# Census Map: Where No One Lives in the United States

Despite having a population of about 318 million people, 47 percent of the USA remains unoccupied.

Block is the smallest area unit used by the U.S. Census Bureau for tabulating statistics. As of the 2010 census, the United States consists of 11,078,300 Census Blocks. Of them, 4,871,270 blocks totaling 4.61 million square kilometers were reported to have no population living inside them.

This map, with areas shaded in green, shows where there is zero population in the United States:

Very curious is how you can distinctly see the border boundary of North Dakota (it is more apparent than the boundary of any other state). Why? Mapsbynik provides a clue:

On a more detailed examination of those two states [North Dakota, South Dakota], I’m convinced the contrast here is due to differences in the sizes of the blocks. North Dakota’s blocks are more consistently small (StDev of 3.3) while South Dakota’s are more varied (StDev of 9.28). West of the Missouri River, South Dakota’s blocks are substantially larger than those in ND, so a single inhabitant can appear to take up more space. Between the states, this provides a good lesson in how changing the size and shape of a geographic unit can alter perceptions of the landscape.

# In 3,000 Years, Someone Alive Today Will Be the Common Ancestor of All Humanity

Dr. Yan Wong explains why everyone alive in the Holy Land at the time of Jesus would have been able to claim David for an ancestor. He provides a simple mathematical explanation (exponential growth) and makes a couple of assumptions (that any two people in any one country probably won’t need to go back many generations before finding a common ancestor due to inbreeding), and then he extrapolates to the future:

What about the wider ramifications? A single immigrant who breeds into a population has roughly 80% chance of becoming a common ancestor. A single interbreeding event in the distant past will probably, therefore, graft the immigrant’s family tree onto that of the native population. That makes it very likely that King David is the direct ancestor of the populations of many other countries too.

How far do we have to go back to find the most recent common ancestor of all humans alive today? Again, estimates are remarkably short. Even taking account of distant isolation and local inbreeding, the quoted figures are 100 or so generations in the past: a mere 3,000 years ago.

And one can, of course, project this model into the future, too. The maths tells us that in 3,000 years someone alive today will be the common ancestor of all humanity.

A few thousand years after that, 80% of us (those who leave children who in turn leave children, and so on) will be ancestors of all humanity. What an inheritance!

Have you ever traced your family genealogy?

# The Largest Biometric System in the World

It has been called “the biggest social project on the planet.”

A major problem in India is that few poor people can prove their identity: they have no passport, no driving licence, no proof of address. They live in villages where many share the same name. These people cannot open bank accounts, and no one wants to lend them money. India has no equivalent of Social Security numbering, and just thirty-three million Indians, out of 1.2 billion, pay income tax.

But India’s relatively new program, the unique identity (UID) authority, will enroll approximately 400 million people by the end of this year. The scheme is voluntary, but the poor are enthusiastic about it. This Economist piece has some details, which relies on maintaining a huge database containing biometric information (ten fingerprints and an iris scan) of each of India’s residents:

For the poor, having a secure online identity alters their relationship with the modern world. No more queueing for hours in a distant town and bribing officials with money you don’t have to obtain paperwork that won’t be recognised if you move to another state looking for work. A pilot project just begun in Jharkhand, an eastern state, will link the new identities to individuals’ bank accounts. Those to whom the government owes money will soon be able to receive it electronically, either at a bank or at a village shop. Ghost labourers staffing public-works schemes, and any among India’s 20m government employees, should turn into thin air. The middlemen who steal billions should more easily be bypassed or caught.

That is just the start. Armed with the system, India will be able to rethink the nature of its welfare state, cutting back on benefits in kind and market-distorting subsidies, and turning to cash transfers paid directly into the bank accounts of the neediest. Hundreds of millions of the poor must open bank accounts, which is all to the good, because it will bind them into the modern economy. Care must be taken so mothers rather than feckless fathers control funds for their children. But most poor people, including anyone who wants to move around, will be better off with cash welfare paid in full. Vouchers for medical or education spending could follow.

The scheme based on biometrics is not without criticism, however. Nevertheless, the cost of enrolling each person into this program is about \$2, so India’s program could be a model for other poor nations.

# How Many People Have Ever Lived on Earth?

The BBC website has a neat interactive where you can plug in your date of birth, and it will output the numbern of where you fit “in the story of human life.”

But the more interesting part was the link to the Population Reference Bureau, where an article attempted to guess the total number of humans that have ever lived on Earth.

First, a caveat:

And semi-scientific it must be, because there are, of course, absolutely no demographic data available for 99 percent of the span of the human stay on Earth. Still, with some speculation concerning prehistoric populations, we can at least approach a guesstimate of this elusive number.

Continuing, the article explains a number of assumptions about early human life:

At the dawn of agriculture, about 8000 B.C., the population of the world was somewhere on the order of 5 million. (Very rough figures are given in the table; these are averages of an estimate of ranges given by the United Nations and other sources.) The slow growth of population over the 8,000-year period, from an estimated 5 million to 300 million in 1 A.D., results in a very low growth rate—only 0.0512 percent per year. It is difficult to come up with an average world population size over this period. In all likelihood, human populations in different regions grew or declined in response to famines, the vagaries of animal herds, hostilities, and changing weather and climatic conditions.

In any case, life was short. Life expectancy at birth probably averaged only about 10 years for most of human history. Estimates of average life expectancy in Iron Age France have been put at only 10 or 12 years. Under these conditions, the birth rate would have to be about 80 per 1,000 people just for the species to survive. Today, a high birth rate would be about 45 to 50 per 1,000 population, observed in only a few countries of Africa and in several Middle Eastern countries that have young populations.

Our birth rate assumption will greatly affect the estimate of the number of people ever born. Infant mortality in the human race’s earliest days is thought to have been very high—perhaps 500 infant deaths per 1,000 births, or even higher. Children were probably an economic liability among hunter-gatherer societies, a fact that is likely to have led to the practice of infanticide. Under these circumstances, a disproportionately large number of births would be required to maintain population growth, and that would raise our estimated number of the “ever born.”

The site starts tallying population growth from 50,000 B.C., and comes to the following conclusion:

This semi-scientific approach yields an estimate of about 108 billion births since the dawn of the human race. Clearly, the period 8000 B.C. to 1 A.D. is key to the magnitude of our number, but, unfortunately, little is known about that era. The assumption of constant population growth in the earlier period may underestimate the average population size at the time. And, of course, pushing the date of humanity’s arrival on the planet before 50,000 B.C. would also raise the number, although perhaps not by terribly much.

So with the current population approaching 7 billion, about 6.5% of humans living today have ever lived on Earth.

# The Limit of Human Population Growth

A good post at The New Yorker, summarizing the growth of human population. Earth should hit the 7,000,000,000 population mark sometime in the next two to three weeks:

Sometime on October 31st, the world’s population will hit seven billion. The baby who does the trick will most likely appear in India, where the number of births per minute—fifty-one—is higher than in any other nation. But he or she could also be born in China—the world’s most populous country—or in a fast-growing nation like Nigeria or Guatemala or, really, anywhere. The idea that a particular child will on a particular day bring the global population to a particular number is, of course, a fiction; nobody can say, within tens of millions, how many people there are on earth at any given time. The United Nations Population Fund has picked October 31st as its best estimate. That this date is Halloween is presumably just a coincidence…

If you aren’t already familiar with Thomas Malthus’s famous treatise, An Essay on the Principle of Population, in which he espouses that the rate of human growth will outstrip the food supply (which he argued, grows linearly), you should take a look at this Wikipedia page. Malthus’s essay is mentioned prominently in The New Yorker piece.

Furthermore, making predictions is hard. Hence, the frequent revisions:

The further ahead you look, the trickier things become. This is partly a matter of birth rates; because the base is now so large, even relatively trivial changes produce enormous effects. In most European nations, and also in countries like Japan and China, birth rates have already fallen below replacement levels. Until quite recently, the U.N. was projecting that rates in other parts of the globe would follow a similar downward slope, so that sometime toward 2050 global population would level out at around nine billion. A few months ago, though, the U.N. announced that it was revising its long-term forecast. The agency now estimates that the number of people on earth in 2100 will be ten billion and still climbing. One reason for the upward revision is that birth rates in many developing countries, particularly in Africa, have remained unexpectedly high.

The big question: is there a theoretical asymptote for the number of humans that Earth can sustain? If so, what is that number, to a first-degree approximation?