homo sapiens

Notes from Nicholas Wade 2006 Before the Dawn. Recovering the lost history of our ancestors.

[page numbers of quotation]

 17 The first walking apes, woodland primates known as australopithecines, appear in the fossil record 4.4 million years ago [mya]. A breathtaking trace of their presence is a line of footprints made nearly a million years later at Laetoli in Tanzania. The tracks of two individuals, perhaps a parent and child, extend for 165 feet across the ash from a nearby volcano, crossed by the tracks of other animals, perhaps fleeing from the eruption. A few frozen seconds of time, with prints that look so human...
gorillas, whose harem-keeping males are twice the size of females. Male chimpanzees are 25% larger than females, but in today's human populations men are only 15% larger than women. Male australopithecines were about 50% larger than females, suggesting that aus. society was much like that of chimpanzees, with strong rivalry between males and a separate male and female hierarchy.

 19 Brain cells are greedy consumers of glucose and oxygen. The modern human brain is only 3 percent of the body's weight but uses some 20% of the energy required for metabolic maintenance.

 26 In every population of the world, women's skin color is 3 to 4% lighter than men's, perhaps through sexual selection by men, and perhaps because of mothers' greater needs for vitamin D.

 27 By comparing the mutations in various versions of the human and ape gene, researchers have calculated that the human version [hair follicles change from terminal to continuous growth] became inactivated some 200,000 years ago. This is long after Homo ergaster has become extinct and about the time that the human line acquired its contemporary physical appearance.

 45 Most adult speakers of English have a vocabulary of 60,000 words, though the top 4,000 words account for 98% of conversation.
...[Stephen] Pinker concludes that know-how, sociality and language are three key features of the distinctively human lifestyle and that the three factors co-evolved, each acting as a selective pressure for the others... This means language would have emerged after 5 m.y.a. and before 50,000 years ago.

 46 Paleoanthropologists have tended to favor the idea that language started early, with Homo erectus or even the australopithecines, followed by slow and stately evolution. Archaeologists, on the other hand, tend to equate full-fledged modern language with art, which only becomes common in the archaeological record some 45,000 years ago. Their argument is that creation of art implies symbolic thinking in the mind of the artist, and therefore possession of language to share these abstract ideas.

 50 By analyzing the variations in the FOXP2 genes possessed by people around the world, Paabo was able to fix a date, though rather roughly, for the time that all humans acquired the latest upgrade of the FOXP2 gene. It was fairly recently in human evolution, and certainly sometime within the last 200,000 years, he concluded.

 52 [depopulation on Africa between 60 and 40,000 years ago; cf. Bill Bryson _A Short History of Nearly Everything_ conjecture of asteroid collision or multiple massive volcanism] The ancestral population itself, geneticist estimate, shrank to as few as 5,000 people.

 70 The ancestral human population is separated from people today by some 2,000 generations [20 generations from 1500 to 2007]. In evolutionary time, that is not so long, yet is still time enough for very substantial evolutionary change to have taken place.

 81 The basic inference that can be drawn from them is that the ancestral group in Africa from which the first emigrants derived was very small, probably just a single band of hunter-gatherers. Such a band would number about 150 people if modern HG groups are typical of ancient ones. The group that left Africa would presumably have been this one band or a part of it.

 82 ...independent evidence: by 46,000 years ago, all large Australian mammals, birds and reptiles weighing more than 220 pounds [100kg] had suddenly fallen extinct. The reason was almost certainly the activity of a vigorous new predator, human hunters. The large animals of the Americas were to undergo a similar extinction shortly after the first hunters reached the New World.

 88 Joseph Greenberg, i0n his classification of the world's [6,000] languages, placed Andamanese in a superfamily he called Indo-Pacific. The other members of IP are Tasmanian and the ancient Papuan languages of New Guinea... feature in common --all are spoken by people in remote regions who may be descendants of the first migration of modern humans from Africa to the foundered continent of Sahul.

 108 ...about 7% of today's Europeans are descended from these first arrivals.
     All but one of the other clusters arrived at various times in between, from 35,000 to 15,000 years ago. Altogether some 87% of Eu. are descended from people who arrived before the end of the Pleistocene ice age. Only 13% are descended from ancestors who came to Eu around 10,000 years ago, mostly in the form of the J cluster of mitochondrial lineages... from the Near East who brought knowledge of agriculture into Eu and were the harbingers of the Neolithic age.

 110 Dogs [first domesticated animal] may thus have played an important role in early human history, especially if they helped make possible the transition from foraging to settled societies. People who settled down in one place would have been under constant risk of attack. It is perhaps significant that the first settlements occurred at the same time as dogs were domesticated.

 111 [precedent of private property rights] Dogs don't belong to a community: they attach themselves to a master. Possibly they forced themselves into human societies as the first major item of ownership, paving the way for the concept of the property-based sedentary societies that were to follow.

 128 Property, value, number, weight, measurement, quantification, commodity, money, capital, economy --these concepts, however natural to the modern mind, would rarely have come into play in the life of mobile foragers. Could it be that the modern mind, the one capable of abstract thought, symbolic notation and writing, is indeed a quite recent development?

 130 One advantage enjoyed by settled societies, and denied to foragers, is the ability to generate and store surpluses. Surpluses form the basis for trade. They can be exchanged for things considerably more vital than extra food, like weapons, or alliances, or prestige.

 149 Warfare is a bond that separates humans and chimps from all other species. "Very few animals live in patrilineal, male-bonded communities wherein females routinely reduce the risks of inbreeding by moving to neighboring groups to mate," write Richard Wrangham and Dale Peterson. "And only two animal species are known to do so with a system of intense, male-initiated territorial aggression, including lethal raiding into neighboring communities in search of vulnerable enemies to attack and kill. Out of four thousand mammals and ten million or more other animal species, this suite of behaviors is known only among chimpanzees and humans."

 157 ...the important and surprising fact adduced by Keeley, that modern societies have succeeded in greatly reducing the frequency of warfare.
...If warfare was the normal state of affairs, it would have shaped almost every aspect of early human societies.

 158 ...humans have extended sociality far beyond the extended family or tribe and have developed ways for many unrelated individuals to cooperate in large, complex, cohesive societies.

 160 "Kinship-organized groups can only get so large before they begin falling apart," Chagnon writes. Disputes break out over the usual things --sexual trysts, infidelity, snide comments or veiled insults. "As villages grow larger, internal order and cooperation become difficult, and eventually factions develop: Certain kin take sides with each other, and social life becomes strained. There appears to be an upper limit to the size of a group that can be cooperatively organized by the principles of kinship, descent and marriage, the 'integrating' mechanisms characteristically at the disposal of primitive peoples."
"...50 to 100 as the general community size within which out recent cultural and biosocial evolution occurred, a maximal community size that was transcended only in the very recent past --within the last several thousand years." [cf. ethnographic examples of hunter-gatherer bands: about 50]

 177 [taming ourselves] ...people were domesticating themselves. In each society the violent and aggressive males somehow ended up with a lesser chance of breeding... [R. Wrangham] "I think that current evidence is that we're in the middle of and evolutionary event in which tooth size is falling, jaw  size is falling, and it's quite reasonable to imagine that we're continuing to tame ourselves... This puts humans in a picture of now undergoing a process of becoming increasingly a peaceful form of a more aggressive ancestor."

 185 [USA] African Americans... have a share of Caucasian genes that ranges from 12% to 23% in various populations, with an average of about 17%... [Hispanic/linguistic grouping] In the southwestern United States, Hispanics are mostly Mexican Americans, whose ancestry is 39% Native American, 58% Caucasian, and 3% African, according to one recent estimate. East coast Hispanics come mostly from the Caribbean and have a larger proportion of African genes.

 191 [Richard Lewontin concludes] "Of all human variation, 85% is between individual people within a nation or tribe" [not *between* populations]

 202 linguists estimate, there are some 6,000 different languages. All are descendants of older languages that are no longer spoken.

 204 ...New Guinea... has some 1,200 languages, a fifth of the world's total, jammed into an area a quarter the size of the continental United States.

 212 [inventor of a method: cognate words as clue to relatedness of the languages] ...Morris Swadesh, from items that are particularly resistant to linguistic change. These include words for numbers, pronouns and parts of the body. A Swadesh list of 100 words is the most commonly used.
...a 22% agreement means a divergence around 5,000 years ago, and two languages that parted ways only 500 years ago will retain 86% of their Swadesh-list vocabulary in common.

 232 Some words --new, tongue, where, thou, one, what, name, how --have half-lives greater than 13,000 years, and another seven words --I, we, who, two, three, four, five --are even more resistant to change... The word for one, he notes [Mark Pagel], has a half-life of 21,000 years. This means it has a 22% chance of not changing in 50,000 years [approximate date of exodus of human ancestors through NE Africa]

 234 [sweeping summation of behavior innovations adopted] They learned to treat strangers as kin, at least in the context of reciprocal exchanges and trade. They coordinated their activities through religious rites. They defended their territory against neighboring tribes, or attacked them when the moment seemed propitious. With settlement came specialization of roles, admistrators to take control of surpluses, priests to organize religious ceremonies, headmen and kinds to manage trade and defense.
     The first cities started springing up in southern Mesopotamia some 6,000 years ago. Uruk, in what is now Iraq, sprawled over some 200 hectares (500 acres) with large public buildings. The city required armies of laborers and an administration to recruit and feed them. As societies became more intricate, their operation demanded more sophisticated skills and perhaps more specialized cognitive abilities, ones at least that no forager had had occasion to exercise. The invention of writing around 3400 BC opened the way to the beginning of recorded history. The first great urban civilizations emerged in Egypt, Mesopotamia, India and China. The next phase of the human experiment had begun.

 255 [900 years of pressures on Ashkenazi Jews] The outcome, they say, is that Ashkenazim have an average IQ of 115, one standard deviation above that of northern Europeans, although some measurements put it at only half a standard deviation higher. This is the highest average IQ of any ethnic group for which reliable data exist. Such an advantage may not make much difference at the average, where most people are situated, but it translates into a significant difference at the extremes. The proportion of northern Europeans with IQs greater than 140 is 4 per thousand but the figure for Ashkenazim is 23 per thousand, a sixfold difference.

 265 Human behavior, whether in the search for reproductive advantage or the defense of territory shows clear continuity with that of apes. But it also developed its own characteristic pattern with two pivotal steps: the emergence of long lasting bonds between men and women some 1.7 million years ago, and at 50,000 years ago the evolution of language.

 266 ...a whole clutch of hominid species. At least three --the Neanderthals, Homo erectus, and Homo floresiensis --survived until modern humans made their exit from Africa. Had these archaic peoples endured till the present day, our own species would surely seem less special, being evidently just one of many ways in which evolution could spin variations out of the basic ape lineage.

 267 Though evolution through natural selection depends on random processes, it is shaped by the environment in which each species struggles to survive. And for social species the most important feature of the environment is their own society. So to the extent that people have shaped their own society, they have determined the conditions of their own evolution. [cf. writing of history: each generation views past facts in the light of current reference points, thus composing a collective representation by looking into a mirror of itself]

 271 After settlement and agriculture came the rearing of livestock. Lactose tolerance, as discussed earlier, is the genetic response to the availability of animal milk. The genetic change evolved some 6,000 years ago among cattle herders of northern Europe and later among peoples of Africa and the Near East who took up pastoralism.