Posts Tagged ‘climate’

4. How we became humans 1

Eight millions years ago [8 mya] our ancestors were normal animals. They were apes. Our ‘nephews’, the chimpanzees and the bonobos, still are apes and normal animals. Apes live in rainforests. When the place where our earliest ancestors lived had not been changed, we would still be apes and normal animals.

However, from 10 mya the climate was becoming cooler and dryer. Rainforest needs heat and wetness; so the rainforest belt, in early Miocene reaching over southern France and Italy, shrank and 8 mya our ancestral jungle turned slowly into open savannah. It is here where our story begins.

Frans de Waal (Bonobo 1997) says that, when we want an image of our earliest ancestors, we can look at the bonobos. They are the only kind of chimpanzee whose environment never changed. A species only changes when its environment changes. The environment of our earliest ancestors changed totally, so our earliest ancestors changed totally. The environment of the ancestors of the chimpanzees changed much later and somewhat, so the chimpanzees changed somewhat.

Here, we will name our earliest ancestors ‘our ANBOS’ (ancestor-bonobos).

It took tens of hundred thousands of years for their jungle to turn into a savannah. The ANBOS never had any idea of this change; for them the world was in every phase like it always was. So the adaptations to the new conditions passed unnoticed. But for our story these adaptations are crucial.

The savannah is a diversified environment consisting of open woodlands mixed with impenetrable shrubs and grasslands accommodating herds of many kinds of grass eaters.

Our ANBOS lived in the woodlands, where they spent the nights in nests high in the trees. But these woodlands along the shores of rivers and lakes didn’t contain the fruit trees their ancestors used for sustenance. For their food, our ANBOS had to roam the open grasslands which was very dangerous because of the big cats that preyed on the grass eaters. Big lions, sabre toothed tigers and similar species were formidable predators. The sabre toothed tigers were specialists in preying on pachyderms: rhinoceroses, hippopotamuses and (ancestors of the) elephants. In a short sprint the sabre tooth ran under them and ripped open their bellies with their sabre teeth. The mighty colossus was felled and after his downfall the ‘tiger’ fed on the entrails only. The sabre teeth were too frail for the rest of the cadaver. The rest of the carrion was left to the giant hyenas. Nature is cruel and doesn’t know empathy.

What I emphasize: the Miocene (22 – 5 mya) savannah was characterised by megafauna and was much more dangerous than the current Serengeti. Though the little ANBOS were much stronger than we are now, they needed special armament to roam the grasslands safely.  As normal apes, they protected themselves by throwing anything they could grasp at their predators.

Jane Goodall tells the story of Mister Worzle. The bananas she put down for the chimpanzees in order to keep them in her neighborhood for studying their behaviour, also allured baboons (a large and brave monkey) who frightened some female chimpanzees. But Mister Worzle did not give a centimeter of ground and threw anything he could grasp: grass, branches, one time a bunch of bananas (the baboons were happy!). But soon he discovered that stones worked and soon found out that bigger stones worked even better.

18. On the verge of extinction


A key moment in the dispersion of AMHs over the rest of the globe happened 74,000 years ago with the disastrous explosion of the supervolcano Toba, located in northern Sumatra. This was the largest volcanic event on earth in the past two million years. It involved the explosive eruption of at least 2,800 square kilometers of tephra (Greek word for ‘ash’) , causing ash plumes to cover a large part of the world, from the south China Sea to the Arabian Sea. It left behind what still is the world’s largest caldera: Lake Toba.

For comparison: the largest volcano event in historical times was the Tambora eruption on the Indonesian island Sumbawa in 1815. It produced the ‘year without summer’ in 1816. But Toba ejected about 300 times more volcanic ash than the eruption of Tambora and caused six years of climatic deterioration (‘volcanic winter’) which in turn caused the decimation of animal and human life over very large areas.

That most paleo authors do not mention the Toba bottleneck – in the discussion between Richard Klein and his critics Hensilwood and d’Errico e.a. we don’t find any reference to the Toba event – can perhaps be ascribed to the fact that thorough research on this catastrophe is fairly recent.[1] How severe the impact has been on the total human population is still unclear, but geneticists Jore and Harpending[2] propose that all humans alive today are descendants from a very small part of the earlier population: perhaps some 8000 breeding pairs about 70.000 years ago[3]. The impact on the northern hemisphere was more severe than in the south; nevertheless also Neanderthals survived the supposed six years of volcanic winter. The AMHs had even better chances, not only because they lived farther south, but also because of their broader subsistence strategy based on hunting and gathering coastal resources (shellfish, fish, sea lions and rodents, as well as bovids and antelope).

In Jwalapuram in India, archaeologists dug through the several metres-thick Toba ash layer (see photo). First, above the Toba tuff, they found many stone artefacts from about 74,000 years ago, made from limestone, chert, chalcedony and quartzite, with blades and bladelets representing a Late Pleistocene assemblage also assigned to the Middle Paleolithic. Digging deeper, below the thick Toba tuff layer, they found many more stone tools that could be dated at about 77,000 years ago, of limestone, quarzite, and chert: scrapers, blades and a burin also identifyable as Indian Middle Paleolithic. This lithic assemblage clusters together with the lithic technology of sub-Saharan Africa, and indicates that the AMHs belonged to the first migration wave out of Africa. We will talk about this in the next paragraph.


The Toba ash deposit layers, as excavated at Jwalapuram in Southern India. The ash layers reach from just above the bottom of the pit to halfway up the ladder. Only the bottom layer dates from immediately after the eruption: the higher layers originate from aeolian transport and slope-wash during annual monsoons into this low location.

According to the excavators, before the explosion this place was a ‘paradise’ on the shore of a lake. Then it got buried under two-to-five metres of volcanic ash. The next six years, with the atmosphere still full of ash particles, were a volcanic winter. During the next thousand years, the climate still was extreme cold: a glacial maximum[4]. But perhaps after some decennia of annual monsoons, big parts of the area became sufficiently overgrown to harbourgrass eaters again. So archaic AMHs must have lived in this area, and after the Toba explosion survivors reappeared as soon as grass vegetation and grazing animals reappeared.

The Jwalapuran excavation is not the only site showing evidence of the Out of Africa (OoA)-migration of the AMHs, both before and after the Toba explosion. Another recent excavation site is Jebel Faya[5], where 125,000 year old hand axes are found, showing a pattern of flaking seen only in early Africa. Indicating an out-of-Africa migration 20.000 earlier than thought before. Indeed, 130,000 years ago, there was a window of climate change. The Arabian Peninsula was more habitable than today.

[1] in an article in October 1993 Ann Gibbons, a staff journalist for Science, first suggested that a bottleneck in human evolution about 50,000 years ago could be linked to the Toba eruption. Rampino and Self backed up this idea in a letter to the journal later that year. The bottleneck theory was further developed by Ambrose in 1998 and Rampino & Ambrose in 2000, who invoked the Toba eruption to explain a severe culling of the human population. (Wikipedia)

[2] Population Bottleneck from Macmillan Science Library: Genetics. Copyright © 2001-2006

[3] Wikipedia “Toba catastrophe theory”

[4] OIS 3 – 63,000 to 45,000 years ago (warm)
OIS 4 – 73,000 to 63,000 years ago (cold)
OIS 5 – 130,000 to 74,000 years ago (warm)

[5] Anthropology Net 27 Jan 2011: Hans-Peter Uerpmann of the University of Tubingen and his team excavating the Jebel Faya site in the United Arab Emirates

22. Overpopulation


Our species started in very harmonious groups with the women as the dominant gender. Survival on the savannahs was extremely precarious. Groups living in harmony flourished better than groups with tensions: natural selection advanced harmony within the groups or tribes. Millions and millions of years of harmony is what made us the most social beings in nature, while the other side of our nature – violently defending ourselves and our kin – was pushed far away to the background. On the sparsely populated savannahs, such violent behavior was just not needed for survival.

Why then are men the dominant gender now? Why did Plato live in a time of civil war and slavery? Why then a Holocaust, Nanking massacre or, more recently, the Rwanda tribal mass murder? Why was our natural tendency to live in harmony overshadowed by other, more violent tendencies? We find the answer in the chimpanzees, and the keyword is overpopulation.

We may assume the ancestors of the chimpanzees lived more harmoniously than their descendants now, and again climate changes were a main cause here. Two million years ago, the start of the Ice Ages caused a dryer climate, shrinking the rainforests area. This shrinking of their territories caused overpopulation among the ancestors of the modern chimpanzees, which incited a more fierce struggle for survival. Struggle and war made the males more important. In the fiercer competition between different groups, the groups with the most violent men had a better survival chance. This process repeated itself with each new Ice Age, over and over again, about twenty times. In the long run, this made chimpanzees more violent (unlike for example bonobos, who thanks to a different environment were able to retail their original nonviolent lifestyle).

For our ancestors, this situation of overpopulation started not 2 million years ago, but just some 100 thousand years ago in Northern Africa, where the Anatomically Modern Humans (AMHs) had appeared as descendants of a local African Middle Stone Age (MSA) population, who in their turn were descendants of the African Homo erectus.

The tropical H. erectus (par exemple Nariokotome Boy) and the MSAs had been long and slender. Just like the stocky figures of the Neandertals (NT-s) had adapted to a colder climate, their African contemporaries (the MSA-culture, you could see them as Afro-NT’s) had adapted to a hot climate. Their being long and slender also meant longer necks with more place for a lower throat and a bigger pharynx. Our pharynx plays an important role in singing and making vowels. This makes spoken language possible.

We already told about the communication moment. In most discussions, you get little time to make your point and each woman wants to contribute her part. From the very beginning, their voices played a role in the sign communication. When communicating in the dark, or with full hands, they always felt pressed to put more lingual content in their vocal sounds, with clicks! and pfffs! and mmms![1]. I also mentioned the influence of the daily dancing-and-singing of the Creation Story in gradually developing more cortical voice control. For the long and slender Afro-NT’s, longer necks may have facilitated this process. 100.000 years ago, the communication of this African population was in the midst of a transition from pure sign language supported by a few sounds, to ever more spoken language supported by gestures.

I think this had to do with the females in the first place. Women were dominant in religious performances, like they were dominant in medical care and magic. Males should never put the success of their hunting at risk by using female speech to pray to the Big Ancestor: they clung on the sacral sign language for their hunting prayers. Nowadays before each hunting trip, the Semai hunters still use sign language to pray to their Big Ancestor. When we look at the important role of gestures in sacred rituals today, we see that sign language must have survived a long time in the sacral singing-and-dancing of the Creation Stories which had such a dominant place in the lives of our ancestors.

To get back to the point: why war and why male dominance? We saw that with chimpanzees, overpopulation brought fighting and fostered violence in males. The same mechanism applies to humans in more recent times. During most of our evolution, populations grew slowly and the world was wide. So equality between the genders or even female dominance was common in the groups and clans. But because women will defend their children, and may quarrel to find their place in the status order, they will often look for a powerful hulk as an arbitrator. It is quite possible that from the earliest times, even female dominated communities had a headman. Of course, he had to be accepted by the women[2] and under female control. In larger and later groups, males and females may have lived apart for most hours of a day, and each have had their own rituals, but even then a headman ‘headed’ a group.

We still see the same in all tribes with incessant and hopeless tribal wars: it occurs always and only in a situation of overpopulation. But why do all these tribes know machism (male dominance) and sometimes severe violence against women? Why this unproductive suppression of their indispensable and attractive partners in life? This may be the consequence of the female dominance in the long, long times before the overpopulation situation. In times of survival fights however, the ‘fittest’ groups are the groups with the most violent males, as we saw. Therefore, women began to see violence as a good quality in males and to promote this warrior-attitude in their men and sons.

The males learned their warrior qualities were very, very important. And by inference, they began to see their own rituals as far more important than the rituals of the women. In many cultural myths all over the world this is illustrated by the element of males taking over the holy flutes for their own ritual use.

The first indication of overpopulation (accompanied by the start of wars and male dominance) in European AMHs may date from the onset of a cold period of OIS-2[3] about 35.000 years ago. Hunting territories shrunk, groups were driven together in the southern refugia. The cave paintings of Chauvet and elsewhere may be seen as male initiation sanctuaries: as places for secluded male rituals, separated from the women. At the same time, female rituals became more concentrated on the growing importance of food plants like peas and lentils, the boons of Mother Earth which they venerated with the renowned Venus figurines such as the Willendorf statuette.

Venus of Willendorf, Austria. Limestone, ca 25.000 BC

Many paleos wonder why the AMHs in Europe developed brilliant cave paintings and Venus statuettes (the ‘Upper Paleolithic Revolution’), while those living in Africa for much longer did not produce that many art works. For example, archaeologist Richard G. Klein theorizes about some brain-related gen mutation leading through symbolic language to symbolic art. We think there is a more simple explanation: artistic activity may have been fostered by a colder climate, where in a long icy winter (when people lived mainly from food gathered in autumn) there was less to do. This may be corroborated when we compare the activities of Inuit gatherer-hunters with African gatherer-hunters such as the San.

Later on, other events contributed to overpopulation and male dominance. About 16.000 years ago, in the northern hemisphere, the big mammals (mammoths, cave bears, giant deer, sabre toothed tiger, etcetera) became extinct. This was the time of the invention of bow and arrow, and the domestication of the wolf. This also was the time of the dispersion of AMHs all over the world, including the Americas. This was the time of beginning horticulture. In regions of Eurasia with a high density of shabono’s (the temporary villages or long-houses of semi nomadic horticulturers) the first acute struggles for survival arose.

But on a more fundamental level, it was only the situation that had changed (war), not the males or the women themselves. So the males had to suppress their incertitude, to allay their own doubts: they declared their newly-won importance holy. A deep incertitude of the males may have contributed to a new phenomenon: a constant denigration of female abilities. Present-day religious fundamentalists still display this primitive incertitude, by isolating and over-protecting their wives, by limiting female freedom of action, or by demonizing love affairs or abortions.

A good question is: was machismo not a legacy of the early AMHs? Was their immigration Out of Africa not a result of overpopulation? Even the most egalitarian tribes like the Mbuti (Congo) know a certain degree of machismo. In the past, Mbuti males annexed the molima, the rites of the holy flutes and excluded the women from it. As a part of the present ritual, women still disturb the males’ ritual crying that the men have stolen the molima and the holy flutes from them.

So when you say machismo may be very old, I agree. For example, as we can see with chimpanzees, machismo may always have been a strategy to cope with situations of overpopulation and/or competition. Both peacefulness and a warrior-attitude have always been strategies to cope with specific environmental challenges. For most of human history, a predominantly peaceful way of living was the most successful way to interact with the environment. When about 20,000 years ago overpopulation started to become an environmental factor, gradually a warrior-like style of living became the more successful attitude.

I paraphrased a few pages from the book The other side of Eden (London, 2001) about the lifestyle of ‘noble wilds’. But human nature is a three-stage rocket. So here is an anecdote about noble wilds in an overpopulation situation, already forty years in my mind, so I have forgotten the source. It is from a visitor or missionary :

Oh what a noble people, so respectful for each other and for their children! So much better humans than we in our western civilization!

One day men learned that strangers were roaming in the north of the territory. So they had to go down there. Perhaps whiteman would like to come along? Oh yes, sure, whiteman was always ready to learn some new.

They stalked the camp of the strangers. It appeared that the men were hunting and the women gathering, so they found only old people and children in the camp. All of them were slaughtered ruthlessly. A desperate girl crawled to the petrified onlooking visitor for help. “Oh, you want to fuck her, whiteman?” asked a helpful Indian, “wait a moment”– and he pushed his spear through the girl’s body into the ground.[4]

From this story we may conclude that we are very social, but only to those we see as fellow humans. For the Indians, the strangers were not fellow humans. Not even humans. To them, these others were rather a form of harmful wildlife that you need to destroy. It can also be concluded that this awful behavior didn’t make them less social: it had survival value. Only one group can make a living from a given territory. Those Indians didn’t have a government to regulate their behavior. In any threatening situation, selfishness is dominating, and this also applies to a GH-collective. Today we still see the same behavior in AGR-societies such as Rwanda. It can be seen in any civilization, such as the Japanese (the Nanking massacre) or the German civilization (Holocaust). Such behavior can be revived by ideological indoctrination and can happen even when the supposed threat is in fact an imaginary one. In the just-mentioned cases, the Tutsi, the Chinese, the Jews were not a real threats, but ideological indoctrination had caused them to be felt as a threat. In a sense, such indoctrination created an imaginary overpopulation situation.

[1] in the 1950s, the American Hayes couple raised a chimpanzee, Vicky, as if she was a human child: this was intended as an experiment of training in speaking. But the only result was ‚mama’, ‚papa’. ‚up’ and ‚cup’, soundlessly spoken

[2] As described by Frans de Waal, even the dominant bonobo females prefer an alpha male, because females to one another have difficulties in amending quarrels; but the alpha female makes the foraging decisions, not the alpha male

[3] Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth’s paleoclimate, deduced from oxygen isotope data reflecting temperature curves derived from data from deep sea core samples.

[4] surely not from Jesuit Relations, field letters from the missionary priests, published for two hundred years beginning in the early 17th century as a fundraising tool. Because the Jesuits found their own civilization superior, and urged the native men to beat their children and to suppress their women

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Used abbreviations

GHs: gatherers/hunters (the phase from 2 million years ago to 10.000 years ago)

AGRs: agriculturers (the phase from 10.000 years ago till now)

NT(s)Neanderthal people

MSA(s): Middle Stone Age people (African NTs)

AMH(s): Anatomical Modern Humans (H sapiens people), like we are

(m)ya: (million) years ago

ANBOs: Ancestor Bonobos (ape-men), our earliest human ancestors

Paleos: all scientists that are important for our story.