selection because this human language trait was clearly adaptive. Then, around
130 kya, a group of modern humans, some of whom had Merge/UG and were
leading the group, migrated out of Africa through the southern route, crossing
the Bab al-Mandab Straits, moving to Oman and Jebel Faya of the Arabian Pen-
insula, and fi nally arriving in southern China. Among each group in each place,
language genes spread among members, and as a result Merge/UG became fi xed
among modern humans. These humans replaced indigenous archaic humans in
each area (if any were present). Subsequently, around 50–100 kya, some groups
of humans, all of whom had Merge/UG, left Africa through the northern route
via the Nile Valley, reaching Eurasia. I suppose that they coexisted and interbred
with original linguistic Homo sapiens with Merge/UG in each area. In this way,
Homo sapiens with Merge/UG spread throughout the world. I assume that after
Merge/UG spread and became fi xed among a certain large number of modern
humans and groups and thus a certain large number of people obtained Merge/
UG, the change and evolution of culture, behavior and tools occurred.
Note that this proposal is consistent with the gradual cultural evolution
hypothesis (e.g., McBrearty and Br ooks 2000). It is thus incompatible with the
so-called “Great Leap Forward,” which claims that the emergence of human
language occurred around 50 kya and then triggered vast cultural and behavioral
change/evolution over a short period (Klein 2009b).
5 Conclusion
In this chapter, which provides ample archaeological/paleoanthropological and
genetic evidence from recent studies, I have proposed that the Early Exodus of
humans out of Africa occurred around 130,000 years ago. Based on the simplest
hypothesis on the relationship between the Out-of-Africa migration and the
emergence of human Merge/UG, I have then suggested the hypothesis of an
earlier emergence of the human language faculty, which claims that human Merge/
UG emerged as early as 130,000–150,000 years ago. It is much earlier than has
been widely assumed that modern humans became “truly linguistic humans.”^17
Notes
This is a revised and expanded version of section 4 of Ike-uchi (2014). I would
like to thank Shun-ichiro Inada and Koji Fujita for allowing me to gain access
to some of the papers relevant to this article.
1 Of course, the question is “when did UG fi rst emerge in the brain of one Homo
sapiens in evolutionary history?” One reviewer for Evolang X asserts that this
formulation of the question is “preposterous.” Fundamentally, language is a
matter of the human brain as the internalized knowledge of language. How
could the origins and evolution of human language/UG be otherwise
formulated?
2 Here, I assume that Pirahã also has the operation of recursive Merge, although
it apparently does not have embedded clausal structures. The question of whether
language has a generative procedure such as Merge is completely different from
the question of whether it has embedded structures.
The hypothesis of earlier emergence 193