11 strange facts that are hard to believe

The number of scientific publications is constantly increasing – according to 2020 data, from one million to two million within twenty years. In the flood of findings that science is accumulating, there are quite a few that are downright astonishing. We present a small and very random selection of facts that are difficult to believe.

The first shark species swam through the seas as early as the Devonian period, 400 to 350 million years ago. In fact, a 2012 study suggests that these cartilaginous fish first appeared in the Ordovician period – about 445 to 485 million years ago. That’s a significant age: the dinosaurs entered their lifespan comparatively late: about 235 million years ago.

The age of sharks is downright astonishing when you compare it to something you think has been around since time immemorial: Saturn’s rings. This planet is indeed considerably older; Like the rest of our solar system, it formed about 4.5 billion years ago. But the rings are more recent, as evidenced by data from the 2017 Cassini spacecraft. Accordingly, the impressive ring system around the second-largest planet formed a maximum of 400 million years ago, but possibly less than 100 million years ago.

We know the phenomenon of fireflies or exotic species such as anglerfish, which use light to attract prey in the darkness of the deep sea: bioluminescence is the emission of cold, visible light by a living creature. In fact, we humans also have our own type of bioluminescence. But it is about a thousand times too faint to be visible to the naked eye.

This strange fact was revealed by a 2009 study by Japanese researchers. They filmed five test subjects with highly sensitive cameras and found that they glowed all day long. The bioluminescence fluctuated depending on the time of day; it was strongest in the late afternoon and weakest at night. The lightest spots appeared on the forehead, neck and cheeks.

Oxygen gas – the essential part of the air we breathe – is molecular oxygen (O₂). This is usually colorless, odorless and tasteless, so we cannot detect an oxygen-enriched atmosphere with our senses. Unlike many other gases in the periodic table, gaseous or liquid (from -182.97 °C) oxygen in thick layers shows a light blue color. Below -218.75 °C it solidifies into blue crystals. Other forms of solid oxygen appear red, black and metallic.

By the way, oxygen is the third most abundant element in space, after hydrogen and helium; In the earth’s crust, the oceans and the atmosphere, it is the element with the largest mass fraction as bound oxygen (O). With about 65 percent of the mass, it is also the element with the largest share in the human body.

Normally light travels in a straight line. But when you point a laser beam at a certain angle at a jet of water, a phenomenon known as ‘total internal reflection’ occurs: the light shines ‘around the corner’, so to speak. It is continuously reflected back at the boundary between the water and the surrounding air, which acts like a mirror, “catching” the laser beam in the water.

From a physical point of view, this requires two requirements to be met: first, the light must travel within a denser medium – here water – and reach the boundary into a less dense medium – air. Secondly, the light beam must hit this boundary between the two different media at an angle greater than the so-called “critical angle”. According to Snell’s law of refraction, this depends on the properties of the medium. The laser beam captured in the water jet perfectly illustrates how a fiber optic cable works.

Estimating the number of people in the distant past is not an easy task. What is certain is that the rapid growth of our species only really started around the year 1800; there were about a billion people on earth at the time. Today there are more than eight billion, about two thousand times more than 12,000 years ago, when the total world population was only four million people – less than half the current population of London or slightly more than Berlin.

Since its appearance about 300,000 years ago, the… homo sapiens have often faced demographic bottlenecks, about 70,000 to 80,000 years ago, when there could only have been between 1,000 and 10,000 people. According to a controversial theory, this ‘genetic bottleneck’ could have something to do with the super-eruption of the Toba volcano in Sumatra, 74,000 years ago. By the way, the total number of people who have ever lived on Earth is approximately 108 billion. The people alive today make up only 6.5 percent of that number.

There are now more than eight billion people on this earth. Nevertheless, all of us together represent only a little more than one ten-thousandth of the total biomass on the planet. This applies if only the carbon content of the organisms is taken into account for better comparability, as variable components such as water content would distort the result.

According to calculations by the Weizmann Institute of Science, Homo sapiens collectively weigh about 0.06 gigatons. This is approximately equivalent to the biomass of all termites on land or the entire krill population in the ocean. All life amounts to 550 gigatons, of which plants make up 450 gigatons, bacteria 70 gigatons and fungi 12 gigatons. All animals, including humans, make up only 2 gigatons. And of that, 1 gigatonne is accounted for by arthropods (arthropods) and 0.6 gigatonne is accounted for by fish.

Of course, no one has counted all the trees on Earth or all the stars in our Milky Way. But there are well-founded estimates and they arrive at a result that will surprise many people: while the Milky Way consists of some 100 to 300 billion stars, according to astronomers – plus large amounts of interstellar and dark matter – there are no fewer than on our small planet 3.04 trillion trees. Procured: 3,040,000,000,000.

That’s ten times more trees than there are stars in the Milky Way, even if you assume a larger number of stars. There are about 350 trees for every person – and the number of people is growing while the global tree population is steadily declining.

Fleas are about 1 millimeter long, but can jump about 30 centimeters high. Within a millisecond, a jumping flea reaches a height of about 8 centimeters. When they jump off, the little insects accelerate about 100 times the acceleration due to gravity (G). 1 G is the force of gravity acting on us near the Earth’s surface. For comparison, a space shuttle peaks around 5 Groughly the same force that acts on the driver of a Formula 1 racing car in a corner.

High-speed camera footage has shown how fleas achieve such acceleration: they have very hard thorns on their feet that they use to hold on to the ground when they jump off. Because no muscle can generate the force a flea needs to jump off, the animals – like grasshoppers or springtails – use a kind of catapult: they hook their legs before they jump, so that they can no longer move. They then slowly contract their muscles to build tension, using a small amount of resilin, a rubbery protein, as a spring. When the captured catapult is released, the energy is released in this spring.

In 2020, a woman gave birth to two babies three weeks apart. This is called superfetation and is extremely rare in humans; there have been only ten confirmed cases so far. However, superfetation is more common in the animal kingdom, for example in hares, rabbits or cats.

Due to the hormonal changes caused by pregnancy, superfetation can only occur in the same cycle in which the first pregnancy occurred. This can happen if ovulation occurs despite an existing pregnancy. Normally a hormone activated by pregnancy prevents this. If the second egg is also fertilized and can implant in the uterus, superfetation takes place. It is not the same as a dizygotic twin pregnancy because two eggs are fertilized, but at the same time.

Bananas are radioactive, but that doesn’t mean you should bring a Geiger counter with you the next time you go shopping. The yellow fruits are a natural source of radiation because they are rich in potassium. This consists of 0.0117 percent of the radioactive isotope potassium-40. The radiation dose received from eating a banana is approximately 0.1 microsievert (μSv). That is bearable: 800 bananas correspond to the radiation exposure of a transatlantic flight. Moreover, we already radiate ourselves: an average adult contains about 16 milligrams of potassium-40, making it 280 times more radioactive than a banana.

By the way, the so-called banana equivalent dose is circulating among scientists: this corresponds to the radiation exposure caused by consuming a banana, namely 0.1 microsievert. This can be used to relate other radiation exposures: the total daily radiation exposure a person is exposed to is equivalent to 100 banana equivalent doses. So eating bananas is actually harmless; you would have to eat several million bananas at once to die from the radiation exposure it produces. In addition, the body excretes excess potassium within a few hours.

Speaking of bananas, if we didn’t have saliva, we would be much less able to perceive their typical taste when we eat them. In order for a food to develop its flavor, the chemicals in it must be dissolved in saliva. Only then can they be recognized by the receptors in our taste buds. In addition, there is an interaction between the food in the mouth and the saliva, which depends on the individual composition of this body fluid and the amount present.

Furthermore, the amount of saliva production depends on the time of day, and it can only increase when you think of a certain food or smell – as the saying ‘makes your mouth water’ puts it. There also appears to be a link between such stimuli – such as certain odors – and the composition of saliva.