From Wired Science by Brandom Keim: Making Sense of 7 Billion People
On the last day of October 2011, the global population of an upstart branch of the primate order will reach 7 billion.
What does it mean?
In itself, not much: Seven billion is just a one-digit flicker from 6,999,999,999. But the number carries a deep existential weight, symbolizing themes central to humanity’s relationship with the rest of life on Earth.
For context, let’s consider a few other numbers. The first: 10,000. That’s approximately how many Homo sapiens existed 200,000 years ago, the date at which scientists mark the divergence of our species from the rest of Homo genus, of which we are the sole survivors.
From those humble origins, humans — thanks to our smarts, long-distance running skills, verbal ability and skill with plants — proliferated at an almost inconceivable rate.
Some may note that, in a big-picture biological sense, humanity has rivals: In total biomass, ants weigh as much as we do, oceanic krill weigh more than both of us combined, and bacteria dwarf us all. Those are interesting factoids, but they belie a larger point.
Ants and krill and bacteria occupy an entirely different ecological level. A more appropriate comparison can be made between humans and other apex predators, which is precisely the ecological role humans evolved to play, and which — beneath our civilized veneer — we still are.
According to a back-of-the-envelope calculation, there are about 1.7 million other top-level, land-dwelling, mammalian predators on Earth. Put another way: For every non-human mammal sharing our niche, there are more than 4,000 of us.
In short, humans are Earth’s great omnivore, and our omnivorous nature can only be understood at global scales. Scientists estimate that 83 percent of the terrestrial biosphere is under direct human influence. Crops cover some 12 percent of Earth’s land surface, and account for more than one-third of terrestrial biomass. One-third of all available fresh water is diverted to human use.
Altogether, roughly 20 percent of Earth’s net terrestrial primary production, the sheer volume of life produced on land on this planet every year, is harvested for human purposes — and, to return to the comparative factoids, it’s all for a species that accounts for .00018 percent of Earth’s non-marine biomass.
We are the .00018 percent, and we use 20 percent. The purpose of that number isn’t to induce guilt, or blame humanity. The point of that number is perspective. At this snapshot in life’s history, at — per the insights of James C. Rettie, who imagined life on Earth as a yearlong movie — a few minutes after 11:45 p.m. on December 31, we are big. Very big.
However, it must be noted that, as we’ve become big, much of life had to get out of the way. When modern Homo sapiens started scrambling out of East Africa, the average extinction rate of other mammals was, in scientific terms, one per million species years. It’s 100 times that now, a number that threatens to make non-human life on Earth collapse.
In regard to that number, environmentalists usually say that humanity’s fate depends on the life around us. That’s debatable. Humans are adaptable and perfectly capable of living in squalor, without clean air or clean water or birds in the trees. If not, there wouldn’t be 7 billion of us. Conservation is a moral question, and probably not a utilitarian imperative.
But the fact remains that, for all of humanity to experience a material standard of living now enjoyed by a tiny fraction, we’d need four more Earths. It’s just not possible. And that, in the end, is the significance of 7 billion. It’s a challenge.
In just a few minutes of evolutionary time, humanity has become a force to be measured in terms of the entirety of life itself. How do we, the God species, want to live? For the answer, check back at 8 billion.
From sfgate.com
Lagos, Nigeria -- One South African mother, just 19, named her newborn "Enough" and shrugged off a nurse who questioned whether she was old enough to know how many children she wanted.
In Nigeria, newborn twins have to share a bassinet in a crowded public hospital that doesn't have enough electricity.
"Where there is life, there is hope," their mother said. But as the world's population surpasses 7 billion, fears were stirred anew about how the planet will cope with the needs of so many humans.
The United Nations marked the milestone Monday, even though it is impossible to pinpoint the arrival of the globe's 7 billionth occupant because millions of people are born and die each day.
At Lagos Island Maternity Hospital, the strain of caring for a burgeoning population was evident. The droning roar of a generator could be heard throughout one hot ward, where it powered ceiling fans and incubators. While Nigeria is oil-rich, it does not produce nearly enough power for its more than 160 million people.
Nigeria's megacity of Lagos is expected someday to surpass Cairo as the continent's most populous.
U.N. Secretary-General Ban Ki-moon said the day was "not about one newborn or even one generation" but "about our entire human family."
At a news conference in New York, he noted "a world of contradictions" - famine in the Horn of Africa, fighting in Syria and elsewhere and widespread protests against economic inequality.
"Seven billion population is a challenge," he said, and "at the same time, an opportunity, depending upon how the international community prepares for that challenge."
Demographers say it took until 1804 for the world to reach its first billion people and a century more until it hit 2 billion in 1927. Soon the numbers began to cascade: 3 billion in 1959, 4 billion in 1974, 5 billion in 1987, 6 billion in 1998.
The United Nations estimates the world population will reach 8 billion by 2025 and 10 billion by 2083. But the numbers could vary widely, depending on life expectancy, access to birth control, infant mortality rates and other factors.
India, which struggles with a deeply held preference for sons and a skewed sex ratio because of millions of aborted female fetuses, is using the day to highlight that issue.
"It would be a fitting moment if the 7 billionth baby is a girl born in rural India," said Dr. Madhu Gupta, a gynecologist. "It would help in bringing the global focus back on girls, who are subject to inequality and bias."
According to U.S. government estimates, India has 893 girls for every 1,000 boys at birth, compared with 955 girls per 1,000 boys in the United States.
Meanwhile, China, which at 1.34 billion people is the world's most populous nation, said it would stand by its one-child policy, a set of restrictions launched three decades ago limiting most urban families to one child and most rural families to two.
"Overpopulation remains one of the major challenges to social and economic development," Li Bin, director of the State Population and Family Planning Commission, told the official Xinhua News Agency. India, with 1.2 billion people, is expected to overtake China around 2030, when the Indian population reaches an estimated 1.6 billion.
