Newborn chicks show inherited variability in early social predispositions for hen-like stimuli

Abstract

Predispositions of newborn vertebrates to preferentially attend to living beings and learn about them are pervasive. Their disturbance (e.g. in neonates at risk for autism), may compromise the proper development of a social brain. The genetic bases of such predispositions are unknown. We use the well-known visual preferences of newly-hatched chicks (Gallus gallus) for the head/neck region of the hen to investigate the presence of segregating variation in the predispositions to approach a stuffed hen vs. a scrambled version of it. We compared the spontaneous preferences of three breeds maintained genetically isolated for at least eighteen years while identically raised. Visually-naïve chicks of all breeds (Padovana, Polverara and Robusta maculata) showed the same initial preference for the predisposed stimulus, suggesting that the direction of the initial preference might be genetically fixed. A few minutes later though, striking differences emerged between breeds, which could indicate different strategies of dealing with affiliative objects: while the Polverara breed maintained a constant preference across the entire test, the Padovana and Robusta breeds progressively explored the alternative stimulus more. We hence documented the presence of inherited genetic variability in the expression of early social predispositions in interaction with environmental stimuli.

A transient time window for early predispositions in newborn chicks

“…Fertilized eggs of three breeds of domestic fowl (Gallus gallus) kept genetically isolated for 20 years in the conservation programme CO.VA 33,34 were obtained from the Agricultural High School "Duca degli Abruzzi", Padova (Italy). Further details on this population, breeds and their early predisposition are available in previous publications 6,35 . Eggs were incubated in darkness at a constant temperature of 37.7 °C, humidity 40% until 3 days before hatching (day 17 of incubation).…”

“…The preference for speed changes has been described as a predisposition to attend to 2 "animacy" cues, the properties associated with living beings 3,4 . Other animacy cues that are attractive for neonates include face-like stimuli [4][5][6][7][8][9] , biological motion 10,11 and self-propulsion 12 . The initial orienting response towards animate objects, in turn, enhances learning and social interactions.…”

“…Imprinting can also modulate predisposed responses 17 . While chicks are a convenient model to investigate early predispositions -because they are a precocial 18 species that can be easily tested in the absence of previous visual experience -human babies show striking similarities in the response to the stimuli preferentially attended and approached by chicks ( 6,(10)(11)(12)(19)(20)(21)(22)(23)(24)(25) ).…”

Embryonic Exposure to Valproic Acid impairs Social Predispositions for Dynamic Cues of Animate Motion in Newly-Hatched Chicks

“…Comparative research on human infants and newly-hatched domestic chicks (Gallus gallus) found striking similarities in the static and dynamic visual cues that attract their attention soon after birth (Di Giorgio et al, 2017). Among static cues, a predisposition to approach a stuffed hen over a scrambled version of the same stimulus has been consistently observed in visually-naïve chicks (Bolhuis and Horn, 1997;Johnson and Horn, 1988;Mayer et al, 2016;Versace et al, 2017). This preferential approach is driven by the configuration of features present in the intact head and neck (Johnson and Horn, 1988).…”

Behavior Variability of a Conditional Gene Knockout Mouse as a Measure of Subtle Phenotypic Trait Expression. The Case of Mouse Executive Function Distortion

“…representing inherited genetic variability (17), and meaning that genetic content is capable to explain (at least partially) an individual's behavioral (in)variability. At the cellular level, neuronal correlated variability for spikes and subjects' performance displays the same relationship as learning and attention (18), perhaps through the affected impulsivity (as shown in this study).…”