Extinction

Biological diversity- the variety among living organisms and their habitats- is more threatened now than at any time in the past. Tropical deforestation is the main reason behind the crisis, but the destruction of temperate forests and the pollution of rivers, lakes, and oceans also play an important role.

The total number of species is not known. Biologists estimate that there between 5 and 30 million species, many of them insects, tiny sea creatures, and lesser known plants and animals. As these species become extinct, they in turn take with them more of nature’s wealth. The removal of a single species, no matter how tiny, can set off a chain reaction affecting many others. It has been estimated, for example, that a disappearing plant can take with it up to 30 other species, including insects, higher animals, and even other plants. Each species, no matter how small or obscure, plays an essential role in maintaining the balance of nature.

Global Warming

Human activity is altering the composition of the atmosphere in ways that could bring the rapid changes in climate. Although naturally occurring green house gases keep the earth’s surface warm by trapping infrared radiation given off by the sun, human activity is increasing the concentration of these gases, as well as adding new, more dangerous chemicals to the atmosphere.

Carbon dioxide, the most important greenhouse gas, has increased in the atmosphere over the past four decades from the burning of fossil fuels and, more recently, from deforestation. Carbon dioxide is pouring atmosphere from motor vehicles and factories.

But perhaps the most dangerous is the production of chemically synthesized chlorofluorocarbons, which are used in cooling systems and aerosol spray cans and in the production of some fast food containers. The greenhouse gas has been blamed for heating up the atmosphere as well as thinning the upper level of the atmosphere, the ozone layer.

Many scientists are predicting an increase of about 1 degree Celsius in the global mean temperature by 2025 and a 3-degree increase by the end of the next century.

UNIT 4

A brief history of the future

1 You are going to read an interview with Stephen Hawking, in which he is asked to predict the future of humankind in the third millennium. Before you read the text, work with a partner and make your own predictions about the following:

1. making contact with an intelligent life form from another planet

2. developments in computer technology

3. genetic engineering on plants, animals and humans

4. developments in human intelligence and knowledge

2. Read the article and find out what Stephen Hawking’s predictions for the areas in 3 are.

I’ve come here – to Cambridge University’s Department of Applied Mathematics and Theoretical Physics, where Hawking holds the professorial chair once held by Isaac Newton – on the turn of the millennium to ask him what he thinks the future has in store for the human race.

If the world’s population continues to grow at its present rate – doubling every 40 years – there isn’t going to be enough room for us all on Earth by the year of 2600. So will we, I ask, be able to spread out to other planets? His hands go in action. The only sounds in the room are the clicking of the pressure pads and the whirring of the computer. The electronic voice delivers the answer five minutes later. “We shall probably manage a manned or, should I say, personned, flight to Mars in the next century”, Hawking says. “But Earth is by far the most favored planet in the solar system. Mars is small, cold and without much atmosphere, and the older planets are quite unsuitable for human beings. We either have to learn to live in space stations or travel to the next star. We won’t do that in the next century.”

I ask whether we humans will keep on changing, or will we eventually reach an ultimate level of development and knowledge? Click click click. “In the next 100 years or even in the next twenty, we may discover a complete theory of the basic laws of the universe (the so-called Theory of Everything, in which quantum theory is unified with Einstein’s theory of general relativity), but there will be no limit to the complexity of biological or electronic systems we can build under these laws.”

I’m just about to ask a supplementary question when the hands start up again. A few minutes pass before Hawking adds: “By far the most complex systems we have are our own bodies. There haven’t been any significant changes in human DNA in the past 10000 years. But soon we will be able to increase the complexity of our internal record, our DNA, without having to wait for the slow process of biological evolution. It is likely that we will be able to redesign it completely in the next 1000 years – by increasing our brain size, for example. Of course, many will say genetic engineering on humans will be banned but I rather doubt that they will be able to prevent it. Genetic engineering on plants and animals will be allowed for economic reasons and someone is bound to try it on humans – unless we have a totalitarian world order, someone will improve humans somewhere.”

“We need to become more complex if biological systems are to keep ahead of electronic ones. At the moment computers have an advantage of speed but they show no sign of intelligence. This is not surprising as our present computers are less complex than the brain of an earthworm, a species not known for its intellectual powers. But computers’ speed and complexity double every eighteen months and this will probably continue until computers have a similar complexity to the human brain.”

But will computers ever show true intelligence, whatever that might be? “It seems to me that if very complicated chemical molecules can operate in humans to make them intelligent, then equally complicated electronic circuits can also make computers act in an intelligent way. And if they are intelligent, they can presumably design computers that have ever greater intelligence and complexity.”

“On the biological side, the limit of human intelligence has been set by the size of the human brain that will pass through the birth canal,” Hawking says. “Having watched my three children being born, I know how difficult it is to get the head out. But in the next 100 years I expect we will learn how to grow babies outside the human body so this limitation will be removed. But ultimately, increases in the size of human brain through genetic engineering will come up against the problem that the chemical messages responsible for our mental activity are relatively slow-moving – so further increases in the complexity of the brain will be at the expense of speed. We can be quick-witted or very intelligent, but not both.”

Its’ time to ask the big one: will we make contact with aliens in the next millennium? He smiles. His fingers click the pressure pads. The answer comes seven minutes later. “Even if life developed in other stellar systems, the chances of catching it at a recognizably human stage are very small. Any alien life we encounter will be much more primitive or much more advanced than us. And if it’s more advanced, why hasn’t it spread through the galaxy and visited Earth? It could be that there is an advanced race out there which is aware of our existence but is leaving us to stew in our own primitive juices. However, I doubt they would be so considerate to a lower life form. Some people believe that the reason we have not been contacted is that when a civilization reaches our stage of development it becomes unstable and destroys itself. But I’m an optimist. I think we have a good chance of avoiding nuclear war and Armageddon.”