Lecture: September 2: Economic Growth Since Deep Time

Lecture: September 2: Economic Growth Since Deep Time

U.C. Berkeley Economics 101b, Fall 2005

The East African Plains Ape Becomes Human

• Very big brains
• Tools
• Culture
• Manipulation of environment

(Some) Humans Move Out of Africa

• 50000 years ago?
• No signs of interbreeding with other non-African proto-human populations
• Genetic differences?
  • 2000 generations is not a long time for Uncle Charles Darwin to work
  • Facial features, hair, lactose-tolerance, sickle cell and anemia resistance, Tay-Sachs
  • And, of course, melanin: rickets, vitamin D, melanoma
    • Skin color as a marker of slave status in the Americas: it kept slavery going for centuries after indentured servitude (which did not use skin color as a marker) broke down
  • Woolier and unsubstantiated stories:
    • Jared Diamond on how people in Papua New Guinea are smarter than the rest of us
    • In northern latitudes keeping warm is important: selection for dumpy and less athletic body types?
    • But don't go there: evolutionary behavior is still nothing more than a source of just-so stories, and has been a source of immense ignorance and terror in the past
  • The way to think of it, I have been told, is that there is less genetic variation in the entire human race than in a single baboon troop

Hunter gatherers * Pretty ferocious--even East African Plains Apes of two million years ago could drive hyenas from their dens * Sophisticated Cro-Magnon technology * Sophisticated Cro-Magnon culture--doing a lot of things that mark them as fully human * Life was nasty, brutish, and short--but athletic * Cro-Magnon hunter-gatherers * Average menarche at 16? * Life expectancy of 25? * Seven pregnancies to term? * But infinitesimal population growth means ferocious infant mortality * But they were buff: adult male heights of 5'8" or so

Neolithic Revolution

• Herd animals to be domesticated
• Plants with big seeds
  • Wheat
  • Rice
  • Corn--an amazing plant
• Agriculture sees like an enormously good deal at the start
• Well-nourished and easy-living agricultural populations expand rapidly
  • Farm sizes diminish
  • And Thomas Robert Malthus shows up
• Agriculture allows human race to grow from ca. 3 million (or less) in 10000 BC to ca. 170 million (or so) in 1
• Agriculturalists stomp hunter-gatherers, and usually herdsmen
  • Exception: people on horses with bows can hold their own
  • In fact, people on horses with bows can sometimes do much more than hold their own: Atilla, Temujin--until reliable firearms

What Is Agricultural Life Like?

• Nasty, brutish, short--and definitely not buff
• Menarche at 18?
• Life expectancy of 25?
• 6? pregnancies to term
• Huge childhood mortality--population growth is once again glacial--except for initial settlement phases
  • Alleviation of Malthusian misery (partial) by European household marriage or Asian lineage family
  • Psychological stress produced by these social institutions--telling your daughter she can't marry her boyfriend until he has a farm, or telling your younger brother he can't have a wife...
• Agriculturalists definitely not buff--adult male heights of 5'2" or so
• Plus
  • Agriculture means thugs with spears--rulers and warrior castes
  • Agriculture means thugs with pens--star watchers who keep records and can tell you when to plan become priests

By the Yeqr 1, the Human Race Was Biologically and Technologically Successful--But Pretty Miserable

Comments

[Matt Austern]

The story should begin with hominids becoming bipedal, not with brain size, shouldn't it? At this point there's extremely good evidence that our ancestors were bipedal long before they had human-sized brains.

[Roger Albin]

The comment about 2000 generations not being a long time for Darwin to work is ambiguous. Does this imply its too short a period for selection effects? If so, this is probably wrong. 2000 generations is plenty for significant microevolutionary changes. Spread of beneficial alleles like the sickle trait will certainly occur in fewer generations than 2000. Under some circumstances, its may also be enough time for speciation events. Transformation of teosinte into maize probably occurred in a shorter period of time.

[John Emerson]

"Neolithic Revolution

* Herd animals to be domesticated
* Plants with big seeds
o Wheat
o Rice
o Corn--an amazing plant"

Everything I've seen indicates that pastoralism came considerably after agriculturalism, and was always interdependent with agriculture.

"Agriculturalists stomp hunter-gatherers, and usually herdsmen

* Exception: people on horses with bows can hold their own
* In fact, people on horses with bows can sometimes do much more than hold their own: Attila, Temujin--until reliable firearms"

Steppe nomads survived on pastoralism if they had to (after military defeats, and when disunited and feuding), but whenever possible they taxed trade, raided the agricultural world, or conquered sedentary states. In other words, they were not pastoral peoples who sometimes went to war against the agricultural peoples; they were nations specialized for warfare who, when unsuccessful, had to rely on pastoralism. A nomad nation at peace, relying on its flocks, was like a factory lying idle.

[a different chris]

I thought sickle-cell was the flip side of a good gene, the one that made you resistant to malaria, IIRC?

So I don't understand its inclusion.

[Thomas Ware]

I just love the first full day of class - the nodding heads, the incredulous stares... the jaws dropping at the mere suggestion that they would read sixty-two pages (there will be a quiz) for Wed. EYup, that's why we went to school for eight years.

Sounds like a fun classes, are you sure it's econ!?

I tend to subscribe to the theory (mine, I think) that the hunter/gatherer agrarian cusp was with the discovery of beer.

[nmg]

I can't believe you're not going to offer equal time to the Intelligent Design approach to economic growth, starting with the rebuilding after Noah's flood....

nmg

[nmg]

You could even have a discussion about how many jobs were probably created in the aftermath of the flood's destruction. After all, economic destruction is actually economic opportunity in the form of new jobs for fixing all the broken windows, right? At least that's what I heard on the O'Reilly Factor.

nmg

[JR]

Hell, why stop with hunter-gatherers? Being an ape was even better than being a man. Look at modern gorillas.

[Roger Albin]

Sickle trait refers to carrying one allele for a specific kind of mutant hemoglobin protein. Your other allele is normal. If you have both mutant alleles, you get sickle cell disease, very bad. Heterozygotes, those carrying one sickle allele and one normal allele, have increased resistance to malaria compared with carrying two normal alleles. In areas where malaria is prevalent, there is enough of an advantage for heterozygotes that it outweighs the negative consequences of generating sickle cell disease children.

[boing!!!]

That's some clear evidence for Intelligent Design. And the following I take exception to: "In northern latitudes keeping warm is important: selection for dumpy and less athletic body types?"
That is a result of underpriced calories for Euroamericans. Alaska Natives, when eating off the land, are often eating the Atkins Diet (and should no doubt sue over prior art). The phrases "moose starvation" and "rabbit starvation" come from times when those animals don't have enough fat on them, and people had to eat the meat and organs alone with no additional fats, which would ordinarily provide the energy needed to digest the proteins and convert some into glucose for energy. Simple carbohydrates are the devil here-straight simple sugars require no energy to digest or process and either turn you into Cornholio (boingggg!!!!-Mike Judge's dad is a prominent archaeologist who sounds a little like Mr. Anderson) or put the recipient into a candy-junky mode. And turn you into a Jabba the Hutt -like creature if you are not careful.

[Scott Martens]

Roger's right about the 2000 generations thing. That's actually quite a lot of time when selection pressures are strong. I'd make the case that selection pressures on humans are very weak and have been so since at least the time of the emergence from Africa. People are smart, and they can do a lot to live in new environments without having to change their biology. This, I think, does a far better job of explaining the lack of biological diversity in humans than the "evolution is slow" claim. Evolution is as fast as conditions make it.

Nor is the claim that pre-agrarian life was nasty, brutish and short nearly as strong as people think it is. It was nasty, brutish and short for some of the last people to escape it - I think for example of the Inuit - but those were the people living in the most marginal ecological niches. All the better spots had been colonised by agrarians for at least a century before agricultural civilisation came for the Inuit. I'm not really sure the Sioux lived such nasty, brutish or short lives. Certainly part-time agrarians like the Iroquois or the Ojibwe weren't so badly off. The Inuit - who must have had the harshest environmental conditions of any pre-agrarian society in recent history - supported significant non-hunting and gathering populations, including their elderly and many women. They even had enough surplus value to develop a very substantial tool-making culture and to displace he lower tech Dorset culture. If the Inuit could get that far ahead under the worst survivable conditions, I expect that those living on more bountiful lands could get a lot further ahead.

I can't recall a citation, but I read somewhere that most hunter-gathers have average workdays of four hours or less, and enough surplus value that they can support significant non-hunting populations. And, as I understand it, present-day hunter-gathers have a lifetime average of taking four pregnancies to term, of which an average of two children reach adulthood. Women reach puberty in their mid teens, carry four pregnancies to term over the course of fifteen to twenty years, reach menopause in their late 30s to early 40s, and live about a decade after that to help raise their grandchildren. 50% infant mortality is less than some historical agricultural socieies, and death of old age at 50 or later not so rare today in the poorest parts of the world.

Furthermore, I might make the snarkily quasi-Marxist claim that agrarian society was nasty, brutish and short only in those places where there was significant surplus value extraction. Certainly the literature on the pre-colonial Tikopian society - you've been reading Jared Diamond, you must have heard of them - suggests that their lives were far from nasty, brutish or short.

Agriculture is hard work, much harder and less immediately rewarding work than hunting and gathering. If I were to toss out a hypothesis, it would be that agriculture developed because it reduced risk, not because it was inherently more productive of valued goods. Its ability to support a larger population on less land, and to support more surplus value extraction, might simply have been side effects of a culture that came into being not on the most fertile land, but on marginal land where the return from hunting and gathering was too irregular to prevent life from being nasty, brutish and short.

I know of no instance of an agricultural society abutting a non-agricultural one for a long period of time except where the non-agrarian society lived on land too marginal for agriculture using the available techniques. This - I think - is a better explanation than horses and bows, which don't explain African or pre-Columbian American hunter-gathers very well.