Arguments for invariance

All individuals and all societies have a similar facial grammar. Everyone smiles the same, and the way we use our eyes to convey cognition or flirtatiousness is the same. Heterosexual females find male faces that are rated more masculine and aggressive, less feminine and sensitive, more attractive during ovulation, the stage of their menstrual cycle when women are most fertile.

No success has ever been scientifically demonstrated in re-assigning an individual's handedness. Although individuals may change their external behavior (picking up scissors with their right hand instead of the left, for instance), their internal inclination never changes. Even people who lose a limb, who physically do not possess the ability to pick up scissors with their left hand, will try to do so if they are "left-handed." The percentage of left-handers in all cultures at all times remains constant (because left-handedness is a recessive trait.[citation needed])

Newborn babies, far too young to have been acculturated to do so, have measurable behaviors such as being more attracted to human faces than other shapes and having a preference for their mother's voice over any other voice.

In his book Human Universals, Donald E. Brown presents his case and identifies approximately 400 specific behaviors that are essentially invariant among all humans.