OUR GREAT LEAP FORWARDOUR CULTUREWe seldom realize…that our most private thoughts and emotions are not actually our own. For we think in terms of languages and images which we did not invent, but which were given to us by our society. Alan W. Watts

I cannot imagine life without art, music, dance, speech, and books. These all are means of communication and what I consider to be the currency of culture. As I argued in Language: A Nurture of Nature, language in all of its forms has a genetic component as well as a learned component. On the genetic scaffold, fundamental rules of grammar are hung as we learn to talk and understand those who speak around us. Jared Diamond and others call the change to symbolic communication by our ancestors The Great Leap Forward. It appears unmistakably in the fossil record around 40,000 or more years ago and is a profound change in our lineage. The real problem in interpreting the leap and what caused it is that structurally modern humans appear thousands of years earlier than the cultural change. What really caused the changes and what led to the explosion in human culture?

OUR PREDECESSORSHumans are not proud of their ancestors and never invite them round to dinner.

–Douglas Adams

The line that gave rise to humanity likely did possess rudimentary means of vocal communication. The chimpanzees, other apes, and monkeys all use vocalizations to varying degrees. These are useful in communicating information that is important for the safety and organization of the social group. There is no compelling reason to assume that our extinct ancestors were any different. Our line split from that of the chimpanzees about 7 million years ago (between 6 and 8 million years ago; see Figure 6-76).

Geological evidence suggests that about 6 million years ago, the time of the separation of the chimpanzee line and the hominid line, Africa experienced a sustained, drier climate. The period was dry enough that the Mediterranean basin, then completely land-locked, dried up. Similarly, the large expanses of African forest retreated to smaller relict patches. Savannah, a biome that has scattered trees in open grassland, replaced forests. In such an environment, a more upright stance and locomotion would have been favored. Studies of the energy expenditure of the knuckle-walking of chimps and other apes show that they are not as efficient when moving over open areas as the bipedal walking of our lineage. Also, the open grassland posed the problem of heat. An upright body presented a smaller cross-section to the tropical sun than the inclined body of a chimpanzee. Likewise, a body in the open sun would more likely be under heat stress. Thus, the loss of excess body hair allowed more efficient cooling. A behavioral advantage of bipedal locomotion allowed the transport of food back to a common location. This could have been important especially if the pairs bonded for life. The savannah then imposed selective pressures that were different that those experienced by the forest apes. There, the apes quickly evolved upright stance, bipedal gait, and loss of hair.

Following the split from the chimpanzees, our line was represented by two major genera, Australopithicus (literally means “southern ape”) and Homo (the Latin word for man). The australopithecines stood upright and walked by a bipedal gait. However, they

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seem to have been partly arboreal which is seen in their relatively longer arms. Otherwise, they looked like smaller versions of us except that they had a larger face and a chimpanzee-sized brain with a brain volume of 450-550ml.

.FIGURE 6-76. A simplified version of the hominid “family tree”. The boxes represent member of an allospecies related to (and including) Australopithecus africanus. A second allospecies is the erectus group of species. Approximate time in the fossil record is given in parentheses.

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The australopithicines remained in Africa and diversified into a number of different species. One line gave rise to a robust line of several species. These stood upright and had a very stocky build. Their skulls and teeth, however show the same kinds of adaptations that we see in gorillas today. They had large molars and a crest of bone on the top of the skull that allowed for the attachment of large jaw muscles. Like the gorilla they seem to have become adapted to eating large volumes of poor-quality food. One of these species, Australopithecus boisei (see Figure 6-77) persisted in the fossil record to within a million years of the present.

Almost certainly our line (as well as the robust australopithecines) came from a generalist, variable, and widespread “species” that ranged over much of Africa between about three to less than 2 million years ago. Technically, this group was an allospecies, or a widespread but separate set of closely related species that likely could interbreed. The most well-known member of this group was Australopithecus africanus (see Figure 6-77), a hominid that stood about 1-1.5 meters tall and had the head of a chimpanzee (400-500ml brain volume and somewhat elongate face.). They seem to have used and fashioned simple tools and lived in small social groups. In fact, this seems to be the case of all of our near relatives, extant and extinct.

About 2.4 million years ago, a near human appeared with the appearance of A. africanus but a head that was more human. It had a smaller face and a brain volume that was almost double that of its known predecessors. Its name is disputed and is placed in either Australopithecus or Homo. Figure 6-76 refers to it as was A. habilis because it seems to have been a different offshoot of the australopithecine generalist line, and, therefore, a dead-end. This new “human” seemed to have greater facility with fashioning stone tools, but remained restricted to eastern Africa.

FIGURE 6-77. Skulls of Australopithecus africanus (left) and A. boisei1 (right). Note the sagittal crest on the boisei skull2.

Nearly 2 million years ago in Africa another allospecies appeared that was clearly related to us. The most well-known member was Homo erectus. Compared to its precursors, this group had species that were master toolmakers and had brain volumes that overlapped our own (750-1250ml). Homo erectus (see Figure 6-78) had a low forehead, and massive brow ridges. It was gracile in its appearance and ranged throughout Africa. Then, about 1.8 million years ago, it left

1 The genus for the robust australopithecines has been changed to Paranthropus.2 All skulls shown in this essay are models.

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Africa and ranged over much of warm Asia and the near east. Likely Homo erectus used fire and had a rudimentary form of language. Within the erectus allospecies sprang Homo ergaster, the species that likely gave rise to the Neanderthals and our own species.

FIGURE 6-78. Homo erectus skull. Note the sloping forehead, heavy brow ridges, and receding chin.

Homo neanderthalensis (see Figure 6-79) and the related Homo heidelbergensis (both of which I will refer to as Neanderthals), first appeared in Europe and the near east around 800,000 years ago. Neanderthals likely appeared in Africa from a stock of the erectus group. They moved into the near east and on into Europe during a warm period between glaciations. Neanderthals were stocky in build and had long, low skulls that housed a brain with greater volume than most of ours. Like the erectus group, Neanderthals had pronounced brow ridges. They seem to have possessed unique structures in their large, bulbous noses which have been interpreted as adaptations to the extreme cold of ice age Europe. However, because Neanderthals seem to have evolved during a warm period, this interpretation seems very unlikely.

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FIGURE 6-79. Homo neanderthalensis skull. Note the large nasal opening and sloping forehead. The brow ridges were not as pronounced as in H. erectus.

The occurrences of arthritic, wounded, and otherwise handicapped individualism among Neanderthal remains suggest that they possessed a culture that revered human life. Further, Neanderthal burials replete with artifacts and evidence of flowers hint at the belief of an afterlife. Clearly, they were not the brutish “caveman” beasts of popular belief. That they, a tropical species, were able to persist in Europe during one of its coldest periods, also points to their having developed a high enough level of technology to allow their survival and then to transmit that technology. However, what marked the Neanderthal technology was its persistence. Almost throughout their range, both in time and space, Neanderthal technology was almost unchanging. Neanderthals were not innovators.

Neanderthals were not simply very conservative Homo sapiens, they were not human. That is, they were not members of our species. DNA taken from bones that had not petrified shows that they were more different from us than the diversity of all living humans today. The most cautious interpretation of those results would be that Neanderthals were a closely-related species. Were they reproductively isolated? That is, did Neanderthal genes find their way into our own species? Almost certainly they did. Several localities point to Neanderthals and our species occupying the same place at the same time. If they could have crossed, they would have left offspring. Either way, Neanderthals disappeared from the fossil record about 27,000 years ago.

An archaic form of our species seems to have appeared about 200,000 years ago (maybe up to 400,000 years ago) in Africa. By archaic, I mean that the adults had a mosaic of modern and “erectus” like features. Unfortunately, all non-Neanderthal remains from the last several hundred thousand years are lumped into the “archaic” human category. The diversity in form and the range of species, particularly through Africa suggests that we may be dealing with another allospecies. The African record certainly points to a good bit of evolutionary experimentation. The modern humans showed smaller brow ridges, higher brows, and a prominent chin.

OUT OF AFRICA AGAIN?We may all be Africans under our skin, but we are all global villagers as well.

–C. Stringer and R. McKie (1996).

Anatomically modern humans appeared in the Levant (Palestine) around 100,000 years ago and overlapped with the indigenous Neanderthals in that region. Surprisingly, they seem to have had the same style of stone-making technology until nearly 50,000 years ago. Then, the human stone technology diverged significantly. This marked the beginning of the displacement of Neanderthals in the Levant and ultimately through Europe. As we moved through Asia and into Australia, we likely came into contact with remnant populations of the erectus group, which, too, we displaced. By 30,000 years ago, we seem to have eliminated all other members of the hominids and for the first time since our line diverged from the chimpanzees, there was but a single species, Homo sapiens (see Figure 6-80).

Where did the modern humans come from? In 1987, Rebecca Cann, Mark Stoneking, and Allan Wilson rocked the world when they reported the results of a study that compared DNA from 147 people from five different geographic populations. In particular, they compared the DNA sequences that occur in mitochondria, organelles that occur in all of our cells. What they found was that differences in the mitochondrial DNA (mtDNA) could best be explained if it

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originated in Africa and repeatedly invaded the outlying regions. Also, because mtDNA likely changes slowly and steadily (a concept called a molecular clock), the time of the “original” modern human mitochondrion should be about 200,000 years ago in Africa. Because the mitochondrion is inherited mother to child (the father contributes essentially no mitochondria to the child), the first modern human was dubbed “Mitochondrial Eve”. In truth, Eve likely represented a small breeding population of 5,000 individuals that eked out a living in eastern Africa. The molecular clock also suggested ages of origin (presumably appearance) for individuals from the other geographic areas (see Table 1).

FIGURE 6-80. Skull of a modern human. Note the high forehead and that brow ridges are absent.

TABLE 6-5. Average age (in thousands) based on a molecular clock calibrated to a 2-4% divergence per million years. Note how these dates correlate with the movement indicated on Figure 6-81.

Geographic Region Average AgeAfrica 90-180Asia 53-105

Australia 43-85Europe 23-45

New Guinea 28-55

The concept of a late African exodus was met with a good bit of skepticism by some archeologists, namely Alan Thorne and Milford Wolpoff who claimed that the fossils and artifacts point to a much older origin. They claimed that evidence nearly 1 million years old suggests modern humans appeared separately in different regions after a much older (and much less frenetic) departure from Africa. Thus, in their view, modern humans appeared gradually in Asia, Australia, and Europe as well as in Africa. They called this the “Multiregional” origin hypothesis. In this theory, Neanderthals gradually changed to modern humans.

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Then in 1998 Stephen Ambrose produced a synthesis of information that considered the influence of climate once again on our history. About 73,000 years ago, Mount Toba in Indonesia exploded with the greatest force of any eruption over the past several hundred thousand years. It coincided with one of the coldest periods of the past 100,000 years. Computer models suggest that the dust and aerosols flung aloft by such an explosion would have plunged the earth into an almost continuous winter for up to 6 years. The cooling effects might not have dissipated for another thousand years. Such a catastrophe likely eliminated the remnant erectus populations and reduced the Neanderthals. Also, it likely eliminated most of Homo sapiens and restricted the survivors to the tropics, Africa. Genetic studies imply that our species may have been reduced to as few as 3,000-10,000 individuals sometime before 60,000 years ago. If our species experienced such a “bottleneck”, rapid changes in form could have occurred in the geological blink of an eye. Then the great human Diaspora began around 50,000 to 40,000 years ago. The “new human” not only had a new form, but a new way of thinking. We had experienced The Great Leap Forward.

THE GREAT LEAPI’ve argued that we were fully modern in anatomy and behavior and language by forty thousand years ago, and that a Cro-Magnon could have been taught to fly a jet airplane.

-Jared Diamond (1992)

That we changed physically, does not explain what happened around 40,000 to cause the great leap forward. Anatomically modern humans had been around for at least 200,000 years before the “awakening”. What took them so long to develop modern behaviors?

Old ideas about the leap had to do with tool use. The litany went something like this. We developed bipedal locomotion, which freed up our hands. The free hands then began to make tools. At first, those tools were primitive and then tool use began to allow for the selection of larger brains to make better tools, etc. It is an interesting story, and it is completely wrong. If bipedal locomotion gave rise to bigger brains, why did the brain size of the australopithecines remain about the same size as a chimpanzee? Why did the brain volume of the non-innovative Neanderthals exceed that of our own? Finally, why did the innovation so characteristic of our species appear after two-thirds of our current tenure on Earth? Tool usage may have played a part in the leap forward, but the answer must be far more subtle and wonderful than tool manufacture.

The awakening of humanity seems to be tied to innovations in culture, and since language is the currency of culture, I would consider the leap to be tied to our ability to communicate. Certainly, we did communicate before the leap. In fact, all primates communicate to a certain degree. However, what Diamond and others have argued is that some structural change, a change in soft tissue that would not necessarily show up in the fossil record appeared sometime before 40,000 years ago. Then, selective pressure provided by culture helped to project language to its modern complexity.

Let me back up and consider culture and its influence. Attributes that are considered good or beautiful would tend to persist in a group. Language allows us to transmit and implant those ideas from one mind to another. That is what Richard Dawkins referred to as thought viruses or memes when he said, A meme is … anything that infects itself from brain to brain (Dawkins. 1998. Unweaving the Rainbow). We see the action of memes at work constantly. We infect each other with ideas and set phrases. For example, I remember when the phrase “yada, yada,

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yada”, would have no meaning at all. Now, most of us steeped in western culture have a similar understanding of its meaning and the proper context for its use.

FIGURE 6-81. Migrations of modern humans from their departure from Africa about 50,000 years ago to their arrival in Eurasia, Australia, and the Americas. Adapted from National Geographic Magazine.

Proverbial language works the same way. If I were to use the phrase, “An apple a day”, you would complete it with “keeps the doctor away” in your mind and apply the appropriate meaning to the situation according to the context. Nowhere is such culture-laden communication greater than in humor and what we think is amusing.

If concepts of beauty can be verbalized and then transmitted, its effects can be felt through the “infected” population like a wildfire. Then, if the concept of beauty also influences mating, the change in body form can be dramatic and rapid. That is exactly what Darwin meant when he used the phrase “sexual selection” in his Descent of Man. That mechanism was for him the driving force of human evolution. It still seems to be the most plausible explanation.

For example, if dark skin and wavy hair became codified and tramsmitted within a culture as a particular paragon of beauty, then they would be the most likely to mate and have children. Thus, in very few generations, a concept of beauty could become manifest in the appearance of the population at large. Curiously, such characteristics as skin color and hair texture serve to define the “races” today. That a small population about 60,000 years ago gave rise to the present diversity of human “races” is a testament to the power of memes.

The first clear signal that human behavior had changed was a modification in stone tool design in the Levant. Then, symbolic sculpture and cave art began to appear in Germany, Southern France, and Spain. This was the Cro-Magnon culture that produced amazing treasures of carvings in ivory and paintings on the walls of caves. The earliest art that we have dates back to 32,000 years as in the cave of Chauvet (more than 300 animal and abstract images). The more well-known cave images from Lascaux were produced 18,000 years ago.

The innovations in tool design and the appearance of art are likely the tip of the iceberg of what was actually produced. We have no clothing or items fashioned from more ephemeral

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materials like wood. Almost certainly major advances in spoken language (the most ephemeral of all possible art forms) preceded symbolic art.

New views of the appearance of language suggest that music and spoken language had the same origin and simply rest at opposite ends of a continuum of sonic communication. Steven Brown called the protolanguage musilanguage (see Figure 6-82). He suggested the relationship can be seen in similarities between music and language:

Both employ phrasing. Both use a limited number of standardized sounds from an infinite number of potential

elements. Both can generate higher order structures.

FIGURE 6-82. The origin of language and music from a more primitive “musilanguage”. Adopted from Steven Brown (2001)

The musilanguage hypothesis implies that communication early in our line was ritualized and rhythmic as it seems to be in other apes today. The phrasing of spoken language and music both point to that. Also, given the unending number of possible sounds, we speak and sing relatively few of them. Even more compelling to me is the remarkable adaptation for singing that appears in our species. The range of sounds (a topic that I discussed in Language, A Nurture of Nature) that we make is enormous compared to all other primates and, as Darwin noted, is “more like bird song”. The singing instinct also seems manifest in our response to rhythm. We can generate rhythmic sounds and vary the tempo, many other species do that though. We are the only animal that responds to external rhythm (rhythms made by devices other than the voice). Such response can be seen in dance, which is music made visible through motion. Music and dance, therefore are communicative, but they communicate in an emotive mode. As such, the communication might be powerful, but not precise.

Consider the song, My Country Tis of Thee. If it is played here in the US, the listener might get patriotic feelings. If the same tune is played in the UK, the listener might feel the same

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degree of patriotism, but for a different reason. In Britain, that song is the English National Anthem, and it is called, God Save the Queen.

Spoken language, however, communicates with precision and allows the transmission of precise commands, instructions, and precise high level thought. Again, consider the example of the patriotic song. If words are used, they become part of the music, but convey a level of precise communication that identifies whether you mean Of thee I sing or God save the Queen.

Precision of meaning would have been very important in a social setting. It would have allowed much more than the transmission of ritualized commands. It would have allowed for versatility of communication and subtle differences in meaning that human language now has.

Poetry occupies a middle ground with emotive and precise components, almost in equal doses. Also, it often is spoken in cadence or rhythm. Contemplate Shakespeare’s poetic rendering of the speech that Henry V gave to his men before the battle of Agincourt.

We few, we happy few, we band of brothers;For he to-day who shed his blood with meShall be my brother; be he ne’er so vile,This day shall gentle his condition:And gentlemen in England now a-bedShall think themselves accursed they were not here,And hold their manhoods cheap whiles any speaksThat fought with us on Saint Crispin’s day.

-Shakespeare; Henry V; Act IV, iiiI cannot read those words and not be moved, even though I have heard them many times. I know that the historical accuracy of the play is minimal, but that does not matter. The sheer beauty of the language and the words used in the construction transcend that “problem”. In part, I am moved and see beauty because I have been acculturated to it.

As levels and layers of communication develop and the facility to communicate (music to language) is valued by a social group, Darwin’s sexual selection will come to play. In this case, then, a witty speaker or an exquisite singer would have a better chance to find a mate and leave offspring. Thus, natural selection would quickly push the development of communication in all of its forms. It is this richness of transmitting ideas with emotion and precision that defines our humanity and permits me to contemplate my own origins at the same time that I listen to Mozart’s Turkish Concerto.

Thus, each day is a celebration of our humanity as we interact with one another wearing bodies that were fashioned in Africa long before the last Ice Age and emotional structures that are suited to small bands as we wind our way through a global village of over 6 billion people. Our communication and the culture that it transmits refashion us and prepare us to meet challenges, understand nature and one another, and to express, and understand, and question goodness and beauty.

-December 2003References:Ambrose, Steven. 1998. Late Pleistocene Human Population Bottlenecks, Volcanic Winter, and

Differentiation of Modern Humans. Journal of Human Evolution. 34(6):623-651.Brown, Steven. 2001. The “Musilanguage” Model of Music Evolution. In: Nils Wallin, Bjorn

Merker, and Steven Brown, eds. The Origins of Music. The MIT Press. Cambridge, Mass. Pp. 271-300.

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Cann, Rebecca, Mark Stoneking, and Allan Wilson. 1987. Mitochondrial DNA and Human Evolution. Nature. 325:31-36.

Cavalli-Sforza, Luigi L. 2000. Genes, Peoples, and Languages. North Point Press. New York.Dawkins, Richard. 1998. Unweaving the Rainbow. Houghton Mifflin Co. New York.Darwin, Charles. 1873 (originally 1871). The Descent of Man, and Selection in Relation to Sex.

D. Appleton and Co. New York.Darwin, Charles. 1998 (1872). The Expression of the Emotions in Man and Animals. 3rd ed. With

an introduction, afterward, and commentaries by Paul Ekman. Oxford University Press. Oxford.

Diamond, Jared. 1992. The Third Chimpanzee. HarperCollins. New York.Diamond, Jared. 1997. Guns, Germs, and Steel. W.W. Norton and Co. New York.Fouts, Roger. 1997. Next of Kin, What Chimpanzees Have Taught Me About Who We Are.

William Morrow and Co., Inc. New York.Hunt, Kevin. 1996. The Postural Feeding Hypothesis: An Ecological Model for the Evolution of

Bipedalism. Sout African Journal of Science. 92:77-90.Johanson, Donald, Lenora Johanson, and Blake Edgar. 1994. Ancestors, In Search of Human

Origins. Villard Books. New York.Kurten, Bjorn. 1993. Our Earliest Ancestors. Trans. Erik J. Friis. Columbia University Press.

New York.Lumsden, Charles J. and Edward O. Wilson. 1983. Promethean Fire, Reflections on the Origin

of Mind. Harvard University Press.Mayr, Ernst. 2001. What Evolution Is. Basic Books. New York.Ovchinnikov, Igor, A. Gotherstrom, G.P. Romonaval, V.M. Kharitonov, K. Liden, and W.

Goodwin. 2000. Molecular Analysis of Neanderthal DNA from the Northern Caucasus. Nature. 404:490-493.

Pinker, Steven. 1994. The Language Instinct, How the Mind Creates Language. HarperPerennial. New York.

Rampino, Michael and Stanley Ambrose. 2000. Volcanic Winter in the Garden of Eden: The Toba Supereruption and the Late Pleistocene Human Population Crash. In: McCoy, F.W. and G. Heiken, eds. Volcanic Hazards and Disasters in Human Antiquity. Geological Society of America Special Paper 345: 71-82.

Stringer, Christopher. 1995. The Evolution and Distribution of Later Pleistocene Human Populations. In: Vrba, E., et al., eds. Paleoclimate and Evolution, With Emphasis on Human Origins. Yale University Press. New Haven.

Stringer, Christopher and Robin McKie. 1997. African Exodus, The Origins of Modern Humanity. Henry Holt and Co. New York.

Tattersall, Ian and Jeffrey Schwartz. 2000. Extinct Humans. Westview Press. Boulder, CO.Thorne, Alan G. and Milford H. Wolpoff. 1992. The Multiregional Evolution of Humans.

Scientific American. 266:76-83.Vrba, Elisabeth. 1995. On the Connections Between Paleoclimate and Evolution. In: Vrba, E., et

al., eds. Paleoclimate and Evolution, With Emphasis on Human Origins. Yale University Press. New Haven.

Wheeler, P.E. 1991. The Thermoregulatory Advantages of Hominid Bipedalism in Open Equatorial Environments: The Contribution of Increased Convective Heat Loss and Cutaneous Evaporative Cooling. Journal of Human Evolution. 21:107-115.

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Questions to Think About

1. What is meant by the Great Leap Forward?

2. About how much time separates our line from the other apes?

3. What are some advantages to walking upright in a savannah?

4. What is an allospecies? Give an example of one in our line. What does an allospecies mean in terms of evolution?

5. What are some characters of Homo erectus that served it in its exodus from Africa?

6. Why can we now say that Neanderthals were not humans (at least not members of our species)?

7. What evidence suggests that our species originated in Africa?

8. Other than speech, what are the forms of language that our species employs?

9. What is the musilanguage hypothesis?

10. What does understanding of our origins have to say about our interactions in a global village?

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