Answers to Dr Darwin’s questions April 2017_1

Answers to questions April 2017_01

1. Why do Darwin’s finches have different shaped beaks?

These finches live in the Galapagos Islands. Their beaks have evolved to eat different seeds – cactus, grass, etc. Peter and Rosemary Grant carried out a study on Daphne Major in the Galapagos over 40 years, and showed that they evolve in real time. If there is a major climate event that wipes out a particular seed, then there is a Natural Selection that operates on the finches so that they can eat alternative seeds. Darwin didn’t realise how important these finches were until he got back to England from the Beagle. It was the ornithologist John Gould who first reported their significance to Darwin and the world.

See for further information.

2. How has this green jellyfish revolutionised biomedicine?

The green in this picture is from the famous green fluorescent protein (GFP) in the small luminous jellyfish Obelia. GFP was discovered by Osamu Shimomura in 1962/3 in the luminous jellyfish Aequorea. GFP has the remarkable property of changing the colour of the light emitted from blue to green. Once the DNA was isolated that codes for GFP it was found that whenever this DNA is expressed ina cell, the cell becomes green fluorescent. It is this a marker and can be used to follow cancer cells in a live organism. Mutations of GFP produced a rainbow of colours. Osamu Shimomura , Roger Tsien and Martie Chalfie received the Nobel Prize for Chemistry in 2008, for the pioneering work on GFP.

3. Who discovered these?

(a) The = sign

The equals sign (=) in mathematics was actually first used by Robert Recorde (c. 1512–1558). He was a Welsh physician and mathematician, who lived in the beautiful town of Tenby in Pembrokeshire, west Wales. His invention of the = sign is to be found in his book ‘The Whetstone of Witte, whiche is the seconde parte of Arithmeteke: containing the extraction of rootes; the cossike practise, with the rule of equation; and the workes of Surde Nombers (London, 1557). Thus Recorde introduced algebra to Great Britain. A copy of this book is held in the Tenby museum. He also was the first to introduce the + sign to Britain in 1557.

(b) π

The first recorded estimate of the value of π was by the Babylonians, 25/8 = 3.125. Then the Egyptians estimated it to be about 256/81 (ca 3.16). The famous Greek mathematician Archimedes of Syracuse (287-212 BC), when he was not in his bath, calculate the first accurate estimation π = 3.14159, and the Greeks proved that the ratio of the circumference to its diameter of every circle is π. I wonder is you can prove this, and that the area of every circle is πr2.

Good luck.




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