51¶¯Âþ

Having read your leader on inequalities in sport, I would say that it is a statistical inevitability, rather than unfairness, that a country with a large population will (all things being equal) have more sports stars than one with a small population. This is the same for any field of endeavour. Is it a problem …

You report artificial intelligence's ability to predict dangerous tipping points in complex systems, such as stock markets. Will it predict and tell us when it is going to take over and unleash our own weapons on us, or create new viruses leading to the extinction of most human life( 3 August, p 18 )?

When considering what makes us human, there is a different way of looking at things. Clearly the journey from non-human apes to us is a continuum, but there are two features that seem undeniably human. We are the only species to truly harness energy other than from what we eat. The second, somewhat more shameful, …

When it comes to ice melt changing currents in the Atlantic Ocean that help keep northern Europe relatively mild, there is another factor at work beyond rising temperatures. Wildfires in North America are burning at ever-increasing rates. Much of the ash and soot is deposited on the Greenland ice sheet, changing its albedo and vastly …

Hands-on experiments to understand Neanderthal food preparation reminded me of my time working with a class of reluctant 14 and 15-year-olds. We were studying early "man", including flint tools. I acquired some large flint nodules and the students could try making simple tools – harder than it looked – then use them in various ways …

I was heartened to read that the benefits of exercise start at low levels. I was once involved in monitoring the exercise people get while doing normal office duties. It often amounts to as much or more than they get in their free time, so office design and practice could significantly improve health. Mobility around …

It seems premature to say that the downsides of anti-ageing therapies are a price worth paying. If they include a population explosion that turns out to be the last straw for an already overburdened planet, I suspect that the people alive at that time would disagree ( Leader, 6 July ).

In the UK, around 60 per cent of 6-year-olds are moderately to strenuously active for an hour a day, but that drops as they age – by 2.5 minutes per day each year ( 27 July, p 42 ). A helium II ion involves the removal of a single electron ( 3 August, p 36 …

Christa Lesté-Lasserre discusses the furore over a horse being whipped while training for dressage events, but doesn't address the major concern: why make a horse dance to order? If animals are unwelcome in circuses, why make a horse dance carrying a rider and call it a sport? Why "train" a horse to jump a very …

You speak of doping in sports as an unfair advantage. I agree. But a few pages later in the same issue ( p 11 ) you report that a Google AI has achieved a silver medal score in a human mathematics competition ( Leader, 3 August ). Considering that a computer uses much more energy …