Heredity, and genetic science, are more complex than one could ever imagine
She Has Her Mother’s Laugh: The Powers. Perversions, and Potential of Heredity – Carl Zimmer (2018)
(A quick note on some awesomeness that has graced this humble book review blog recently. Several weeks ago I received notice that RXTT’s Intellectual Journey has been included in Feedspot’s Top 200 Book Blogs, currently found at #193! Amazing! Many thanks to blog master Mr. Anuj Agarwal, and the good people at Feedspot. BOOKS RULE!)
The past decade has seen the world of genetic research explode, in both the amount and the scope of what is being attempted. Researches the world over have new tools with which to explore the genetic codes that provide the instructions to make all parts of living organisms. As with all emerging scientific fields, the general public’s discourse is decades behind the forefront of research. This leads to reactionary angers, manipulation of the ignorant through fear, and an inability to properly fund cutting edge research. Carl Zimmer has done an amazing job corralling the wild and weird history of the human study of heredity and genetics, and made it truly enjoyable to read.
Humans have been genetically altering the natural world around us for millennia; way before we knew what drove heredity, or had any idea about why offspring acquired certain characteristics of their parents and lost others. These early genetic experimenters were the early humans that began to cultivate wild plants. An example of this is the modern tomato. The original fruit, which is exceedingly rare to find these days, was basically a tiny, tart and seedy berry. The humans in the New World (many of our modern foods were not found in Eurasia, Africa, or Australia) would choose a plant with slightly lager or sweeter berry, collect those seeds, and propagate it. Each new generation, the human would choose the plants with the best fruit, propagate that one, and dispose of the lesser plants. Over the centuries, that basic method created whole new species of tomato plants, capable of producing much bigger, sweeter, and more nutritious food. The same process allowed our New World ancestors to create what we now call corn, chili peppers, potatoes, and a host of other vegetables that are ubiquitous in modern diets worldwide. This same process was undergone by early humans domesticating cattle, goats, swine, etc. By breeding only the animals whose traits were preferred, more animals capable of reproducing those traits existed, soon making them the norm.
In spite of the long history of humans altering the plants and animals around us, it seems that as a species, we humans have an extremely short memory of our collective past. We allow ideas that have no relation to the world around us to color how we see the world itself. One of the biggest restraints to developing the science of heredity and genetics came from organized religion, and the blind obedience that their dogma requires of their followers. Ideas that are in opposition to religious dogma are disposed of without exploration, and people are kept blind, ignorant and happy in their stupidity. For centuries, the idea that the world was truly static, truly unchanging, was prevalent in Western culture. This stems solely from theologians and priests demanding that everyone see their little collection of stories, history, genealogy, myths, and fables as LITERAL TRUTH, never to be questioned, never to be doubted. In this world view, every animal species was perfectly crafted by an omniscient creator, and these species have remained unchanged since the beginning of time. This belief depended on the unchallenged assumption that the world was just over 6,000 years old, an assumption so stupid and wrong yet strictly dogmatic, that it was unchallenged for centuries, even causing the execution of people willing to claim otherwise.
It is quite fitting that despite these idiocies pushed on people by organized religions, it was ordained members of the clergy who did the most groundbreaking work on genetics. Gregor Mendel, an Augustinian friar and abbot, decided he was going to do his own experiments, regardless of the consequences. He used the common pea plant, and its many colorful flowers, as his subject. By cross-breeding them over and over, and carefully observing the results, he developed the idea that the outcome of reproduction is due to the offspring inheriting some sort of instructions from both of its progenitors. He showed how, for these plants, and it turns out, for much of life on Earth, there is a rigid set of probability controlling which traits are passed on and in what quantity. By selectively breeding only tall plants, an d then pollinating them with pollen from short plants, he was able to show the existence of dominant, and recessive, traits.
Dominant traits are those that will appear in an offspring if only one of its parents carries that trait. Recessive traits can spring up in offspring, but only if both parents carry the recessive trait themselves. He also determined the ratio in which these traits would appear, and was vindicated by his experiments. People condemned the man, ignoring his work. It was only after his death that recognition came, and now Mendel is considered the father of genetics for his efforts.
Breeders and scientists continued working in this manner for centuries, through trial and error, until a great discovery was made. This was the discovery of the DNA molecule, and how it is found in every single form of life on the planet, from bacteria to trees to humans. Understanding that this complex and huge molecule encoded instructions for the creation of all parts of an organism was something that, even today, many people are not willing to accept. Once this was found out, scientists and researchers sought to decode what was now called a genome. Some animals have few chromosomes containing DNA, and others have dozens and dozens. Each species is different, yet each species carries so much “junk” DNA (DNA that is left over from previous ancestors or organisms) that looking for the genes that are actually shaping our bodies was a herculean task. Over the past 30 years much groundbreaking work has been done in studying genes, what they are responsible for, how to alter them, and how to use gene therapy to help people suffering from genetic diseases.
Another awesome part of this book discusses the study of heredity, as it relates to what traits and genes are passed on to our children. Humans are pretty selfish and stupid, for the most part, and because of this many people were convinced that having “bad” parents automatically created “bad” offspring. This was such a racist and classicist idea, yet it persisted for a long time, because, of course, most “educated” people canme from the rich white upper crust of society. It allowed people to classify a pecking order of human quality, with white Europeans on top of the list, and African and tribal people at the bottom. These morons made the grievous mistake of assuming that genetics count for everything in a person’s makeup, and that environment, opportunity, and nutrition had no bearing. These idiots fought the hardest, and still fight today, to try and maintain the status quo which keeps them fat and happy while everyone else deserves their shit lot in life. It has been shown, countless times, that human achievement and quality is an ongoing process, and results from everything that shapes a person, from their family life, to their education, to their nutrition, to where they are born.
Even after these dumb-ass ideas were discounted, people continued to stick to strict ideas of heredity, ideas which have no bearing in the real world. In one example, around the 1920’s, the comedian Charlie Chaplin was sued by a young lady claiming her son was his illegitimate child. Chaplin sought to have the court accept scientific evidence (blood type) that the child could not be Chaplin’s, but at the time the courts were scientifically ignorant, and would not allow it. In recent decades, this mindset has flipped, and in most courts, only DNA evidence is accepted and it is seen as irrefutable. The blind stupidity of this is pointed out by the case of a woman with three children, who, in a custody battle, had blood work done. The blood work showed that her kids did not share her DNA, so the courts accused her of stealing the babies when they were young. She tried everything, including testimony from the doctor that delivered her babies, but had no luck. It was not until several scientists did extensive work on the lady that it was discovered that she is a chimera. Her body is composed of two distinctly different sets of DNA. Her blood contained DNA that did not match her kids, but her muscle and skin contained matching DNA. Genetic chimeras are quite common, in fact, it is estimated that most humans are genetic chimeras on some level. Some of them are formed when two eggs are fertilized by two sperm I the uterus, and then these two combine into one embryo, creating one human. Sometimes these come out hermaphroditic, other times it is seemingly undetectable. Even other people have stripes across their skin, from two separate genetic pools.
One other seeming insanity I came across while reading this book is the discovery that human mothers exchange DNA with their offspring, and vice versa. It used to be thought that the placenta was a protective barrier, keeping the fetus separate, but that is not the case. The mother’s DNA does enter the child, and sometimes the child’s DNA goes back through the umbilical cord in the form of stem cells and become part of the mother’s body. In some cases it was found that the fetus’ stem cells became neurons in the brain of the mother, sometimes months after the child had been born. The implications are awesome.
I could write about the amazing stuff in this book forever. I think it is a very engaging read, and worth the time it takes, for anyone interested in heredity, genetics, science history, and the foolishness of man’s assumptions about our own nature. Highly Recommended.
(This book can be purchased here: SHE HAS HER MOTHER'S LAUGH )