Family history testing is “genetic astrology”; we need to relearn everything we know about DNA and cells.
From body planning to the organization and function of the nervous system, cells govern gene expression and make us who we are.
While there is immense fascination in imagining these connections to distant peoples, places, and times, the tests of our ancestors are largely “genetic astrology.” If you go back far enough–and “far enough back” in human history is not that far back–gene is not our identity, no matter what the DNA testing companies say.
Genes are necessary for development and tissue maintenance, but it is the cells that govern their expression and make us who we are, from body planning to the organization and function of the nervous system.
Throughout the 20th century and up to the present, the prevailing assumption has been that our identity is inextricably linked to our DNA. As Shakespeare said, “the past is but a preface,” but when it comes to development, the cell’s relationship to its genetic history is quite different. It is therefore worth pausing for a moment to briefly reflect on the reasoning behind the dominant view of the genome as the master of our existence. The strings G, C, As, and T make up the hardware store catalog called your genome. This catalog has been updated over millions of years and is unique to each of us, not in our repertoire of tools and materials, but in every detail of color and design. Through these subtle differences, you can trace the history of your genome, just as you can trace the transformation of a clunky computer from the 1950s into an iPhone. Add to these genetic relationships a historical narrative, or genealogy, and you have a genealogy of your ancestry, which is said to connect you to people and places far away and, if you go back far enough, to all people to each other.
We humans feel a great desire to know and belong to our origins. For the past 100 years we have been so fixated on our genes that we have written our own story in the language of genetics. Ancestry.com and 23andMe, two of the leading commercial DNA testing companies, together manage the genomes of over 30 million people. Based on these data, you might be told that you are 37% West Bantu, 27% Germanic, 26% Scottish, and 10% Nigerian. Some companies claim to be able to compare your DNA to that of people who lived thousands of years ago, including Vikings, ancient Egyptians, and Chumash Indians. They are descended from pharaohs.
There is something immensely fascinating about imagining connections to such distant peoples, places, and times. But an organization called Sense About Science has this to say about such claims. Geneticist Adam Rutherford also correctly points out that if you go back far enough, and “far enough back” in human history is not that far back, we are all related to one another. This is true. The tools and fixtures of the genome are necessary for us to be animals, primates, and humans.
Genetic ancestry can be quantified; we can say we are 50% or 25%. But what do these numbers really mean? The history of our species may be inscribed in our genome, but the genome is not what makes us who we are.
Immediately after gastrulation, the process that draws the blueprint of the organism, we look a lot like chickens, fish, and frogs.
An equally interesting human history is contained in the story of our cells as they divide, beginning with the first division of the zygote and making differences in the process, building us up. Recall the features of embryonic development first noticed by Carl Ernst von Baer. Immediately after gastrulation, that is, the process that draws the blueprint of the organism, we are very similar to chickens, fish, and frogs. The similarity of animal embryos ties us to the first multicellular organisms. Eukaryotic cells (“true,” i.e., cells with a properly formed nucleus) began to use the genome in new ways, controlling genes to create robust and efficient organisms capable of conquering the earth.
To accomplish this, cells discovered a handful of approaches that work well, including hermaphroditic body plans (mirror left and right sides) and gastrulation. In all animals, cells utilize the same tools and equipment to lay the foundation for their bodies. Then, after gastrulation, stem cells go their own way, building species-specific characteristics and unique, individualistic entities based on their interactions with each other and, since we are mammals, with our mothers. This building process will continue throughout our lives as long as stem cells create new cells and keep our bodies in good condition.
Regardless of what DNA testing companies say in their ad campaigns, our genes are not our identity. In fact, these companies are using the DNA from the tests to study how to treat diseases caused by a single genetic mutation. In other words, they know that genes are tools, and they are looking for ways to exploit the fact that these tools are sometimes repairable.
Source: Family history testing is “genetic astrology”; we need to relearn everything we know about DNA and cells.
The Simplest Synthetic Cells Have Been Seen Evolving Faster Than Natural Ones
Family history testing is “genetic astrology”; we need to relearn everything we know about DNA and cells.