The Evolution of Homo Sapiens [chapter]

John Cartwright
2008 Evolution and Human Behaviour  
Considering recent data coming from different disciplines like molecular biology and palaeontology -handled as elements of an inference towards the best explanation -here we explore the hypothesis that the development of a fully articulated language favoured key cultural innovations, which in turn pushed the last population wave of Homo sapiens out of Africa about 60 to 50K ago. Human biogeography could be the keystone for the correct interpretation of the fragmentary data concerning the
more » ... ed "Paleolithic Revolution". It is possible that the "final wave" of people out of Africa after the period of 60K, associated with the L3 haplogroup, was the bearer of the behavioural innovations which until now have been associated with the symbolic revolution. In "The Final Wave" model, the evolutionary process is continuous, but with punctuated bursts of innovations in small populations; there is a direct liaison between biological evolution and cultural evolution (with the latter grafted onto the former); a growing interdisciplinary collection of evidence is unified in a frame stressing the role of biogeography in the evolution of cognitively modern human behaviour. When we observe the wonderful results of the so-called "Paleolithic Revolution", everyone is driven to associate them with a global reorganisation of human cognition and behaviour. For the first time, a human species is able to show, in a systematic and no longer episodic way, the complete and unprecedented package of intellectual modernity (KLEIN and EDGAR 2002) . Around 45 to 40K ago (K signifies up to 1000 years), as well as being anatomically modern we developed a modern mind and the ability to exercise symbolic and abstract thought: extraordinary cave paintings, enlivened by realistic hunting scenes, symbolic and stylized figures; exquisite works of art carved in bone; sophisticated ritual burials; body ornaments, jewels and embellishments; the first musical instruments, new technology for stone workinginitially Aurignacian and then rapidly diversifying according to distinct regional cultures; and the construction of more complex shelters, even in open spaces (TATTERSALL 1999) . A new species is in action: one imagining itself, asking questions about the surrounding nature and its patterns: seasons, tides, moon cycles, and plant and animal yearly rhythms. Except for a few sporadic hints there are no comparable explosions of creativity in the other four species that lived at the same time as Homo sapiens. As Tattersall pointed out, it is as if we had learnt to imagine possible worlds inside our heads, instead of passively accepting the harshness of nature as it was (TATTERSALL 2009a) . A new modern human mind was born, ready to explore new paths, such as art, music and dance, using artefacts and behaviours as marks or signs of something else (in this sense here we intend the blurred term "symbolic") (ACZEL 2009). Splendid Homo sapiens burials discovered in Sunghir, dated to 30-28K ago, display all the creativity of the Palaeolithic revolution and the first sharing of beliefs. An unprecedented form of human intelligence is able to devote long hours to make objects of beauty that had no immediate practical purposes for survival, but which had become part of the symbolic life of the Homo sapiens society. The double birth of Homo sapiens Who were the humans that were able to do all that? What evolutionary novelty triggered this behavioural change? Was it a punctuated global innovation or the culmination of a slow evolutionary trend? Here we are going to present a model that could make this question old-fashioned. One of the most interesting unanswered questions of our evolution is the time mismatch between the appearance of Homo sapiens species and the cognitive abilities of its members. Why was the Palaeolithic Revolution so late, at least in its more systematic version? The time gap is possibly just an illusion due to a lack of evidence or to long periods during the Glaciations when the human population shrunk in numbers. Other experts believe our species always had the physical and cerebral potential to display such behaviour from the onset, but that for reasons due to changes and previous adaptive needs a trigger was needed to release these resources. This process of "functional coopting" is known by evolutionists as exaptation, whereby a structure evolved for a certain function (pre-adaptation) or as a side-effect of others (spandrel) is then reused for new functions in subsequent contexts (GOULD and LEWONTIN 1979; GOULD and VRBA 1982; PIEVANI 2003; PIEVANI and SERRELLI 2011) . Considering recent data from different disciplines like molecular biology and palaeontology -handled as pieces of a puzzle and elements of a model intended as an inference towards the best explanation -here we are explore the possibility that the development of a fully articulated language favoured the key cultural innovations which in turn pushed the last population wave of Homo sapiens out of Africa about 60 to 50K ago. So, there could be a causal correlation between the evolution of the specific language of Homo sapiens, the symbolic behaviour and the geographical globalisation of human populations (CAVALLI SOFRZA and PIEVANI 2012). Human biogeography could be the hidden side of a story that still needs to be completely disclosed by science. Let us start from the beginning of our species. Eight thousand generations ago (about 200K ago) the first Homo sapiens made their appearance in sub-Saharan Africa, during the umpteenth dry phase which coincided with the last Quaternary Ice Age. It was a small population with some identifying traits such as a tall and slim build, large skull and cranial capacity (exceeding 1400 cc), good stone working skills and different modulation of gene expression regulating our extended growth and RIFL (2012) SFL: 203-216
doi:10.1007/978-1-137-05296-4_5 fatcat:6ijpv6hghfe4lcnljlkxfpyw5u