A Brief History of Everyone Who Ever Lived: The Human Story Retold Through Our Genes by Adam Rutherford is a well-written, entertaining book about the journey of humanity through time. Genetics is a topic frequently discussed in popular media, at least in part because it presents discrete variables (genes) which allow comparison between individuals on a common substrate (the human genome). However, as Rutherford so eloquently presents, popular genetics encourages many biological misconceptions that are oversimplifications, at best.
Here are my A Brief History of Everyone Who Ever Lived Key Takeaways:
A Brief History of Everyone Who Ever Lived Key Takeaways
Key Takeaway #1: We are all related
While religions have been touting the “brothers and sisters” view of humanity for eons, in our modern era we have irrefutable genetic evidence that shows all humans are related to one another. From the book:
We only have to go back a few dozen centuries to see that most of the 7 billion of us alive today are descended from a tiny handful of people, the population of a village.
Indeed, all humans alive have a common ancestor as recently as 3,400 years ago, as seen in a study conducted by Joseph Chang :
Ancestry is such that genes can spread very quickly over generations. It might seem that a remote tribe would have been isolated from others for centuries in, for example, the Amazon. But no one is isolated indefinitely, and it only takes a very small number of people to breed out with people from beyond their direct gene pool for that DNA to rapidly descend through the generations. Chang factored that into a further study of common ancestry beyond Europe, and concluded in 2003 that the most recent common ancestor of everyone alive today on Earth lived only around 3,400 years ago.
However, as we’ll see in our second key takeaway, being related to others doesn’t actually mean what we think it means.
Key Takeaway #2: We have less in common with our ancestors (genetically) than we realize
But you have far less in common with your ancestors than you may realize, and there are people in your family from whom you have inherited no genes at all, and who therefore have no meaningful genetic link to you, even though in a genealogical sense you are most definitely descended from them.
Although it may sound counterintuitive to those who are just starting to learn about genetics, the fact that we have ancestors who we didn’t inherit any genes from isn’t all that surprising. Genes get diluted over time and the contribution of any single ancestor in our family tree is bound to be minimal, especially if they are not a recent ancestor.
Key Takeaway #3: DNA does not determine identity, especially racial identity
This was an eye-opening point for me as we increasingly hear from people claiming heritage based on DNA testing (see Elizabeth Warren). According to Rutherford, DNA test kits use dubious statistical methods to link snippets of the genetic code with specific races. The author experienced this himself when finding some supposedly Native American and circus performer DNA in his genome. He cautions readers to be skeptical of DNA testing kits, especially those that emphasize ancestry:
Even if the genetics and the genealogy are correct, it is equally possible—and indeed in my opinion more likely—that the sliver of supposedly Native American DNA in my genome is merely noise in a file comprising hundreds of thousands of data points. Even if the family tree is correct, it is quite possible that I harbor literally no DNA from Neil Huntley and the Catawba people, as it has been diluted through generations. It’s exciting to discover circus performers in one’s family tree, but I must be very careful not to fall into the trap I am decrying throughout this book, that DNA has some power to determine identity. The truth is that it means next to nothing. Ancestry is a matted web.
Furthermore, Rutherford emphasizes that “racial science” is a dubious way of thinking, and not actually scientific, at least from a genetic standpoint:
There are no essential genetic elements for any particular group of people who might be identified as a “race.” As far as genetics is concerned, race does not exist.
Key Takeaway #4: Genetics has been disappointing in living up to its immense potential as a therapeutic pathway
Our knowledge of genetics can no longer be said to be in its infancy. Given the time, money, and manpower put into genetic research, the results so far have been massively disappointing. Rutherford makes sure to call this out:
We know that the genomes of cancers change and evolve as the tumors grow, making medicine’s quarry even harder to tackle, but potentially offering up new and highly personalized treatments. However, the number of diseases that have been eradicated as a result of our knowing the genome? Zero. The number of diseases that have been cured as a result of gene therapy? Zero.
Hopefully this changes in the very near future.
A Brief History of Everyone Who Ever Lived Key Takeaways is just a brief preview of the interesting genetics related information Adam Rutherford includes in this highly readable book. If you’re looking for an insightful but entertaining read, this is a great one to check out.
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