Emergence of individuality in genetically identical mice.
Level 5 - mechanism / opinion, no new human data
Preclinical animal research (CEBM Level 5).
PubMed 23661762 · doi:10.1126/science.1235294
What was done
Dense longitudinal activity tracking was performed on 40 inbred (genetically identical) mice co-housed in a single large enriched environment. The authors evaluated changes in territorial exploration over time (measured via cumulative roaming entropy) and correlated these behavioral trajectories with adult hippocampal neurogenesis.
What was found
Exploratory activity diverged over time, leading to increasing behavioral individual differences as the mice aged. Individual variation in cumulative roaming entropy correlated positively with individual differences in adult hippocampal neurogenesis. The abstract reports directional associations but provides no specific correlation coefficients, variance metrics, or p-values.
Why it matters
This demonstrates an animal paradigm where behavioral individuality and structural brain plasticity diverge among genetically identical individuals sharing the same environment, offering a model for nonshared environmental mechanisms.
Limits
The study is restricted to a small cohort of 40 inbred mice in an artificial enriched environment, limiting direct generalizability to human behavioral genetics. The abstract does not establish whether neurogenesis drove the behavioral divergence or resulted from it, and no numerical effect sizes or quantitative data are reported in the text.
Cited by
- supports Genetically identical animals—such as inbred mice, nine-banded armadillo quadruplets, and clonal fish—exhibit emergence of individual behavioral variability even when reared in identical environments, a phenomenon scientists term developmental noise.