Chimpanzee males compete for position in a dominance hierarchy; status often depends on support from other members, including females, of the group. High ranking males have much greater sexual access to females in estrus. Males control females by physical violence and intimidation. Chimpanzees also engage in purposeful raids to kill members of other chimpanzee groups. This inter-group violence can help explain intra-group violence. To fend off attack from other groups, males must remain in...

Reproduction is not simple or easy, nor is it fair. Females often bear a larger reproductive burden of child bearing and child rearing. Reproductive strategies can be simplified into two primary strategies for males and two for females: males either engage in sperm competition or physical competition while females strategize to get resources from males, or to find the best male genes for the offspring. Rape and violence, as reproductive strategies, occur in few species, but violence is...

China's early demographic history is similar to that of Europe; population grows only slowly due to war, disease and Malthusian resource limitation. Later, introduction of American foods allowed cultivated land to expand, but population expanded even more rapidly, leading to an extremely dense, but poor population. During this time, female infanticide was frequent, but almost all surviving girls got married. Within marriage, their fertility rate was much lower than that of their European...

Data shows, consistently, that poor people have more children than rich people; economically speaking, children are an inferior good. Children are production goods because they do work, consumption goods because they are enjoyable, and investment goods because they support parents in old age. Jobs in the modern sector require education and health. To pay for this, parents have to focus their resources on fewer children.

World population will continue to rise until at least 2050. Environmental impact is the product of the number of people and how much of their income and technology is devoted to either consumption or conservation. So far, the balance is far at the consumption end and, globally, environmental problems are increasing. Environmentalism has not come close to counteracting the footprint of a billion extra people every dozen years. The only massive success has been the decline in global fertility....

The idea that "life begins at conception" is not a scientific one. Since the disproof of 'spontaneous generation' (1668-1859), we have known that life only derives from life. Life arose billions of years ago and has continued since as a cycle. Assigning a beginning to a cycle (like the year) is arbitrary. The Bible describes the cycle as "Dust to Dust." Exodus describes a forced abortion as a property crime, but taking the life of the mother as a capital crime. The New Testament does not...

Guest lecturer William Ryerson is President of the Population Media Center which produces radio and TV serial dramas in developing countries that aim to effect behavior change on women's status, family planning and AIDS. Working with governments and in-country media professionals, these melodramas run for hundreds of episodes and are watched by millions. Careful research shows major changes in audience knowledge, attitudes and practices.

Abortion is very common: worldwide, and in the US, there is 1 abortion for every 3.2 live births. In places where contraception is not used, abortion is used as birth control. Neither legal nor religious proscriptions have a strong effect on abortion rates. In countries where abortion is illegal, maternal death rates are extraordinarily high. Legal, medically done abortions are safer than getting pregnant. Psychological responses depend on the individual and the culture.

Rates of teen pregnancy in the US are quite high, in contrast to European countries which have much lower rates, especially those with liberal attitudes toward sexuality. Traditionally, puberty and marriage were simultaneous. Now, the many years spent in education leaves a long time between those life stages. Sex education is not particularly strong. Contraception has allowed the rate of teen pregnancy to decrease steadily in spite of the fact that teen sex is consistently increasing....

1) Population in China: Until recently, Chinese families did not much alter their fertility depending on life events like deaths of children. However, under government prodding and eventually coercion, fertility drops drastically in China in the 1970s, but, to counteract momentum, the One-Child Policy starts in 1979-80. 2) Population Growth and Economic Development: In Asia, rapid fertility drops have preceded economic booms by ~15 years. In this time, children grow up and become workers....

Families lived together in traditional China and sons remained on the land; division of family land led to tiny plots and rural poverty. Because labor was so cheap, the country did not urbanize or mechanize. The Communist government started out with a pro-natal stance, but, after experiencing the famine of the Great Leap Forward, moved strongly to fertility control. Fertility declined rapidly in the 1970s, but to counter momentum, the one-child policy was introduced in 1979-80. Nevertheless,...

In East and South Asia there are many more boys than girls. Previously, this resulted from female infanticide, now it is sex-selective abortion. In those cultures, girls generally marry out of the family as teenagers and thus provide no benefit for the family that raised them. Bangla Desh is agriculturally very rich, but its population is so dense that per capita income is one of the lowest in Asia. Despite the poverty, an excellent family planning program has greatly reduced fertility.

By 1950, in most of the underdeveloped world, mortality had fallen to about half its pre-modern rate. The birth rate, however, had remained high and, by 1950, was about twice the death rate. For the rest of the century, both rates fell dramatically and in parallel, maintaining the gap. The enormous excess of births over deaths in this period is known as 'the population explosion.' By 1990, the world population was growing at almost 90 million a year. Comparing the Demographic Transition in...

Surveys show that most women are having more children than they would prefer to have. Further, studies show that the vast majority of women know about various forms of contraception. One World Bank study has shown that family planning programs have little impact unless they are attended by improved living standards and increasing status of women.

Until recently,the world population has been growing faster than exponentially. Although the growth rate has slowed somewhat, there are about 80 million more people each year and about 3 billion more will be added by 2050 (a 50% increase). Population will probably increase more beyond that. Such growth is unprecedented and we cannot predict its long-term effects. The environmental impact of this population increase is bound to be astronomic. Large populations engender two problems:...

Concerns about low fertility have been present in many countries for at least 100 years. A large population was considered essential to national power. But the issue is never simply a shortage of warm bodies: overall the world population has increased dramatically over this period and untold numbers would immigrate, if allowed. The issue is the number of the 'right sort' of people, defined as those having preferred national, religious, racial, ethnic, or language characteristics. Fertility...

Census data is often politically influenced and hence inaccurate. The birthrate in developing countries is nearly twice that in developed countries. Most humans live in less developed countries, so the world birthrate is near the higher number. The world birthrate is two and a half times the death rate; we are not close to population stabilization. Almost everywhere, the death rate has been drastically reduced; further changes will not massively affect demographic trends. Changes in fertility...

Prior to the Demographic Transition, fertility in northwestern Europe was controlled by limiting marriage. Marriage was regulated by landowners and the churches, and was not allowed unless a man had accumulated the resources necessary to support a family. Long periods of being landless, a servant, or an apprentice, precluded marriage. Once married, there was no control of fertility. But, only about half of adults were married at any given time, so fertility was about half of what it might...

Prior to Malthus, population growth was seen as good for the power and wealth of a country. The rapid population growth of America was crucial in expelling England (via the Revolution) and France (via the Louisiana Purchase) from the US. But in fact, the numbers of the poor were growing in Europe in the 1700s. Malthus argued that poverty was due to an imbalance between people and resources; since population could rise very fast, it could always outstrip any gains in productivity. He did not...

European population grew only slowly during the period 1200-1700; factors include disease and wars. Human feces and rotting animal remains were not sequestered and often contaminated drinking water. Cities were so filthy that more people died in them than were born. About a third of children died in infancy, many from abandonment and lack of care during wet-nursing. Children that survived were subjected to harsh discipline to control their tendency to sin. Ineffective and even harmful...

In many regions, the central cultural idea is that of a lineage, a family and its line of male ancestors and descendants. The prime duty in these cultures is to keep the lineage going. Religion is small scale with the ancestors performing many of the functions of gods. Denser populations and larger political entities lead to large-scale religion where conformity is stressed and cultural rules are codified in a book and not subject to discussion with the ancestors. In pre-modern Sub-Saharan...

In addition to cultural controls acting to maximize fertility, there are important, and often competing, interests of individual families to limit fertility. Unwanted births are dealt with by infanticide in many cultures. Additionally, fertility is regularly controlled by limiting marriage within a culture. Another very important factor in population growth, especially in the tropics, is food availability. Heavy rains in the tropics wash nutrients away, leaving deficient soils. Much of Africa...

Hunter-gatherer populations were much less dense than later agriculturalists. The variety of their food supply protected them from crop failures and their sparseness reduced the spread of infectious diseases. Hunter-gatherers were healthier and worked less than early agriculturalists. Why didn't their numbers increase up to the same level of Malthusian misery? Their numbers may have been limited by violence between groups. Agriculture is more work intense and offers a less varied diet....

Throughout prehistoric, written, and recent history, human warfare has been commonplace. Nearly all societies engage in regular or periodic war. In many examples, human warfare has characteristics similar to chimpanzee war: an in-group fights with and kills members of the out-group. This information is not to be misinterpreted as either justifying human violence or considering it inevitable. When it comes to births and fecundity, though, humans are very different from the other great apes....