There is one common theory shared by both scientists and believers – we are all related! Believers attribute our close relationships to Adam and Eve, who were the first human beings on Earth. This applies to Christianity and Islam, the two most popular religions.
As for scientists, they claim that all human beings can trace their origin back to one common female ancestor. The idea that all human beings are related may seem easy to understand on paper. However, biological relationships are extremely complex. For the skeptics, here is an in-depth analysis of whether we are all truly related!
What Scientific Studies Say
Back in 1987, a group of scientists sampled 147 DNAs from people of all races. They discovered that human beings originate from two family trees. One was the African lineage and the other a different group, which also contain an African lineage. This research also concluded that all humans on Earth come from one female ancestor, the Mitochondrial Eve. We all contain the Eve gene, which belongs to a female ancestor who most likely lived in Africa 200,000 years ago.
The idea to compare DNAs from all races stemmed from research by Dr Wesley Brown in 1980, which proved that two human beings share DNAs that are more similar than those of other primates, such as chimpanzees. Wesley’s research demonstrated that humans had a more recent ancestor, which fueled the research in 1987.
According to this research, Mitochondrial Eve is not the first woman to give birth to the human race. On the contrary, Eve is used as a misnomer for the Bible Story. She lived amongst other women. The only difference is that her DNA is the most recent female ancestor that current human beings can trace their origin.
Why This Particular Eve and Not Other Women of Her Generation?
Although scientists think the current human race started from the Mitochondrial Eve, there were other women at the time. So, why this Eve and not any of the other women? Well, scientists have a few explanations for this. The first assumption is that there may have been an evolutionary bottleneck that wiped out most of the population 200,000 years ago. An example could be a comet hitting Earth or a catastrophe such as a flood.
The second theory is that, about 70,000 years ago, the human race almost went extinct. Only a population of about 15,000 was left behind. The previous evolutionary bottleneck was caused by a volcanic eruption at Mount Toba in Sumatra. This ushered in a 1,000-year-long ice age.
Such events may have led to the existence of a “Lucky Mother” who gave birth to the future generation. Please note that women contribute more to the DNA of a baby. So, if other mothers produced only male offspring, they didn’t pass their mtDNA, and that’s why the Mitochondrial Eve DNA became dominant.
How We Are All Related
To highlight how we might all be related, let’s use this example: Assume that your great-great-grandmother from your mother’s side had a sister who moved to another country in search of a better life. Along the way, she cut ties with her old family and started her own.
Your great-great-grandmother and her sister shared a similar mtDNA. Assuming that they both gave birth to girls who gave birth to more girls, two hundred years later, if you and one of her offspring participated in ancestry mapping, you’ll discover that you share the same mtDNA. This applies to the billions of people who live on Earth. There is probably someone out there who you are not even aware of their existence, but they do share a similar mtDNA to yours.
After discovering Mitochondrial Eve, who lived 200,000 years ago, the ancestry of a modern human being can be traced back to 7 or 8 generations. This means that some of our ancestors unknowingly married their first cousins. Factors such as migration and genetic mutation played a role in this.
In 2004, a professor from Yale University, Joseph Chang, developed a mathematical model that traced our common ancestor to 3,000 years ago. Joseph assumed that if each generation had a lifespan of 25 years, we would have a common ancestor 125 generations back.
In this model, he factored in aspects such as migration and geography. Though convincing, Joseph’s theory does not mention who this ancestor was or where they may have lived. The other weakness of this model is that in only 40 generations, we have around one trillion ancestors. That would be impossible because scientists estimate that the total number of humans to ever live on Earth is 117 billion.
Conclusion
Despite both theories having strengths and weaknesses, it is a known fact that we are all related. At one point in this life, we all shared a common ancestor. If humanity is viewed from a broader perspective, it represents a global family tree. Even though the branches might differ significantly, they share the same roots. Despite the definition of a relative referring to a close family member, the stranger you meet on the train has intersected with your lineage at some point in the past.