The human genome was roughly mapped out in the year 2000. This was a major step in understanding our DNA and how everything comes together to make us human. It also allowed us to look at the building blocks of human life much more closely. Research into the human genome shows us how we are similar to other animals but also how humans are still evolving.
It also sparks controversy as people begin to question whether scientists will decide to clone humans like Dolly the sheep. Either way, the human genome still fascinates all those who study it as they try to discover what other secrets it holds.
In this book summary readers will discover:
- The basics of human genetics
- Junk DNA
- What genes help identify
- Eugenics – an unfortunate part of our history
- The new era of genetics
Key lesson one: The basics of human genetics
To understand the human genome and why mapping it was such a breakthrough, you have to first understand the basics of human genetics. The human genome contains the complete set of DNA needed for human life. It is made up of 23 pairs of chromosomes with approximately 3 billion DNA base pairs. Each pair of chromosomes vary in size and the number of genes it carries. DNA is made up of nucleotides called adenine, guanine, cytosine and thymine. They exist in pairs with adenine pairing with thymine and guanine pairing with cytosine.
These pairs are replicated as they come together in strands making up our chromosomes. What makes each of us unique is how these nucleotide pairs arrange themselves. They truly are the building blocks that make us. With billions of combinations, the human genome can be considered the longest book in the world and attempting to read it is anything but easy. And while the genome is so large considering the building blocks, it all fits in the nucleus of a cell so small that it could get lost on a tip of a pin.
The remarkable thing about the human genome is that our history and origins can be found. As much as we are unique, our genes can actually be found in other species. Genetically speaking, our genetic makeup is only 2 per cent different from a chimpanzee. Chimpanzees have one more chromosome pair than humans. This pair, in humans, fused together to become one which translated into the differences seen between humans and chimpanzees today. This fusing of chromosomes is an adaptation that likely took several generations to occur. Humans have long lifespans compared to other organisms and therefore more time is needed to genetically adapt to a changing environment. This is in contrast to bacteria who adapt quickly and are therefore able to live in some of the harshest climates known.
Beyond these stories of the past that the genome relays, we can also learn if there is a potential of disease lurking in our futures. The possibilities are seemingly endless as we continue to discover more with each passing moment.
Key lesson two: Junk DNA
When trying to decipher the mysteries that the human genome holds, scientists have to be able to sift through the junk. Yes, that’s right, our genomes contain junk DNA that has no meaning or function. Can you imagine what it must be like trying to figure out what is junk and what is useful amongst 3 billion base pairs? It’s almost as if our bodies have set up distractions to lead researchers astray!
As one can imagine, when researchers first started mapping out the human genome they thought that everything would be important. Then they started discovering strings of repetitive genes which were basically useless. Over time, they discovered that junk DNA can be dangerous as many of them were once viruses that had become embedded in the genome. Certain repetitions, as well, can cause abnormalities which can lead to illness and death. However, they also found that junk DNA is not completely useless as they first thought it was. It comes in handy during DNA fingerprinting as the repetitions within junk DNA are unique and thus easy to identify.
The fascinating thing about the human genome is that only three per cent of our genes are actually deemed useful. Therefore, researchers continue inspecting junk DNA to find out if they have more information than they originally thought.
Key lesson three: What genes help identify
Genes are responsible for the way we look and for how long we will live. How? Well, some illnesses are coded in our genes. Huntington’s disease, for example, is caused by gene mutation. It is a disease that affects a person’s motor function and is unfortunately fatal. Children of people with Huntington’s disease usually inherit the disease from their parents.
Interestingly, everyone carries the gene that causes Huntington’s disease. However, some people tend to have more repetitions of the gene. Researchers have determined that people with Huntington’s disease have more than 39 copies of the gene. Even more informative is that the nucleotide repetition that causes Huntington’s disease is also responsible for six other diseases in humans.
But it’s not only diseases that genes can identify. Your very personality could be determined by your genes. You might think that your personality is something you have developed along the way but your genes have a say as well. A good example of this is the gene on chromosome 11 that codes for dopamine receptors in your brain. Dopamine helps control the reward and pleasure centres of the human brain. How effective your dopamine receptors are is based on the number of repeats of this gene you have. Low levels of dopamine could result in you being indecisive. However, too little dopamine can lead to Parkinson’s disease and too much dopamine can result in schizophrenia.
This is just one example out of a possible 500 genes that code for personality traits. These genes, in combination with the environment you grow up in determine your personality. By understanding this, we can better understand ourselves and our sometimes strange behaviour.
Lastly, our genes can also tell us a lot about how we age. As humans, we need to stay alive until our kids can reach adulthood and fend for themselves. This is why most people don’t start really ageing until their mid-50s. By this time, their kids should have children of their own. However, many factors have changed this timeline as people are now having kids later in life and we have longer lifespans due to modern medicine. Despite these factors, our genome tries to keep dangerous genes at bay whilst we are young. As we get older, however, they stop and diseases can start to creep in. This is especially true for cancer.
Key lesson four: Eugenics – an unfortunate part of our history
Information about our genes is something that we gain insight from in hopes to better understand human life. Historically, however, there have been those who looked to genetics to provide superior beings. First named by Francis Galton in 1885, eugenics described the breeding of such superior humans in a bid to obtain pure genes.
This sounds strangely similar to what the Nazis aimed for during World War II but they were definitely not the first to think about it. In fact, in 1904, American scientists decided they would identify the so-called bad stock in the US. These included alcoholics, drug addicts and those considered feeble-minded. The scientists believed that these individuals spoiled the gene pool of the nation by breeding. So, in 1911 officials forcefully sterilized the individuals they deemed unworthy to produce the next generation. Eugenics was approved by many of the influential leaders and thinkers. Theodore Roosevelt, H.G Wells and even Winston Churchill all supported eugenics.
Nowadays, people argue that the practice of testing for Down Syndrome in embryos is a form of eugenics. However, there is a choice involved which differs from the horrific practices of eugenics in the past. Parents have a choice to continue with the pregnancy whilst classic eugenicists would have deemed the child unfit for society without considering the parents’ decision.
Key lesson five: The new era of genetics
Genes have given us a large amount of information about what causes some diseases. Recently, researchers have been looking at how genes can tell us how to cure illnesses as well. Indeed gene therapy has gained much popularity in recent years because genetic modification may be the answer.
Gene therapy essentially introduces the genes needed to battle a specific disease directly into diseased cells. Most of the focus of gene therapy has been on cancer treatment although other medical trials are ongoing. The difficulty of expanding gene therapy lies on the ethical front. People question the morality of genetically modifying plants and animals, for humans, it is amplified. There have been objections in fear that scientists are playing God and there is always a risk that something will go wrong that will result in the creation of a monster. Genetic modification may seem scary but if it could one day cure genetic diseases should we not give it a chance when the time comes? We will have to wait and see.
The key takeaway from Genome is:
Mapping the human genome was a major breakthrough for scientists. Being able to study the building blocks of human life gives us information about our origins and what our futures may hold. Every small discovery enables scientists to get closer to understanding the human genome. Junk DNA tends to throw them off course from time to time but even that has its own information to give. As research progresses, we get closer to being able to identify the genes which may code for various diseases. The future is filled with possibilities, we just have to be open to the idea that our genes may be the key.
How can I implement the lessons learned in Genome:
It is possible to have your genome sequenced to find out more about what lies in your DNA. If you are curious about your ancestors or looking to identify any potential, harmful genes you carry, then genome testing is a great way to find out.