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Why do your fingers shrivel up in the bath? – Kobus, Grade 8 Actually, your fingers are expanding rather than shrivelling. The outer layers of skin consist of flattened, dried-out cells. While you’re in the bath, water moves into the cells, causing them to expand. The bigger cells now need extra space to fit on your finger (which hasn’t become any bigger), so they start pushing into neighbouring cells, which in turn push upwards. This transforms your fingertips into a landscape of peaks and valleys. Once you’re dry, the water moves out of the cells and evaporates, and your fingers will return to their pre-prune state.

YOU KnOW Can people live to 200?

– Lebo, Grade 12 The oldest known person was a French woman, Jeanne Calment, who lived 122 years and 164 days. Predictions say it’s possible to extend this to 200, but not without technological help. Cells have a fixed life span, which is controlled by a tiny tail called a telomere at the end of each strand of DNA. Over time, a cell’s telomeres begin to wear down and when they become too short to protect the DNA, the cell knows it’s time to go. Cells that just won’t die become cancerous and cause other life-threatening conditions. Which means that only if technology can halt the ageing process and ward off the negative side effects might Grandma still be around when you become a grandma. Imagine the family photos! By Linda Pretorius • PHOTOGRAPHS: istock photos, Gallo/Getty images

You had questions. We have answers.

Is there anything harder than diamond? – Tebogo, Grade 10

Yup, diamond has officially handed over the crown to two naturally occurring materials: lonsdaleite and wurzite boron nitride (w-BN). Lonsdaleite can handle almost 60% more stress, while w-BN can cope with about 20% more pressure before it cracks. The materials are in some ways similar to diamond, but they differ in the way their atoms are bound. Materials like these are valuable for industrial drilling or use in space flight. But because very little is found naturally, engineers may have to settle for man-made superhard stuff called aggregated diamond nanorods – also much harder than natural diamond, but not nearly as pretty. 21

The Progress Issue  

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