Abstract

There exists a remarkable correlation between genetic distance as measured by protein or DNA dissimilarity and time of species divergence as inferred from fossil records. This observation has provoked the molecular clock hypothesis. However, data inconsistent with the hypothesis have steadily accumulated in recent years from studies of extant organisms. Here the published DNA and protein sequences from ancient fossil specimens were examined to see if they would support the molecular clock hypothesis. The hypothesis predicts that ancient specimens cannot be genetically more distant to an outgroup than extant sister species are. Also, two distinct ancient specimens cannot be genetically more distant than their extant sister species are. The findings here do not conform to these predictions. Neanderthals are more distant to chimpanzees and gorillas than modern humans are. Dinosaurs are more distant to frogs than extant birds are. Mastodons are more distant to opossums than other placental mammals are. The genetic distance between dinosaurs and mastodons is greater than that between extant birds and mammals. Therefore, while the molecular clock hypothesis is consistent with some data from extant organisms, it has yet to find support from ancient fossils. Far more damaging to the hypothesis than data from extant organisms, which merely question the constancy of mutation rate, the study of ancient fossil organisms here challenges for the first time the fundamental premise of modern evolution theory that genetic distances had always increased with time in the past history of life on Earth.

Highlights

  • Two valid data sets were evident from the early studies of protein homology across different species (Doolittle and Blombaeck, 1964; Fitch and Margoliash, 1967; Margoliash, 1963; Zuckerkandl and Pauling, 1962)

  • Neanderthals are more distant to chimpanzees than modern humans are Neanderthals are a group of extinct hominids that inhabited Europe and western

  • Analysis of molecular genetic variation in the mitochondrial and nuclear genomes of living human populations have generally supported the view that Neanderthals were completely replaced by modern humans without contributing any genes (Armour et al, 1996; Hammer et al, 1998; Stringer and Andrews, 1988; Tishkoff et al, 1996; Vigilant et al, 1991)

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Summary

Introduction

Two valid data sets were evident from the early studies of protein homology across different species (Doolittle and Blombaeck, 1964; Fitch and Margoliash, 1967; Margoliash, 1963; Zuckerkandl and Pauling, 1962). The genetic equidistance phenomenon suggests that, if Neanderthals were alive today, they and living modern human would be distant to the outgroup chimpanzees. The molecular clock hypothesis predicts that ancient Neanderthals of 40,000-100,000 years ago cannot be more distant to chimpanzees than extant humans are.

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