Predictions and Falsifications

"The wrong view of science betrays itself in the craving to be right."

 

                                                          Karl Popper
  • The strength of any scientific theory is its ability to generate testable predictions. These predictions are then compared with established data to determine how consistent theory is with these data. Testability lies at the heart of the scientific enterprise, which is based on unique, specific prediction. In principle, a scientific hypothesis should rule out conceivable possibilities, which is the essence of the Popperian falsifiability criterion (Popper 2002). The model can provide many valid predictions.
Prediction 1: Every species has “Eves” and “Adams”
  • According to the model, every species have Eve or Eves. The “Eve” or ‘Eves” is a single mother, or group of females with very similarly genetically structure, who are the first generation or “seed” of new species. Every species are from the second “Eve”. Laboratory studies of mtDNA could show all sexual species are traced to a single mother or group of female with similar genomic structures.
Evidence
  • In 1987, University of California geneticist Allan Wilson announced the results of a study utilizing mitochondrial DNA as a marker to trace the ancestry of modern humans. They collected and analyzed mtDNA material from 147 women from Africa, Asia, Europe, Australia, and New Guinea. Their findings support the conclusion that “the common ancestor of modem humans lived in Africa, about 200,000 years ago (Cann, Stoneking, Wilson 1987)”.
  • The only way to test the story of mitochondrial Eve was to trace the ancestry by using the Y chromosome to determine if separate lines of evidence also led back to African ancestors, as the human Y chromosome is strictly paternally inherited and, in most of its length, does not recombine during male meiosis. Michael Hammer at the University of Arizona surveyed noncoding region of the Y chromosome in 1544 men worldwide and found the same pattern in Haplotype 1A(Gibbons 1997). 
 Falsification 
  • Similar studies can be performed in other sexual species. If we could confirm multiple origins of geographical locations for any sexual species, it would be catastrophically problematic for the GMCMI model.

Prediction 2: Similar mtDNA sequences among initial members of species
  • As speciation occurs with only a few members randomly, it is almost impossible to identify what the new species is, where and when it formed. There are many newly found species reported each year, some of them are old species, just discovered recently, some of them are newly formed species. By this model, all species had similar mitochondria in females and Y chromosomes in males at the beginning. Statistically, the mitochondrial DNA should be more homologous in the newly found species, comparing with other well known old species.

Evidence

  • Lake Victoria is youngest of the three large lakes in East African, formed about 250, 000 to 750.000 years ago. It contained over 300 endemic cichlids. The mtDNA variation among fish of the Victoria flock was found to be very small as no variation was detected in 363 base pairs of the cytochrome b gene (Johnson and others 1996).

Falsification

  • If lab results show less mtDNA in multiple well-established species than what is present in the newly found species, then the model would have failed.

Prediction 3: Inconsistency of molecular phylogeny

  • Based upon Darwin’s theory, phylogenetic trees should be approximately the same regardless of which molecules are chosen for comparison, whereas by the models, speciation is the outcome of gross mutations by a random process. No specific patterns explain how, why, where the mutations occur, and only few segments of DNA structures could be involved in each event of speciation, leave the rest of genome much less modified. Study genomic structure within same species will show gross irregularities of genes and inconsistence in molecular phylogeny is a rule, not an exception.

Evidence

  • A variety of genes from different organisms demonstrated that their relationships contradicted the evolutionary tree of life derived from rRNA analysis. Different molecules lead to different phylogenetic trees. According to biologist Carl Woese, an early pioneer in constructing rRNA-based phylogenetic trees, “No consistent organismal phylogeny has emerged from the many individual protein phylogenies so far produced. Phylogenetic incongruities can be seen everywhere in the universal tree, from its root to the major branching within and among the various [groups] to the makeup of the primary groupings themselves (Dolittle 2000).

Falsification

  • Many whole genome sequences have become available. By comparing different genes across several species, ones could compare molecular data of phylogenetic trees. These data should show inconsistency in some genes or proteins much more prominent than others should. Consistency among many genes will challenge the model.

References

Cann RL, Stoneking M, Wilson AC. 1987. Mitochondrial DNA and human evolution. Nature 325(609):31-6.

Dolittle FW. 2000. Uprooting the tree of life. Scientific American 282(2):90-5.

Gibbons A. 1997. Y chromosome shows that adam was an african. Science 278(5339):804-5.

Johnson TC, Scholz CA, Talbot MR, Kelts K, Ricketts RD, Ngobi G, Beuning K, Ssemmanda II, McGill JW. 1996. Late pleistocenedesiccation of lake victoria and rapid evolution of cichlid fishes. Science 273(527):1091-3. 

Popper KR. 2002. The logic of scientific discovery. London ; New York: Routledge.

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