Big cities get a bad rap - they’re more congested, they create more pollution, and they have more crime. Yet a new study shows that bigger is better. ”As cities get larger, they create more wealth and are more innovative at a faster rate,” says Jose Lobo, an economist at Arizona State University who worked on a study that weighs cities’ consumption of resources against their contributions to society.
Today, a little more than half of the world’s population lives in large urban areas, and by 2030, that figure is expected to jump to two-thirds.
Lobo and his team looked at data on the growth of cities in the US, Europe and China over the past 150 years, measuring consumption of resources and then calculating creative output - using measures such as patents issued, R&D employment and total wages.
They found that, as a city grew, it required fewer resources to sustain it. Moreover, as cities got bigger, their creative output - jobs, wealth generated, innovation - grew faster and faster. ”The increase you get in wealth creation is greater than the increase in size of the city,” says Lobo.
Lek it or not
Researchers believe they have solved a mystery that has baffled evolutionary scientists for years: if ”good” genes spread through the population, why are people so different? The ”lek paradox”, that sexually selecting species should have much less individuality than is the case, has been seized upon by creationists as evidence that Darwin’s theories are flawed.
The problem with current evolutionary theory is that if females select the most attractive mates, the genes responsible for attractive features should proliferate through a population, resulting in males becoming equally attractive, to the point where sexual selection could no longer take place.
But two scientists from Newcastle University have now shown how sexual selection can cause more genetic diversity than might be expected. Since genetic mutations can happen anywhere in the genome, they argue, some will affect the ”DNA repair kit” held by all cells. This means some people have less efficient kits, resulting in greater variation in DNA.
Using a computer model to map the spread of genes in a population, the scientists showed that the tendency towards reduction in genetic diversity caused by sexual selection is outweighed by the greater genetic diversity generated by mutations affecting DNA repair.
How to get A’s from zzzzz’s
If you’re cramming for a test, the best preparation may be a good night’s rest. According to a new study by researchers at Harvard Medical School, sleep not only strengthens memories, but also protects them from outside interferences (competing information).
The researchers divided adults with normal sleep routines into four groups. The first two were taught 20 word pairings at 9am and then tested on them at 9pm, after 12 hours awake. The next two were taught the same word pairs at 9pm and tested at 9am, after a night of sleep. Just before testing, one group from each time slot was given word lists with competing information. These two groups - trying to cope with interference - were then tested on both lists.
The study found that people who slept after learning the information performed best. Those in the sleeping group without interference were able to recall 12 per cent more pairings from the first list than the wake group without interference. With interference, the recall rate was 44 per cent higher for the sleep group.
