Outline Lecture 16 Parenting 2
1. Discriminative Parental Care
– The basic logic: invest parental investment optimally & avoid wasting it
– parental investment is costly!
-prediction: parental love should have evolved to allocate parental resources optimally
-types of discrimination:
Quality: will this offspring make it?
Need: how much would this offspring benefit from P.I?
Age: are they almost at a “safe” age?
Identity: is this baby mine?
2. Some Bases for Discriminating
- Phenotypic quality: can this offspring convert parental investment into parental fitness gains?
- Need: how much difference will this investment make?
– Age: how close to independence is this child?
– Identity: is the kid really mine? (e.g., paternal uncertainty)
when will organisms recognize own young?
Razorbill does not recognize own eggs/young, will feed offspring in nest
-nest in cliffs: far apart nests. Unlikely mix-ups of young
Guillemot recognizes own offspring, rejects unrelated offspring
-nest in colonies: mix-ups possible of young
-recognizes individual offspring to target parental investment
general point: some species use individual recognition cues for DPS,
others use different cues that are just as effective in species' natural
3. Cinderella Effect: treating genetic children better than step-children
– Introduction, evidence in mistreatment rates, + cross-cultural ubiquity
– could be because step-parents' abuse is more likely to be reported
– homicide per million co-residing parent-child dyads (much higher in step-parent)
– Generalization to other forms of discrimination
– cross cultural: big difference in child homicide rates by step vs. Genetic parents in
Australia, Britain, Canada, USA
– big differences in nonlethal abuse in studies inAustralia, Britain, Canada, Columbia,
– Big difference in child mortality rates inAche hunter-gatherers
– Strong parental sentiments vs. Those of surrogate parents
– prediction: more positive behaviour & less negative behaviour from a biological
parents than from a surrogate (all else equal)
– cinderella story: mistreated step child in many cultures. Inhibition to mistreat your
child because of parental mechanisms.
– Abuse as a “negative assay”
– per 1000 children with genetic parents, and one genetic and one step-parent – abuse much higher in families with one step-parent, especially for young
children (age of 0-2 highest, 3-5 also high)
– Eliminating alternative explanations for the effect