Four scientific anecdotes to liven up your family meals!

Why does the Moon have spots? How many living things does a single teaspoon of soil contain? To provide you with some consensual topics of conversation at Christmas, while dangling the next release of our paper review, here are four scientific anecdotes from the four files of our magazine.

Let’s face it: many of us will not escape the traditional anti-science clichés at year-end family reunions. There always comes a time when the climate-skeptic uncle or the anti-ax sister-in-law finds it opportune to launch a remark likely to degenerate into a heated debate and spoil the digestion of the Yule log.

To avoid falling into such a vicious circle, we offer four backfires to light in an emergency. Four scientific anecdotes, astonishing extensions of the field of knowledge and sources of a priori consensual wonder. Cherry on the cake: these anecdotes are taken from the four files of our new magazine, which will be released in January. One way for us to make you wait until then, and to wish you happy holidays!

1. Why does the Moon have spots?

We can admire him almost every night and some have fun imagining characters in his contrasts dark. Several mythologies even see in its spots the outline of a divine rabbit living on the Moon. The Chinese rover Yutu 2, the first human machine to run on the dark side of the moon in 2019, gate for this reason a name meaning « jade rabbit ». We also owe toastronomer Michael Florent van Langren, author of one of the first lunar maps in 1645, the denomination of « sea » to designate these large craters, because it was thought then these dark spots reflected the existence of oceans on the Moon.

In reality, these darker areas reveal the presence of basalt. They are the vestige of ancient flows of make gigantic craters that filled the largest lunar craters 3.7 to 3.3 billion years ago. This lava came from inside the moon, which was extremely hot at the time. The magma, under the effect of the pressure, then tended to rise towards the surface but it did not manage to pierce the crust lunar than in the places where it was the thinnest: where impact craters had thinned it. That is why this basalt, these spots, today follow the rounded shape of these craters. In a sense, these were seas and oceans … but lava oceans!

2. Our genes are only a tiny part of our DNA

We tend to use the two terms interchangeably, yet our Genoa maybe only … 2% of our DNA ! To be more precise, researchers now estimate at around 20,000 the number of genes encoding protein within the genome human. These genes are made up of sequences of nucleotides along the double helix structure of theADN. But large parts of this long sequence of nucleotides (the human genome has 3.2 billion nucleic bases in all) do not encode any protein: 90 to 98% of the whole according to the researchers.

If these sequences were previously nicknamed « junk DNA », scientists are gradually discovering the fundamental role that these regions of the genome can play. Some, located next to genes and called promoters, are used to regulate their expression or have a role in epigenetic mechanisms. Another example, sequences repeated identically and located at the end of the chromosomes, called telomeres, serve to preserve theintegrity chromosomes. Telomeres shorten with each cell division, which plays a role in aging but also protects against cancers. Other large swathes of DNA fulfill a function still unknown to researchers, including among the genes themselves.

3. How many living things does a teaspoon of soil contain?

It’s a world in itself. A universe teeming with life forms rich, diverse and intertwined with complex relationships like no other. In a teaspoon (5 grams) of forest soil under our latitudes, we find up to 50 million bacteria owned by thousands ofcash different, thousands of species of mushrooms but still amibes, nematodes, algae, mites, ciliates, viruses …

There is nothing fortuitous about this wealth: on the contrary, it is this wealth which gives the earth its fertility, which forms thehumus and allows plants to feed, some micro-organisms living in symbiosis with their roots, providing them with minerals essential to their metabolism in exchange for sugars offered by plants. If you take a little more than a teaspoon, you will easily find a little larger animals, insects and worms, veritable ploughmen of the soil. All these beautiful people represent 50 to 75% of the biomass alive on Earth and 26% of listed species. They have a key role to play in capturing the carbone face au global warming and in the optimization of agricultural practices … on condition of better understanding and respecting them.

4. The machine overtakes the human brain … by consuming 50,000 times more energy

In 2016, l’IA AlphaGo developed by DeepMind (acquired two years earlier by Google) beats Korean Lee Sedol, one of the best players in the world, in the game of go. The event caused a sensation because go had until then been considered one of the most difficult games to simulate for an AI, the possible combinations being vastly more numerous than in chess, for example. But to beat its human opponent, DeepMind’s algorithm deployed a huge amount of energy, estimated at up to 1 megawatt, against … 20 watts for the human brain. Or 50,000 times less.

Since this symbolic confrontation, engineers have certainly not stopped improving the performance of their AIs and optimizing energy consumption. But this remains a major issue, especially during the learning phases of algorithms. In 2019, AI researchers (artificial intelligence) from the University of Massachusetts estimated for example that the training of a single artificial neural network could emit as much CO2 that five cars over their entire life cycle. If you get complex the next time you play against a computer, remember that your brain and its 86 billion neurons remain an unparalleled wonder of efficiency and learning abilities.

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