Sunday, December 31, 2006

*** Before the Dawn by Nicholas Wade

When the first woman uttered “I don’t have a thing to wear”
When humans lost their body hair, the body louse’s domain shrank, confining it to the lonely island of hair on the head… It patiently bided its time and many millennia later, when people started to wear clothes, it evolved into a new variety that could live in clothing… The branch point at which the body louse first evolved from the head louse turned out to be 72,000 years ago… People first addressed their nakedness only in the most recent stage of evolutionary history. P5

Moving on up
Upright walking is more efficient than knuckle-walking. For the same expense of energy, a chimp can walk 6 miles a day but a man can walk 11. Bipedalism probably evolved because it was a better way of getting about… The other advantages were probably coincidental – freeing up the hands for carrying things, and higher stance allowing better surveillance. P17

Darwin was right again perhaps
Darwin’s idea of sexual selection as the driver of human hairlessness has been reinvoked by biologists. They suggest that lack of hair was favored among early humans because it was a sure signal that no parasites were lurking in their fur. P24

Who to blame for your bad hair day
Human hair differs from apes in that it never stops growing… The reason why uncontrolled growth was favored by natural selection may have been that it offered a means of signaling copious amounts of social information… But for this social signaling to occur humans had to abandon the self-maintaining hairdos of the other apes and acquire hair that required continual attention. P26 But why would we go bald if hair had such an advantage?

All talk and no action
Different monkey species spend varying amounts of time on grooming one another upto a max of 20% of their waking day and this is among a species whose typical group size is 50. This has effectively capped the size of monkey social groups at 50. How did the human grouping size grow to 150, a number that would require 43% of their waking hours on grooming? Because of language, which is a more efficient way of establishing and confirming social bonds. In a wide range of human societies, the amount of time people spend in social interaction is 20%. The driving force behind the evolution of language was the need to bond people in larger social groups. P44

About 50,000 years ago, the ancestral population in Africa may have shrank to as low as 5000 people. P52

Unlike most pairs of chromosomes the X and Y don’t exchange segments of DNA between generations… The Y is therefore passed down essentially unchanged from father to son. Mitochondrial DNA escapes shuffling in another manner… When the sperm fuses with the egg, all the sperm’s mitochondria are destroyed, leaving the fertilized egg equipped with only the mother’s mitochondria. P53

The real Adam
All men in the world carry the same Y chromosome… Every Y chromosome that exists today is a copy of the same original, carried by a single individual in the ancestral human population… The root of this Y chromosome tree dates to 59,000 years ago with a range of 40,000 to 140,000. This date fits well with a date of 50,000 years ago for the ancestral population. P56

And his wife Eve
The mitochondrial Eve appears to have lived considerably earlier than the Y chromosome Adam – about 150,000 years ago. P58

And they lived in a nice house in East Africa
The mitochondrial DNA from women of the Oromo and Amhara peoples indicate that Ethiopia or East Africa is the place from which the first modern humans left Africa. P64

A hunter gatherer woman can carry one child easily along with all her possessions, but 2 are a burden. Such women would tend not to have a 2nd child until the first can walk well. Children were not weaned until the age of 4 and before that age they were carried almost everywhere. The child must be able to walk 1500 miles a year. P68

Why dad’s should stay in the waiting room
Because a woman must invest so much care and labor in raising a child she examines the newborn carefully for signs of defects. If it is deformed, it is the mother’s duty to smother it. Infanticide is not murder in hunter gatherer societies because life begins not with birth but when the baby is taken to camp and given a name… Women typically give birth outside camp and men are excluded because the father’s absence makes it easier for the mother to decide whether to keep the newborn or not. P68

Evolution is not done with us
2 new versions of genes that determine the size of the human brain emerged only recently, one around 37,000 years ago, and a second at 6,000 years ago. Given the brain’s continued development, the people of 50,000 years ago, despite archaeologist’s tag for them as ‘behaviorally modern’, may have been less cognitively capable than us. P71

Form a single file line, and proceed to the exit.
Based on genetic analysis there seems to have been just a single migration for modern humans from Africa, and the number of émigrés was probably quite small. Indeed it could have as few as 150 people, raising the puzzle of why only one group managed to escape?... Could it be that there was only one easy way out – near the southern tip of Arabia and the horn of Africa (during the last ice age these were very close)? Perhaps the first people to cross stayed put on the other side and prevented others from invading their territory? P78 What about crossing over from the Sinai to Israel? It’s possible but the genetic studies point only to southern Arabia. In addition, the Neanderthals may have blocked this northern route.

These first migrants could have expanding along the coast for 1000s of miles without encountering an obstacle until they reached Indonesia where they would cross 60 miles of open sea to Australia… The evidence for this is from 46,000 years ago when all of the large Australian mammals, birds, and reptiles weighing more than 220 lbs suddenly went extinct. P82

It is surprising that Australia should hold the earliest archaeological sites outside Africa… But since sea levels were much lower during the ice age, and the ease of migrating along the coastline instead of venturing inland, many of the other sites might be 200 feet under the sea. P82

The noble savage myth
Like many human groups and chimps, the New Guinea natives know that killing a few of the enemy leaves the remainder thirsting for revenge, so a more effective solution is extermination. About 30% of all highland social groups become extinct each century because they are defeated. P86

Home is where the dog is
Dogs have lost their working status in most modern societies. But they spread like wildfire in the prehistoric world. Yes, they could be trained to help herd, they make good bed warmers, they are a self transporting source of meat. But none of these probably are the reason dogs spread so quickly from Eurasia to all corners of the world… Wolves never bark, dogs do. Barking was probably selected by the dog’s first domesticators. That suggests that they weren’t much interested in using dogs for hunting, where a bark is no asset. But if the first use of dogs was in sentry duty, to warn of strangers and attackers creeping in for a dawn raid, the a fierce and furious bark would have made a dog an invaluable defense system… 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. P110

Archaeologists long assumed that the improving climate [post Ice Age] made agriculture possible, which in turn opened the gateway to settled living. But because of improved dating techniques, they have come to see that the reverse is true; it wasn’t agriculture that led to settlement, but rather sedentary life came first, and agriculture followed. P125

One advantage enjoyed by settlers but denied to foragers is the ability to generate and store surpluses. Surpluses in turn form the basis of trade. P130

Einkorn was the first cereal to be cultivated about 12,500 years ago… Domesticated emmer wheat which is easier to harvest than einkorn, was found as early as 10,400 years ago. Modern wheats stem from emmer and wild grass hybrids, which occurred in northern Iran about 7000 years ago. Rye and barley were also domesticated about 10,000 years ago in the same region. P132
A band of brothers
Most hunter gatherer societies are patrilocal, where the wife goes to live with the husband’s family. The biological reason is to avoid inbreeding. But the almost universal solution in primates is the opposite – matrilocality. Patrilocality has evolved in only 4 other species besides humans and chimps. Chimps also share another quality with humans, and with no other creature – the propensity to conduct murderous raids on neighbors… Chimp society turns out to be matched to their food supply, which is principally fruit. The trees come into fruit sporadically, and they tend to be scattered. Females bear children faster when their territory is larger. Chimp males could try to achieve success by guarding one female. But it seems to be more efficient for the males to band together and defend territory that includes a larger number of females. One reason this makes sense is that the males tend to be related to each other (this is the same as bees and ants). P143

Being a slutty chimp has its advantages
When female chimps enter their fertile period they became very gregarious and do their best to mate with every male in the community, with an avg of 7 couplings a day. One female achieved 50 in a day. The purpose is to confuse paternity, so the male is less likely to kill a baby if he thinks it might be his. Given this chaotic mating system, how do high ranking males in fact reap rewards? First, they secure more matings though rarely exclusive. Second, there is sperm competition. Advantages will accrue to the male who can deliver the most sperm and flood out the competition. Hence evolution has favored males with very large testes for their body size… Reigning alpha males account for 36% of all conceptions, and for 45% if one excludes close female relatives. Suggesting that alpha males owe a lot of their fatherhoods to victory in the sperm competition wars. P145

At first sight, there is no obvious difference between a chimp and a bonobo habitat. Chimps are found all across Africa from west to east, but bonobos live south of the Zaire river, and chimps north of it. South of the river there are no gorillas. Gorillas are voracious plant eaters. Chimps north of the river, eat only fruit. But bonobos eat both… This difference in diet has far reaching consequences. Female chimps forage for fruit alone in core feeding areas. Bonobos travel in large groups and have more sources of food. This gives females an opportunity to bond together. Hence bonobos are matrilocal. P147

Dogs played an important role as sentinels. The goal in all warfare among Eskimos was annihilation, and women and children were not spared.

Why has the British epidemic of mad cow disease proved not nearly so deadly in that nation of beef eaters? It seems that Britons have been in part protected by their ancient cannibal heritage. 75% have a prion protein gene that every person infected with mad cow lacks… This genetic frequency is an indication of how widespread cannibalism may have been, and in turn attests to the prevalence of warfare among the earliest humans. P156

Old time religion
Human societies long ago discovered the antidote to the freeloader problem. It is religion… Religion began as a mechanism for a community to exclude those who could not be trusted… Later it grew into a means of encouraging communal action. It was then co-opted by the rulers of settled societies as a way of solidifying their authority and justifying their privileged position… Can the origin of religion be dated? Religious rituals are very verbal, and can’t predate language. If religion had to await the evolution of modern, articulate language, then it too would have emerged shortly before 50,000 years ago. P164

With the institution of pair bonds, sex became something conducted within families. It was at this time that the taboo of public sex was formed, a custom that would bring chimp and bonobo society to a standstill. Such privatization would help considerably in removing sex as a provocation of male rivalry. P169

And may the best man win
4% of people in Britain are conceived under sperm competition, when a women has more than one lover in a short time… Of fraternal twins born of white women in the US, 1 in 400 pairs is estimated to have 2 fathers. And among cases where paternity has been disputed 2.4% of cases have been found to be heteropaternal. P172 Sperm competition is alive in well in humans.

Taming the beast within
Gracilization of the human skull and body looks very much like one of those changes that come along for the ride when a species is undergoing domestication to make it more tame. And who exactly was domesticating humans? We were domesticating ourselves. In each society violent and aggressive males ended up with a lesser chance of breeding. We’re still in the middle of an evolutionary event in which tooth size, jaw size are falling, and its quite reasonable that we are still taming ourselves. P177

Run like the wind
The Kenyan Kalenjin who comprise less 2% of Kenya’s population represent 20% of all winners in major distance running events… How did this happen? For centuries the Kalenjin have been cattle rustlers, though they regard their actions as repossession of property that was theirs by divine right. The repossession [rustling] procedure often required journeys of over 100 miles so that the livestock could be far away before their ex-custodians realized their loss. The better a young man was at raiding – in large part a function of his speed and endurance – the more cattle he accumulated. And since cattle were what prospective husband needed to pay for a bride, the more cattle he had, the more brides he could buy, and the more children (with his genes) he could father. P197

Jared Diamond [Guns, Germs, & Steel] “Natural selection promoting genes for intelligence has probably been more ruthless in New Guinea than in more densely politically complex societies, where immunity to disease is more potent.”… But if the New Guineans had the smarts, why was it the dumber, disease ridden Westerners who figured out to escape from the Stone Age’s tribalism and perpetual warfare, a problem the New Guineans never cracked? [Read the Pulizter prize winning Guns, Germs, & Steel to find out]. P198

New Guinea has 1200 languages, 20% of world’s total, for a country only 25% the size of the continental US… Such diversity occurs because language mutates so rapidly, even from generation to another, that in only a few centuries it passed beyond recognition. P203

This variability is extremely puzzling given that a universal, unchanging language would seem to be the most useful form of communication. That language has evolved to be parochial, not universal, is surely no accident. Security would have been far more important to early human societies than ease of communication with outsiders. Given the incessant warfare between early human groups, a highly variable language would have served to exclude outsiders and identify strangers the moment they opened their mouths. P204

Genghis got around baby
An astonishing 8% of males throughout the former lands of the Mongol empire carry the Y chromosome of Genghis Khan. This amounts to 16M men, or .5% of the world’s population. P236 I’m sure Wilt Chamberlain is jealous.

Smarter than the average bear
Moneylending cira 1100AD was an intellectually demanding profession, not least because the Arabic numerals used today, and the concept of zero, didn’t become widespread until 1500. Figuring out xviii percent of ccel, without a zero, is not so easy…
Restrictions on Ashkenazi Jew employment were lifted around 1700, bringing to an end a period of 900 years during which most of the population would have had to earn a living in occupations like moneylending, which require more mental ability than most. Given what’s known about heritability, scientists calculate that even in as little 500 years there would have been time for the intelligence of the Ashkenazi population to be raised appreciably… Ashkenazim have an avg IQ of 115, one deviation above that of other Europeans, and is the highest avg of any ethnic group. The percentage of Europeans with an IQ greater than 140 (mensa level) is .4%, but is 2.3% for Ashkenazim, nearly 600% more. P255

Enjoy it while it lasts
When people first started to abandon their way of life as hunter gatherers some 15,000 years ago, they had much less need for 2 kinds of genes, the olfactory genes, and liver genes necessary for detoxifying natural poisons from wild plants… When mutations crop up in genes that don’t matter anymore, the gene may survive, even though it has lost its function… More than 60% of olfactory genes are now inactive, and this process is still active… The faculty of smell [and taste] is inexorably being degraded… The enzymes made by liver genes for natural plant poisons have assumed a new role – that of metabolizing medicinal drugs. This unnatural stimulus doesn’t happen often enough, however, many of the genes are being lost through disuse. This process explains the variability in response to drugs, including why some people have severe side effects. People have lost the gene that breaks down a certain drug will maintain a high does of it in their blood, whereas those who still retain the gene will clear the drug rapidly. P270


Human Microbiome Search Engine said...

Wow! Awesome quotes! I presume you noticed that some of the quotes contradict others ... like the statements that all human males share the same Y chromosome and the other claim that some chromosomes can be traced to the late unlamented Mr. G. Khan.

I stumbled across this while I was looking for information for my own blog,

Now I'm going to have to come back later and check out more of your selections Thanks!

Jim Purdy

Yamin said...

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