Life

Scientists Find Evidence of Earth’s Oldest Life

Researchers have discovered hints of life hundreds of millions of years earlier than previously known, according to a new study published in Nature. An international team of scientists led by University College London’s Matthew Dodd have found the oldest microfossils ever in what was once a hydrothermal vent system near Quebec, estimating they could be up to 4.3 billion years old.

Located on the eastern edge of Canada’s Hudson Bay, the Nuvvuagittuq Greenstone Belt is left over from Earth’s earliest oceanic crust. There, within the quartz layers of banded iron formations, the researchers found remains of tubes and filaments (seen attached to a clump of iron in the image below) formed by bacteria on that early crust, which was part of an ancient deep-sea hydrothermal vent network.

The bacterial remnants can be dated back at least…

Oldest microfossils suggest life thrived on Earth about 4 billion years ago

hematite
SIGNS OF LIFE In rocks left over from ancient hydrothermal vents, these microscopic tubes of hematite, an ore of iron, may be remnants of early microbes.

Tiny, iron-rich fossils exhumed from the depths of an ancient ocean could reveal the cradle of life.

These micrometer-scale structures are probably remnants of microorganisms that once lived amidst ancient hydrothermal vents, researchers suggest March 1 in Nature.

“In a nutshell, what we’ve found are the oldest microfossils on Earth,” says study coauthor Matthew Dodd, a biogeochemist at University College London. The rocks that hold the fossils came from Quebec and date to somewhere between 4.28 billion and 3.77 billion years old — when Earth was still a baby. The next oldest microfossils reported are just under 3.5 billion years old, though their validity has been debated (SN: 2/8/14, p.16).

If Dodd’s structures truly are remnants of microbes, “it’s fantastic. I love it,” says astrobiologist Martin Van Kranendonk of the University of New South Wales in Sydney. But he’s not convinced. In fact, he says, “there’s just not definitive proof that any of the textures or the minerals or features they have is unique of life.”

Claims of early life are frequently fraught with controversy. For one, says Dodd, “these are big claims — these are our origins.” And scientists studying early life typically don’t have a lot to work with. It’s not like they’re looking at dinosaur bones. In billions-of-years-old microbes, obvious cellular bits and other familiar flags of life have often been stripped away. And in Earth’s oldest rocks, extreme heat and pressure can cook and squash any remnants of life…

5 Strange Facts About the Planet Earth

You know what it’s like: You live somewhere all your life but never realize just how great it is until someone comes to visit. While it’s just a shame we don’t get any visitors to marvel at all the peculiarities of our home planet, here are five facts you might still appreciate.

1. EARTH’S A GIANT DYNAMO.

The core of the Earth is a solid lump of nickel and iron, rotating in a sea of molten iron and nickel. This rotation functions the same way winding up a hand-held generator does, giving Earth an enormous magnetic field that extends up to 50,000 kilometers out into space. This magnetic field is crucial for life on Earth, as without it we would be exposed to the full force of the Sun’s radiation. As well as causing cancers and other radiation-aggravated conditions, the radiation’s sheer force would blow our atmosphere into space, as happened with Mercury, and to a lesser extent, Mars. Instead, charged particles are (mostly) harmlessly deflected away, giving rise to the auroras.

It’s not all good though: Any particles that hit the Earth head-on tend to get trapped in the field and can’t get out. These so-called Van Allen Radiation Belts can pose a hazard for astronauts who leave low Earth orbit.

2. IT’S THE DENSEST PLANET IN THE SOLAR SYSTEM.

While Earth may not be the biggest planet in the system, it is the biggest rocky planet in the solar system, and also the densest. Therefore, Earth has by far the highest surface gravity of any terrestrial object in the solar system. This is both a blessing and a curse.

The reason for the high density is the large deposits of heavy elements in the Earth’s makeup. Elements such as lead and uranium are much rarer on other worlds, which gives us a huge advantage in the amount and variety of construction materials available here on Earth. The high gravity has also demanded that humans develop the reflexes and endurance necessary to cope with such gravity, meaning we are far more durable than the potential delicately boned, sloth-like creature we could be had we evolved in low gravity.

Unfortunately, that high gravity makes Earth the worst place…

The Weird Event That Led to You and Ewe and Yew

Life arose on earth over three billion years ago, and for a long time, there were only one-celled organisms. These prokaryotes diverged and evolved in many ways, but making the leap from one cell to many cells (eukaryotes) was a paradigm shift that led to every living thing on earth that’s big enough for us to see -including us. How did that happen? Before we could sequence genes, the prevailing theory was a gradual development as cells mutated, diverged, and evolved. However, recent genetic research has led credence to the idea that the first two-celled organism was a merger that only happened once.

The alternative—let’s call it the “sudden-origin” camp—is very different. It dispenses with slow, Darwinian progress and says that eukaryotes were born through the abrupt and dramatic union of two prokaryotes. One was a bacterium. The other was part of the other great lineage of prokaryotes: the archaea. (More about them later.) These two microbes look superficially alike, but they are as different in their biochemistry as PCs…