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What are snakes? Evolution and biology

By | 2017-10-05T09:50:11+00:00 September 16th, 2017|Biology|

Two pythons Snakes evolved from lizards only about 150 million years ago, during the Jurassic Period. This is during the time of the dinosaurs, about the same time that the first birds evolved from small dinosaurs. Like birds and mammals, though, snakes really began to take over after most of the dinosaurs died about 95 million years ago, at [...]

The human body in medieval and modern science

By | 2017-09-06T23:14:25+00:00 September 6th, 2017|Biology, Science|

Chinese drawing of the organs (about 1200) Between the Middle Ages and modern times, doctors have learned a lot of new things about how human bodies work. The Islamic doctor Al-Tabari, in the early 800s, learned that light bounces off objects into your eyes. Al-Tabari's student Al Razi figured out that a fever is your body's way of fighting illness, not [...]

What is cholera? History of disease and medicine

By | 2017-09-06T17:31:15+00:00 September 6th, 2017|Biology, Science|

Washing clothes in the river (India) Cholera (KOLL-uh-rah) is a very serious sickness. It probably first got started in India. People in India were dying of cholera by the time of Chandragupta, about 300 BC, and maybe earlier. Cholera epidemics in India usually got started during monsoons. During the monsoon, warm rain fell and raised the water [...]

Triassic period – pine trees and pterodactyls

By | 2017-06-25T01:47:43+00:00 June 25th, 2017|Biology, Geology|

A turtle in the desert During the Triassic period (about 248 to 199 million years ago), most of Earth's land continued to stick together in one big supercontinent, Pangaea. Because the middle of Pangaea was so far from the oceans, it was very dry there, like a desert. The whole world was generally [...]

Tertiary period – mammals and mountains

By | 2017-06-25T01:35:37+00:00 June 25th, 2017|Biology, Geology|

Large animals evolved like moose The Tertiary period begins with the catastrophe that killed off the dinosaurs, about 65 million years ago, and it lasts down to 1.8 million years ago. With nearly all of the dinosaurs gone, there was plenty of room on Earth for the mammals to have lots of babies, [...]

Silurian period – Fish get jaws

By | 2017-06-25T01:28:05+00:00 June 25th, 2017|Biology, Geology|

Trout swimming The beginning of the Silurian period was about 443 million years ago. Some environmental problem at the end of the Ordovician period (probably ice ages) killed most of the plants and animals on Earth. The creatures that survived this extinction were the ones that were most able to change quickly to [...]

Quaternary period – modern times

By | 2017-06-24T16:56:54+00:00 June 24th, 2017|Biology, Geology|

The Quaternary period began about 1.8 million years ago (1,800,000 years ago). It is still going on today - we live in the Quaternary period. So far, it's a much shorter period than the others. At the beginning of the Quaternary period, early people in Africa were already using stone tools. The climate was mostly [...]

Proterozoic Eon – eukaryotes to worms

By | 2017-06-24T16:51:41+00:00 June 24th, 2017|Biology, Geology|

Two and a half billion years ago, the Archaean Eon ended and the Proterozoic Eon began. Trillions of prokaryote cells lived in Earth's oceans. Some of these cells could photosynthesize their energy from sunlight, water, and carbon dioxide. These photosynthesizing cells pooped out a lot of oxygen. By about 2.3 billion years ago, the iron [...]

Permian period – Reptiles and pine trees

By | 2017-06-24T16:42:29+00:00 June 24th, 2017|Biology, Geology|

Crocodiles About 290 million years ago, the Carboniferous period ended and the Permian period began. Almost all of the land on Earth grouped together in one big supercontinent we call Pangaea, which reached all the way from the North Pole to the South Pole. With all the land grouped together, the climate got [...]