|Title||Genomic data support the hominoid slowdown and an Early Oligocene estimate for the hominoidâcercopithecoid divergence|
|Publication Type||Journal Article|
|Year of Publication||2004|
|Authors||Steiper, ME, Young, NM, Sukarna, TY|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Keywords||2010-11-16, divergence, molecular clock, mutation, mutation rate, primates|
Several lines of indirect evidence suggest that hominoids (apes and humans) and cercopithecoids (Old World monkeys) diverged around 23â25 Mya. Importantly, although this range of dates has been used as both an initial assumption and as a confirmation of results in many molecular-clock analyses, it has not been critically assessed on its own merits. In this article we test the robusticity of the 23- to 25-Mya estimate with â150,000 base pairs of orthologous DNA sequence data from two cercopithecoids and two hominoids by using quartet analysis. This method is an improvement over other estimates of the hominoidâcercopithecoid divergence because it incorporates two calibration points, one each within cercopithecoids and hominoids, and tests for a statistically appropriate model of molecular evolution. Most comparisons reject rate constancy in favor of a model incorporating two rates of evolution, supporting the âhominoid slowdownâ hypothesis. By using this model of molecular evolution, the hominoidâcercopithecoid divergence is estimated to range from 29.2 to 34.5 Mya, significantly older than most previous analyses. Hominoidâcercopithecoid divergence dates of 23â25 Mya fall outside of the confidence intervals estimated, suggesting that as much as one-third of ape evolution has not been paleontologically sampled. Identifying stem cercopithecoids or hominoids from this period will be difficult because derived features that define crown catarrhines need not be present in early members of these lineages. More sites that sample primate habitats from the Oligocene of Africa are needed to better understand early ape and Old World monkey evolution.
Genomic data support the hominoid slowdown and an Early Oligocene estimate for the hominoidâcercopithecoid divergence
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