Dr Tom Smith: Standing tall

Why are we the only animals to walk so upright?

My pet anthropologist suggests two reasons. The first is that around eight million years ago, when we were in what's now east Africa, the climate changed from forests to savannah with tall grasses as the main vegetation. We had to learn to stand upright to look over the grasses to detect sabre-toothed cats, our main predator at the time. The other is that our ancestors spent about four million years in the lagoons between the shore and the reefs of east Africa, during which time we were slowly becoming marine animals - which naturally had to be streamlined. We then came back to live on land, by which time our bodies had evolved into their current shape.

I take a small dose of aspirin every day for angina. I also get arthritic pains, and have been taking ibuprofen. Now my doctor says I should change that for another anti-inflammatory. Why should I? I've found it's the most effective.

Ibuprofen may counteract the protective effect of aspirin on clotting and on changes in the blood vessel walls, so by taking it you could be putting yourself at a higher-than-normal risk of a heart attack or stroke. Other anti-inflammatory drugs in the same group as ibuprofen, such as diclofenac or naproxen, don't appear to have this anti-aspirin effect, so take one of them instead. If you are taking daily low-dose aspirin, discuss with your doctor the drugs you can take, say, for those odd aches and pains or colds everyone has from time to time.

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