Building complex brains - Missing pieces in an evolutionary puzzle

Hanna Jaaro, Mike Fainzilber

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The mechanisms underlying evolution of complex nervous systems are not well understood. In recent years there have been a number of attempts to correlate specific gene families or evolutionary processes with increased brain complexity in the vertebrate lineage. Candidates for evocation of complexity include genes involved in regulating brain size, such as neurotrophic factors or microcephaly-related genes; or wider evolutionary processes, such as accelerated evolution of brain-expressed genes or enhanced RNA splicing or editing events in primates. An inherent weakness of these studies is that they are correlative by nature, and almost exclusively focused on the mammalian and specifically the primate lineage. Another problem with genomic analyses is that it is difficult to identify functionally similar yet non-homologous molecules such as different families of cysteine-rich neurotrophic factors in different phyla. As long as comprehensive experimental studies of these questions are not feasible, additional perspectives for evolutionary and genomic studies will be very helpful. Cephalopod mollusks represent the most complex nervous systems outside the vertebrate lineage, thus we suggest that genome sequencing of different mollusk models will provide useful insights into the evolution of complex brains.

Original languageEnglish (US)
Pages (from-to)191-195
Number of pages5
JournalBrain, behavior and evolution
Issue number3
StatePublished - Aug 1 2006
Externally publishedYes


  • Accelerated evolution
  • Brain size
  • Cephalopod
  • Complexity
  • Microcephaly
  • Mollusk
  • Neurotrophic factor

ASJC Scopus subject areas

  • Developmental Neuroscience
  • Behavioral Neuroscience


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