A complexity drain on cells in the evolution of multicellularity.

Area of Science:

• Evolutionary biology
• Cell biology
• Developmental biology

Background:

• A hypothesis suggests that during evolutionary hierarchical transitions, lower-level entities decrease in internal complexity.
• This complexity loss may occur because functions are transferred to higher-level entities, making lower-level parts redundant.
• Selection may favor this reduction for efficiency and economy.

Purpose of the Study:

• To test the hypothesis of complexity reduction at the lower level during hierarchical transitions.
• To investigate if free-living eukaryotic cells (protists) exhibit greater internal complexity than cells within multicellular organisms (metazoans and land plants).

Main Methods:

• Comparative analysis of the number of "part types" within cells.
• Examining free-living protists as single-celled entities.
• Examining cells from metazoans (animals) and land plants as components of higher-level entities.

Main Results:

• A significant difference in the number of part types was observed between the compared cell types.
• Cells within multicellular organisms showed a reduction in internal part types compared to free-living protists.
• The findings are consistent with the proposed hypothesis of complexity drain.

Conclusions:

• The study provides evidence supporting the hypothesis that evolutionary hierarchical transitions lead to a loss of internal complexity at lower levels.
• The cell level serves as a valid testing ground for this hypothesis.
• Further investigation at other hierarchical levels is warranted to confirm the generality of this evolutionary trend.