Current archaeological, biological
and linguistic evidence points to a lower Central American
origin for Chibchan speaking populations who are thought to
have continuously occupied the region for the last 10,000
years. However, the biological relationship of these groups
to Chibchan speakers from Northern South America remains largely
unresolved. This thesis examines mitochondrial DNA (mtDNA)
haplogroup and haplotype diversity in three Sierra Nevada
de Santa Marta Chibchan (Kogí, Arsario, Ijka) speaking
populations and one neighboring Arawakan (Wayuú) group
from Northeast Colombia in order to determine: (1) the nature
of the biological relationship between the four study populations,
(2) whether or not a relationship between Central and Northern
South American Chibchan groups exists (3) a potential timeframe
for a Chibchan diaspora, (4) hypothetical models regarding
the initial peopling of the Santa Marta region and (5) the
role of Chibchan populations in the peopling of the Americas.
Amerindian mtDNA haplogroups were characterized for 190 individuals
using RFLP analysis and 61 HVS-I sequences were obtained.
Three of the five founding Amerindian mtDNA haplogroups (A,
B, C, D, and X) were found in these populations. The Kogí
and Arsario exhibited only haplogroups A and C (Kogí
65% A, 35% C, Arsario 68% A, 32% C). The Ijka primarily exhibited
haplogroup A (90%) with a single B (2.5%) individual and small
number of haplogroup C (7.5%) individuals. The Wayuú
contained haplogroups A (34%), B (24%), C (32%), and undetermined
(10%). Haplogroup D was not found in any of the groups examined.
R-matrix analysis demonstrates that the three Santa Marta
Chibchan populations are related to each other but not to
the neighboring Wayuú. Analysis of these three South
America Chibchan populations at the sequence level shows that
they share low mtDNA haplotype diversity, low negative or
positive values for Fu’s Fs and Tajima’s D and
a peak between zero and one unit of mutational time with linguistically
related populations from lower Central America and not with
other indigenous South American groups. Phylogenetic reconstruction
of these populations using median-joining networks indicates
that all Chibchan speaking populations had undergone a bottleneck
and were highly influenced by founder effect at the maternal
level within the last 10,000 years. Using the rho-statistic
of Saillard
et al. (2000) on two clusters of Santa Marta Chibchan
haplotypes gives mtDNA coalescence dates of 8,072 (±4943)
and 6,985 (±3557) both of which are consistent with
other temporal estimates of Chibchan genetic history. This
time depth points to a long term occupation of Chibchan populations
within Northern South America suggesting an in situ
development for the Santa Marta groups.
This study concludes that while there are biological similarities
between the Chibchan speakers from the Sierra Nevada de Santa
Marta and the Panamanian isthmus they diverged in the distant
past. If a Chibchan diaspora occured then it may have been
geographically widespread and early in the peopling of the
Americas. This diaspora may have blocked gene flow from the
north and south leading genetic drift to become the primary
evolutionary force on the South American continent.
