A few days ago I mentioned a new book, "More Than Human", by Ramez Naam. I still haven't read it, but as luck would have it, sample chapters are available online. You might also want to check out his blog.

Over at "The Longevity Meme" Reason has posted a heartening exploration (by Mr. Naam) of twenty first century demographics. I've swiped a little bit of it to pique your interest, but you should read the whole thing.

Because the birth rate is double the death rate, phenomena that affect fertility can have a far larger impact than similar size effects on the death rate. For example, between 2000 and 2050, the UN expects around 3.7 billion people on earth to die, while another 6.6 billion are born. Cutting the death rate in half would increase population by around 1.9 billion people. Doubling the birth rate would increase population by a further 6.6 billion. Thus the birth rate is a more significant lever on the size of the population.

In 2000, world population stood at 6 billion people. Looking forward, the UN predicts that in 2050, world population will be somewhere between 8 billion and 11 billion, with a "medium" prediction of 8.9 billion.

Demographer Jay Olshansky...has shown that extending human life would have an incremental, rather than exponential, effect on population...If everyone were made completely immortal today, he calculates, and taking into account declining birth rates, global population would hit about 13 billion in 2100, rather than the 10 billion currently projected.

The immortality Olshansky is talking about isn't achievable. If we halted all aging, accidents, homicide, suicide, and infectious diseases would still kill people...More likely, we'll achieve the technology to slow but not halt the rate of aging in the next 10 to 20 years. Then it will take additional years for people around the world to gain access to the technology...