I learned this today. The first evidence for a wedding ceremony between a man and a woman is from Mesopotamia in 2350 BC. In the time of hunter-gatherers, people lived in small groups, probably of about thirty people. Each group would have several male leaders who shared the women. They would all care for and […]
#112 When did people first start getting married? Read More »
I learned this today. Evergreen trees keep their leaves for longer because they have evolved to survive in colder areas with less yearly sunlight. An evergreen tree is a tree that doesn’t lose its leaves all at once in the way a deciduous tree does. The leaves do fall off, but when they are old,
#111 Why don’t evergreen trees lose their leaves in the winter? Read More »
I learned this today. The Malthusian theory of population doesn’t apply today because we can basically produce more food than was previously possible. Thomas Malthus lived from 1766 to 1834 and he was an English cleric, scholar, and economist. Malthus did a lot of work, but he is primarily remembered for the theory on population
#110 Why doesn’t the Malthusian theory of population apply today? Read More »
I learned this today. Graphene is a one-atom-thick layer of carbon atoms arranged in a hexagonal lattice. It is incredibly thin and incredibly strong. In 1859, Benjamin Brodie noticed that graphite oxide contained lots of layers. In 1947, P. R. Wallace published a paper on the band structure of graphite and theorized that a single
#109 What is graphene and why is it so important? Read More »
I learned this today. The International Prototype of the Kilogram, kept in Paris, is not accurate enough to be the standard for all kilograms around the world. Different measures for different things have been used around the world since people began measuring things. These measurements were usually related to the human body or common things
#108 Why is the official kilogram in France no longer used? Read More »
I learned this today. Adolf Hitler had three brothers, two sisters, one half-brother, and one half-sister. Because of the things he did, it is difficult to see Hitler as a real person, but of course he was, and he has a family. Adolf Hitler was born on April 20, 1889, to Alois Hitler and Klara
#107 Did Adolf Hitler have any brothers or sisters? Read More »
I learned this today. The Milky Way Galaxy orbits the barycenter of the Local Group. The barycenter is the center of mass of two bodies that orbit each other. It is the point that they orbit around. The word comes from Ancient Greek and means “heavy center”. When two objects orbit each other, there is
#106 What does the Milky Way Galaxy orbit? Read More »
I learned this today. Vikings is the name given to the seafaring people from Scandinavia who raided through Europe from the late 8th century to the late 11th century. The Vikings didn’t call themselves “Vikings” and the word wasn’t used to refer to all of the people and the time period until the early 18th
#105 Why do we use the word Vikings? Read More »
I learned this today. Cats don’t so much retract their claws as lift them off the ground using tendons. Their claws are then hidden by their fur. Cats have five claws on their front paws and four claws on their back paws. The front claws are usually sharper than the back ones. Cats’ claws continue
#104 How do cats retract their claws and why can’t other animals? Read More »
I learned this today. Shoe sizes in America and the UK are measured in barleycorns. Nobody knows when people first started wearing shoes, but experts think it might have been about 40,000 years ago. The little toe bones of skeletons found after 40,000 years ago are thinner than the bones found before. They deduce that
#103 Why do we use those measurements for shoe sizes? Read More »
