer, Getty Images

Twenty years after it was discovered in an African cave, one of the most important fossils in the quest to demystify human evolution is finally on display. As Smithsonian reports, Little Foot, an Australopithecus specimen dating back more than 3 million years, was revealed to the public this month at the Hominin Vault at the University of the Witwatersrand’s Evolutionary Studies Institute in Johannesburg, South Africa.

Paleontologist Ron Clarke discovered the first bone fragments from the fossil in 1994. The pieces came from the remains of a young female’s feet, hence the nickname. Clarke and his team spent years excavating Little Foot bit by bit from the Sterkfontein cave system in South Africa until the bones were fully removed in 2012. The shattered remains had been embedded in a concrete-like material called breccia, making them incredibly tricky to recover. But the sum of the parts is monumental: Little Foot is the most complete Austrolopithecus fossil known to science.

The hominid genus Austrolopithecus played an essential early role in the chain of human evolution. Lucy, another famous hominid fossil, is a member of the same genus, but while Lucy is only 40 percent complete, Little Foot retains 90 percent of her skeleton, including her head. It’s also possible that Little Foot surpasses Lucy in age. Most paleontologists agree that Lucy lived about 3.2 million years ago, while one analysis places Little Foot’s age at 3.67 million years.

Austrolopithecus is believed to have spawned Homo, the genus that would eventually contain our species. The discovery of Lucy and other fossils have led scientists to designate East Africa as the cradle of human evolution, but if Little Foot is really as old as tests suggest, then South Africa may deserve a more prominent point in the timeline.

Following Little Foot’s public debut, the team that’s been studying her plans to release a number of papers exploring the many questions her discovery raises.

[h/t Smithsonian]

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NM Museum of Natural History & Science
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science
Scientists Find a 245-Million-Year-Old Horseshoe Crab Fossil That Resembles Darth Vader
NM Museum of Natural History & Science
NM Museum of Natural History & Science

Horseshoe crabs have scuttled through Earth’s shallow ocean waters for hundreds of millions of years, but scientists recently discovered the fossil of one that looks like it’s from a galaxy far, far away. As Newsweek reports, the 245-million-year-old creature’s shell is shaped like Darth Vader’s helmet, which prompted researchers to name the prehistoric critter Vaderlimulus tricki. (Tricki pays homage to Trick Runions, the man who found the fossil.)

Paleontologists from the New Mexico Museum of Natural History and Science and the University of Colorado described the Vader horseshoe crab in a new report published in the German journal Neues Jahrbuch für Geologie und Paläontologie. Discovered in Idaho, Vaderlimulus tricki lived during the late Triassic era and belonged to a now-extinct family called Austrolimulidae. During its lifetime, it inhabited the western coast of the supercontinent Pangea.

Vaderlimulus tricki's unique shell can be chalked up to evolution, scientists explain in a news release, as the creatures were “expanding their ecological range from marine into freshwater settings during the Triassic and often exhibit body modifications that provide them with a bizarre appearance by modern standards."

Horseshoe crabs have survived at least 470 million years on Earth, and are often referred to as “living fossils.” But individual species died out over the millennia (only four are currently alive today), and fossils of horseshoe crabs are few and far between. When new ones are discovered, they often belong to a species that was previously unknown to science. Vaderlimulus tricki, in particular, is the first horseshoe crab from the Triassic period to have been found in North America.

[h/t Newsweek]

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