Lester A. Mitscher and Victoria Toews
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 In studies of human populations, the results have not been as clear-cut. A cohort study of men in London suggested that drinking black tea increased, rather than minimized, the risk of lung cancer. A handful of other studies of human populations failed to find any relationship—positive or negative—between tea consumption and lung cancer. |
Devra Davis
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 In modern human populations studied so far, the proportion of males born relative to females in a healthy human population is .515. This can also be presented as the sex ratio of males to females of 1.06. For the past three decades in many industrial countries, this number is declining by very small amounts. Today there are nearly 4 million births in a single year in the United States. Since 1970, the proportion of baby boys born has fallen by just one out of every thousand births. |
Mark Lynas
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 A drastic reduction in human populations is unambiguously the most likely outcome of a rise in global temperatures towards five degrees - what James Lovelock unhappily terms 'the cull'. Even at present numbers, the planet will have trouble supporting human society indefinitely, as we already see in a myriad of ways from overfishing to soil erosion. But with human population growth projected to add still further to our ballooning numbers, the overall situation will become steadily more precarious as the world warms up. |
Bill Sardi
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 Journal National Cancer Institute 85: 1448, 1993] The segments of human populations that consume the least amount of fruits and vegetables exhibit the highest rates of cancer and are the most likely to benefit from antioxidant supplements.
How much antioxidant power do your foods plus dietary supplements provide?
In order to answer this question it helpful to gain an understanding of the need for antioxidant protection, which varies from individual to individual. Also, it is important to keep in mind that there is a big difference between prevention and treatment. |
| Vitamin D supplementation should be mandated for human populations of blacks, those living in northern latitudes, smokers, over-consumers of alcohol, and all other high-risk groups for colon cancer.
Patients will likely ask their physicians about the potential for vitamin D overdose and are likely to receive mistaken advice. Most physicians have been trained that high-dose vitamin D causes excessive buildup of calcium in cells. This only occurs in a small number of people, and is reversible, while thousands die needlessly of colon cancer. |
| Observational studies, that is studies of human populations and what they eat, how much sun they are exposed to, etc, don't always equate with a practice that can be used to prevent cancer because there are so many other variable factors (composition of the diet, intensity of sun exposure, etc.). That's why controlled interventional clinical trials are considered the "gold standard' of studies.
So a few years ago, Larry Clark, Ph.D., M.P.H, a cancer researcher at Cornell University and later at the University of Arizona, began such a study. |
Mike Adams, the Health Ranger
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 The acceleration of natural disasters and radical climate change
Today, as mankind continues to destroy the planet's environment and ecosystems, some rather inconvenient natural events are about to be unleashed that will no doubt severely impact human populations. It doesn't mean trees will uproot themselves and march upon our cities, of course. That's just a cartoon depiction. What's far more likely to happen is that imbalanced ecosystems will unleash famines and infectious diseases that will ultimately devastate humankind.
Why famines? |
Bill Sardi
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| Cancer is prevalent, far beyond the number diagnosed in human populations, and most adults will die with, but not of, their cancer. Treatment and invasive or toxic screening methods (radiation from x-rays, mammograms, needle biopsies) for tumors that may never progress to cause symptoms or death in an individual's lifetime would represent overdiagnosis and needless treatment.
Autopsy studies reveal how many people incidentally had cancer on the day they died, which did not contribute to their death. |
Mark Lynas
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| Further conflicts could arise with India if millions of Pakistani refugees cross the border in order to find sustenance in better-watered areas served by the Ganges but already supporting dense human populations.
All of human history shows that given the choice between starving in situ and moving, people move. In the latter part of the century tens of millions of Pakistani citizens may be facing this choice, as the river which has sustained their civilisation for centuries runs dry, and the breadbaskets which it supported are overcome by the spreading desert. |
Devra Davis
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| When we look at patterns in human populations of any age-group, we rely on two basic principles to see whether what we observed is important. First, where the differences between any two groups are big, they are less likely to be random. Big differences delight epidemiologists, precisely because they are so unusual in public health. When they occur, they tend to signal something important is going on. Second, your chances of finding a difference are greater the more times or things you observe. This is called the law of large numbers. |
Bill Sardi
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| Disease detectives have determined by study of human populations that women who consume fewer colored vegetables that contain carotenoids (lutein, beta carotene, lycopene) incur more than twice the risk for breast cancer compared to women who consume large amounts of these foods. Researchers conclude that "low intake of carotenoids, through poor diet and/or lack of vitamin supplementation, may be associated with increased risk of breast cancer. |
David R. Montgomery
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 The Reverend Thomas Malthus infamously proposed that a boom-and-bust cycle characrerizes human populations in his 1798 Essay on the Principle of Population. A professor of political economy at Haileybury College, Malthus argued that exponentially growing populations increase faster than their food supply. He held that population growth locks humanity in an endless cycle in which population outstrips the capacity of the land to feed people. Famine and disease then restore the balance. |
Dr. Abram Hoffer, MD, FRCP (C) and Dr. Harold D. Foster, PhD
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 It was concluded that "the basic research reviewed in this article illustrates the potential of niacin status to impact on genomic stability and cancer incidence in human populations." Clearly, it is essential to maintain high enough levels of the enzyme poly (ADP-ribose) polymerase (PARP) to repair damaged DNA. It is not for nothing that this enzyme is called the guardian of the genome. Niacin deficiency decreases PARP activity and so limits DNA damage repair, increasing the chance of developing cancer. |
David R. Montgomery
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| Population growth during the preceding several thousand years led to the advent of sedentary communities of hunter-gatherers and contributed to the effect of this climate shift on human populations. Still, the starving people of Abu Hureyra could never have imagined that their attempt to adapt to a drying world would transform the planet.
Such adaptation may have occurred around the region. The end of the Younger Dryas coincides with changes in culture and settlement patterns throughout much of the Middle East. |
| Despite their active manipulation, small human populations and mobile lifestyles left little discernable impact on natural ecosystems.
Transitions from a glacial to interglacial world occurred many times during the last two million years. Through all but the most recent glaciation, people moved along with their environment rather than staying put and adapting to a new ecosystem. Then, after living on the move for more than a million years, they started to settle down and become farmers. What was so different when the glaciers melted this last time that caused people to adopt a new lifestyle? |
| Outside of the tropics even unglaciated areas experienced extreme environmental changes. human populations either adapted, died out, or moved on as their hunting and foraging grounds shifted around the world.
Each time Europe froze, North Africa dried, becoming an uninhabitable sand sea. Naturally, people left. Some migrated south back into Africa. Others ventured east to Asia or into southern Europe as periodic climate upheavals launched the great human migrations that eventually circled the world. |
Mark Sircus
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 In contrast, in Japan with its low cardiac death rate, the daily magnesium intake was cited as high as 560 milligrams. The human populations that consume the most calcium tend to have the highest mortality rates in the world. The Scandinavian countries, the USA and New Zealand are the dairy consuming countries and mortality rates soar in these countries. In Japan where the consumption of calcium from dairy products is the lowest on the planet so are the mortality rates. |
David R. Montgomery
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| Extreme environmental shifts also isolated human populations and helped differentiate people into the distinct appearances we know today as races. Skin shields our bodies and critical organs from ultraviolet radiation. But skin must also pass enough sunlight to support production of the vitamin D needed to make healthy bones. As our ancestors spread around the globe, these opposing pressures colored the skin of people in different tegions. The dominant need for UV protection favored dark skin in the tropics; the need for vitamin D favored lighter skin in the northern latitudes. |
| Development of more intensive and effective subsistence methods allowed human populations to grow beyond what could be supported by hunting and gathering. Eventually, communities came to depend on enhancing the productivity of natural ecosystems just to stay even, let alone grow. Early cultivators became tied to a place because mobility did not allow for tending and harvesting crops. Once humanity started down the agricultural road there was no turning back. |
Donna Jackson Nakazawa
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 Andrew Cunningham, a zoologist with the Zoological Society of London, recently raised a red flag about new viruses emerging from global encroachment into wildlife in an essay in the British medical journal BMJ, arguing that while this has probably happened many times in the past, such viruses failed to spread because those infected lived in remote enough areas that they either died or got well before they interacted with larger human populations. In today's world, however, the increases in international trade and travel make any kind of virulent new flu outbreak an overnight global emergency. |
Lester A. Mitscher and Victoria Toews
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| Animal studies are suggestive, but evidence from studies of human populations would be more clearly pertinent. Researchers from the National Cancer Institute in the United States and the Shanghai Cancer Institute in China teamed up in 1994 to use epidemiological methods to investigate the effects of green tea in a human population. A cancer registry in China identified 902 esophageal cancer patients, and another 1,552 cancer-free men and women were included in the study as controls. |
Ann M. Coulston and Carol J. Boushey
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 However, few observational studies have investigated the overall impact of differing diets and supplementation on the risk for DR in human populations [254?60]. Medical nutrition therapy for patients with diabetes could be targeted at preventing DR or its progression and may be less costly than current treatment.
C. Dietary Fat and Fiber
Some of the original investigations of the associations between dietary intake and DR were conducted in the 1980s and involved intervention studies of linoleic acid, an omega-6 PUFA [261, 262]. |
Bill Sardi
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| British Journal Cancer 63: 963, 1991]
However, the consensus that saturated fat contributes to prostate cancer incidence and mortality simply doesn't hold up in all human populations. Saudi Arabian men have very low rates of prostate cancer yet consume high-fat diets. Among 2,270 Saudi men screened, the incidence of prostate cancer was only 3.1/100,000 person-years. A nutritional survey revealed that recent fat consumption was greater than 120 grams per person daily, of which about 40% was from meat and dairy products. Saturated fat comprised about 50% of the total fat intake. |
Dan Buettner
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 That interest led him to join the laboratory of renowned geneticist Luigi Luca Cavalli-Sforza at Stanford, where he studied human populations by looking at their genes. His specialty was analyzing mitochondrial DNA to identify the origins of peoples—dead or alive. He had examined mummies found in China's Taklimakan Desert and revealed that they were of Indo-European origins, a discovery that had brought him fame.
"We have 46 chromosomes, half from our mother and half from our father," he explained, hands flying about like those of an orchestra conductor. |
Peter J. Whitehouse and Daniel George
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 Genes have alleles—or alternative forms—that arise through mutation, contributing to the hereditary variation we see in human populations.
Figure 10. A Closer Look at DNA. Our genetic material is located inside the nucleus of cells in structures called chromosomes. Chromosomes themselves are made up of DNA (and other substances); DNA is built from pairs of amino acid bases. |
Lester A. Mitscher and Victoria Toews
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| Epidemiological studies of human populations support this theory. In recognition of findings such as these, tea drinking has been identified by the Mediterranean Osteoporosis Study as a protective factor against osteoporosis.1
Green tea may also give hope to sufferers of another bone disorder, osteogenesis imperfecta. Osteogenesis imperfecta is a rare inherited disease in which the bones are abnormally brittle and fragile. Fractures are the main symptom, and the most severe cases are fatal. The only treatment currently available is to take measures to reduce the risk of fractures. |
| Investigations into the effects of green tea included laboratory experiments, experiments on animals, experiments on humans consuming various ordinary diets, and statistical studies of human populations. One of the most convincing studies was undertaken not in Asia but in Iowa. Epidemiologists from the University of Minnesota sent a questionnaire to 35,369 middle-aged Iowa women asking questions about their health status, lifestyle, and diet (including their average daily tea intake). |
Mark Lynas
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| Recent evidence from both modelling studies and investigations of past Earth climate suggest that El Nino may not just become stronger, it may become permanent -spelling disaster for human populations and ecosystems around the globe. At the moment transitory floods and droughts mean terrible hardship for the people affected, but sooner or later normality always returns. This may not be the case in our globally warmed future.
However, the scientific community is far from united on the El Nino issue. |
Peter J. Whitehouse and Daniel George
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| Newspapers and magazines would have us believe that Alzheimer's is spreading throughout human populations, and especially baby boomers, like an epidemic and claiming millions more victims.
However, what you aren't told is that we don't even know how to diagnose Alzheimer's disease, let alone tabulate the numbers of disease victims. Because there is no single biological profile for AD, every clinical diagnosis is considered "probable"—and, frankly speaking, not even postmortem examination can differentiate a so-called AD victim from those who have aged normally. |
Ann M. Coulston and Carol J. Boushey
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| Epidemiologic studies have the advantage of being a study of human populations with gene frequencies and exogenous exposure levels at the pertinent levels. However, there are other concerns with studies of this kind.
In epidemiologic studies, an individual's genotype can be determined from DNA extracted from cells. The DNA is typically obtained from blood cells, from sloughed cells in saliva, or from sloughed cells from the inside of the mouth. |
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