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How Humans Could Evolve Into Another New Species

Could the first "Martians" be a new species of human?

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Tom Hale

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Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist

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A display a human ancestor hominin skulls on display at a natural history museum

Along with Homo sapiens, at least eight other species of human have existed: Homo habilis, Homo rudolfensis, Homo erectus, Homo antecessor, Homo heidelbergensis, Homo floresiensis, Homo neanderthalensis (the Neanderthals), Homo naledi, and the mysterious Denisovans.

Image credit: Micaela Parente/Unsplash

Once upon a time, around 300,000 years ago, numerous human species roamed the Earth. They often crossed paths, intermingled, competed, and almost undoubtedly clashed. Ultimately, just one species prevailed: Homo sapiens. 

Aside from the odd nuclear threat and global pandemic, this single species has been doing a pretty good job at remaining the planet’s apex ape. This might not be the end of the story, though. With monumental changes to our civilization on the horizon, it’s possible that Homo sapiens could diverge into multiple different species, creating a world (or even galaxy) of multiple hominins once again.

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Are Humans Still Evolving?

Now we sit in heated apartments and stare at electronic devices all day, it’s all too easy to think we’ve escaped the confines of the natural world and we’re no longer bound to evolutionary pressures. However, we’re still in the constant process of evolution.

“Natural selection is still here. It's still it hasn't gone away. It's still operating,” Scott Solomon, an evolutionary biologist at Rice University and author of the book Future Humans: Inside the Science of Our Continuing Evolution, told IFLScience.

One example is the simple ability to drink milk. This capacity to break down lactose only evolved in the past 10,000 years – a blink of an eye in evolutionary terms – since the advent of agriculture when humans began herding animals and drinking their milk. In some parts of the world, such as Europe, milk-drinking powers only emerged 5,000 years or so ago. 

Another more recent example is Caesarean sections. The number of babies that are too large to naturally pass through the birth canal has increased from 30 in 1,000 in the 1960s to 36 in 1,000 births today. It’s possible that the rise is due to increased numbers of Caesarean sections, which has resulted in the proliferation of genes that code for large babies and/or small birth canals. Historically, these genes would not have been passed down as both would have died in labor.

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Other changes might be even more subtle, but no less significant.

“If a genetically based trait, like hair color, becomes more common or less common from one generation to the next then that is considered evolutionary change,” Solomon added.

“That's often different from what your average person on the street might think about evolutionary change. It doesn't necessarily mean new traits coming into existence, it could just mean existing traits are more common or less common,” he explained. 

How To Make A New Species

Evolutionary changes like this can build up in a population over a long period of time and eventually result in the emergence of a new, separate species. 

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Scientists call this speciation, a complex process that can happen through a variety of means. Perhaps the easiest to imagine is allopatric speciation, whereby a population splits into two geographically isolated populations that can no longer exchange genes with each other.

A simplified diagram of the process of allopatric speciation
How allopatric speciation works.

Imagine a river suddenly splits an island into two halves, dividing its native ground-dwelling creatures into two populations. The north of the island is more mountainous and barren, while the south is flat and covered in trees. It’s a safe bet that, over time, the two separate populations will eventually evolve different adaptions to suit their two separate environments. Given enough changes, perhaps they might diverge into two species. 

It's been widely pondered whether something like this might have caused the split between chimpanzees and bonobos over 1 million years ago when the Congo River sliced the jungle’s ape population into two halves. 

Could A New Species Of Humans Evolve?

Just like this split in the family tree of great apes, could Homo sapiens undergo a similar divergence? In many respects, the 21st century has made this scenario less likely, but it has simultaneously opened more opportunities where crazy things might be possible.

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Throughout our history, humans have routinely migrated to far-flung locations, crossing ice plains, lava fields, oceans, and mountains to set shop in a part of the world, cut off from others. Despite this, no new human species have evolved at least in the past 300,000 years.

Solomon explained: “One possible explanation [is] there wasn't enough time for them to do that. They weren't isolated long enough. Another possible answer is they were isolated, but not maybe completely isolated.”


“We have the opposite happening today. If anything, we're moving away from a scenario of speciation, we're moving towards more of a homogenization of the human species,” he added

“Today, there is more interaction between human populations than ever before in human history. It’s so easy to move around the planet, there really are essentially no true isolated human groups. Maybe just a few Indigenous groups that are ‘uncontacted,’ but these are very, very small numbers of individuals,” Solomon noted. 

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However, that doesn’t mean that future human speciation is impossible. Along with artificial intelligence and human-computer interfaces, gene editing is set to become one of the defining technologies of the 21st century. With the help of CRISPR-Cas9 and other genetic technologies, we could soon have complete mastery of our genomes, cutting and pasting chunks of DNA as we please.

If wielded by people who didn’t learn any lessons from Brave New World, this God-like ability could become a force that’s powerful enough to force humans down different evolutionary paths.

Like many of the sci-fi stories that dabble with these ideas, it could be a very grim road to tread down. Imagine a scenario where gene editing could eliminate all diseases, imbue brains with superintelligence, and forge the body of a demigod  – but it was only available for the rich and uber-privileged. 

“CRISPR gene editing or another similar gene editing technology could be done to some individuals and not others, and could create something of a two-tiered system where the genetically modified people can't or don't exchange genes with the unaltered people,” he said 

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“There's been plenty of science fiction that's explored those types of scenarios, but now that technology exists,” Solomon added.

Another scenario (which is vaguely less dystopian) would be the prospect of colonizing other parts of the solar system and beyond. Humans are deeply intertwined on Earth and it’s hard to imagine a geographical factor that could divide humans into two populations exposed to vastly different evolutionary pressures. Even a continent splitting in two wouldn’t be much trouble for plane-faring, boat-building humans.

However, the colonization of other planets could be this catalyst.

“The other scenario for how we could evolve into new human species is if we leave Earth. If you there are settlements, let’s say on Mars, that is a really interesting scenario to explore,” Solomon explained

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“We understand quite a lot about how isolated populations evolve. If you look at islands on Earth, that’s one of the places where evolutionary biologists have done much of their work. In many ways, planets in the solar system are like islands in the ocean,” he noted.

“We also understand quite a lot about how evolution could happen because we understand quite a lot about how the conditions of space, or the conditions on Mars, affect the human body,” continued explained.

It would be tricky to predict precisely how these alien conditions might influence human evolution, but it’s evident that Homo sapiens that live on Mars will be subject to an array of never-before-seen evolutionary pressures: different diets, different atmospheres, different everyday lives, and different social settings. Given enough time and separation from Earth-bound individuals, these changes have the possibility to add up and create a new species. 

In this sense, perhaps the very first Martians might be humans.


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