New evidence from a study entitled Prenatal development of neonatal vocalizations focuses on the early vocalizations produced by human and non-human primates. The study zeroes in on those sounds made immediately upon their birth. Like human babies, newborn monkeys “cry and coo to get their caregiver’s attention.” [i]

It has since been a mystery how these vocalizations and rhythmical sounds are developed. Research indicates that the orofacial movements required to produce vocalizations “have distinct spatiotemporal signatures.” Using ultrasound imaging, researchers sampled “fetal head and orofacial movements in marmoset monkeys.” [i]

The results indicated that the orofacial movements “necessary for producing rhythmical vocalizations differentiate from a larger movement pattern that includes the entire head.” The results further indicate that the development of these orofacial movements is necessary for vocalizing to occur prenatally, even lacking sound production. [ii]

Researchers found that marmoset monkey fetuses “began making cry-like facial expressions nearly two months before birth.” These expressions were separated from other mouth movements known to be performed by babies in utero. The face shapes documented in vitro matched “the face shapes made after birth when the infants begin calling out to their parents.” [iii]

Because the expressions consistently appeared in pattern and duration, “researchers had strong confidence they were practice cries, even though the animals weren’t yet capable of making sound.” The video below shows footage of the fetus in utero and the marmoset after birth. [iv]

Like humans, marmoset monkeys raise their offspring together as couples, unlike many other primates. Similarly, like human infants, marmoset babies are nearly helpless upon birth. Researchers have stated that this information will help highlight the moment speech development begins. By studying pre-birth, researchers are hopeful that findings “may help identify speech or motor development problems earlier.” [v]

References

[i] Darshana Narayanan, Daniel Takahashi, Lauren Kelly, Sabina Hlavaty, Junzhou Huang, Asif Ghazanfar, Prenatal development of neonatal vocalizations, (Jul. 26, 2022)

[ii] Id.

[iii] Joel Sartore, Babies may practice crying months before they’re born, (Aug. 26, 2022)

[iv] Amanda James, Do Babies Learn to Cry Before They’re Born? (Aug. 30, 2022)

[v] Id.