19.9 Dating the Navigators’ Line
339
Tu-te-rangi-marama to undertake major voyages of exploration in search of lands
for his people to colonize, or whether he sought to exploit an El Niño northerly to
speed his voyage or New Zealand, or whether he sought to do both, the Huguang
Maar proxy data shows that in 360 BC he had a possible motivation and strong El
Niño support for his voyaging.
Correlating genealogical estimates with climate proxy dates for these three navigators has utilized a chain of deductions in order to make use of joint information
relating to the various voyages. However, not all intervening steps are necessary for
subsequent conclusions. For example, Maui can be dated without reference to our
conclusion about Irapanga. Given a date of AD 689 for Ui-te-Rangiora and given
that Maui preceded him by 23 generations, we arrive at a point estimate for Maui of
AD 78 with a standard error of 68 years, and the AD 100 dating based on Ambrym
stands as before.
Genealogical estimates and climate data proxy estimates link the voyages of
Irapanga, Maui and Tu-te-rangi-marama to rare and extreme climate events. This
continues a pattern that is now observable for the span of Pacific voyaging history
so far considered for which we have genealogical data: from the main Rarotongan
line, that is, the 1,400-year span from Tu-te-rangi-marama to the southern migrations to Hawaii in 1096. Over this span major oceanic migrations and significant
voyaging activity can be correlated with rare extreme climate events. That such correlations persistently occur, though extreme climate events recorded in both the El
Niño low Nile flood proxy data and in the Huguang Maar data are rare, supports the
significance of the pattern.
In the next section we extend our analysis to cover the active voyaging period of
the Medieval Climatic Optimum.
19.9 Dating the Navigators’ Line
All evidence we have supports the consonance of the Heke lines with the main
Rarotongan line. We noted in Chapter 18 the genealogical (and therefore genetic)
links of some Heke migrants to the main Rarotongan line. Our analysis in Chapter
18 of 48 Heke lines with common end-points enabled us to establish a 25.5 year
mean generation length with a 14.2 year standard deviation. It is not possible working from a single line to achieve such statistical clarity and certainty. Analysis of the
48 Heke lines involved a database of 1,540 generations. The main Rarotongan line
has only 93 generations. We have therefore used the statistically derived mean generation length of 25.5 with a 14.2 year standard deviation (as opposed to a simple
average of 25.2) for the main Rarotongan line as a more refined and therefore likely
estimate for the mean generation length of this related line.
Working backwards from the eclipse of 1383 we can use this generation length
to create an approximate maximum likelihood chronology for the navigators in the
main Rarotongan line from Kuhukura to Paikea – the segment that we have called
the Navigators’ Line.
339
Tu-te-rangi-marama to undertake major voyages of exploration in search of lands
for his people to colonize, or whether he sought to exploit an El Niño northerly to
speed his voyage or New Zealand, or whether he sought to do both, the Huguang
Maar proxy data shows that in 360 BC he had a possible motivation and strong El
Niño support for his voyaging.
Correlating genealogical estimates with climate proxy dates for these three navigators has utilized a chain of deductions in order to make use of joint information
relating to the various voyages. However, not all intervening steps are necessary for
subsequent conclusions. For example, Maui can be dated without reference to our
conclusion about Irapanga. Given a date of AD 689 for Ui-te-Rangiora and given
that Maui preceded him by 23 generations, we arrive at a point estimate for Maui of
AD 78 with a standard error of 68 years, and the AD 100 dating based on Ambrym
stands as before.
Genealogical estimates and climate data proxy estimates link the voyages of
Irapanga, Maui and Tu-te-rangi-marama to rare and extreme climate events. This
continues a pattern that is now observable for the span of Pacific voyaging history
so far considered for which we have genealogical data: from the main Rarotongan
line, that is, the 1,400-year span from Tu-te-rangi-marama to the southern migrations to Hawaii in 1096. Over this span major oceanic migrations and significant
voyaging activity can be correlated with rare extreme climate events. That such correlations persistently occur, though extreme climate events recorded in both the El
Niño low Nile flood proxy data and in the Huguang Maar data are rare, supports the
significance of the pattern.
In the next section we extend our analysis to cover the active voyaging period of
the Medieval Climatic Optimum.
19.9 Dating the Navigators’ Line
All evidence we have supports the consonance of the Heke lines with the main
Rarotongan line. We noted in Chapter 18 the genealogical (and therefore genetic)
links of some Heke migrants to the main Rarotongan line. Our analysis in Chapter
18 of 48 Heke lines with common end-points enabled us to establish a 25.5 year
mean generation length with a 14.2 year standard deviation. It is not possible working from a single line to achieve such statistical clarity and certainty. Analysis of the
48 Heke lines involved a database of 1,540 generations. The main Rarotongan line
has only 93 generations. We have therefore used the statistically derived mean generation length of 25.5 with a 14.2 year standard deviation (as opposed to a simple
average of 25.2) for the main Rarotongan line as a more refined and therefore likely
estimate for the mean generation length of this related line.
Working backwards from the eclipse of 1383 we can use this generation length
to create an approximate maximum likelihood chronology for the navigators in the
main Rarotongan line from Kuhukura to Paikea – the segment that we have called
the Navigators’ Line.