Paleoanthropology & the Emergence of Adam
We shall explore the anthropology, geology and biology of human evolution.
Paleoanthropology
Two scientific explanations for human origins exist — the punctuated and the gradualist models.
Ian Tattersall, a punctuationist, thinks symbolic behavior emerged from one chance mutation that suddenly and dramatically transformed the human mind.[1]Modern humans arrived from somewhere into Europe (Cro-Magnons) around 40 thousand year ago (tya) and replaced the prior Europeans (Neanderthals). In Becoming Humans, Tattersall points out that in humans, “the potential arose in the mind to undertake science, create art, and discover the need and ability for religious belief, even though there were no specific selection pressures for such abstract abilities at any point during our past.”[2] The regular burial practice by the Cro-Magnons compared with the occasional burial practice of the Neanderthals marked the true development of religious cognition. Burial of the dead with grave goods is accepted as evidence to indicate belief in an afterlife. Our capacity for speech that creates complex art, music and religion is found nowhere else in the animal kingdom. We are not an improved version of the apes; even though we seem to share a common physiological heritage, we are a new being altogether, qualitatively distinct from our ancestors.[3]
David Reich of the Broad Institute at Harvard and M.I.T. has advanced a theory that human and chimp ancestors, after diverging into separate species millions of years ago, came back together and interbred. When two species split from a common ancestor, their genes will continue to diverge, or mutate, at a regular rate. After comparing some 20 million base pairs from humans and chimpanzees, Reich and his team found that different genes began diverging at different times — with genes located on the X chromosome of humans and chimps parting ways most recently. Reich postulates that the two populations interbred on repeated occasions over millions of years, producing hybrids of protohumans and protochimpanzees. While the males may have been sterile, the females are likely to be able to mate with males of one of the original species. This explains why genes on the X chromosome of humans and chimpanzees diverged more recently. The hybrids could play an important and positive role in speciation, introducing advantageous traits into a gene pool — including the human gene pool.[4]Alvin Powell reports that according to Reich “… the findings may cause scientists to re-examine beliefs about speciation and the role of hybridization. Current thinking is that although hybrids do occasionally occur in nature, they are sterile or less fit than the parent populations and so eventually die out. It may be the case, however, that the rare hybrid is fit enough to survive, which would make hybridization between species a creative process in evolution, rather than a negligible happenstance, as is now thought … Maybe hybrids that successfully adapt occur only once every million years, … if hybridization between human and chimp ancestors did occur, either we’re the hybrids or the chimpanzees are the hybrids, but we can’t tell which.”[5]
The possibility of hybrid hominids that include DNA from Homo sapiens sapiens, while inconclusive, complicates the simple story told so far by both theology and science. It also explains the hybrid characteristics of fossils such as Lucy’s Child or Dikika Girl. The discovery of a 3-year old girl who lived about 3 million years ago in Ethiopia was recently announced in Nature. Although first discovered in 2000 by Zeresenay Alemseged and Tilahun Gebreselassie at Dikika in Ethiopia, this partial skeleton was buried in sandstone some 3.3 million years ago and took almost 6 years to recover from the earth. In September 2006, it was announced to the world as “the most complete partial skeleton of an early juvenile hominid ever discovered.” Dikika Girl has a mix of primitive, apelike traits and more modern traits such as ankle and knee bones adapted for upright walking. The skeleton includes all the teeth. It also preserves only the second ancient voice box ever found.
For Tattersall, one of the major functions of religious belief has always been to provide explanations for the deep desire to deny the finality of death, and the curious reluctance of our species to accept the inevitable limitations of human experience.”[6]Both evolutionary epistemology and paleoanthropology indicate the significance of religious belief. Steven Mithen, on the other hand, is a neogradualist with regard to the cognitive capacities that allow for symbolic behavior, and a discontinuist with regard to the manifest appearance of such thought.[7]In Prehistory of the Mind, Mithen coined the term cognitive archaeologyas an interdisciplinary investigation into the origin of the human mind.[8]For Mithen, the Homo sapienmind possessed a highly adaptive domain-specific mentalityand was fundamentally different from other hominids. Natural selection molded each type of intelligence to help us solve problems within relevant behavioral domain. General intelligence is followed by the appearance of specialized intelligences; social, technical and natural history.
There were three key intelligences: social intelligencefor managing the complex social world; natural history intelligencefor understanding animals and plants, the weather and the seasons, and aspects of the world for a hunter-gatherer lifestyle; and a technical intelligencewhich enabled the complex manipulation of artifacts and especially the production of stone tools. While the Homo sapiensmind is based on multiple intelligences, he also has cognitive fluidity- the capacity to integrate ways of thinking and stores of knowledge from separate intelligences to create types of thought that cannot exist within a domain-specific mind. In this view, a Neanderthal would not have had the capacity to combine his natural knowledge of a wolf with his social intelligence about human minds to create the idea of a wolf-man who thinks like him. The two current models of the mind views it as either a single general purpose function, or one akin to a Swiss-Army knife, with unique intelligences to fit individual situations (Tooby and Cosmides). Mithen believes that the modern mind incorporates both of these elements. Using the metaphor of a church building, he envisions a small general intelligence, several specialized intelligences, and an overall communication through language and consciousness. This complete architecture is a recent development, and we can interpret the fossil record according to the progression from earlier, incomplete stages of development.[9]
Paleoanthropology challenges the myth that humans were part of a single hominid lineage — the single species hypothesis. In 1959 Mary and Louis Leakey discovered Zinjanthropus(nutcracker man),[10]later classified as Australopithecus boisei. A year later Louis Leakey, John Napier and Phillip Valentine Tobias[11]discovered Homo habilis.[12]Both were dated to at least 1.8 million years ago (mya). They were contemporaries! Hominids were shown to have lived at the same time as Australopithecines.[13]If this is correct, it means that the first humans were not alone. There were more than one genera of hominids co-existing. What happened to the others? Could one have extinguished the other? The apparent arbitrariness of paleoanthropological taxonomy is inescapable in an age when interdisciplinarity has entered the study of human origins with bioarchaeology and genetic archaeology making significant contributions.[14]Even the dominant method of nomenclature and classification is up for grabs and new discoveries show that earlier assumptions about how many kinds of hominids existed, their distributions and dates of existence, when type specimens were correctly identified, all because archaeology is always dependent on what was discoverable under the circumstances of the discoverers. The older fossil-dating method is giving way to the methods of molecular biology and gene mapping. The success of humans on earth is often linked to our superior intelligence.
For Christian theology, it begs the question, “Are we here by chance?” Yes, said the late Stephen J. Gould. We just got lucky. He claims that the outcomes of evolutionary pathways are endless and we happen to be the contingentoutcome of our collective worldline[15]– hence, we are here by accident. However, in Life’s Solution, Simon Conway Morris (one of the three paleobiologists who reworked the fossils of the Burgess Shale) now argues that we are ‘inevitable humans in a lonely universe,” i.e., although we are alone, the laws of nature are such that we evolved the way we did because the options are limited and the emergence of human intelligence arose from convergent features of the natural order. His theory of the convergentoutcome in the evolution of matter and life permits the possibility that this was planned. The principle of inherency leads to convergence as the guide in evolution.[16]Van Huyssteen sees Conway Morris’ view as a corrective on Gould’s over emphasis on contingency in biological evolution. Ironically, in his earlier reports, Morris interpreted the Burgess Shale findings as different fossils of extinctanimals.[17]For Conway Morris, human existence is inevitable because “for all its exuberance, the forms of life (of which origin we do not even know) are restricted and channeled” despite the contingency of evolutionary pathways.[18]If we are not here purely by chance, how does biological evolution explain our existence? Perhaps another form of evolution is necessary — cultural evolution. For van Huyssteen, biological evolution can explain how our minds arise and acquire their talents and capacities, but only cultural evolution can explain what we do with them. Biology can explain the emergence of human rationality, but the way we use it is what I call transbiological.This term is derived from transcendent biology and refers to the abiological expression of biological componentry. The emergent quality of volitional consciousness in rationality cannot be reduced to mere biology even though it has biological roots. Thus, a biological person made up of most hydrogen atoms exhibit organic life when combined with other elements under the right circumstances. But upon death, they are reduced back to their component elemental nature.
Religious belief based on experience is not reducible to evolutionary accounts of physical processes. According to the best current data available, hominid evolution began sometime between 5 to 7 mya. The earliest fossils bits currently date to around 5 mya. Jaw fragments and footprints date to about 3.5 mya. It is only from 3 mya onwards that more substantial fossils have been found in Ethiopia, Kenya, Tanzania and South Africa. Fewer finds come from Europe and Asia. Paleoanthropology provisionally concludes that while there were both human and non-human hominids from 7 mya, Homo sapiensare the only known surviving hominids. This suggests the tremendous successes of three adaptations (bipedalism, significant increase in the prefrontal cortex, and cognitive fluidity), which made the capacity for speech and control of fire possible.
5 hominid adaptations
i) Bipedalism
One hominid adaptation that contributes to human uniqueness is bipedalism, the ability to walk on justtwo legs and freeing two limbs to be arms, thus arming the person with the most complex and useful tool — hands. The most ancient hominid fossil found is called Australopithecus afarensis, dated to about 3.75 mya. An example is Dikika Girl, discovered in 2000 but announced in September 2006.[19]Unlike the apes, she has jaws and dentition designed for grinding tough material. Although she can walk upright, this may not have been a full-time preference. But what advantages do bipedalism and stronger dentition bestow? Better homeostasis (regulation of heat equilibrium) but compromised speed and balance in locomotion. Bipedalism decreases solar energy absorption with less surface area exposed to the sun. Bipeds are also slower and clumsier than tetrapods, requiring greater computational power and more advanced inner-ear equilibria registrations. But their capacity to tear into meat with bigger jaws provides more energy while requiring more efficient digestion. With more time left over from chewing vegetation, these hominids could begin to exploit its other capacities. Life became more than just an exercise in survival, so that existence of life turned from eating to live into living to eat, since there was now more to life than food. Increasing efficiency in food production or access to nutrients meant that not all the wakeful hours were spent on eating. With more time on their hands, curiosity had the opportunity to emerge. Joy became a novel experience for the emerging human. This may have marked the shift from mere survival to the exploration beyond the boundaries of avoiding pain and acquiring relief from hunger and shelter to optimize reproduction. Studies of Bonobo monkeys who seem to enjoy sex and especially masturbation, including mutual masturbation, suggest an evolutionary pathway of sex in hominids that culminated in Homo sapiens sapiens, where even the promise of unattainable sex in fantasy shapes preconscious urges.Although some Australopithecus genus could walk on two legs for a while, they are not optimized for it. The genus Homowalked upright all the time, the earliest being Homo habilis, dated to about 2 mya. By 1.7 mya, Homo erectusappeared[20]and was probably a meat-eater. The fossils of a H. erectusfossil named Turkana Boy discovered by Richard and Meave Leakey and dated 1.6 mya showed adaptation to long-distance running. Although most animals can outrun humans, they have to pant to lose heat. But when an animal runs, it cannot pant and builds up a heat deficit. We can run farther than most animals because our lack of body hair means our skin can lose heat more efficiently than hairy animals. We can run more effectively than say, an ape. This also means we can hunt in a specific way — persistence hunting (San people of the Kalahari) by outlasting the prey. Run the prey to exhaustion. The animals have little chance to cool down while the sweating humans can control body heat. After about 1.5 mya, genus Australopithecusand genus Homocoexisted until the former eventually diedout and the last species being Australopithecus boisei. By about 1 mya, H. erectuswas the lone hominid in Africa. [21]But he was not the only hominid in the world. From about 500 thousand years ago, some hominids that appeared in Africa, Europe and Asia bore both H. erectusand modern human features. They are nicknamed “archaic sapiens” and may have been a transitional form between H. erectusand H. sapiens.
ii) The Prefrontal Cortex
The second adaptation is a significantly increased brain size.[22]The shift to walking upright was the single most important physiological change. It makes it possible for significant increase in brain size. Brain development is held up by two obstacles. The brain is the hungriest organ in the body.When active, brain tissue takes 22 times more energy to maintain than muscle tissue. The brain also requires a cooling system, as its efficiency is greatly influenced by temperature changes. Eventually, bipedalism, a network of cooling veins in the brain, and carnivorism (meat-eating) allowed brain evolution to progress. In Homo sapiens, the increase was nothing short of stunning, from about 300 to 1400 cubic centimeters of cranial capacity in just a few million years. This rapid development suggests that intelligence was being selected for. E. O. Wilson said of the brain, “No organ in the history of life has grown faster.”[23]How quickly did the brain grow? In the past 5 million years, the entire brain tripled in volume, but the prefrontal cortex (PFC), itself increased in size sixfold! The PFC is responsible forthe executive functionsof planning complex cognitive behaviors, personality expression, decision-making and moderating correct social behavior. The basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals. As such, it is the primary brain region that shapes moral cognition and religious inclinations. The PFC forms our very personality and is the human brain’s command post to which virtually every functional part is directly interconnected and plays a fundamental role to the brain’s internally guided behavior, i.e., actions influenced by intentions, decisions and plans that originate in the individual’s brain rather than from external sources such as a game of chess, watching television, etc.
The PFC helps us to differentiate among conflicting thoughts, to determine good and bad, better and best, same and different. It allows us to consider the future consequences of current activities, to work towards self-defined goals, to predict possible outcomes, to manage expectations based on actions. Finally it monitors when we ought to activate social ‘controls’ (the ability to suppress urges that, if not suppressed, could lead to socially-unacceptable outcomes) that is a part of nolition.The PFC is connected to four principal areas: the premotor cortex, the posterior association cortices, the cerebellum and the basal ganglia[24]. All these areas are responsible for motor control and movements. The PFC is also connected to the dorsomedial nucleus, a part of the thalamus[25]responsible for the integration of stimuli, as well as to the hippocampus[26], amygdala[27], and the hypothalamus.[28]The PFC also connects directly with the brain stem nuclei that activities arousals such as flight or fight responses. But most importantly, its anterior segment plays a major role in human cognition[29]
iii) Cognitive Fluidity
The third adaptation is the coming together of several intelligences into what is called cognitive fluidity, a term coined by Steven Mithen. It is the combination of knowledge and ways of thinking from different mental modules, which enables the use of metaphor and produces creative imagination. Mithen believes that music and language developed together. This, coupled with Terrence Deacon’s co-evolution of mind and language, offers a tri-evolution of brain, music and language.[30]Cognitive fluidity made possible art, science and religion — products ofcultural evolution. They rely on neurological and psychological processes that originally evolved in different specialized cognitive domains. Thus, art, science and religion emerged only when these processes could all work together. Cognitive fluidity gave birth to the symbolic mind and allowed for the possibility of metaphorsand analogy that are crucial for the imaginative fuel in art, science and religion.
Cognitive fluidity is likely to have been both a biological as well as cultural adaptation. Since we have no access to ancient brain matter, our speculations are limited to what we can infer from the study of primate brains.According to Steven Mithen, the evolution of the human brain reached a turning point some 77 tya when the human mind might have attained cognitive fluidity, a phase in its development which coincides with an almost limitless capacity for imagination.[31]Mithen points out that even if non-human minds were strictly modular, the appearance of language demodularises the mind.[32]The characteristic of human mentality is the ability to integrate. Rather than the Swiss-Army knife model (advanced by Tooby and Cosmides[33]), Rose believes the brain functions like a general-purpose computer[34]while Mithen thinks it behaves in both ways. It is therefore noteworthy that both cognitive fluidity and grammatical language in humans were the precursors to the evolution of a mind that can form beliefs.
iv) Speech
The three adaptations allowed for the development of grammatical and symbolic speechpossible. While bipedalism and brain size are biological adaptations, cognitive fluidity and speech provided the basis for cultural evolution, a far swifter means of information transmission than any form tied to physiological structures.[35]Speech was a critical factor in the evolution of the mind. The dramatic growth of some universal grammar among all languages suggests a single initial impulse that maintained its pedagogic integrity as it underwent transmigration through time and space, i.e., through history and geography. Some common causal agent made it possible for all human beings to share a linguistic grammar that adapts to all languages. We shall explore the power and implications of speech for the development of religious disposition later.
V) Cooking
The fifth adaptation is the discovery that fire can be controlled. Some one million years ago, the first hominids learned how to tame this ‘red flower’ as Rudyard Kipling’s Jungle Bookdescribes it. This remarkable achievement of managing combustion changed forever how humans lived and thrived. Cooking is predigesting food outside the body. It frees up a great deal of effort and time to break down plant cellulose and animal protein. It significantly reduced the chances of food poisoning. No longer must the human person spend endless hours digesting raw food and risk poisoning. This gave them the gift of timefor more advanced pursuits such as music, art and religious reflection.
Geology
What was the pattern of migration in early humans? Did they all come out from Africa or were there different locations where modern humans appeared independently? Geologic time zones in Europe, for our purpose, may be divided into the Lower Paleolithic (3 mya — 220 tya), Middle Paleolithic (220–45 tya), and Upper Paleolithic (45–35 tya) periods. In Western Europe, early hominids in the Lower Paleolithic period included H. habilis and H. erectus. The Middle Paleolithic period gave rise to Homo neanderthalensiswhile the fully anatomical human or Homo sapienscame later, during the Upper Paleolithic period and are also called Cro-Magnons.
For thousands of years during the transition between the Middle and the Upper Paleolithic periods, Neanderthals and Cro-Magnons (H. sapiens) lived side by side. With their lighter frame and running ability, Cro-Magnons probably replaced their competitors for survival to become the sole survivors by around 28 tya. It was during this Upper Paleolithic period, also known as the “Creative Explosion,”[36]that human consciousness probably emerged. This gave rise to creative, artistic and religious imagination. Moral cognition is also one of the likely fruits of this development.
Later hominids of Europe and the Middle East were immigrants from Africa — this is the “Out of Africa” model. It consists of four migrations: In Out of Africa 1 (OOA1), H. erectuswalked out around 1 mya. In Out of Africa 2 (OOA2) H. sapienswalked out in three waves, about 270 tya, 130 tya (via the northern route) and 70 tya (via the southern route).[37]
However, the OOA theory of human migration is not the final word. The recent dating of Mojokerto Boy[38]of Indonesia, a specimen of Homo erectus, to 1.49 mya, suggests the possible existence of an Asian ‘Adam” the first modern human, Homo sapiens.
Molecular Biology & Genetics
Molecular biology offers another method todetermine the genealogy of early humans — mitochondrial DNA analysis. The DNA of the mitachondria, itself a cell living within another cell, passes on unchanged in the female. It forms a convenient marker for population geneticists to analyze migrations of human DNA. This method supports the OOA2 hypothesis that fully anatomically modern humans (AMHs) left Africa some 100 tya and arrived in Europe for the first time. The inference from this line of evidence is radical and controversial. It suggests that modern humans or Homo sapiens sapiens,who arrived in Europe, and who we now call Cro-Magnons, completely replaced their competitors, the indigenous species called Neanderthals. If we are descendants of winners in the competition for life, our very existence was contingent on this outcome. The rise of the human species was the product of a war to extinction — a theme that Frans De Waals noted about the nature of biological evolution.
In summary, evidence from anthropology, geology and biology suggest the emergence of humans as migratory and violent competitors. This challenges any cozy idea of fully morally mature persons who failed to live up to standards of ethical norms drawn from prelapsarian cosmology.While any paleoanthropological inference has to be open to revision, the main thrust seems evident and any theological account of biblical creation must be understood in the light of this discovery. Even the emergence of humans came about by reproduction (no adult animal was created in isolation from other forms of life); predation (death is necessary for the compilation of complex proteins); mutation (for the variations of gene pools to avoid extinction); adaptation (to withstand changing environments and migratory consequences); competition (in situations of economic scarcity); cooperation (to ward off common predators or to ride out environmental challenges); reciprocity (for kin-selection purposes); and development (acquisition of capacities for utilitarian advantages).
[1]Van Huyssteen, Alone in the World?, 199.
[2]Van Huyssteen, Alone in the World?, 214–215. Antonio Damasio and others take a different view and suggest that in fact, there were selective pressures that gave rise to the evolution of religious belief.
[3]Ian Tattersall,Becoming Human: Evolution and Human Uniqueness(New York: Harcourt, 1998),188.
[4]See “Did ancestral humans, chimps interbreed?” http://www.news.harvard.edu/gazette/2006/05.18/11-chimp.html.
[5]http://www.broad.mit.edu/cgi-bin/news/display_news.cgi?id=1003and “When Humans, Chimps Were Kissin’ Cousins” in http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2006/05/18/MNGGDITQ6D1.DTL.
[6]Tattersall, Becoming Human, 201.
[7]Van Huyssteen, Alone in the World?, 199.
[8]Mithen, The Pre-History of the Mind, 11.
[9]Steven Mithen, The Singing Neanderthals: The Origins of Music, Language, Mind, and Body(Cambridge: Harvard University Press, 2006), 263–265.
[10]Ann Gibbons, The First Human(New York: Doubleday, 2006), 53–54.
[11]In my personal conversation with Tobias on October 2011 at Witwatersrand University Medical School, Tobias postulated that the simultaneous existence of Australopithecus and Homo does not in itself prove that interbreeding took place but certainly opens up such a possibility. Tobias died a few months later in June 2012, the last member of the team that identified Homo habilis.
[12]Gibbons, The First Human,93–94.
[13]Van Huyssteen, Alone in the World?, 54.
[14]Van Huyssteen, Alone in the World?, 51.
[15]Drawn from the philosophy of time, I coin the phrase to mean the outcomes of all possible decisions of free agents in the universe that led to this instant’s ontological reality for the collective consciousness of six odd billion humans and all other sentient life forms.
[16]Simon Conway Morris, Life’s Solution: Inevitable Humans in a Lonely Universe(Cambridge: Cambridge University Press, 2003), 166.
[17]Gould adopted this early view of Conway Morris in his Wonderful Life,published in 1989. See Stephen Jay Gould, Wonderful Life: The Burgess Shale and the Nature of History(New York: W. W. Norton, 1989). But to Gould’s dismay, Conway Morris now rejects his earlier conclusions and wrote Crucible of Creationin 1998 to challenge Gould’s published position. Conway Morris now believes that most of the fossils were in fact partial remains of modern animals. For him, “the constraints of evolution and the ubiquity of convergence make the emergence of something like ourselves a near-inevitability. How could two eminent biologists come to such opposite conclusions from the examination of the same evidence from the Burgess Shale fossil remains? Gould argues that humans are unlikely to arise if the universe started again. Conway Morris says that something like us, not necessarily Homo sapiens sapiens, would inevitably emerge. In his reply to Conway Morris in Natural History, Gould said, “…any general view of life must read evidence in the light of a favored theory … I always explicitly identify as tentative, undoubtedly wrong in places (but not, I hope, in general approach), and embedded (as all ideas must be) in my own personal and social context.” See“Showdown on the Burgess Shale. Simon Conway Morris; Stephen Jay Gould,” in Natural History, Dec. 1998, vol. 107, Issue 10, 48. Gould was committed to an ateleological abduction of evolutionary history while Morris does not feel so restricted. But do the rules of scientific investigation not curtail the speculations of Morris? Not really. The methodological naturalism of science does not rise to a philosophical naturalism. Science is methodologically agnostic about the purpose of the universe but can benefit from inferences of another method of knowing. This describes transversal rationality in postfoundationalism. Both science and theology maintain their integrity but enjoy the benefits of drawing from the resources of rationality from different strata.
[18]Van Huyssteen, Alone in the World?, 58.
[19]Ann Gibbons, “Lucy’s ‘Child’ Offers Rare Glimpse of an Ancient Toddler” in Science, Vol. 313, September 22, 2006, 1716 and http://news.bbc.co.uk/1/hi/sci/tech/5363328.stm.
[20]While it was assumed that H. erectusreplaced H. habilis, recent findings in South Africa suggest that in fact, both species shared habitats for as much as 500,000 years.
[21]Van Huyssteen, Alone in the World?, 60–61.
[22]Although the human brain is around three times larger than expected for a primate of our body size, it is not a scaled-up version of a nonhuman primate brain. Neural tissue is evolutionarily expensive (for metabolic and maturational reasons), so changes in relative proportions in different parts of the brain are likely to be behaviorally adaptive. Thus, determining the differences between the human brain from nonhuman primate brains is crucial to understanding human evolution. The prefrontal cortex mediates such behaviors as planning, working memory, memory for serial order, temporal information, aspects of language (Broca’s area and symbolic behavior), attention and social information processing. This suggests that some combination of these behavioral dimensions were particularly important to our evolutionary history.
[23]E. O. Wilson, On Human Nature(Cambridge: Harvard University Press, 1978), 87.
[24]A subcortical structure (putamen– involved in the regulation of voluntary movement, caudate nucleus- involved in the detection and perception of a reward, as well as producing motivation to actually obtain it, forming a part of the brain’s reward system of incentivization, and globus pallidus — relays information from the caudate and putamen to the thalamus) that is involved in cognition, emotional, and motor functions.
[25]The primary relay center between the subcortical centers, including the limbic structures and the cerebral cortex.
[26]A subcortical structure of the limbic system that works in tandem with the amygdala for fixing mostly short-term memory.
[27]A part of the limbic system, it is activated by emotional reactions, most particularly, fear, and possesses the capacity to store emotional memory.
[28]One of the limbic structures that functions as the regulator of the autonomic, immunological, and endocrine structures of the body.
[29]Laurence Tancredi, Hardwired Behavior: What Neuroscience Reveals about Morality(Cambridge: Cambridge University Press, 2005), 38ff.
[30]Steven Mithen, The Singing Neanderthals: The Origins of Music, Language, Mind, and Body(Cambridge: Harvard University Press, 2006), 4.
[31]Steven Mithen, The Pre-History of the Mind: The Cognitive Origins of Art, Religion and Science(London: Thames and Hudson, 1996), 71.
[32]Rose, The Future of the Brain, 112.
[33]John Tooby and Leda Cosmides are co-directors of the “Center for Evolutionary Psychology” at the University of California Santa Barbara where they are respectively professors of anthropology and psychology. They serve as joint editors of The Adapted Mind: Evolutionary Psychology and the Generation of Culture, a book that helped to widely launch Evolutionary Psychology as a widely influential field of study.
[34]Rose, The Future of the Brain, 101.
[35]Kim Sterelny, Thought in a Hostile World: The Evolution of Human Cognition(Oxford; Blackwell, 2003).
[36]This is also called the recency hypothesis, a reference to a so-called cultural big bang — the Upper Paleolithic revolution some 45 tya. See van Huyssteen, Alone in the World?, 66–67.
[37]Van Huyssteen, Alone in the World?, 63–65. Van Huyssteen summarized the competing Multiregional and Unilinear models.
[38]Discovered by Tjokrohandojo or Andoyo — an Indonesian who worked at excavating animal fossils in the Kendeng Hills (Pegunungan Kendeng) in East Java on a team led by Ralph von Koenigswald. In the early 1990s, geochronologist Garniss Curtis and paleontologist Carl C. Swisher III used the argon–argon dating method to propose a date of 1.81 ± 0.04 Ma for the fossil, that is, 1.81 million years ago, with a margin of error of plus or minus 40,000 years. Their rock sample — “hornblende grains from volcanic pumice that appeared to match the filling of the skull” — came from a site shown to them in 1990 by Teuku Jacob, an Indonesian paleoanthropologist who had studied under Ralph von Koenigswald. Swisher and Curtis announced their findings in Science magazine in 1994. Their conclusion meant that the Mojokerto child was as old as the oldest known specimens of African Homo ergaster (also called Homo erectus sensu lato), suggesting that Homo erectuscould have left Africa much earlier than thought, or even evolved in Southeast Asia rather than Africa. In 2003, a paper published by a team led by archeologist Mike Morwood presented 1.49 ± 0.13 Ma as the latest possible date, based on “fission-track dating of single zircon grains”. Morwood argued that the rock samples Curtis and Swisher dated came from a pumice bed located 20m below the one above which the Mojokerto skullcap was found. The geological horizon immediately under the fossil dates back to 1.49 Ma, whereas the one just above dates from 1.43 ± 0.1 Ma. In 2006, Frank Huffman used pictures and fieldnotes from the 1930s to identify the exact site of the excavation and confirmed that the fossil was indeed found between the two layers that Morwood had dated.
