Do We All Come From the Same Two Ancestors?

Beyond representing and Adam and Eve, there is a genetic explanation that tells us this is the case

We live in the United States, where a pivotal election will occur. Thus, it is an understatement to say that the country is widely divided in a way not seen since the Civil War.

Political conversations are commonplace, and with such a different idea of what the country should look like in the future, it is quite common for people to argue and question the other side’s humanity.

Like anyone else, I have strong opinions. However, I try to remind myself that we are all humans, after all. Recently, when someone gets too agitated, I try to remind them that we all come from the same two ancestors, so we are all like family and should ultimately protect one another.

I always get puzzled looks. “What do you mean by that? That’s not possible,” they say.

Well, to bring some humanity into all human conflicts, I would like to explain why this is not just possible but also the case. Get ready for some science.

Have you ever wondered who your ancestors were? I’m not talking about your grandparents and maybe great-grandparents, not even the first in your family to move into the country you live in. I mean your hundreds of thousands of years of ancestors.

Well, as it turns out, every person on Earth today can trace their roots back to two distinct ancestors — a man and a woman who lived hundreds of thousands of years ago.

But these two people, often referred to as “genetic Adam” and “mitochondrial Eve,” weren’t the first humans, nor were they a couple. They lived in different places and different times, separated by thousands of years.

Yet, through the curious pathways of genetic inheritance, they are the only two individuals whose genetic material has survived untouched, in specific ways, in all of us. Yes, ALL of us.

So, how is it possible that we all share these two ancestors? And how do scientists even know this? Let’s break it down.

To understand how this works, you need to know a bit about our DNA. DNA is like a blueprint, carrying all the information needed to build and maintain our bodies. Think of it as the LEGO instructions to build our bodies. We inherit DNA from both our parents, but not all DNA behaves the same way.

First, there’s mitochondrial DNA (mtDNA). This type of DNA is found in mitochondria, tiny structures within our cells that provide energy. What’s interesting about mitochondrial DNA is that it’s passed down exclusively from mother to child.

The reason is simple: egg cells contain a lot of mitochondria, while any mitochondria in sperm are destroyed after fertilization. This means that the mitochondrial DNA you have today came directly from your mother, who got it from her mother, and so on, in an unbroken chain that stretches back through time.

Then, there’s the Y chromosome, which is part of our genetic material that determines sex. If you’re biologically male, you have one X and one Y chromosome and received that Y chromosome solely from your biological father. Your father got it from his father, and on and on in an unbroken line of men passing their Y chromosomes down through the generations.

Now, because mitochondrial DNA and the Y chromosome are passed down in these special ways — almost unchanged from generation to generation — scientists realized that they could trace these particular pieces of genetic material back in time.

By studying the patterns of small mutations that accumulate in mtDNA and Y chromosomes, researchers discovered that all humans today share a single common female ancestor for mitochondrial DNA and a single common male ancestor for the Y chromosome.

The woman who lived around 200,000 years ago is sometimes called “mitochondrial Eve.” She wasn’t the only woman alive at the time. Still, she is the only one whose mitochondrial DNA survived in every person alive today (see the graphic above to have a better understanding of how this is even possible).

Similarly, “Y-chromosomal Adam,” the man whose Y chromosome has been passed down to all men today, lived about 200,000 to 300,000 years ago. Just like Eve, he wasn’t the only man alive, but for whatever reason, only his Y chromosome lineage survived.

It’s important to note that these two people weren’t particularly special in any way. They weren’t the first humans, nor were they the “most successful” in some measurable way. In fact, scientists estimate that our species, Homo sapiens, existed for tens of thousands of years before mitochondrial Eve or Y-chromosomal Adam came onto the scene.

The fact that their DNA survived is really just a matter of chance. Think about it: in any given generation, a woman might have only sons, meaning her mitochondrial DNA won’t be passed on.

Or a man might have no sons, ending the chain for his Y chromosome. Over the course of hundreds of thousands of years, the odds of a specific piece of DNA making it through each generation can be pretty slim. Eve and Adam’s DNA just happened to be the lucky ones that survived.

You might be wondering — if we all share mitochondrial Eve’s mtDNA and Y-chromosomal Adam’s Y chromosome, does that mean the rest of our DNA comes from them, too?

Not quite. In fact, most of our genetic material comes from countless other ancestors who lived alongside or even long after these two individuals.

The key thing to remember is that mitochondrial DNA and Y chromosomes represent only tiny parts of our overall genome. They’re useful for tracing these specific lineages because they don’t “recombine” like most of our DNA does.

What do I mean by that? In the process of creating egg and sperm cells, our other chromosomes exchange genetic material in a process called recombination, which mixes things up and makes it difficult to trace a clear lineage. This is how our bodies make sure that species keep genetic variability so that a population has different traits to adapt to different future scenarios.

However, mitochondrial DNA and Y chromosomes remain largely unchanged, which is why we can track them back to a single individual.

Understanding that we all come from two ancient ancestors might not change how we go about our daily lives, but it does offer a powerful reminder of how interconnected we are. Despite our many differences — culturally, geographically, and physically — there is a deep genetic connection that ties all humans together. And that’s something we should always keep in mind.

In many ways, this insight affects the way I see our place in the world. We are part of an unbroken chain of life that stretches back hundreds of thousands of years, and our shared ancestry showcases the resilience of life itself.

All in all, knowing we all come from these two ancestors is a humbling and fascinating part of our story.