Why the coming decade marks a new stage in human evolutionS

On New Year's Day, the giant population bump known as the baby boom started turning 65. By the decade's end, more humans will be over 65 than under 5. Homo sapiens is entering uncharted territory. What will happen?

Over at the health research site Tracker, there's a terrific roundup of news and research about what comes next for humanity. Editor J.A. Ginsburg sums up:

Globally, the median age is 28, meaning there are just as many people older than that as younger. In less than a decade, there will be more people over 65 than under the age of 5. By 2045, there will be more people over 60 than children, period . . . demographers predict there were be 3.2 million centenarians in the world by 2050, a more than 6-fold increase from the current numbers.

What happens to a species whose least-reproductive members are dominating the population? Does humanity grow more wise in its ways?

Possibly over time, an aging population will make public policies more far-sighted, but in the immediate short term we're going to see a health crisis followed by an economic one. Ginsburg writes:

The rates of age-related chronic illnesses-diabetes (exacerbated by an obesity epidemic), cancer, impaired vision and dementias-are spiking upwards with no end in sight. Beyond the incalculable heartbreak, the economics are staggering. According to a new study released by Alzheimer's Disease International, "the worldwide costs of dementia will exceed 1% of global GDP in 2010, at US$604 billion."

Even diseases that don't affect the elderly directly can have a tremendous impact on them. Pandemic influenza, for example, usually takes its biggest toll on adults in the prime-of-life. But since those people are also the caregivers, their loss can easily cascade into another round of tragedy.

Although the problem is one of demographic relativity-the ratio of old to young-the answer is not more babies. The absolute population numbers are still rising-expected to hit 9 billion by mid-century-while limited natural resources are either under siege or running low and food production barely keeps pace with demand.

Of course many of these aging people won't become ill or demented, and thanks to medical breakthroughs may remain productive workers well into their 80s. What kinds of changes will the post-65 active population bring to workplaces, politics, and culture? We're about to find out.

Check out more of Ginsburg's commentary, which is full of interesting links to scientific research, via TrackerBlog (Spotted on BrainPicker)