Limb preferences in non-human vertebrates.

Area of Science:

• Comparative Psychology
• Evolutionary Biology
• Ethology

Background:

• Debate exists on whether population-level limb preference asymmetries are exclusive to humans or widespread in vertebrates.
• Understanding vertebrate lateralization provides insights into evolutionary pathways of behavioral traits.

Purpose of the Study:

• To systematically analyze limb preferences across all non-extinct vertebrate orders using cladographic comparisons.
• To determine if population-level limb asymmetries are a common feature among vertebrates and compare them to human handedness.

Main Methods:

• Systematic analysis of existing studies on limb preferences in 119 non-extinct vertebrate species.
• Application of cladographic comparisons to investigate evolutionary patterns of limb asymmetries.
• Statistical analysis of species exhibiting population-level, individual-level, or no limb preference asymmetries.

Main Results:

• Population-level limb asymmetries were found in 51.26% of studied species, while 16.81% showed individual-level asymmetries, and 31.93% showed none.
• Key taxa like Chondrichtyes, Crocodylia, Atlantogenata, and Palaeognathae research is crucial for understanding the evolution of vertebrate limb preferences.
• Non-human limb preferences are generally less skewed, include more individuals without a preference, are less task-invariant, and more influenced by external factors than human handedness.

Conclusions:

• Population-level limb preference asymmetries are a common feature across the vertebrate lineage.
• While common, vertebrate limb preferences exhibit significant differences from human handedness, particularly in pattern skewness, prevalence of non-preference, task invariance, and external modulation.