Why is almost everyone right-handed? A new study connects it to bipedalism

Study’s Claims and Limits

• Paper is read largely as explaining when/how strong handedness emerged, not why right dominates.
• Main claim: across primates, degree of handedness strength correlates with bipedalism; handedness direction correlates with brain size.
• One commenter emphasizes two separate traits:
  • Strength of preference ≈ linked to bipedalism.
  • Direction (right vs left) ≈ linked to brain expansion.
• Several readers complain the press and title oversell “why” right-handedness exists; the paper doesn’t really answer that.
• Statistical approach draws skepticism: adding variables until humans are no longer outliers is compared to finding a fragile correlation; some call the study “fluff.”

Why Right and Not Left? Competing Hypotheses

• Thread floats many untested ideas: heart/organ asymmetry, venom exposure, infant cradling bias, protection of vital organs with the left arm, coordination with language centers, social standardization for teaching and tool use.
• Others note these are speculative “just-so stories”; no consensus “why right” emerges.

Innate Bias vs Learning and Culture

• Evidence cited that handedness may be observable in utero, but sample sizes are small and timing of fixation is unclear.
• Many accounts of cultural suppression of left-handedness (schools forcing right-handed writing, especially in older generations and some countries).
• Users note that tools, writing direction, and computer mice strongly favor right-hand use, likely reinforcing population-level bias.
• Several personal anecdotes of retraining (mice, instruments, driving, sports) suggest motor skills are highly trainable, though perceived innate preference remains.

Variation: Left, Mixed, Ambidextrous

• Discussion of mixed-handedness and cross-dominance (different hands or feet for different tasks) as common and not pathological.
• One link says ~20% of people are not strictly right-handed; commenters argue that makes it “normal,” not a disorder.
• Some mention correlations of left-handedness with conditions like autism or schizophrenia, but this is treated cautiously and not as determinative.

Brain Lateralization and Methods

• Pop “left-brain logical / right-brain creative” story is called a myth, though commenters accept real hemispheric specializations (e.g., language, face processing).
• Left-handers being excluded from many MRI studies is noted as a serious bias that should temper strong claims about lateralization.

Bipedalism and Causality

• One line of argument: once forelimbs were relieved of locomotion, specialization into “holding” vs “manipulating” roles became advantageous; bipedalism may be effect, not cause.
• Others accept the paper’s framing (bipedalism + big brains → strong handedness) but still find mechanism and directionality of causation unclear.