ibbica

Depends on what context you're talking about. The most basic definition of 'behavioural problems' includes any actions that occur much more frequently or much less frequently, or with much greater intensity or much less intensity, than is considered 'normal' for a child's age. In this case, the study in the OP used the "inert-fretful infant scale of the GRS" for infants, which "rates the infants’ attention to his environment, level of activity and affective state." For scoring at 12 months, they used the "Child Behavior CheckList (CBCL)" as their measuring stick. It described a child's exhibition of different behaviours; included behaviours are classified as oppositional, aggressive, or overactive. (They used the CBCL "for ages 1½–5 years", though, so there's a bit of additional concern over using a scale that is unverified for the age they were studying.)

I don't think we have a good idea. What sort of information would you need to look for, to figure that out? Where would that information come from? Prehistory means there's no written record, and we don't have too many frozen pregnant prehistoric women. You're left extrapolating from more modern societies that you think might live in conditions similar to whatever prehistoric folks you're talking about (environmental factors can affect this sort of thing fairly easily). And then, even if you think you've accounted for environmental factors, you still need to worry about whether any of the genetics underlying such a process have changed over tens of thousands of years...

It's not that high in sugar, actually; ~3% of the total diet. And feeding straight grain isn't exactly great for cows either... it's done to increase body weight ridiculously quickly, and frankly beef cattle bound for market aren't typically around for long enough to fuss over 'long term effects'. It's also used to increase yield in dairy cattle, so that's where there might be a bit of cause for concern. But again, if the concern is high yield in the short term, you don't typically keep dairy cattle for very long either... There is a bit of protein in corn that's of course higher than in candy (!), but as a protein source other grains are nearly always used rather than corn anyway, as corn is low in protein relative to other grains. (...I feel like I should be sticking a "The More You Know" banner here )

Study here (for those who have access): http://onlinelibrary...12.02583.x/full I'll highlight a few things, for those who can't access the whole article: "In the seat setting, the infant was placed in an infant seat with the parent sitting facing them. For the second setting, the infant was placed on a floor mat on their back with the parent positioned face to face with their infant. For both interactions fathers were instructed to play with the infant in any way they chose without the use of toys or objects, for 3 min." (NB: statistically significant correlations with 12-month-old behaviour were only found in the 'floor' setting) "Father–infant interactions were assessed using the Global Rating Scales (GRS)..., a video-based assessment of the quality of parent-infant interaction. They were developed to assess differences between mothers with and without postnatal depression.... ...Parental behaviour is rated on four dimensions: sensitivity, intrusiveness, remoteness and behaviour relevant to depression (e.g. sad or tense). The videotaped interactions were scored by a trained researcher who had not been involved in the family visit." "We selected maternal sensitivity as the key dimension to control for mother-infant interaction, as it is the domain of mother-infant interaction most consistently and strongly associated with adverse child outcome... This was measured by the sensitivity scale of the GRS during mother-infant interactions." (NB: not the entire GRS) "Infant temperament was measured on the inert-fretful infant scale of the GRS during mother-infant interactions. This scale runs from −2 (withdrawn) to +2 (fretful) and rates the infants' attention to his environment, level of activity and affective state." What I take away from this study is a suggestion that 'more remote' interactions with a parent tend to increase 'behavioural problems' at 12 months. Their analysis suggests that paternal engagement, yes, may play a role, but I'd point out that their analysis does not in fact exclude or account for maternal engagement, or the interaction between the parents (although they do talk about this in their Discussion). Further aspects I'd like to see explored: Are GRS scores (total or separate dimensions) from the father and the mother correlated with each other? How strongly related is each parent's GRS score to the risk of early behavioural problems? Are GRS scores (total or separate dimensions) from two parents who share direct caretaking responsibilities equally or unequally (regardless of which parent is the 'primary caregiver') correlated with each other? And again, how strongly related is each to the risk of early behavioural problems? Can one engaged parent with the infant compensate for a 'disengaged' partner? (e.g. as a function of time spent with each parent, or of the 'engaged' parent putting extra effort into being 'maximally engaged'?) 1. Shriek/screaming alone is not indicative of a behavioural problem. 2. The study does not exclude a contribution of the behaviour of the mother (or "second parent" more generally). It does not demonstrate a specific effect of 'paternal behaviour'.