In the Light of Evolution Volume IV: The Human Condition (2010) / Chapter Skim
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3 Phylogenomic Evidence of Adaptive Evolution in the Ancestry of Humans-Morris Goodman and Kirstin N. Sterner
3 Phylogenomic Evidence of Adaptive Evolution in the Ancestry of Humans-Morris Goodman and Kirstin N. Sterner
Pages 47-62
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From page 47... ...
in Charles Darwin's tree model for life's evolution, natural selection adaptively modifies newly arisen species as they branch apart from their common ancestor. in accord with this Darwinian concept, the phyloge nomic approach to elucidating adaptive evolution in genes and genomes in the ancestry of modern humans requires a well-supported and well sampled phylogeny that accurately places humans and other primates and mammals with respect to one another.
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From page 48... ...
viewing the ancestries of many mammals, not just the ancestry of modern humans, could provide examples of convergent adaptive evolution, which may point to specific categories of genetic changes that are associated with important phenotypic changes. This phylogenomic approach could help identify the positively selected genetic changes that shaped such distinctive modern human features as prolonged prenatal and postnatal development, lengthened life spans, strong social bonds, enlarged brains, and high cognitive abilities.
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From page 49... ...
Phylogenomic Evidence of Adaptive Evolution / lowing five passages encapsulate for us Darwin's thinking about the place of humans in primate phylogeny and about the uniqueness of modern humans. if the anthropomorphous apes be admitted to form a natural subgroup, then as man agrees with them, not only in all those characters which he possesses in common with the whole Catarhine group, but in other peculiar characters, such as the absence of a tail and of callosities, and in general appearance, we may infer that some ancient member of the anthropomorphous subgroup gave birth to man.
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From page 50... ...
Molecular evidence inferred from proteins and DnA data generated during the past 50 years have vindicated Darwin's foresightedness and have decisively established that among living species, modern humans have their closest kinship to common and bonobo chimpanzees. USE OF MOLECULAR METHODS TO INFER OUR PLACE IN NATURE More than 100 years ago, nuttall (1904)
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From page 51... ...
instead, in their proteins, humans, chimpanzees, and gorillas diverged only slightly from one another. The degrees of interspecies antigenic divergence of serum albumin challenged the conventional view that many millions of years of evolution separated modern humans from our nearest nonhuman relatives (sarich and Wilson, 1967a,b)
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From page 52... ...
however, these data suggest that, rather than having a mere subfamily to ourselves, we modern humans should perhaps have no more than a genus or just a subgenus to ourselves; that is, common and bonobo chimpanzees and modern humans would be the only extant members of either subtribe hominina or genus Homo (Goodman, 1996; Goodman et al., 1998; Wildman et al., 2003)
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From page 53... ...
The close genetic correspondence of chim panzees to humans and the relative shortness of our evolutionary sepa ration from chimpanzees suggest that most of the adaptive evolution that produced the distinctive modern human phenotype had already Microcebus murinus (mouse lemur) + Otolemur garnettii (bushbaby)
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From page 54... ...
PHYLOGENOMIC ASSESSMENT OF HUMAN BRAIN EVOLUTION REVEALS ADAPTIVE EVOLUTION IN MULTIPLE STAGES OF HUMAN ANCESTRY expanded cognitive abilities are hallmarks of modern humans. Why such abilities were selected for in modern humans and in the human lineage, and how they are maintained, is of great interest.
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From page 55... ...
Moreover, there was also positive selection for amino acid replacements in the placental galectins of the common ancestor of anthropoids, of catarrhines, and of humans. This adaptive evolution contributed to distinctive but not unique modern human features such as lengthened gestation and increased brainto-body size ratio.
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From page 56... ...
. This adaptive evolution may have occurred in archaic humans ancestral to both neanderthals and modern humans, an inference drawn from the finding that neanderthal FoXP2 has the same two amino acid replacements that distinguish modern human FoXP2 from the orthologous chimpanzee protein (Krause et al., 2007)
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From page 57... ...
Considering that mitochondria play an essential central role in the aerobic production of energy, it may be inferred that the adaptive evolution of AeM genes improved the molecular machinery that facilitates the functioning of a high-energy-demanding encephalized brain. Phylogenomic analysis of approximately 15,000 human coding sequences confirmed that AeM genes were favored targets of positive selection in the ape stem period of human ancestry (i.e., between 25 Mya
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From page 58... ...
The phylogenomic patterns of adaptive evolution are more similar between elephant and human than between either elephant and tenrec lineages or human and mouse lineages, with adaptively evolved AeM genes being especially well represented in the elephant and human patterns (Fig.
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From page 59... ...
. THE HUMAN BRAIN, DIFFERENT BY DEGREE AND NOT KIND Darwin's insight that the modern human mind does not differ in kind but rather in degree from other mammalian minds, in our opinion, should serve as the main guidepost for pursuing a phylogenomic search for the genetic roots of the modern human mind.
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From page 60... ...
Parallel or convergent patterns of adaptive genetic evolution among these species might help elucidate mechanisms contributing to enhanced brain plasticity in modern humans during childhood when the capacity for learning is greatest. nevertheless, the search for genetic correlates of distinctive human phenotypic features should explore the possibility that some molecular aspects of modern human brain plasticity might be uniquely human.
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From page 61... ...
Phylogenomic Evidence of Adaptive Evolution / ACKNOWLEDGMENTS We thank Derek Wildman and larry Grossman for insightful discussion. This study was supported by national science Foundation Grants BCs0550209 and BCs0827546.
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