Viswanathan K's Thoughts

We are told of the importance of a balanced diet – carbohydrates, proteins, vitamins etc. But have you noticed almost no other species seems to need this?! Not pets, not wild animals – they die if they starve, but they don’t get diseases because they didn’t get a balanced diet. So why is it only humans need a balanced diet, asks (and answers) Nathan Lent in Human Errors .   When it comes to micronutrients (vitamins, minerals, amino acids): “Our bodies fail to make many of the things that other animals do.” Our terminology adds to the confusion: we call some nutrients “essential”, which sounds like “critical”. Wrong. Every nutrient is critical. When we say “essential”, we mean the body can’t produce it, so it has to be ingested. Never heard of Vitamin K or Q? That’s because the human body produces them; so we don’t care about them.   From an evolutionary point, something weird happened to us humans: we have lost the ability to make certain nutrients. In case of Vit...

After the eye, Nathan Lent looks into the “design defects” of human nasal sinuses in Human Errors . They are those huge cavities (there’s a lot of empty space in our skull) with mucus membranes. When we breathe air, it passes through these “filters” to prevent dust and germs from entering the body. In addition, they also warm and humidify the air we breathe. Of course, eventually the mucus gets saturated, at which point it is dumped into the stomach: “(Stomach is) the safest place for the mucus, since the bacteria and viruses it contains can be dissolved and digested by the acid there.”   Sinus problems start when this system gets “gummed up”. At that point, the bacteria aren’t getting cleared, accumulate enough to form colonies, and in the worst cases, sometimes manage to enter the (rest of the) body.   So why do humans suffer more sinus problems than almost any other species? There are many reasons, and one of the important ones is that: “The mucus drainage syste...

Nathan Lent’s book on the “design defects” in the human body, Human Errors , is endlessly fascinating. But why write a book on errors when there are so many “working” things? For one: “By exploring human shortcomings, we can peer into our past. Each and every flaw… tells a story about our species’ evolution.”   He starts with the most famous flaw that lies in our eyes: “The photoreceptor cells of vertebrate retinas appear to be installed backward – the wiring faces the light, while the photoreceptors face inward, away from it.” BTW, it’s not just us – it’s the same for all vertebrates, from fish onwards. But not all species have their eyes wired this way: “Interestingly, the retina of… octopi and squid – is not inverted.” This proves that: “Nature ‘invented’ the camera-like eye at least twice, once in vertebrates and once in cephalopods.”   The problems this arrangement creates for vertebrates are many: Light must travel around the bulk of photoreceptor...

In his awesome book, Sapiens , Yuval Noah Harari says that the “historical record makes Homo Sapiens look like an ecological serial killer”. He says that while the speed at which we drive species to extinction has gone to warp speed in recent centuries and decades, we even managed to wipe out species with just Stone Age technologies at our disposal! He says it would be a remarkable coincidence if the timing of extinction events in Siberia, the Americas and Australia just happened to overlap with humans landing in those areas. The usual other suspect in such extinction events, climate change, is probably not the culprit in those cases because it was always life on land that suffered when man landed, never life in the seas (an area in which our capabilities have built only in recent centuries). Ian Fleming one wrote: “Once is happenstance. Twice is coincidence. Three times is enemy action.” Like it or not, humans have been the enemy for other life forms, long before modern techn...