Why do dragonflies have four wings? So that they can hover and fly in any direction that they wish. Most insects have two pairs of wings but the second set in some of them have evolved to have a different purpose. Two examples of these are flies and beetles. (I know we are talking about […]
#322 Why do dragonflies have four wings? Read More »
How does crop rotation work? By alternating crops to give the soil a rest and to replace nutrients that are removed. People transitioned from a hunter-gatherer culture to an agricultural culture in about 12000 BC. First, they domesticated animals. This happened in different places on Earth within a few thousand years. In about 9500 BC,
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How does an electroencephalogram work? By measuring electrical activity in different parts of the brain using electrodes on the scalp. EEGs are used to diagnose disorders with the electrical activity in the brain. These can be epilepsy, sleep disorders, anesthesia, coma, and even brain death. It is most commonly used for diagnosing epilepsy, which is
#311 How does an EEG (electroencephalogram) work? Read More »
What happens when you are bitten by a venomous snake? The venom either attacks the cells, the circulatory system or the nerve system. There are 3,500 species of snake and 600 of those are venomous. Many of them are not dangerous to people but some of them can be lethal. Venomous snakes inject venom through
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Why can we only hear certain frequencies? Our cochlea is only stimulated by frequencies between 20 Hertz and 20,000 Hertz. First, let’s look at how we actually hear. Our ear is a detector for sound waves. It is shaped to funnel them into the ear canal, which ends in the eardrum. The sound waves make
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How do hummingbirds flap their wings so fast? By having very strong, fast twitch chest muscles, by twisting their wings instead of flapping them, and by being able to use oxygen and energy very quickly. There are 361 species of hummingbird altogether. The smallest species grow to about 5 cm and weigh 2 grams The
#300 How do hummingbirds flap their wings so fast? Read More »
Why do ant bites hurt? Ants both bite and sting. They drip formic acid onto your skin and some ants inject venom. Not all ants bite. There are estimated to be 22,000 different species of ant and they are on pretty much every landmass except for Antarctica. It is estimated that ants make up between
#297 Why do ant bites hurt? Read More »
Why do we get headaches? There are many theories, but nobody actually knows. There are 200 different types of headaches, but they are divided up into primary and secondary headaches. Primary headaches are headaches that aren’t caused by a disease or damage to the brain. Secondary headaches are caused by a disease or damage to
#294 Why do we get headaches? Read More »
What makes us itch? Itching is caused by the release of the chemical histamine. There are different types of itch. Almost all animals have an itch and scratch response. Bears scratch themselves on trees and dolphins scratch themselves on rocks, or at the bottom of their tank if they are in captivity. It is an
#292 What makes us itch? Read More »
Why do women live longer than men? There are many reasons, but having two copies of the same sex chromosome and testosterone might be the most significant. Obviously, both men and women age. Their bodies undergo similar changes that ultimately result in death. However, across the world, women tend to live on average 8%
#288 Why do women live longer than men? Read More »
