July 26, 2003
Notes: In the Shadow of Malthus
Begin with the shape of the demographic transition since 1820, with population growth rates plotted as a function of levels of guestimates of levels of real GDP per capita (measured in Maddison's 1990 "International Dollars") for the world's various regions for six irregular (but sensible) subperiods.* The figure shows how population growth rises rapidly as societies progress and grow their annual per-capita incomes from a Malthusian near-subsistence level of $400 (1990 International Dollars) per person per year up to $1,100 or so. Then population growth levels off--typically at 1.75% per year or so--as fertility restriction becomes widespread. Once societies pass $4,000 per capita a year or so, the demographic transition proper sets in, and population growth rates start to decline markedly.
Underlying data source: Angus Maddison (2001), The World Economy in Millennial Perspective (Paris: OECD). Raw preliminary spreadsheet at: http://www.j-bradford-delong.net/movable_type/data-TCEH/Maddison_Millennial_Numbers.xls.
Let's concentrate on the left-hand side of the figure--the one that lets us hypothesize that human population growth rates are essentially zero when annual GDP per capita levels (guessed-at in 1990 international dollars) are around $400, and that each ten percent increase in living standards above that subsistence level boosts population growth rates by about 0.2 percentage points per year: a population whose annual income level was at about $485 would be growing at a rate of 0.2% per year; a population whose annual income level was some $660 would be growing at a rate of 0.5% per year; and so on.
Now let's take a look at what we know (or, rather, guess) about human population growth rates:
Underlying data source: Michael Kremer (1993), "Population Growth and Technological Change: One Million B.C. to 1990," Quarterly Journal of Economics 108:3 (August), pp. 681-716. Raw preliminary spreadsheet at: http://www.j-bradford-delong.net/movable_type/data-TCEH/Maddison_Millennial_Numbers.xls.
Not until 1800 does the (worldwide) rate of human population growth exceed 0.5% per year. If we take the post-1820 relationship between population growth and material prosperity seriously, the conclusion is inescapable: back before 1800, average human material standards of living always stood at less than $660 per year--with a margin of at most 50% between material standards of living and those of bare subsistence--and sometimes much less.
Now there are caveats: Major wars. Virulent plagues (like that that struck the Roman Empire under Marcus Aurelius, or the Black Death) can cause people to die like flies even if they are not especially poor. To some degree "subsistence" is a cultural construct: strong social institutions like the European Marriage Pattern ("You can't marry my daughter until you own a farm of your own") or the Asian Lineage Pattern ("Younger brother, you can't bring a wife into my house until I'm confident we can afford to feed her") that delay childbearing can push up (by 10%? 30%?) the level of material prosperity at which births balance deaths.
These, however, are relatively minor caveats. We know what a pre-industrial pre-birth-control population that is moderately well-off (an annual per-capita GDP of, say, $1100 in Maddison's 1990 international dollars) does: like the North American colonists, it doubles in a generation with a population growth rate of more than 2% per year. We know that the pre-1800 human race as a whole never achieved this.
What held back population growth? What keeps the numbers of the human race from growing at more than 0.2% even under the most favorable pre-industrial conditions? The conclusion seems inescapable: desperate poverty. For the overwhelming bulk of recorded history, population growth rates have been kept low by poverty so dire that women's fat reserves are so low that ovulation is a hit-or-miss affair, and by poverty so dire that nutritional deficits are so great as to seriously compromise immune systems' abilities to deal with the endemic disease pool.
*Regions are: Western Europe, Western "Offshoots", Eastern Europe, Former Soviet Union, Mexico, Southern Cone of Latin America, Rest of Latin America, Japan, China, India, Other Asia, and Africa. Periods are Maddison's: 1820-1870, 1870-1913, 1913-1950, 1950-1973, 1973-1990, and 1990-1998.
Posted by DeLong at July 26, 2003 07:26 AM
Through southern Africa we are seeing a demographic pattern that is sadly different than any I know of since 1800. There is a gentle decline in population over 50. A population between 20 and 50 that shows quite slow growth. A population below 20 that swells gently to infancy. Age groups from 20 to 50 form a chimney rather than a pyramid.
AIDS is attacking the 20 to 50 age group, leaving family after family of grandparents taking care of grandchildren. The old are caring for the young. Orphan status is large and steadily growing.
Imagine what happens especially in a farm family when a young adult becomes ill. Imagine the burdens on any family when a most productive adult becomes ill.
Life expectancy is declining because of AIDS, but that does not tell of the problems that are experienced in family after family.
"[...] population growth rates have been kept low by poverty so dire that women's fat reserves are so low that ovulation is a hit-or-miss affair"
Sounds unlikely to me. The increase in global population, at least in the last 200 years, has almost invariably been due to declining death rates (especially in infant and child mortality), rather than increasing birth rates.
Your point would have been well made it you'd stopped your data at say 1900 since that would have captured a world with countries were poverty physically restrained breedin and one where it didn’t. Population growth is also not the best guide here since migration has obviously been a very important factor.
I think it would be hard to argue that the 20th century represents the same model since in the higher income countries, as we’ve had baby booms mid century and busts in the 30s and 90s. So I think that the 20th century represents a very different scenario with very specific factor in play. In the short term, economic conditions are important with depressions and recessions casting an icy wind over breedin prospects.
Over the long term, market structure is the most important; the countries with the largest welfare state (in particular pensions) / state regulation have the lowest fertility rates on average –Italy, Singapore etc while countries with relatively little state regulation/ welfare maintain a higher growth rate – US, Australia etc.
However the humped red line in the first graph captures a popular perception, common in the low growth/no growth movement – namely that if you move your country back into the centre of the GDP per capita pack, you’ll increase the breedin rate. Which is why women are more likely to be no growth advocates. The graph adds fuel to the argument, but I think its wrong.
A focus on the well-being of children under 1, can result in strides in life expectancy. The Chinese began to focus on infant well-being in the 1950's, and though medical care was rudimentary in the countryside there was a spurt in life expectancy.
December 2001 -
663,815,000 total population of sub-Saharan
291,310,000 population of adults 15 to 49.
28,500,000 sub-Saharan Africans HIV/AIDS
26,000,000 adults 15 to 49. 9.0% adult rate.
15,000,000 women 15 to 49. 57.7% of infected.
2,600,000 children 0 to 14.
22,000,000 - 35,000,000 range of sub-Saharan
Africans HIV/AIDS positive.
6.41 - 11.39% range of women 15 to 24
3.13 - 5.56% range of men 15 to 24 infected.
19,400,000 deaths estimated for sub-Saharan
Africa's adults and children of diseases
caused by AIDS from beginning of epidemic to
2,200,000 deaths of Africans from diseases
caused by AIDS in 2001.
500,000 deaths of children.
1,300,000 - 2,300,000 range of deaths for
380,000 - 650,000 range of deaths for
3,400,000 Africans newly infected in 2001.
700,000 children newly infected.
11,000,000 orphans cumulatively at end 2001.
An orphan is described as a child who by 15
has had a mother or both parents die of
diseases caused by AIDS. Mothers generally
are the leading care takers of Africa's
44 countries in sub-Saharan Africa.
37 countries studied.
20% or more adults infected in 7 African
11% or more infected in 12 countries.
5% or more infected in 24 countries.
But will Aids raise or lower GDP per head in Africa?
The error in the logic is to assume that the subcells have the same growth as the aggregate - that is that all sub-populations have the same growth rate as the aggregate total. Instead, dumping this highly suspicious assumption, another, simpler, explanation for the data becomes immediately obvious:
There is only so much arable land at a time, this represents the bottleneck to total population growth - marginal cultivation.
At any given time, some groups occupy the best land, and through a combination of technology and social organization, grow quickly, others, with less marginal land, are at subsistence level or less, and do not grow at all.
Periodically, one group takes large swathes of land from the dominant group, and then procedes to grow rapidly as it brings the best land under its control.
An example is the pattern of conflict in Mayan kingdoms. The core royal families occupy the best land, with progressively more marginal land brought under cultivation as population grows - thus limiting growth rate. When there is a catastrophically bad harvest, this touches off a control for the most usable land, since the marginal land is now below its cost, in human energy, to cultivate. Royal houses survive or are overthrown, new houses establish themselves, and the marginal land is brought back under cultivation as the new reign of stability propers.
As the number of people grows, the number of people who are supported by production which is above the minimum productivity of the land grows. That is, there are more and more people who are going to die if there is a dramatic drop in food production. When one of these drops occurs - famine, war, disease - become inevitable, as populations scramble to control enough arable land to feed themselves, or, failing this, starve or fall victim to disease.
The one example of how this cycle works is the classic collapse of agrarian populations under the introduction of new arable regions. Marginal farmers lose their ability to compete, they then pour into the cities looking for work, and become part of the desperate urban poor. The paradigmatic case is the introduction of Egyptian grain into the Roman grain market, which put out of work huge numbers of farmers in the core latin areas, these then entered the cities, and forced the institution of "the dole".
The succession of empires in the fertile crescent, and other patterns of barbarian migration are all examples of this: that there are centers of great wealth, and even greater subsistence level population, and that these groups are, necessarily, unstable, in their positions.
This explains why language groups, kingdoms and so on rise and fall in a way that the "steady state poverty" model proposed does not explain - namely that a large group grows rapidly, reaches a growth limit or suffers a reversal of fortune which weakens it dramatically, and falls prey to some other group. It matches the studies of other mamalian population groups. Individual groups or troops do not grow with strict logarythmic proportionality, but rather, they explode in population, and then fall rapidly, with unsuccessful groups being absorbed or destroyed by successful ones, which then grow rapidly again afterwards.
The simplest explanation then is that homo sapiens have the same population growth characteristics - growing rapidly in fat times, and falling rapidly in lean times, leaving those occupying marginal feeding areas vulnerable to being over run by excess from areas which are still in a surplus mode.
Decidedly, AIDS is and will lower GDP per capita in Africa. The idea that Africa could benefit by a mass loss of population is an impossible idea. Remember, how do children effectively raise themselves or even effectively rely on grandparents who are of less strength than young adults. AIDS destroys per capita income and wealth.
If you look at the previously posted charts of average life expectancy over time, then it is clear that in previous times, people (a lot of them) died young before bearing children. If you look at the list of the top ten causes of death in the US in 1900 vs now, you will find that diseases such as influenza, smallpox, whooping cough, etc were among the top killers. They are not even on the top 10 list today. This is due to improvements in health, especially vaccinations and sanitation. Of course, vaccination and sanitation require money, so there is a link between economics and death rate. Remember that the plague wiped out over 1/4 of all Europeans in the 15th century. Plague and smallpox wiped out over 95% of the AmerIndian population in parts of the Americas. We just don't have these causes of death at this massive scale today.
What is hard to grasp is how severe AIDS is in southern Africa. How explosive it can be. Now that Angola is at peace, the flow of people across borders threatens a potential rise in AIDS cases such as was experienced in such a sealthy manner in South Africa after freedom. We must not under-state the problem and threat. To my knowledge there is a single American doctor working with the Angola army to keep the army from becoming a major vector for AIDS.
5.8% adult rate of infection in Nigeria.
53.1% of infected adults are women 15 to 49.
4.66 - 6.99% estimated range of women 15 to
9.7% adult rate of infection in Cote d'Ivoire.
58.0% of infected adults are women 15 to 49.
6.67 - 9.95% range of women 15 to 24
15.0% adult rate of infection in Kenya.
6.09% of infected adults are women 15 to 49.
12.45 - 18.67% range of women 15 to 24
20.1% adult rate of infection in South Africa.
57.5% of infected adults are women 15 to 49.
20.51 - 30.76% range of women 15 to 24
33.7% adult rate of infection in Zimbabwe.
60.0% of infected adults are women 15 to 49.
26.40 - 39.61% range of women 15 to 24
38.8% adult rate of infection in Botswana.
56.7% of infected adults are women 15 to 49.
29.99 - 44.98% range of women 15 to 24
What did you use to produce the smooth? LOWESS? What smoothing parameter and how chosen?
Note that Angola is already becoming a major oil producer. Angola has more extensive reserves and could soon be producing more oil that Kuwait. America is and will be a desired market.
The PBS study of AIDS and the Angolan military is on "Wide Angle." Excellent.
AIDS is definately a big health threata in Africa. However, malaria is still the number one killer in Sub-Saharan Africa.
"Decidedly, AIDS is and will lower GDP per capita in Africa. "
clearly nonsense Anne - for a country like Botswanna - where most income comes from a fixed source minerals requiring very little labor input, a smaller population equals a higher GDP.
For agricultural countries - the precedent of the Black death may be relevent - it rasied workers incomes (but not land owners).
For manufacuting economies - i.e. South Africa - we dont really have a precedent. But I suspect that it will not raise incomes per head.
Please refer to the World Bank report on economic costs of AIDS. Anne is perfectly correct. AIDS will significantly lower per capita GDP in Africa. An most important matter along with the astounding demographic toll of the disease.
Malaria kills over one million people each year, about 3,000 a day: the majority of victims are children.
At least 300 million people suffer from acute malaria each year.
Nine out of 10 cases occur in Africa south of the Sahara.
Malaria is continuing to spread in Africa.
The cheapest anti-malaria drug - chloroquine - is rapidly losing its effectiveness in almost
all endemic countries.
AIDS' Threatens Economic Catastrophe'
Lagos - Aids mainly affects the most productive members of society. The economic impact of HIV/Aids may be far worse than previously thought and some African countries may face complete collapse, a report has warned. The study, jointly authored by economists from Heidelberg University and the World Bank, models the impact of the virus in various scenarios.
In South Africa, one of the countries worst affected by HIV/Aids, a failure to fight the disease will cause incomes at least to halve over the next three generations, the study predicts....
...For a country like Botswanna - where most income comes from a fixed source minerals requiring very little labor input, a smaller population equals a higher GDP....
Nonsense indeed. I suggest studying the labor intensive mining techniques employed in Botswana, as well as the struggle there against AIDS. "AIDS," as the President of Botswana declared, "is a dire threat to the very existence of its people."
Anne, I cant see how and OLG model is applicable to Botswana 90% of whose wealth is mineral.
Fact - Aids may well increase GDP per capita.
Giles - I understand your argument, but suggest we need to think beyond. AIDS appears to be a different threat than we might have supposed beyond the personal sadness.
"The traditional reasoning is not the result of down-playing the spread of the disease.
"Rather, it reflects the theory that a shrinking labour force will enjoy progressively higher wages, and people in overpopulated regions will benefit from greater access to land and other fixed assets.
"This effect, often observed in the wake of epidemics, should go some way to replacing the costs of treatment, welfare and lost production.
"The Heidelberg-World Bank report differs from its predecessors in its focus on so-called 'human capital', the stock of experience, skills and education which contribute to an economy's potential for growth.
"The survivors will not benefit from higher wages
"'The real economic threat of Aids is its potential to kill young adults,' says Professor Hans Gersbach, one of the authors.
"'By doing that, it prevents the transfer of human capital from one generation to another.'
"As young adults die off, more and more children will be taken out of education and pushed into the workforce.
"Dying parents will have fewer resources to educate their children, and infected children will have less incentive to acquire an education. The overall effect, the authors say, will be rapidly to erode a nation's intellectual capacity, and to produce an economy wholly dependent on child labour.
"And the usual post-epidemic effect of higher wages will not emerge.
"By pushing economies back towards primitivism - making subsistence farmers out of the children of engineers, for example - the disease will actually reduce the individual earning potential of the survivors."
In other words, for nations whose GDPs consist mostly of mineral extraction for foreigners while the locals live in a subsistence economy, if almost all the natives died the country would become more much prosperous.
Post 1800's was development of smallpox vaccine.
Also, in the book Kristin Lavransdatter, which took place in the 1300's, it describes a life where it was more common for people to give their lives to the Church. I don't know how you could get any exact figures, but I wonder if that was more common practice, and perhaps women had more career opportunity in the single life. The book also gives an account of the Black Plague.
Newberry hits on the fat time lean times. The story of civilization is storing food to buffer against the lean times. This can be disrupted by major shifts in climate that last for decades or even centuries.
Very large population densities were not possible until the transportation system to get food from the agricultural areas to urban areas were developed. That is why the earliest population centers were located near shipping ports. Using animals or people to haul food is limited by the amount of food that must be fed to the animals. It was not until the use of fossil fuels to transport agricultural products that very large urban areas even became possible and especially those located in the interiors away from the ports.
Until the development of the railroads, it was impractical to ship grain from the midwest to the east coast cities. Once established, transportation could overcome regional crop failures from drought or disease. Prior to this transportation infrastructure, people were dependent upon the food they could store. Famines, such as the Irish potato famine were in part because the potato disease prevented the storage of potato over the winter. With no currency to import food and a demand by the empire to export their wheat, starvation came to Ireland. Where civilization can store and transport food efficiently, starvation can be eliminated. The famines of today are not due to a lack of food, but to a lack of transportation of the food to the starving people.
from the world bank's world development report 2003:
Most current estimates suggest that 2 billion people will be added to the world's population over the next 30 years and another billion in the following 20 years.1 Virtually all of this increase will be in developing countries, the bulk of it in urban areas. In these same countries, 2.5 billion to 3 billion people now live on less than $2 a day.2 The core challenge for development is to ensure productive work and a better quality of life for all these people. This will require substantial growth in productivity and incomes in developing countries.
The challenge may seem daunting-and it is. But over the past 30 years world population also rose by 2 billion.3 And this growth was accompanied by considerable progress in improving human well-being, as measured by human development indicators. Average income per capita (population-weighted in 1995 dollars) in developing countries grew from $989 in 1980 to $1,354 in 2000.4 Infant mortality was cut in half, from 107 per 1,000 live births to 58, as was adult illiteracy, from 47 to 25 percent.5
Looking back to the 1950s and 1960s, it was feared at the time that the developing countries -particularly China, India, and Indonesia- would not be able to feed their rapidly growing populations. Thanks to the green revolution in agriculture, the doomsday scenarios of famine and starvation did not materialize in these, the most populous, developing countries. In the 1960s and 1970s the Club of Rome and many other groups forecast that the Earth would rapidly run out of key natural resources. So far, this has not happened, again because changes in technology and in preferences have allowed the substitution of new resources for existing ones-for example, fiber optics in place of copper. Global action has also led to major strides in eliminating disease scourges (smallpox and river blindness), and in addressing new problems (ozone depletion).
But accompanying these achievements were some negative social and environmental patterns that must not be repeated in the next 50 years if development is to be sustained...
There is a current of thought about AIDS in Africa that suggests the epidemic will have a minimal effect on GDP. Such thought may be even under-cutting efforts to focus on the dire seriouness of the AIDS epidemic. Such thought makes not a fig of difference on a moral level. The suffering from AIDS is sad beyond proper description and must be addressed. The economic impact of AIDS beyond the profound sadness will be a disaster of disasters.
An argument that the mining industry of Botswana will assure that GDP per capita is higher after the AIDS epidemic has run its course, shows no care for the people of Botswana, no knowledge of Botswana or mining in Botswana. A willfully awful argument.
Until the development of the railroads, it was impractical to ship grain from the midwest to the east coast cities.
umm.. I seem to recall a canal built across upstate New York....
Wow, weird. I've been thinking a lot about Malthus for the past week or so (looking for a second disertation topic) and here Brad goes and plops up three excellent posts on the subject,
together with very useful references (though I've
already read the Kremer and Lee/Anderson papers -
but it's been a while). Thanks a lot!!!
By the way the original Malthus Essay on Population can be read online:
It's fairly short as far as these things go.
Reading it (for the first time) I was struck at
how well written it is compared to modern writing
(economic or generally academic):
"It has been said that the great question is now
at issue, whether man shall henceforth start
forwards with accelerated velocity towards
illimitable, and hitherto unconceived improvement,
or be condemned to a perpetual oscillation between
happiness and misery, and after every effor remain
still at an immeasurable distance from the wished-
Now that's a sentence!
I've always had a soft spot for those scatterplot smoothers.
Brad DeLong writes, "[...] population growth rates have been kept low by poverty so dire that women's fat reserves are so low that ovulation is a hit-or-miss affair"
Elliot Oti responded, "Sounds unlikely to me. The increase in global population, at least in the last 200 years, has almost invariably been due to declining death rates (especially in infant and child mortality), rather than increasing birth rates."
Yes, exactly. The reason human population swelled in the 20th century was that people stopped dying like flies, not that they started breeding like rabbits. It was reductions in infant and child mortality that caused the 20th century "population explosion," not increases in birth rates.
Dr. DeLong's theory simply isn't supported by facts. Women had MORE children--more ovulations resulting in pregnancies--prior to 1820 than they have today...at least in the U.S. and other developed countries. It's just that an unbelievably high percentage of the children that were conceived prior to the 1820s never made it to the age that they could reproduce.
For example, I think it was Oliver Wendell Holmes who observed that, as of the start of the 20th century, a doctor's care was as likely to harm as it was to help. And even as late as the U.S. Civil War, sanitary practices in miliary hospitals were shockingly poor. Only 1 in 4 (!) Civil War patients could be expected to live after receiving treatment in military hospitals.
Even the poorest groups of people today can have large population growth rates, if they understand and follow basic principles of sanitation (e.g. separate human waste from drinking water) and disease prevention (e.g. Anopheles mosquitoes cause malaria, use DDT inside dwellings).
Radek writes, "Wow, weird. I've been thinking a lot about Malthus for the past week or so (looking for a second disertation topic) and here Brad goes and plops up three excellent posts on the subject, together with very useful references (though I've already read the Kremer and Lee/Anderson papers - but it's been a while). Thanks a lot!!!"
I suggest you don't arrange your thesis around Dr. DeLong's questions of, "What held back population growth? What keeps the numbers of the human race from growing at more than 0.2% even under the most favorable pre-industrial conditions?"...
...and his ANSWER(S) of, "The conclusion seems inescapable: desperate poverty. For the overwhelming bulk of recorded history, population growth rates have been kept low by poverty so dire that women's fat reserves are so low that ovulation is a hit-or-miss affair, and by poverty so dire that nutritional deficits are so great as to seriously compromise immune systems' abilities to deal with the endemic disease pool."
These answers are NOT even supported by the preponderance of available data, let alone an "inescapable conclusion." Dr. DeLong's "inescapable conclusions" are contradicted by:
1) Population growth was not caused by having more babies, but by having more children who children who subsequently reached reproductive age (as could be determined from birth records from the early 19th century, versus birth records for the middle 20th century), and
2) Population growth was caused by knowledge of the causes of death and disease (e.g. knowledge of microbiological foundations of improper sanitation, and communicable diseases like malaria). This knowledge became available to even the poorest people in the 20th century. For example, the populations of India and China exploded in the middle of the 20th century. But the per-capita wealth of those two countries in that period probably wasn't substantially greater than the per-capita wealth of the colonists and early 18th century U.S. citizens. What was available in India and China, that was not available to the colonists, was knowledge of the causes and preventative measures for diseases (both diseases caused by improper sanitation, and diseases like malaria, diptheria, and whooping cough).
I was thinking about a related issue at church yesterday, when the Gospel reading was on the miracle of the loaves and fishes (I think it was the version from John). It said that there was a crowd of 5,000, and the economist in me started to wonder: that sounds like an unrealistically high number. What was the population of Israel at that time? What fraction of the population would 5,000 represent? Do we think that's plausible? How big would a realisticly large crowd look like in Israel, c. 30 AD? (I'm not a fundamentalist, so I'm allowed to question the numbers in the Bible.)
Unfortunately, the numbers in Brad's spreadsheet don't really help out in this regard. Any thoughts?
"The cheapest anti-malaria drug - chloroquine - is rapidly losing its effectiveness in almost
all endemic countries."
The cheapest drug would be almost unnecessary if the cheapest pesticide/repellant, DDT, was extensively used to protect people from being bitten inside their dwellings.
I wish "environmentalists" would stop promoting practices that have killed literally millions of people. They give people like me a bad name.
Mark Bahner (environmental engineer)
"I was thinking about a related issue at church yesterday, when the Gospel reading was on the miracle of the loaves and fishes (I think it was the version from John). It said that there was a crowd of 5,000, and the economist in me started to wonder: that sounds like an unrealistically high number. What was the population of Israel at that time? What fraction of the population would 5,000 represent?"
One estimate (by Josephus, who was governor of Galilee) is 3 million people. Even if that's exagerating by a factor of 3 (i.e., 1 million people) a crowd of 5,000 doesn't seem outrageously large.
Of course, even crowd estimates made in 2002-2003 seem open to subsequent large revisions.
Brad's conclusion that « desperate poverty » and chronic malnutrition held back the growth rate of the human population up to say 1800 CE becomes doubtful if you try to extend it beyond the dawn of agriculture (≈ 10 000 BP). Demographic growth rates in the long hunter-gatherer era must have varied quite a lot, first constrained by competition in Africa and expanding rapidly when skilled hunters moved in on unexploited Eurasian and American fauna, but overall they must have been modest. Still, the modern and archaeological evidence is that hunter-gatherers are pretty healthy. Their population is too low to support endemic infectious disease, and is controlled by other factors than chronic, Malthusian malnutrition: predation, accidents, intraspecies violence, infanticide, catastrophes and late weaning. I’m not sure about parasites.
Recently discovered bones of very early African humans show big frames; they had to be strong because the diet included hippos. Imagine hunting hippos with stone-tipped weapons, poor-quality ropes and nets, and shallow pit traps. If the humans won there was plenty of food to share; but many must have died trying.
I like the baby-food theory: hunter-gatherer mothers must breast-feed infants and wean them late on to a chewy mixed diet, farmer mothers can substitute some gruelly pap early and get pregnant again. The population booms, the farmers drive out the hunter-gatherers by force of numbers; but are now locked into a Malthusian trap, where their health deteriorates by loss of diversity in diet and greater susceptibility to diseases. (In fairness I should state that I tried this theory on the eminent food historian Felipe Fernandez-Armesto, who says it doesn't fit the known facts about adoption of farming.)
The Malthusian constraint is a good theory for the Era of Agriculture. It doesn't fit either the preceding Hunter-Gatherer Era or the Knowledge Era we live in.
Infanticide, especially practiced against female children, was probably also common.
An excerpt from a letter, year 1BCE from an Egyptian worker to his wife:
“If by chance you bear a son, let it be, if it is a girl, cast it out [to die].”
From Jesus: a Revolutionary Biography, by J.D, Crossan
An excerpt from a letter, year 1BCE from an Egyptian worker to his wife:
“If by chance you bear a son, let it be, if it is a girl, cast it out [to die].”
From Jesus: a Revolutionary Biography, by J.D, Crossan