Life on Earth is Old

Life on Earth began somewhere. Scientists think that there was one single ancestor, which they call LUCA (Last Universal Common Ancestor). This would have been a unicellular organism that eventually diverged to create every living thing we have today. And I mean everything, from tiny bacteria to blue whales. And LUCA began a long, long time ago.

About 530 million years ago, the Cambrian Explosion saw the major expansion of complex life. It’s been estimated that LUCA appeared 4 billion years ago, about 600 million years after Earth’s formation.

But one study pushes that arrival back to about 4.2 billion years ago. It also indicated fascinating details of what life for LUCA might have been like.

To find exactly when life appeared on Earth, scientists had to work backward. They first compared genes in species living today and counted the number of mutations that have occurred since the common ancestor. Using a genetic equation, they worked out that LUCA must have existed as early as 400 million years after the planet’s creation. That would put his organism in the middle of the Hadean Eon, which was a hellish geologic nightmare. During this time, Earth experienced frequent collisions, including the one that created the moon. The surface was unstable, with lava bubbling to the surface.

The evolutionary history of genes is complicated. Scientists had to use complex evolutionary models to reconcile the history of genes with the genealogy of species.

The team also retraced the physiological characteristics of living species to discover what LUCA must have been like. Surprisingly, even though it was a unicellular organism, it appears to have had an immune system. This would indicate LUCA was already fighting off primordial viruses, which makes one wonder if viruses are truly alive.

While LUCA was exploiting and changing its environment, it’s likely it didn’t live alone. Its waste would have been eaten by other microbes such as methanogens, which produce methane as a by-product of their metabolism. Such arrangements might have created a recycling ecosystem.

Although this is the oldest common ancestor known, scientists don’t understand how life evolved from its very origins to the early communities that LUCA was part of.

 

https://www.msn.com/en-us/news/technology/all-life-on-earth-comes-from-one-single-ancestor-and-it-s-so-much-older-than-we-thought/ar-AA1So3MH?ocid=hpmsn&cvid=694052ebf2b54b488c496cce3ccd1493&ei=107

A 400,000-Year-Old Hearth

Humans may have tamed fire earlier than we thought, according to a 400,000-year-old hearth discovered in England.

Researchers found evidence of the ancient hearth, along with flint tools and bits of iron pyrite, at what used to be a woodland and pond site where Neanderthals are known to have lived or camped. It may be evidence that our ancestors knew how to strike the pyrite with flint to make sparks and start blazes.

The discovery was made at the Barnham site. It suggests human ancestors were making fire roughly 350,000 years earlier than thought. But they aren’t sure what the fire was used for. It might have been for cooking, carving tools, or sharing stories. Knowing when our ancestors learned to use fire could unlock mysteries of human evolution and behavior.

There are two theories that try to explain why the ability to make fire led to an increase in the size of the brain (over evolutionary time). One is that cooking increases calorie intake because cooked food is easier to digest. Another idea is that having a fire helped create a gathering space at night, which increased human sociality, prompting a cognitive evolution.

However, the finding does not show the start of humans making fire. It is the earliest known example of using fire that the researchers are confident about. There are earlier suggestions that our ancestors used fire in such places as South Africa, Israel, and Kenya, but those examples are not as definitive as this discovery. In archaeology, it’s difficult to know if a fire was started by nature or if humans had made it.

Did they collect it from natural sources? Carry it around and curate it? Or did they make it? The Barnham site is a compelling case that they knew how to make fire. The researchers found sediments that contain fire residue, as well as stone tools such as fire-cracked flint hand axes, and fragments of iron pyrite. Geologic analysis suggests the pyrite was extremely rare, so it was probably brought to this site to make fire.

But not all researchers are convinced. One stated that other Neanderthal sites, dated to around 50,000 years ago, featured flint tools that showed traces of having been struck by pyrite to make sparks. But not at this much older site.

Fire would have been useful for staying warm, nutrition, keeping predators away, and melting resin into glue, as well as other things.

It is important to realize that learning to make fire was not a linear process. It was a scattered process, with many different groups learning on their own. There’s also evidence that some groups of our ancestors learned to make fire and then lost the ability or stopped using fire for some reason. Some of those may have rediscovered how to make fire and possibly lost it again. It seems to be a complicated history.

 

https://www.msn.com/en-us/news/technology/in-a-400-000-year-old-hearth-hints-of-humans-taming-fire-earlier-than-thought/ar-AA1S5WuY?ocid=hpmsn&cvid=693a2c55b82340d7890331455cdc1239&ei=24