There’s Another Missing Link in the Human Evolutionary Chain

Look in the mirror. What you see is not what humans looked like millions of years ago. There were many evolutionary steps along the way, with ancestors branching off to create species entirely different than us. Unearthed fossils blur the line between who’s considered human or another species.

So, how did we get to where we are today?

Scientists are constantly on the lookout for missing links in the chain of human evolution. But contrary to those iconic photos portraying human evolution, the process is more complicated than that. Evolution is not linear, and scientists are still working to untangle the web that connects all species. That’s why it’s no surprise that another missing link has shown up in the evolutionary tree.

Where did the gap come from?

Scientists sampled genomes from different populations all from west African countries. They were shocked to discover that nearly a fifth of their DNA came from a missing link! These populations have something the rest of us do not, and scientists are trying to figure out why.

Here’s the likely explanation. Neanderthals and modern humans (who we are today) share the same ancestors. Tens of thousands of those ancestors went rogue and decided to mate with the ancestors of modern west African humans. All humans today are the same, yet with slightly different genetic makeups.

Interbreeding was not out of the ordinary millions of years ago. Many subspecies of humans roamed the Earth back then. Geographic location played a huge part in turning humans into what we are today. Europeans have a bit of Neanderthal in them, and Australians have a bit of Denisovan, for example.

Just like Europeans and Australians, west Africans have ancestors that gave them a unique set of genetics, too. The difference is that scientists don’t yet know who those ancestors are. Identifying these ancestors is key to understanding who made us into who we are today.

The search for the ‘ghost population’

The group of ancestors that split off are known as the ‘ghost population.’ This is because scientists have yet to unearth evidence of their identity. In other words, we know there’s a missing link. We just don’t know who they are yet.

However, scientists might find the answer soon. Since the ghost population DNA is centered on west Africa, we know where to look for fossils. Fossils are the key to learning more about the lives from this ghost population. They offer clues about how the species interacted amongst themselves and what life was like for them on Earth.

Scientists are also speculating how the genome string survived evolution during these past tens of thousands of years. They don’t have any definitive answers yet, but some hypothesize those genetics were vital for helping west African ancestors survive and continue their legacy. Once scientists discover an identity for the ghost population, they can start figuring out their ancestors as well.

We’ve investigated missing links before

This new ghost population isn’t the first missing link for scientists to discover. Several fossils came under scrutiny in the 20th century. They had different genetic makeups, but all were crucial in connecting the links of human evolution. Some were legitimate, and some were not.

The most well-known missing link is called Java Man. At the turn of the 20th century, a team led by Eugene Dubois excavated a set of human-like bones on the island of Java. It was just a skull cap, tooth, and thighbone, but it was enough to know it was something other than human.

Back then, the bones were the oldest fossils belonging to the hominin tribe. Dubois claimed that Java Man was a link between apes and humans, but many scientists debated this theory. Some thought Java Man was an ape while others thought he was a modern human. Eventually, Java Man was labeled as Homo erectus, making him a direct ancestor of us.

Another famous missing link is known as the Taung Child. The skull of a young primate was discovered by miners in Taung, South Africa. Miners uncovered fossils at their quarry all the time, but this one was different. It’s part of the Australopithecus africanus family, which makes sense because their fossils were only found in southern Africa.

Then, there was Piltdown Man, which turned out to be a fraud. In 1912, scientists “found” a mysterious skull in England. But in the 50’s, others revealed that Piltdown Man was not in fact a newfound missing link. In fact, the skull was put together with orangutan teeth and a modern human skull!

But in west Africa, there’s a real missing link this time. Nearly a fifth of the sampled population’s DNA originates from ancestors we’ve never heard of. While their identity is still a mystery, we at least know they’re underground, waiting to be discovered.

Abhishek Chauhan

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