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THE LAST WORD Born to drive How did we evolve to be able to safely control cars travelling at 100 kilometres per hour?
n In climbing, running, fighting, exploration and experiment over many millions of years, long before cars existed, our ancestors evolved strength, reflexes and intelligence adequate for driving. Humans and roads were therefore preadapted to cars, which were necessarily adapted rapidly to match. Context is all:
“Given that over a million people die in road accidents every year, it is clear we are not adapted to drive” had our preadaptations been different, so would our cars. No matter who drives, we want roads to match our vehicles and vehicles to match our evolutionary heritage that can be controlled in a way that does not kill us. Our roads evolved over millennia to serve foot traffic, then wagons, coaches, bicycles, and finally motorised traffic. We now demand vehicles and roads that allow us to read traffic situations a good 2 seconds in advance, for which our reflexes and coordination are adequate. If we had been given, say, the physical attributes of slugs or snakes, our cars would have been different, even if the performance and functions were similar. Jon Richfield Somerset West, South Africa
The writers of answers that are published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Please include a daytime telephone number and an email address if you have one. New Scientist retains total editorial control over the published content. Reed Business Information Ltd reserves all rights to reuse all question and answer material that has been
n The question has put evolution in the wrong place. We did not evolve to be able to safely control cars travelling at 100 kilometres per hour. It is cars that have evolved to be safely controlled by us. Early cars were certainly unsafe at any speed, and it was only user pressure that forced those off the road and applied the rule of survival of the fittest to roads and motor vehicles. Given that more than a million people die in road accidents every year, it is clear that evolution has not adapted us to drive. We can only hope that the evolution of the driving environment continues until it succeeds in counteracting our genetic shortcomings. Crispin Piney Mougins, France
Brewed at altitude How does atmospheric pressure affect the boiling point of water?
n Water molecules can always escape from their liquid phase to form vapour. These escapees exert a vapour pressure, which contributes to the overall atmospheric pressure and depends sensitively on temperature. At higher temperatures, water molecules in liquid move faster and are thus more likely to escape into the air. It is the most energetic molecules that escape, lowering the average speed of the remainder – which is why evaporation cools the
submitted by readers in any medium or in any format and at any time in the future. Send questions and answers to The Last Word, New Scientist, 110 High Holborn, London WC1V 6EU, UK, by email to [email protected] or visit www.newscientist.com/topic/lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
remaining liquid. For water to boil, vapour bubbles must form within the bulk of the liquid. However, these will be squeezed shut by the surrounding atmospheric pressure until the vapour pressure in the bubble matches it. Hence, water boils at the temperature at which these pressures become equal. This happens at a lower temperature when the atmospheric pressure is lower – up a mountain, for example. Conversely, it boils at a higher temperature if the pressure is increased, which is why food can be cooked more quickly in a pressure cooker. Chris Evans Earby, Lancashire, UK n A liquid boils when the atmospheric pressure above its surface equals its vapour pressure. So as the former decreases, the liquid’s boiling point does too. Thus at the top of Mount Everest, where the pressure is only about 34 kilopascals (compared to 101.3 at sea level), the boiling point of water is only about 71 °C. Eventually, when you reach outer space where the pressure is zero, liquid water boils instantly no matter what its temperature. One practical consequence of this is that although you can boil an egg at the top of a mountain, it may not actually cook because the temperature of the boiling water is too low. Simon Iveson Chemical Engineering Discipline
Faculty of Engineering and Built Environment The University of Newcastle New South Wales, Australia
This week’s questions Green machine
I bought too much broccoli a couple of weeks ago. Not wanting to waste it, I boiled and froze it. But when I came to defrost and eat it, it wasn’t as nice as the pre-frozen broccoli from a supermarket. Even though I hadn’t overcooked it, it was soft and a bit mushy, and the florets had all stuck together – whereas pre-frozen ones are separate in their bag. What do the producers do to avoid the problems I had? Billy Sturman Chelmsford, Essex, UK Rooting out trouble
I read that when cooking root vegetables, you should put them into the water when it’s still cold and bring them to the boil. But I also read that other types of vegetables should be placed in already boiling water. Why? Annemieke Wigmore Ilminster, Somerset, UK Playback payback
Why, as a general rule, do we not seem to like the sound of our own voices when we hear them in recordings? Melanie Green Hemel Hempstead, Hertfordshire, UK
Question Everything The latest book of science questions: unpredictable and entertaining. Expect the unexpected Available from booksellers and at newscientist.com/questioneverything
THE LAST WORD Born to drive How did we evolve to be able to safely control cars travelling at 100 kilometres per hour?
n In climbing, running, fighting, exploration and experiment over many millions of years, long before cars existed, our ancestors evolved strength, reflexes and intelligence adequate for driving. Humans and roads were therefore preadapted to cars, which were necessarily adapted rapidly to match. Context is all:
“Given that over a million people die in road accidents every year, it is clear we are not adapted to drive” had our preadaptations been different, so would our cars. No matter who drives, we want roads to match our vehicles and vehicles to match our evolutionary heritage that can be controlled in a way that does not kill us. Our roads evolved over millennia to serve foot traffic, then wagons, coaches, bicycles, and finally motorised traffic. We now demand vehicles and roads that allow us to read traffic situations a good 2 seconds in advance, for which our reflexes and coordination are adequate. If we had been given, say, the physical attributes of slugs or snakes, our cars would have been different, even if the performance and functions were similar. Jon Richfield Somerset West, South Africa
The writers of answers that are published in the magazine will receive a cheque for £25 (or US$ equivalent). Answers should be concise. We reserve the right to edit items for clarity and style. Please include a daytime telephone number and an email address if you have one. New Scientist retains total editorial control over the published content. Reed Business Information Ltd reserves all rights to reuse all question and answer material that has been
n The question has put evolution in the wrong place. We did not evolve to be able to safely control cars travelling at 100 kilometres per hour. It is cars that have evolved to be safely controlled by us. Early cars were certainly unsafe at any speed, and it was only user pressure that forced those off the road and applied the rule of survival of the fittest to roads and motor vehicles. Given that more than a million people die in road accidents every year, it is clear that evolution has not adapted us to drive. We can only hope that the evolution of the driving environment continues until it succeeds in counteracting our genetic shortcomings. Crispin Piney Mougins, France
Brewed at altitude How does atmospheric pressure affect the boiling point of water?
n Water molecules can always escape from their liquid phase to form vapour. These escapees exert a vapour pressure, which contributes to the overall atmospheric pressure and depends sensitively on temperature. At higher temperatures, water molecules in liquid move faster and are thus more likely to escape into the air. It is the most energetic molecules that escape, lowering the average speed of the remainder – which is why evaporation cools the
submitted by readers in any medium or in any format and at any time in the future. Send questions and answers to The Last Word, New Scientist, 110 High Holborn, London WC1V 6EU, UK, by email to [email protected] or visit www.newscientist.com/topic/lastword (please include a postal address in order to receive payment for answers). Unanswered questions can also be found at this URL.
remaining liquid. For water to boil, vapour bubbles must form within the bulk of the liquid. However, these will be squeezed shut by the surrounding atmospheric pressure until the vapour pressure in the bubble matches it. Hence, water boils at the temperature at which these pressures become equal. This happens at a lower temperature when the atmospheric pressure is lower – up a mountain, for example. Conversely, it boils at a higher temperature if the pressure is increased, which is why food can be cooked more quickly in a pressure cooker. Chris Evans Earby, Lancashire, UK n A liquid boils when the atmospheric pressure above its surface equals its vapour pressure. So as the former decreases, the liquid’s boiling point does too. Thus at the top of Mount Everest, where the pressure is only about 34 kilopascals (compared to 101.3 at sea level), the boiling point of water is only about 71 °C. Eventually, when you reach outer space where the pressure is zero, liquid water boils instantly no matter what its temperature. One practical consequence of this is that although you can boil an egg at the top of a mountain, it may not actually cook because the temperature of the boiling water is too low. Simon Iveson Chemical Engineering Discipline
Faculty of Engineering and Built Environment The University of Newcastle New South Wales, Australia
This week’s questions Green machine
I bought too much broccoli a couple of weeks ago. Not wanting to waste it, I boiled and froze it. But when I came to defrost and eat it, it wasn’t as nice as the pre-frozen broccoli from a supermarket. Even though I hadn’t overcooked it, it was soft and a bit mushy, and the florets had all stuck together – whereas pre-frozen ones are separate in their bag. What do the producers do to avoid the problems I had? Billy Sturman Chelmsford, Essex, UK Rooting out trouble
I read that when cooking root vegetables, you should put them into the water when it’s still cold and bring them to the boil. But I also read that other types of vegetables should be placed in already boiling water. Why? Annemieke Wigmore Ilminster, Somerset, UK Playback payback
Why, as a general rule, do we not seem to like the sound of our own voices when we hear them in recordings? Melanie Green Hemel Hempstead, Hertfordshire, UK
Question Everything The latest book of science questions: unpredictable and entertaining. Expect the unexpected Available from booksellers and at newscientist.com/questioneverything