Even though science made a significant progress in the last couple of decades and clarified many mysteries of life, some of them remain completely unexplained.
Here we represent a couple of those unsolved problems:
Why do grazing cows always face south or north?
Scientists analyzed thousands of photographs of grazing cows (all of them came from Google Earth satellite) and discovered that they always face the North or the South magnetic pole. However, nobody knows why. Earlier discoveries showed that some animals have so-called inner compass, but this is the first time this kind of behavior was detected with bigger mammals.
Why did some mammals choose life in water?
Land forms of life evolved from water, they developed limbs enabling them to walk on the ground. Nevertheless, some of them, such as remote ancestors of whales and seals, chose to go back to water. One thing is certain: life in the sea is much more difficult than life on the ground because it requires extensive amount of energy. This is why scientists are bothered with this fact so much.
In addition to this, sea mammals developed efficient method of tail navigation, which raises a question if they ever even tried to settle on the ground.
Scientists still do not know why plants contain alkaloids. The most famous alkaloid is morphine and there are 7000 types of this substance that can cause different reactions in human organism after consummation. In case of poppy, plant that also contain morphine, scientists believe that morphine serves to deter predators.
Why are flowers everywhere?
Floriferous plants form a class of plants known as angiosperms, which can be found everywhere. Interesting thing is that they were not so common in the past. About 400 million years ago, angiosperms replaced many other plant types and now they represent 90 percent of all plants on earth. Even Charles Darwin could not explain this phenomenon, he named it “abominable mystery”.
Why is biodiversity the greatest near the Equator?
Moving from colder regions of earth towards Earth’s equator, number of plant and animal species increases. The first one to notice this was Prussian explorer Alexander von Humboldt about 200 years ago, yet he couldn’t explain it. Scientists today suggest around 30 hypotheses, but they still do not offer unanimous conclusion.
Paradox of the phytoplankton
Phytoplankton represent a class of marine organisms with many subclasses. These floating organisms developed in so many different forms that, considering very limited resources, scientists cannot understand how they managed to survive. However, these plants are still there.
The same confusion remains when it comes to other numerous maritime organisms that live from the limited quantities of nutrients in the seawater. This phenomenon is known as the paradox of enrichment because it is expected that biodiversity is higher in nutrient-rich areas.
How do Argentine ants maintain their colonies around the world?
Argentine ants look like ordinary insects. However, with an exception of people, they are the only species that managed to colonize three continents. Super-colonies of these ants can be found in Europe, South America and Asia. All three colonies have the same genetic traits, and essentially, they are the same population. Additionally, they are capable of recognizing members of their own species, but they tend to be aggressive towards each other. Their genetic code has not changed for thousands of years, which is unusual because organisms outside their homeland usually evolve rapidly.
The mysterious human ancestor
The origin of modern humans has been thoroughly studied in recent years. That is why we know a lot about our ancestors. However, everything we learned so far became questionable after the discovery of a different DNA. The new DNA was found in the remains of Denisovans, hominids close to Neanderthals. We do not know much about Denisovans but we at least know where they came from and where they settled. The same cannot be said for the species that lived and mixed with Denisovans 30.000 years ago.
Animals that live without oxygen
Almost all living organisms need oxygen in some of its forms. That is why the scientists were surprised when they discovered animals in the depths of the Mediterranean Sea which have no need for this gas. It is a class of tiny animals that scientists believe have evolved in a way that they can live on salt. Previously, nobody knew that multicellular organisms which can survive without oxygen even existed. This is the reason we still don’t know anything about their evolution.
Apart from some microbes and plants, almost all living beings in the world reproduce sexually. We take that for granted, so we do not realize that this is an important evolutionary anomaly. Half of each species – males – is not capable of giving birth, but that half still uses the same amount of resources from the environment. What is the reason for investing so much effort in developing this kind of reproductive mechanism, which obviously has its drawbacks?
This is often explained with a theory that sex reduces chances of harmful mutations, but this probably is not the right answer. Scientists examined 700 genes of different organisms and they found that each generation has 0.5 deleterious mutations. This means that previously stated point of view is not enough to justify sexual reproduction. Sex is still something that scientists do not fully understand.