The DCIDE framework: systematic investigation of evolutionary hypotheses, exemplified with autism

Area of Science:

• Evolutionary psychiatry and psychology
• Genetics, neuroscience, and epidemiology
• Systematic evidence synthesis and analysis

Background:

• Evolutionary explanations for mental disorders face challenges due to heterogeneity and modern environmental influences.
• Previous hypotheses have been criticized as speculative ('just-so stories') due to a lack of systematic evidence integration.
• Existing evidence from genetics, neuroscience, and epidemiology is often not marshalled effectively to test evolutionary hypotheses.

Purpose of the Study:

• To present a novel framework (DCIDE) for systematic evidence synthesis and analysis to investigate evolutionary explanations of psychiatric traits.
• To exemplify the DCIDE framework by systematically reviewing evidence related to evolutionary explanations of autism.
• To provide a robust method for comparing competing evolutionary hypotheses and countering critiques of speculation.

Main Methods:

• The DCIDE framework involves five stages: Description, Categorisation, Integration, Depiction, and Evaluation.
• Categorisation excludes non-adaptive cases using genetic, neuroscientific, and environmental data.
• Integration considers factors like onset, duration, prevalence, sex differences, and correlated traits to refine adaptive explanations.
• Evaluation assesses hypotheses against all available evidence using theoretically motivated principles.

Main Results:

• In the autism review, 20% of cases were categorized as non-adaptive (e.g., due to mutations, trauma).
• Evidence supporting the social niche specialization hypothesis for high 'systemising' cognition in autism was found.
• The intelligence by-product hypothesis for autism was not supported by the evaluated evidence.

Conclusions:

• The DCIDE framework provides a systematic approach to evaluating evolutionary hypotheses for psychiatric conditions.
• The social niche hypothesis offers a more robust evolutionary explanation for autism than the intelligence by-product hypothesis.
• The DCIDE framework can strengthen evolutionary psychology by providing a structured method for evidence analysis and hypothesis testing.