Spring 2008 Lecture #14: Origins of agriculture; early evidence of human culture Agricultural revolution and evolution of modern societies: Great Nature spoke; observant Man obey’d;
Cities were built, societies were made:
Here rose one little state; another near
Grew by like means, and join’d, through love or fear.
Alexander Pope, in Essay on Man
Guns, Germs and Steel: The Fate of Human Societies, by Jared Diamond (1997): a widely read recent book that emphasizes the influence of geographical features and the distribution of particular plants and animals in determining where agriculture began and how it spread. Diamond describes the relation of locations where agriculture first developed to distribution of plant and animal species that are suitable for domestication
Domesticated animals used for food and/or for work: sheep, goats, cattle, horses, pigs, chickens, turkeys, water buffalo, llama, dogs (derived from wolves)
Crop plantTime of domestication Pea, wheat, olive 8000 B.C.
Rice, millet 7500 B.C.
Corn, beans, squash 3500 B.C.
Potato, manioc 3500 B.C.
Acorns not used as human food, but are utilized by some animals
Wild almonds contain a very bitter compound, amygdalin, that breaks down to yield cyanide---can be deadly---occasional wild almonds do not produce amygdalin and these can be eaten---perhaps some of these were selectively eaten (didn’t taste bitter) and their seeds may have sprouted around garbage heaps near human habitations---eventually subjected to cultivation---by 8000 BC wild almonds show up in excavated sites in Greece, and by 3000 BC they were domesticated in Mediterranean regions---around 1325 BC almonds were left in the tomb of Tutankhamen
Wild ancestors of watermelons, potatoes, eggplants and cabbage also were bitter or poisonous
Plant toxins---are they simply accidental or have they evolved as protection against herbivorous animals?
Some plants also produce hormone mimics--- phytoestrogens---estrogenic compound in clover ---in 1940s, sheep in Australia showed unusual number of still births and infertility---this traced to consumption of red clover--- some plants produce compounds that are not directly estrogenic, but which are converted to estrogenic compounds by action of gut bacteria
A juvenile hormone mimic is produced in some trees---juvenile hormone prevents metamorphosis so that the insect remains in the larval state
Endocrine disruptors---study of naturally occurring compounds and also industrial by-products that interfere with normal endocrine function
Examples of ‘agriculture’ in animals:
leaf cutter ants
b. naked mole-rats?
Use of artificial selection to produce strains of crops that are resistant to bacterial or viral pathogens---i.e., many varieties of disease resistant tomatoes and corn
Qualities of animals that make them suitable for domestication---ease of taming them, ability to maintain and breed them easily, usefulness for meat, hides, performing work---most domesticated species originated in Europe/Asia---Diamond argues that only a small percentage of wild species have characteristics that make them suitable for domestication
Germs: several of the most devastating pathogens (smallpox, influenza) were transferred from domesticated animals to humans
Technology (steel, guns, etc.): made possible by efficient agriculture, allowing for specialization
Possible growth rates of populations (as applied to the relatively rapid population of the Americas by hunter-gatherers: If an initial population of 100 colonists has a growth rate of 1.1%/year (and rates as high as 3.4%/year have been observed in modern times when people colonized virgin islands), then a population of 10 million could be achieved in 1,000 years
Extinction of many large mammals in the Americas occurred approximately coincident with the spread of humans (~11,000 years ago). This left few large animals available for domestication.
A similar correspondence between extinction of large animals and human expansion holds for New Guinea/Australia ~40,000 years ago
Stages of human social evolution: a. bands---typically 5-80 people, mostly close relatives by birth or marriage---probably all humans lived in bands until at least 40,000 years ago---bands generally have no permanent single base of residence---no regular economic specialization, except by age and sex; all able-bodied individuals forage for food
b. tribes---often a close-knit cluster of villages (political definition)---tribal organization began to emerge around 13,000 years ago in the Fertile Crescent and later in some other areas---consists of more than one formally recognized kinship group (termed “clan”), which exchange marriage partners---land belongs to a particular clan, not to the whole tribe---number of people in a tribe still small enough that everyone knows everyone else by name and relationships---tribes, like bands, have no ranked lineages or classes (egalitarian social system)
c. chiefdoms----larger than tribes---arose around 5500 B.C. in the Fertile Crescent and by around 1000 B.C. in Mesoamerica and the Andes---several thousand to several tens of thousands of members----size creates much potential for conflict because, for any person living in a chiefdom, the vast majority of other members of the chiefdom are neither closely related by blood or marriage nor known by name---chief holds a recognized office, filled by hereditary right---permanent centralized authority---chiefs generally wore distinguishing clothing or ornaments---large population in small area required much food, usually obtained largely by food production, sometimes by hunting-gathering---chiefs and their families generally have higher standard of living than others; people often ranked in terms of their genealogical distance from the chief
d. states---first appeared around 4000-3500 B.C. with early kingdoms of Mesopotamia (now Iraq) and Egypt; later, states developed in India and China---by 2500 B.C., states were developing in Mesoamerica and in the Andes region of South America---states first appeared in societies with large-scale, intensive agriculture---states are socially stratified into largely distinct classes in terms of wealth, power, and prestige
Humans are the only animal that has evolved to sometimes live in large social/political groups containing genetically unrelated individuals who cooperate with each other---this typified in its most extreme form by the appearance of the political groupings that we refer to as “states” Robert Carneiro proposed a theory about the origin of the state that placed emphasis on competition, conflict, conquest, coercion. Carneiro argued that states developed when groups of people living in close proximity began to run out of space for agriculture and could not easily leave the region due to geographical constraints of some sort. Competition among groups under these conditions led to the development of states. This idea is in sharp contrast to Rousseau’s “Social Contract” hypothesis.
Stone tool “cultures” of hominins: Oldowan stone tools:
rounded stones that have been flaked to make an edge
debate whether the real tools were the flaked cores or the flakes themselves, or both
not clear which species made the first stone tools---may have been H. ergaster, although first tools appear to have been dated to about 2.5 mya (contemporary with H. habilis), whereas H. ergaster not known from before 1.9 mya (however, stone tools probably better preserved than fossils, so possible that H. ergaster was present before 1.9 mya)
humans depend on hard-to-learn skills to acquire foods and this may have been a major factor in evolution of slow development, intense care of juveniles, and cultural development
contemporary humans rely far more on extracted and hunted foods and on food sharing as compared to apes---though chimpanzees do hunt red colobus monkeys and share meat
much more specialization in foraging activities among humans as compared to apes
learning by imitation---evidence from early stone tools
Taphonomy: study of the processes that produce archeological sites---for example, by comparing features of contemporary and archeological sites---this approach used to obtain evidence for probable use of fire, perhaps by H. ergaster; baked earth found near stone tools at a site dated to about 1.6 mya
flaked core on all sides to form a biface
hand ax was a common type of tool
first evidence of this style of tool about 1.6 mya and persisted until about 300,000 ya
standard design of hand axes suggests that the tool-maker had a design in mind (as compared to more random shapes of Oldowan tools)
hand axes most likely used to butcher meat
hand axes continued to be made until about 300,000 years ago, even though H. ergaster disappeared about 1.0 mya
Beginning about 300,000 ya, hand axes became less common and were replaced by more elaborately flaked tools, some of which were apparently hafted (attached to a handle). H.heidelbergensis probably made stone-tipped spears, a major innovation for hunting big game
African Homo living at the same time as Neandertals were not like Neandertals in skeletal features, but they did have similarly large cranial volumes (1370 – 1510 cc)
Africa was probably inhabited continuously by species of the genus Homo since their first appearance about 2.5 mya. New stone tool technologies seem to appear first in Africa and then later appear in Europe and Asia, suggesting successive migrations out of Africa and successive replacement of Eurasian Homo populations.
There are two conflicting and vigorously debated hypotheses regarding the early history of human culture. One idea is that there was a rather sudden explosion of culture in Europe beginning about 50,000 ya. This idea is supported by the findings of a number of cultural artifacts such as clay figures and cave paintings that have been found in Europe and dated to about that time. The earliest known cave paintings are those at Chauvet in southern France, dated to about 32,000 ya. Interestingly, these early European cave paintings did not include representations of people; they only depicted animals like horses and deer. The earliest known drawing of human figures was on a rock face in northwestern Australia. It was not possible to date the drawings themselves, but a wasp nest that was constructed on a part of one of the drawings was dated to 17,000 years ago, so the drawing must be older than that.
An alternative hypothesis is that the apparent ‘explosion’ of human culture in Europe is misleading, and stems from the fact that there has been far more intense exploration of sites in Europe than in Africa. This hypothesis suggests that development of culture was more gradual in Africa and that the apparent ‘explosion’ of culture artifacts in Europe occurred because migrants from Africa brought culture with them and continued to develop cultures in Europe and Asia. Evidence for this idea is the finding of cultural artifacts such as stones with abstract engravings and necklaces made of drilled shells dating from 70,000 years and more.