Mosquito bites frequently induce a sharp sting in people and some animals, with severe evolutionary consequences for the mosquito when it gets swatted.
Are any mosquitoes evolving with delayed-action stings or reduced sting secretions so they can drink blood without the threat of imminent death?
The C-14 within an organism is continually decaying into stable carbon isotopes, but since the organism is absorbing more C-14 during its life, the ratio of C-14 to C-12 remains about the same as the ratio in the atmosphere.
Libby in 1949, and has become an indispensable part of the archaeologist's tool kit since.
As the Earth's upper atmosphere is bombarded by cosmic radiation, atmospheric nitrogen is broken down into an unstable isotope of carbon - carbon 14 (C-14).
The unstable isotope is brought to Earth by atmospheric activity, such as storms, and becomes fixed in the biosphere.
Because it reacts identically to C-12 and C-13, C-14 becomes attached to complex organic molecules through photosynthesis in plants and becomes part of their molecular makeup.
There are two basic approaches: relative age dating, and absolute age dating.
Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.A man called Willard F Libby pioneered it at the University of Chicago in the 50's. This is now the most widely used method of age estimation in the field of archaeology.Unlike people, you can’t really guess the age of a rock from looking at it.Is it because feral domesticated animals can somehow live on in poor health through their association with humans, whereas nature would ruthlessly pick off any weaklings in the wild animal population?In your article about housework ("Germ warfare", 14 January), you said that after washing dishes we should "rinse with plenty of water, preferably hot". Wouldn't it save money if they were rinsed with the cold water that comes directly from the mains?I have seen this advice before, saying it is not safe to keep cooked rice for more than a short time, even in the fridge.