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Matt Ridley is the author of provocative books on evolution, genetics and society. His books have sold over a million copies, been translated into thirty languages, and have won several awards.

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Archive for date: 01-2012

Why do diseases cause species decline?

My latest Mind and Matter column in the Wall Street Journal is about the role of disease in species conservation:

Some beekeepers, worried by the collapse of their bee colonies in recent years, are pointing a finger this month at a class of insecticide (neo-nicotinoids) that they think is responsible for lowering the insects' resistance to disease. They may be right, but I'm cautious. History shows that, again and again, blaming chemicals for the decline of a species has prematurely exonerated the real culprit, which is often disease alone.

The role of parasites in causing species to decline is often overlooked. Native European red squirrels, for example, have long been retreating in Britain at the hands of the American gray squirrel, which menagerie-owning aristocrats introduced in the 19th century. For years it was thought to be the competition for food that prevented the squirrels' co-existence, but now scientists place most of the blame on a parapox virus that causes a mild illness to the grays but kills the reds.

Where blue eyes came from

My latest Mind and Matter column for the Wall Street Journal is on gene-culture co-evolution:

Human beings, we tend to think, are at the mercy of their genes. You either have blue eyes or you do not (barring contact lenses); no amount of therapy can change it. But genes are at the mercy of us, too. From minute to minute, they switch on and off (i.e., are actively used as recipes to make proteins) in the brain, the immune system or the skin in response to experience. Sunbathing, for example, triggers the expression of genes for the pigment melanin.

As a recent study confirms, on a much longer time scale, genes are even at the mercy of culture. The paradigmatic example is lactose tolerance. All mammals can digest lactose sugars in milk as babies, but the lactase gene switches off at weaning when no longer needed. In much of Europe and parts of Africa, by contrast, most people can digest lactose even as adults, because the lactase gene remains switched on. (About 90% of East Asians and 70% of South Indians are lactose-intolerant to some degree.)

On Ice

One of my favourite writers these days is Willis Eschenbach, whose essays at wattsupwiththat often combine ingenious scientific rationality with lyrical prose. Here he is on the subject of the sea ice off Alaska:

My point in this post? Awe, mostly, at the damaging power of cold. As a seaman, cold holds many more terrors than heat. When enough ice builds up on a boat's superstructure, it rolls over and men die. The sun can't do that. The Titanic wasn't sunk by a heat wave.

The thing about ice? You can't do a dang thing about it. You can't blow up a glacier, or an ice sheet like you see in the Bering Sea above. You can't melt it. The biggest, most powerful icebreaker can't break through more than a few feet of it. When the ice moves in, the game is over.

The distorting of the human sex ratio

My latest Mind and Matter column in the Wall Street Journal: Even a rational optimist is pessimistic about some things. Here's one: the gradual distortion of the human sex ratio by sex-selective abortion. A new essay by the demographer Nicholas Eberstadt concludes that "the practice has become so ruthlessly routine in many contemporary societies that it has impacted their very population structures." He finds "ample room for cautious pessimism" in the fact that this phenomenon is still very much on the increase.

For obscure reasons, the human sex ratio is always slightly male-biased, but in the natural state it rarely goes above 105 male births per 100 female ones, except in small samples. In China's last mini-census in 2005, the ratio was nearly 120 to 100 and in some districts over 150. That this is caused by sex-selective abortion (and not, for example, by a hepatitis-B epidemic, which can favor male births) is proved by a ratio of 107 to 100 among first-born children but nearer 150 among ones born later.

China is not the only country where this is happening. By the early 21st century, all four Asian "tigers"-South Korea, Singapore, Hong Kong and Taiwan-had a "naturally impossible" ratio of 108 or higher. India has an increasing ratio, as high as 120 in some states. Even some European and central Asian countries (including Albania, Georgia and even Italy) have unnaturally male-biased births. Nearly half the world falls in this category.

The best explanation in the world

Each year, John Brockman's website, The Edge, asks a question and gets many answers to it. This year, the question is: What is your favourite deep, elegant, or beautiful explanation? Some of the answers are fascinating. Here's mine:

It's hard now to recall just how mysterious life was on the morning of 28 February 1953 and just how much that had changed by lunchtime. Look back at all the answers to the question "what is life?" from before that and you get a taste of just how we, as a species, floundered. Life consisted of three-dimensional objects of specificity and complexity (mainly proteins). And it copied itself with accuracy. How?

How do you set about making a copy of a three-dimensional object? How to do you grow it and develop it in a predictable way? This is the one scientific question where absolutely nobody came close to guessing the answer. Erwin Schrodinger had a stab, but fell back on quantum mechanics, which was irrelevant. True, he used the phrase "aperiodic crystal" and if you are generous you can see that as a prediction of a linear code, but I think that's stretching generosity.

The slow cooling of our interglacial

Here's my latest Mind and Matter column in the Wall Street Journal, with added links and charts. On interglacials. The entire 10,000-year history of civilization has happened in an unusually warm interlude in the Earth's recent history. Over the past million years, it has been as warm as this or warmer for less than 10% of the time, during 11 brief episodes known as interglacial periods. One theory holds that agriculture and dense settlement were impossible in the volatile, generally dry and carbon-dioxide-starved climates of the ice age, when crop plants would have grown more slowly and unpredictably even in warmer regions.

This warm spell is already 11,600 years old, and it must surely, in the normal course of things, come to an end. In the early 1970s, after two decades of slight cooling, many scientists were convinced that the moment was at hand. They were "increasingly apprehensive, for the weather aberrations they are studying may be the harbinger of another ice age," said Time in 1974. The "almost unanimous" view of meteorologists was that the cooling trend would "reduce agricultural productivity for the rest of the century," and "the resulting famines could be catastrophic," said Newsweek in 1975.

Since then, of course, warmth has returned, probably driven at least partly by man-made carbon-dioxide emissions. A new paper, from universities in Cambridge, London and Florida, drew headlines last week for arguing that these emissions may avert the return of the ice age. Less noticed was the fact that the authors, by analogy with a previous warm spell 780,000 years ago that's a "dead ringer" for our own, expect the next ice age to start "within about 1,500 years." Hardly the day after tomorrow.

Noise versus signal

My latest Mind and Matter column in the Wall Street Journal: Coral reefs around the world are suffering badly from overfishing and various forms of pollution. Yet many experts argue that the greatest threat to them is the acidification of the oceans from the dissolving of man-made carbon dioxide emissions.

The effect of acidification, according to J.E.N. Veron, an Australian coral scientist, will be "nothing less than catastrophic.... What were once thriving coral gardens that supported the greatest biodiversity of the marine realm will become red-black bacterial slime, and they will stay that way."

This is a common view. The Natural Resources Defense Council has called ocean acidification "the scariest environmental problem you've never heard of."

Catching the species in the act of being born

My Mind and Matter column for the Wall Street Journal on 1 January 2012 is here:

Here's a New Year's thought. With some nine million species on the planet, and with each species lasting a million years on average, about nine species will go extinct naturally this coming year (with more, almost certainly, going extinct unnaturally). But about nine new species also will be born in 2012.