Buzz
Genetic diversity is vital for the survival of any species. We inherit a blend of genes from our parents, some of which have been passed down through many generations. Over time, these genes can undergo mutations – for instance, a single base pair in our DNA could be swapped during replication, or entire segments might be deleted or duplicated by mistake. While many of these mutations are silent and detectable only by geneticists in laboratories, others result in fascinating mutations with noticeable effects on those who carry them.
8. Double Eyelashes
Elizabeth Taylor, renowned for her stunning eyes, didn’t just rely on makeup to create the effect of dark, defined eyelids. She carried a genetic mutation called distichiasis. This mutation, caused by a change in the FOXC gene—responsible for embryonic tissue development—led to the actress having double eyelashes. While this extra set of lashes enhanced Taylor's allure, distichiasis isn’t always beneficial. Many people with this mutation have eyelashes that grow inward, risking damage to the corneas. Additionally, distichiasis can be linked to lymphedema-distichiasis syndrome, which may also be associated with congenital heart disease and other health complications.
7. Satiety
Genetics play a significant role in shaping eating behaviors, in addition to external factors that affect weight gain or loss. One such gene, the melanocortin 4 receptor gene (MCR4), can be mutated, which either increases or decreases hunger sensations in affected individuals. The MCR4 protein is crucial for signaling the brain when you are full. When this gene is mutated, some individuals may never feel satiated, leading to overeating and obesity. However, the mutation may also result in constant fullness, protecting individuals from overeating and potentially obesity.
6. Alcohol Flush
Many of us know someone, or may even be that person ourselves, who turns bright red after just a drink or two. Though facial flushing is commonly linked with alcoholics, certain individuals have a genetic mutation that makes them extremely sensitive to even small amounts of alcohol.
When alcohol is consumed, the body must break down its ethanol content to eliminate it. A byproduct of alcohol metabolism is acetaldehyde, which is highly toxic. The enzyme aldehyde dehydrogenase 2, coded by the ALDH2 gene, is responsible for neutralizing acetaldehyde before it can accumulate. However, for about 8% of the population, the ALDH2 gene is mutated, causing the enzyme to work inefficiently. As a result, acetaldehyde builds up quickly during alcohol metabolism, causing blood vessels in the face to dilate and a red flush to appear shortly after drinking. While this facial flushing doesn’t pose a direct health threat, symptoms like nausea may accompany the redness, making drinking uncomfortable. Some studies also suggest that this mutation could increase the risk of developing high blood pressure.
5. Painlessness
A woman from Scotland left scientists puzzled when they discovered that she couldn’t feel pain or anxiety, living nearly 60 years without realizing this wasn’t typical. After a hand surgery that would normally cause pain caused her no discomfort, her doctors referred her to a geneticist. Jo Cameron, the woman in question, recalled not noticing she had burned herself on a stove until she smelled the scent of her own flesh burning, and even found childbirth to be pleasant. Genetic analysis revealed that her FAAH gene was suppressed, and her FAAH-OUT pseudogene was missing certain information. The FAAH gene codes for a protein, fatty acid amide hydrolase, that typically breaks down anandamide in the body, a substance that helps alleviate pain and anxiety. For Jo, this process doesn’t happen as she doesn’t produce the FAAH protein, meaning she feels no pain, never worries, and never experiences anxiety.
4. Addictions
Addictions, like alcoholism, have not been directly linked to a specific gene mutation, but there may be a connection to gene expression. Epigenetics is a fascinating field that looks at changes in gene expression influenced by external factors, rather than mistakes in the DNA code itself. For example, DNA methylation involves adding methyl groups to parts of the DNA sequence, which can prevent genes in that segment from being expressed. Even though the gene might not have mutations, this methylation can interfere with its function. Studies suggest that alcohol consumption can alter the expression of genes in areas of the brain involved with behaviors like dependence and tolerance, such as those in the amygdala. There is also evidence that epigenetic changes can be inherited by offspring. Essentially, if a parent is an alcoholic and undergoes changes in gene expression due to alcohol exposure, those changes may be passed down to their children, making them more susceptible to addiction.
3. Female Infidelity
While male infidelity is often explained by a biological drive to spread their genes, the same explanation doesn’t necessarily apply to women. Men, in evolutionary terms, may seek multiple partners to increase the chances of having offspring, which benefits the survival and evolution of the species. Women, however, are generally limited by their ability to bear children rather than the number of partners available. Of course, this is a simplistic, biological perspective that ignores factors like emotional intimacy, commitment, and the possibility of male infertility. Despite this, the basic idea is that women don’t have the same biological urge to cheat. So, why do they do it?
There are many reasons why some women may cheat, but one possibility you might not have considered is that certain women may be genetically predisposed to infidelity. A significant study on human mating behaviors discovered that mutations in the vasopressin receptor AVPR1A gene are associated with infidelity in women, though not in men. Vasopressin is a hormone involved in bonding and sexual motivation. Mutations in this gene may affect how a woman responds to vasopressin, impacting her emotional connection with her partner and her attraction to seek sexual encounters outside of the relationship. Since this is a genetic mutation, it could be passed down to a woman's children, giving them the same tendency. While further research is needed to verify these findings, it offers a potential biological explanation for why some women may be more inclined toward infidelity—it might simply be in their genes.
2. Pungent Smell
Trimethylamine is a strong-smelling compound that has been likened to the odor of decaying fish or garbage, among other unpleasant smells. The FMO3 gene produces an enzyme that breaks down substances like trimethylamine found in the foods we consume, neutralizing the strong odor. However, in some people, this gene is mutated, either completely missing or significantly impaired in its function. This results in a condition called trimethylaminuria, where the person emits a strong odor through sweat, urine, or breath. The smell, caused by an accumulation of trimethylamine in the body, can be highly isolating. People with this mutation, sometimes referred to as having stale fish syndrome, may experience depression and social isolation as a result.
1. Mountaineering
When attempting to summit a mountain like Everest, it is highly recommended to bring a Sherpa along for guidance—and for good reason. Sherpas, a group native to Nepal and the Himalayas, are genetically adapted to perform far better than most people at high altitudes. Hypoxia, or low oxygen levels in tissues, is a major concern when mountain climbing, as it can lead to nausea, confusion, and even death. Although Sherpas are not immune to altitude sickness, they have evolved over generations to thrive in the high-altitude, low-oxygen environment. Genetic variations, especially those found in the EPAS1 gene, are common in the Sherpa population, allowing them to endure and adapt better than others when scaling these towering heights.
The EPAS1 gene controls the production of hemoglobin in environments with low oxygen levels. Hemoglobin is the protein in red blood cells that transports oxygen to tissues and carries carbon dioxide away. The EPAS1 gene mutation found in Sherpas helps them adapt to high altitudes by allowing them to maintain normal hemoglobin levels at elevated heights, similar to those at sea level. In contrast, individuals with a non-mutated EPAS1 gene at high altitudes would experience an overproduction of red blood cells. While having more red blood cells increases the blood’s oxygen-carrying capacity, it also makes the blood thicker and slows its flow, which can lead to serious conditions like mountain sickness, added strain on the heart, and hypoxia.
