人生苦短

New Roman">Life Is Short...

Sure, Michael Phelps may have snapped a string of Olympic records like so many Rice Krispies in milk, but what was this child of Poseidon up against, anyway? Elite human athletes from 250 countries.

当然，迈克尔.菲尔普斯可能像牛奶里的大量噼叭作响的麦通一样打破一系列的奥运记录，但这个海神之子所面临的是什么呢？他面临的是来自250个国家的体育精英。

small, speckled, asparagus-green chameleon of Madagascar, by contrast, holds a world speed record among just about all of the nearly 30,000 different animals equipped with four limbs and a backbone.

相比而言，个头小，浑身布满斑点，披着芦荟色外衣的马达加斯加变色龙，在所有世界上拥有四条腿和脊骨的近3万种不同的动物中，保持着一项世界记录。

Admittedly, it’s not a record many of us would aspire to best. As researchers recently reported in The Proceedings of the National Academy of Sciences, the entire life span of the Furcifer labordi chameleon — from the moment of conception to development in the egg, hatching, maturation, breeding and right through to its last little lizardly thud to the ground — clocks in at barely a year.

然而，这种世界记录并不是我们当中许多人所渴望的。正如国家科学院最近在《进化》杂志中所报道的那样，这种变色龙的整个生命过程---从在卵中开始孕育到孵化，至成熟，到长成，直到最后那只小蜥蜴砰然落地---整个周期仅仅只有一年的时间。

That hypercondensed biography, the scientists said, may well make the chameleon the shortest-lived tetrapod on Earth, a creature chronologically more like a butterfly or a sea squirt than like the other reptiles, frogs, birds and mammals with which it is taxonomically bundled.

科学家说，这是一个浓缩的传记，最好把这种变色龙命名为地球上寿命最短的四足动物，按时间先后顺序排列，是一种更像蝴蝶或海鞘的生物，而不像其它的爬行动物，蛙类，鸟类和哺乳动物。

Equally bizarre, said Christopher J. Raxworthy, an author of the new report, the chameleon spends some two-thirds of its abbreviated existence as an egg buried in sand, with a mere 16 to 20 weeks allocated to all post-shellular affairs.

这份新报告的作者克里斯托夫J.热可斯说，同样奇怪的是，这种变色龙是在埋在沙中的卵中度过其短暂一生的三分之二的时间 ，即仅仅留下16至20周来度过出壳后所有生命时光。

Moreover, the chameleons operate by a synchronized schedule, hatching, growing, mating and dying at more or less the same times and at the same pace throughout the year. As a result, said Dr. Raxworthy, associate curator of herpetology at the American Museum of Natural History, “if you go into a forest during the dry season, the whole population of chameleons there will be represented by eggs.”

更有意思的是，这种变色龙都按照一种同步的时间表在成长，孵化，长大，交配，走向死亡，这些过程在整个一年中几乎按照相同的步调在进行。美国自然历史博物馆爬虫馆相关管理人员热可斯博士说，其结果是，如果你在干旱的季节去森林里，变色龙家族几乎都是以卵的形式存在。

Counterintuitive though it may seem, the extremity of F. labordi’s schedule could prove valuable for tracking down genes and other biological factors that promote longevity. The researchers observed that the chameleon is not merely short-lived as a matter of averages. It is an obligate annual species, destined for death after a single spin around the sun, and that stated fate differs markedly from the varying degrees of perenniality found throughout the tetrapod clan.

这似乎有点违背直觉，这种极其严格的时间表可能在查找基因和其他生物因子以促进延长寿命方面显示出价值。研究人员发现这种变色龙不仅是一种短命的普通生物。

“There are about a dozen lizard species known to be short-lived, in which a good proportion of individuals die off by a year,” said Kristopher B. Karsten of the zoology department at Oklahoma State University, another author of the report. “But there are always some that make it to the next year, so the species’ maximal longevity is greater than one year.”

 

No such luck for our bug-eyed Malagasy friends, which live in the arid, scrubby southwestern region of the giant island. “Once they reach the end of the season,” Dr. Karsten said, “they’re done,” and they will drop from the trees with the papery grace of autumn leaves.

Assuming the execution orders are somehow part of the chameleon’s program, researchers might be able to identify the specific genetic or hormonal assassins in lizard cells, find their analogues in human cells and put a cap in them.

The new work also underscores the growing use of so-called life history theory to trace the history and contours of life on Earth.

Scientists have determined that many essential features of an animal’s portfolio are linked, among them whether at birth it looks fetal and helpless like a newborn kitten or precocious and competent like a neonatal giraffe; how big the average litter is; the speed with which the animal reaches sexual maturity; the length of time between births; and the pace at which an adult ages.

Try to improve or optimize one of these parameters and you end up paying somewhere else along the line. “One of the most robust things to come out of life history theory is that trade-offs exist,” said Steven N. Austad, the author of “Why We Age” and a professor of cellular and structural biology at the University of Texas Health Science Center.

“If you increase the number of young, the cost is often accelerated aging. If you get something that lives longer, you get costs early in life, with lower fertility and even sterility.”

Selective pressures in the environment push species toward one life history course or another. One example is that if you’re a species in which the great majority of adults end up being killed by predators or disease, it’s best to invest your resources in breeding early and often and not to bother worrying about long-term needs like a robust DNA repair system. And so it is that rodents beloved by carnivores everywhere have high fecundity and relatively poor longevity.

If you’re a species in which infant and juvenile mortality is comparatively great, as it is with giant tortoises, for example, the emphasis is often on making the best of adulthood, with delayed maturity and extended life spans.

Catastrophic extrinsic changes may quickly rewrite a species’ game plan. In another new report from the National Academies journal, researchers presented evidence that Tasmanian devils, the largest of all carnivorous marsupials, have responded to an epidemic of fatal transmissible news articles about Tumor." href="http://health.nytimes.com/health/guides/disease/tumor/overview.html?inline=nyt-classifier">tumors among adults with a 16-fold increase in precocious puberty among the young. If you’re likely to be gone tomorrow, you’d better start begetting today.

Furcifer labordi’s extreme life history likewise seems born of extreme adversity and volatility. The chameleon is one of the smallest members of its genus, and adults are readily, avidly snacked on by birds and snakes. The local climate is harsh and unpredictable, lowering the odds of survival beyond a single rainy season.

In addition, the rainy season, which begins in November, when the chameleons hatch en masse, is brief and must be frantically exploited. The young coil-tongued lizards immediately start lassoing insects, and they eat so much, Dr. Raxworthy said, “that they practically grow in front of your very eyes.”

By January the chameleons are ready to mate, a nasty, often violent business of males fighting males, females fighting males, and all of them wishing they were somewhere else. Despite their cuteness, Dr. Raxworthy said, “chameleons can be very antisocial, and if you crowd them, they’ll happily fight to the death.”

Dr. Karsten suspects that Furcifer labordi’s compressed breeding season fosters such high levels of aggression that the chameleons die, in part, of hormone overdose.

Another athletic career cut tragically short by steroids.