As soon as Fubao got home, he started showing off his bamboo. He is a bear, so why does he choose to be a vegetarian? | Expo Daily

As soon as Fubao got home, he started showing off the bamboo.

It’s obviously a bear, why choose to be a vegetarian?

The ancestors of giant pandas mainly ate meat, which could be said to be at the top of the food chain. Later they became vegetarians, which was also determined by objective conditions.

The early giant panda had sharp canines and carnassial teeth, a short intestine, and the digestive physiology of a carnivore, but it was not as ferocious and agile as other carnivorous animals (such as tigers and leopards). If the meat source was insufficient, it could only look for other food and gradually evolved into a herbivorous animal.

Herbivores such as rabbits and antelopes are agile in obtaining food, and cattle have rumens to store food and then regurgitate it in a safe environment to digest it slowly. Giant pandas have neither such agility nor such an organ structure as a rumen, so they "take a different approach" and choose food types that other animals do not eat.

The giant panda's choice of a "vegetarian" diet is also related to its ancient habitat. The formation of the giant panda fauna has undergone multiple complex evolutions in biogeological history and habitat, and ultimately took the large-scale cold-temperate subalpine evergreen coniferous forest in the middle of the vertical zone spectrum on the eastern edge of the Qinghai-Tibet Plateau as its main habitat.

Among so many plants, why did it choose bamboo?

As the dominant species and community-building species in the subalpine evergreen coniferous forest shrub layer, the number of individuals of the bamboo is large, the growth density is high, and the bamboo is asexually reproduced, and the iteration speed is fast. Therefore, these characteristics of the bamboo can meet the food needs of the giant panda. The bamboo genus is the basic food of the giant panda and is called the staple bamboo. This is also a result of co-evolution.

As soon as he got home, Fubao ran straight to Zhuzi.

Image source: Xinhua News Agency

Are my parents not lying? Did humans come out of cracks in the rocks?

Laboratory experiments published in Nature find that heat flowing through rock fractures - such as occurs in volcanoes or geothermal systems - can purify molecules associated with the chemical origins of life.

Scientists have discovered that the precursors of life macromolecules must undergo a very complex transformation process to polymerize into real macromolecules. The by-products formed by these complex reactions are so numerous that the output of life-related macromolecules is extremely small.

Christof Mast and his colleagues discovered in their geology research that there were a large number of chambers formed by cracks in the early Earth's crust, and geothermal flows would flow through these chambers to form temperature differences. Chambers with different temperatures formed different temperature gradients, which means that specific types of reactions would only occur in chambers with specific temperatures.

The researchers verified this hypothesis by simulating these crustal chambers in the laboratory and conducting corresponding synthetic experiments. In the simulated chambers, the concentrations of life molecules such as 2-aminoazole and amino acids increased by 10 times and 3 orders of magnitude respectively.

The experiment was successful at various temperatures, solvents, and pH values, and the coupling of amino acid molecules was isolated in the experimental product, which is equivalent to the synthesis of protein. This study shows that naturally occurring geothermal heat flow may have driven the compounds needed for the origin of life on the early Earth. Maybe life really did pop out of the cracks in the stone.

An underground network of interconnected rock fractures facilitated the early chemical processes that led to the emergence of life.

Image source: Christof B. Mast

No hay fever? Don’t be too happy yet…

Spring is the peak season for allergies. While most people are immersed in the beauty of spring, some people experience symptoms such as runny nose, sneezing, and itchy eyes, and are miserable.

Allergy is an abnormal immune response, which means that the immune system is not performing its normal functions and is "out of control". The immune system mistakenly judges some substances that are harmless to the human body as harmful, thus generating a series of reactions to attack, causing discomfort to the human body. This is the so-called "allergic reaction", and allergic reaction is one of them. The culprit is various allergens, such as hay fever caused by pollen.

Simply put, hay fever is the body's allergic reaction to certain specific proteins on the wall of pollen. Even if you don't have hay fever, try to stay away from allergens, because this disease can be "learned". Beautiful flowers are often insect-pollinated and do not cause hay fever. Instead, it is the pollen of greening trees such as juniper, cypress, willow, and ginkgo that makes people complain.

Some people may have never experienced the power of hay fever since childhood, but this does not mean that they will never experience it. Sufficient stimulation, or temporary low immunity (perhaps hyperimmunity is more severe), or just moving to a new city and being exposed to new allergens may make you "learn" hay fever. Once you learn it, you will never forget it, and even pass it on to the next generation. Moreover, the symptoms may gradually worsen. For example, if the patients with rhinitis caused by hay fever are not treated, half of them may develop asthma within a few years. It is better to wear a hat and mask as much as possible to avoid the limelight~

Bees pollinating.

Image source: Pixabay

23:59:60≠00:00:00, this second can be delayed for another three years

The international standard time we rely on, Coordinated Universal Time (UTC), is facing a new challenge. The Earth's rotation is gradually increasing, which may force us to use "negative leap seconds" to adjust time for the first time. However, a new study may provide metrologists with a little respite.

Changes in the speed of Earth's rotation are affected by a variety of factors, including changes in the distribution of Earth's mass, earthquakes, and the melting of the polar ice caps. These factors cause a deviation between UTC and the Universal Time (UT1) of Earth's rotation. To keep the two in sync, we introduce leap seconds - an extra second that is occasionally added to UTC to compensate for this deviation.

However, as digital technology developed, the irregularity of leap seconds began to cause problems for precision timekeeping systems such as the Global Positioning System. Therefore, the International Conference on Weights and Measures decided to suspend leap second adjustments from 2035. However, the acceleration of the Earth's rotation means that we may soon need to subtract a leap second, which has never happened before in history and may cause greater damage to computer systems.

However, a new study finds that melting ice sheets are changing Earth's moment of inertia, slowing its rotation. This process could delay the first possible negative leap second from 2026 to 2029, buying metrologists extra time to adjust international timekeeping standards.

Image source: Pixabay

Is blood test reliable?

Is it a scientific judgment or a false case? The "blood test" invented during the Three Kingdoms period and regarded as a golden rule by the world is a must-see in novels, TV series, and movies. The method of judgment is also very simple. As long as the blood of two people mix, they are biological father and son. So the question is, is the "blood test" reliable? Click on the video to find out.

The content is compiled from China Science Popularization Expo Weibo, Science Academy, Principle, Science Network

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