Cultural differences in milestones have been observed in all developmental areas.
Once 3-year-olds develop a theory of mind (the realization that people think), then this cognitive ability can be combined with language and social skills. One result: Children begin to lie. They understand rules, actions and outcomes, and they may lie to avoid punishment. But there are other reasons they might lie, and it might differ from culture to culture.
For example, one study compared the differences between North American and Chinese children. The North American children indicated they would lie to their coach to protect a teammate who was missing a game to study, even if the team was adversely affected. This could show that, in this society, the individual is highly valued. The study also found that the Chinese children would not lie under those circumstances but would lie if it benefited the team. This may reflect an emphasis on group accountability in Chinese culture [source: Price].
Although a developmental advancement, lying is not generally admired by most parents. Milestones can be distressing, such as stranger anxiety. But could there be an advantage to a strong fear of outsiders? In some parts of the world, adults perceive the presence of any stranger as a potential threat. Living on a secluded Israeli kibbutz, for example, may increase its members' chances of being targeted by terrorists. Adults there can be suspicious of any unknown persons, and, sensing this, their babies may have a dramatically higher level of stranger anxiety [source: Berk].
Children often rely on adult guidance, and this can be reflected by differences in toddlers' language development. A 2-year-old in an English language society will verbalize at least 50 words, but they will be nouns, primarily, because that's what she's hearing from her caregivers: "Here's your bottle," "See the doggie," "Mommy's home!" In contrast, Chinese and Korean youngsters hear more verbs and social phrases from their mothers, so toddlers are reproducing that kind of language [source: Berk].
Language and social development rely on personal interactions, so it's unsurprising that there are cultural differences, because people connect differently depending on where they are from. Physical milestones can also be affected as parents respond to cultural norms.
For example, many Western societies promote putting infants to sleep on their backs to prevent SIDS (Sudden Infant Death Syndrome). These babies may spend comparatively less time on their stomachs and be slower to roll over, crawl and sit up. To counter this, parents are often encouraged to place infants on their stomach during waking hours ("tummy time").
In Mexico, the Zinacanteco people of Mexico delay physical development of their babies because of safety concerns. Toddlers' unrestricted running and walking can be hazardous because they lack the cognitive awareness that will keep them away from open fires.
In Jamaica, many parents encourage some accelerated physical development. By placing babies waist-deep in holes in the ground and supporting the infants' posture with blankets, the parents hasten independent sitting skills [source: Berk].
Monitoring milestones is worldwide, even if there are cultural variations. However, some specialists prefer using other methods to track children's development, as we discover in the next section.