Before dawn : recovering the lost history of our ancestors – nicholas wade – 2006

wade

 

Pair bonding was a critical shift giving all males a chance of reproduction and hence a stronger interest in the group’s welfare, making human society larger and more cohesive.

The increase in brain probably evolved in response to the most critical aspect of the environment, the society in which an individual live.

50,000 years ago, perhaps just 150 people planned to live Africa. The land outside was not unoccupied. 1.8M years ago early humans had left Africa. In the course of time they had become Homo erectus (in east asia) and Homo Neanderthals (in Europe and near east).

None of the previous group who tried to move north fromm Africa had succeeded: Neanderthal occupied the main exit point from Africa (near East) and prevented most attempts to go through.

Champs could stay much as they were because there was no evolutionary pressure to adapt to the environment.

Global climate cooled between 10 and 5 million years ago, with 6,5 to 5 being particularly harsh.

The drought 5 million years ago may have forced evolutionary change on the apes ancestral to both chimps and humans. The original population of apes must have been 50 to 100,000 breeding animals – according to genetic calculations. Assuming that its way of life ressembled that of chimps it would have lived in communities about a 100 strong or so, structured around a group of males.

Bipedalism is simply better than knuckle-walking: it frees the hands to carry things, better surveillance of surrounding and less energy demanding (same energy can support a knuckle walk for 6 miles, a walk for 11 miles).

The first walking apes appear 4.4M (Laetoli in Tanzania).

Larger male size, in primate society, reflects competition between males for females (harem keeping gorillas are twice the size of females). Today men are only 15% larger than female. Males australopithecines were about 50% larger than females, suggesting australopithecines society was much like that of chimpanzees.

From 3 to 2M years ago, Africa’s forest shrank (dry climate): australopithecine were vegetarian mostly until 2.5M years ago. Two new species came up : one robust australopithecines develop strong cheek teeth suitable for eating coarse leaves; the other, Homo habilis, decided to try its hand at carnivory. Habilis brain started to expand as brain requires high quality diet such as meat but not vegetation. About the same period, the first stone tool appear (known Olduwan Industrial Complex). But the likeliest reason for habilis’s greater brain size would be increaseing social complexity.

Tools remained unchanged for 800,000 years. This may reflect a similar conservatism in the lifestyle of its maker.

Homo ergaster, 1.7M years ago, is the third evolutionary step, with new stone stool (Acheulean Industry) which would last until 250,000 years ago. The pace of change after this would be much faster.

Ergaster had learned to inhabit dry land, hot areas of east Africa where tubers florish. No evidence tthat he could use fire to cook his food yet. It is the first species to show a sharp reduction in male size compared to female, hinting at a change from separate male-female hierarchie of chimp community to male-female bond characteristique of human society.

His brain was only slighty larger, in relation to his body size, than that of habilis, but he was capable of a whole new level of stone tool making.

Ergaster unlike his predecessor possessed an external nose. The role of the nose being to conserve water by cooling and condensing air from the lungs before it leaves the body.

Nakedness is a complex issue: different cause for different mammals. For human the prime cause may have been the need to sweat. Another secondary reason may have to do with sexual preferences: shedding body hair freed humans from the burden of parasites like lice, fleas and ticks. No hair would be sure signal that no parasites were lurking in their fur.

Lighter skin makes its owner more vulnerable to the sun’s ultraviolet radiation, which destroys folic acid. Destruction of folic acid is more likely to reduce fertility. With less descendants, the variant gene will in time be eliminated from the population. Hence everyone living under the African sun has the same version of the gene, no deviations allowed.

In every population of the world, women’skin color is 3-4% lighter than men’s perhaps through sexual selection, perhaps because mother’s greater needs for vitamin.

Middle stone age tools were the descendants of ergaster becoming large brainer homo sapiens. Mousterian artifacts are handiwork of ergaster’s cousins, the Neanderthals.

Humans of 100,000 years ago did not behave like modern humans but they looked liked them. Modern behaviour appear most prominently around 45,000 years ago (the upper paleolithic with more complex tools – bones, ivory-, beads, flutes, burials of the deads with rituals, denser population, trade to obtain distant material). Human with modern behaviour first evolved in Africa and later reached Europe. Why anatomic change 100,000 years ago and behavioural change 50,000: it was obviously a genetic change, not a cultural one, that allowed the emergence of language. (Australopithecine stand up 4.4M years ago, Habilis makes stone tools 2.5M ago, erectus uses pair bonding 1.7M ago. Behaviouraly modern human 50,000 years ago with emergence of language.

Lake mungo burial site is only 42,000 years old, with artifacts from somewhere around 50,000: in line with modern human living Africa around the same time.

No site in Africa show evidence of fishing before 25,000 years ago.

Human language is not possessed – not even in rudimentary form, by any other species. It seems to have popped up into the recent human line out of nowhere.  Human capacity for syntax might have evolved out of an animal brain module designed for some other purpose, such as navigation (adding words to a phrase being equivalent to add new location/direction in a trip when road is blocked). The gene for navigation may have been duplicated accidentally and the second set free to evolve and acquire the function of encoding thought into language.

Chomsky/ there must be a universal system in human brain for allowing children to learn whatever language they hear spoken around them. This is opposed by researchers who believe the mind is a general purpose learning system, a blank slate with no preprogramming.

Chomsky asseserted that Universal grammar was innate, and indeed the language-learning machinery seems to be one of the many developmental programs that are wired into the genes and scheduled to unfold at a given time.

Stephen Jay Gould “Human language, like other specialised biological systems, evolved by natural selection”.

Once language started, its further evolution would doubtless have been rapid because of the great advantages it provides and make possible a whole new level of social interactions.

“social grooming” theory of language of Dunbar: driving force behind the evolution of language was the need to bond people in larger social group. Bonding by grooming each other fur is possible in small groups of up to 50. But for 150 people, this would require too much time – bonding with language was the solution to maintain the group cohesion. Eloquence and articulate speech signal the quality of an individual mind and will be favoured by women and men in their sexual partners.

Paleoanthropologists have tended to favour the idea that language started early, with homo erectus, with slow evolution afterward. Archeologist tend to equate full-fledged modern language with art, common some 45,000 years ago.

Discovery of a gene that is intimately involved in many of the finer aspects of language – FOXP2. It changed significantly in humans but not in chimps. FOXP2 probably makes protein transcription factor that helps wire up some brain regions correctly for language. FOXP2 underwent one single change from 70M to 5M year ago. But its evolution suddently accelerated after human and chimp lineages diverged. The human version differs in tow units from that of chimps, suggesting it was subject to some strong selection pressure. All human acquired the last upgrade of FOXP2 sometimes within the last 200,000 years. This would support a key change in the 50,000 leading to modern language.

50,000 ago, the ancestral humans (modern, with language hability) shrank probably as few as 5,000 people (dry climate that shrank forest and savannas in Africa between 60,000 and 40,000 years ago). Not a trace has been found by archaeologist. They must have lived in a small area – perhaps the size of Swaziland. Archeologist have not yet located this ancestral homeland. But geneticist have figured out where it may have been located, the clues lie not just in genees but also in tongues, specifically the click languages of Africa.!kung is one of the most ancient population in the world, they split off from the ancestral population at an early date and have remained distinct since then. The Hadzabe, from Tanzania, also use a click and are one of the most ancient population as well. The language and genetics are now very different but the clicks – also different – remain in both languages.

Clicks were present in the mother tongue.

The mithochondrial DNA from women of Oromo and Amhara peoples in Ethiopia indicates that east Africa is the place from which the first humans left Africa. Ethiopia is the best candidates for being the birthplace of modern humans.

Chimpanzees seem to have changed very little in the last million years – so period of evolutionary stability are not our of question for human society too. San are foragers and a way of life that must have been quite similar to the ancestral population. !kung lived in small group of 30-40 people (family near kin and in laws), they are strictly egalitarian, no authority to resolve conflicts and keep order (but they have leaders). Without specialised roles and some kind of hierarchy, a human society cannot grow beyond a certain level of size or complexity. When the grow beyond 150 or so, disputes were more frequent and, with no chief, the group would break up into smaller ones. And only one group of people, only a few hundred strong, succeeded in overcoming the daunting odds of leaving homeland altogether (if there was more than on group, they must have come from the same original population, genetics says)

2 new version of genes that determine the size of human brain emerged recently 37,000 years ago and 6,000 years ago. The ancestral population, although modern, may have been less cognitively capable than people today.

Genetic drift: one version of a gene, expecially in small population, can displace all the other existing versions of the same gene in just a few generations.

A date around 59,000 years ago seems a reasonable estimate for the time when the Y chromosomal Adam walked on earth.

50,000, sea level were much lower allowing the ancestral population to travel from Africa to Australia. It is likely that the first group leaving Africa behave as foragers. When getting too large the group would split with one group staying put and the other moving into an unclaimed territory. As territories of foragers are large, great distances can be covered  in only few generations.

Africans south of the sahara belong to mitochondrial lineages L1, L2 and L3. All the rest of the world belongs to the 2 daughter lineages of L3 (known as M and N).

By 46,000 all large Australian mammals, birds and reptiles weighing more that 220 pounds had suddenly fallen extinct. The reason was certainly the activity of a new predator – human hunters. The same would happen to large animals in the Americas…

Modern human may have been prevented from penetrating Eurasia by the archaic humans – homo erectus – that occupied the land, forcing them to skirt the periphery. This would have help push the modern human to find Australia by following coast lines (while homo erectus never made it there before)

Overlap between modern human and homo erectus : human remains from Flores – from 95 to 13,000 years old. They were not pygmies but downsized version of homo erectus. However they made sophisticated stone tools, this can t be explained given their small brain. They have survived only because they were hiding the forest on a remote island…(a lot is unexplained about the men of Flores).

Neanderthals evolved west of Ural some 127,000 years ago. They seem to have displaced anatomically modern humans from the Near East 100,000 years ago. Human mitochondrial DNA and Y chromosome trees each coalesce into a single ancestor in Africa, with no sign of Neanderthal contribution in either lineage. Neanderthal DNA is different from that of modern human. The possibility that some Neanderthal genes may have been incorporated elsewhere in the genome cannot at present be ruled out.

Human evolution continued after the dispersal of the ancestral population. It could be that the spread of the microcephalin allele some 37,000 years ago expanded cognitive powers of Caucasian population and underlay such striking cultural advances as the Aurignacian people’s adeptness at painting caves.

Only 13% of Europeans are descendant from ancestors who came to Europe around 10,000 years ago, presumably coming from the near east with Agriculture. Europe was recolonised some 15,000 by population from the south of france and north of spain, where they found whelter during the ice age.  Archeologist assumed that people who introduce farming in Europe overwhelmed the earlier inhabitants with larger population. But in reality the local people did not die out, they switched ffrom foraging to settlement and adopted new farming techniques.

Dogs don’t belong to 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 property based sedentary societies that were to follow. Domestication was probably around 15,000 years ago.

Greenberg identified 3 separate language groups representing three waves of migration into the Americas from Siberia.

Clovis people, about 11,000 years ago (and extinction of the mammoths…) considered for long as the first people in America. Evidence suggests that a first wave of migration has taken place 34,000 years ago, followed by a second migration 16,000 to 13,000 years ago. Many of the tribes of South America show strong signs of genetic drift, an indication that their populations have bred in isolation for many thousand years.

Mongoloid skull does not show up indisputably in the archeological records until about 10,000 years, a very recent evolutionary development. 2 explainations: 1- by chance, through genetic drift, with the population in the north split into smaller group by the last glacial maximum (small population increase the speed of the genetic drift). 2- by natural selection, as an adaptation to cold (extra fat in the eyelid give eyes more insulation) and pale skin lets in more sunlight for synthesis of vitamin D. The light skin of east Asians seem to have evolved light skin independently of the Europeans.

Sedentary life came first, well before Neolithic age began and agriculture followed in its train. Some signs of sedentary life can be seen as early as gravettian mammoth bone houses of 18,000 years ago.

The Natufians, in near east some 15,000 years ago as the first successful and long term settlers (in Israel, Jordan, Syrian). They did not invent agriculture but gathered grains, prepared them and stored them, they developed the tools that would later be needed for agriculture. They separated teh body from the skull and covered the skulls with plaster, giving them new faces. They were kept in houses as close bond between living and dead.

Transformation of cultivated wild cereals into their domestic forms could have happened very quickly, in as little as 20 to 30 years.

Unlike other animal species, horses seem to have been domesticated on many separate occasions.

Population of Catak Hoyuk pushed into Europe gradually mixing with the local population. Their farming techniques became universal…

Primitive warfare was incessant so the casualties exceeded the losses of state society when measured as % of population. If warfare was the normal state of affairs, it would have shaped almost every aspect of early human society. What does it means to say that Aurigancien culture was succeeded by the Gravettina? Were the new populations welcomed with open arms?

War is a universal behaviour that has been with us as we went from ape to human.

It seems that the Britons were protected from the mad cow disease by their ancient cannibal heritage. Britons (and all other populations by the Japanese) have a gene that has been selected through time to protect them from prions. The fact that we all have it shows that it was a positive gene for the society that must have been regularly expose to the prions, through consumption of human meat (Japanese develop their own protection on their own). The frequency of cannibalism attests to the prevalence of warfare among the earliest population.

One principle that biologist think may explain larger societies is that of reciprocal altruism, the practice of helping even a non-related member of society because they may return the favour in future. Vampire bats must feed every three days or they die. Successful Bats regurgitate blood to those who went hungry. They are likely to donate to their friends, with whom they have grooming relations.

Oxytocin and vasopressin, 2 hormones (generated in the pituitary gland) are playing a central role in modulating certain social behaviour. Ocytocin induces the production of milk, promote trusting behaviour…trust is essential to society but increases its vulnerability to freeloaders (benefits of social living without contributing to the cost. They are a threat to society. And religion was one of the best freeloader defense system.

Religion coevolve with language, because language can be use to deceive and religion is a safeguard against deception.

It has been argued that language attained its modern state shortly before  the exodus from Africa, so did religion.

The emergence of the sacred possibly helped maintained key features of society in the face of new threats posed by an ever increasing capacity for lying.

Long plumage are hard to grow and therefore serve as an overall indicator of good genes. Physical features that have evolved as fitness indicators in the human mating dance – symmetry of features, fine skin – are known by another name: beauty. Male and female minds have evolved to look for and appreciate such qualities in a potential mate.

Gracilisation of human skull started 40,000 as part of the process of domestication of people. Early human were becoming  tamer. The violent and aggressive males somehow ended with a lesser chance of breeding. With tamer people, society could become more complex.

DNA print genomics: American can be assigned to their continent with just 100 markers, as they all descend from their Siberian founders. Middle easterners are more complex and require 377 markers.

Genotype:  thegenome of hereditary information, Phenotype : the physical feature that is generated from the genotype.

All of the 32 finalists of the last 4 olympic men’s 100 meter races are of west African descent.

Kenyan runner dominate 3000 to 10,000 meter race. Most are Kalenjin speaker from the great rift valley region, a  small population called the Nandi (2% of the population).  It has to do with cattle-raiding, of which the Kalenjin were for a long time the leading practicioners. (speculation, not proof).

Diversity of language: given the incessant warfare between early human groups, a highly variable language would have served to exclude outsiders.

The proto indo European split around 8,700 years ago: this suggest that it was the language of the people who introduced farming into Europe from the middle east.

8% of the males throughout the former lands of the mongol empire carry the Y chromosome of Genghis khan. This amount to a total of 16M men, or 0.5% of the world’s total.

Star trek Vulcan greeting is the jewish cohen’s blessing (an important family called first to read the torah in synagogue)

Did rice farming encouraged the conformity for which eastern societies are known and small scale farming the rugged individualism of the west?

Money lending was intellectually challenging in the middle age thus leading the jew to develop a specific set of skills for the profession. Inter marriage contributed to a rapid genetic drift. Jews population today – Ashkenaze, jews from Europe – are more intelligent (gene releasing constraints on the growth of the brain). But they also suffer from specific genetic diseases as a result of specific genes they have.