When is an embryo a person?

Transcription

1 AKC Autumn 2008 Lecture 2 When is an embryo a person? roger.morris@kcl.ac.uk Head, School of Biomedical & Health Sciences

2 In essence Human mental and social development occurs postnatally in critical periods Failure to provide the appropriate maternal/social interactions during these critical periods leads to defective development that cannot be recovered Such deprivation is not uncommon in our society

3 When a life begins?

4 Brain development in utero

5 Experience driven brain development Pre-mammals, neurons are produced in amounts to match their source (external sense organs) Mammals, particularly their cortices, come with excess neurons, than connect with up to 10x more other neurons than they will in the adult. Post-natal experience then re-inforces useful connections/neurons, which remain. The rest wither.

6 Critical periods Hamster: ability to locate the source of sound in space Requires both sight and hearing to function Between the postnatal days If normal sight/hearing is blocked during this time, the adult hamster can never learn to locate a sound

7 Grammar in human language The human brain is hard-wired to order speech within grammar This ability functions between birth and early teens Languages created by late teens/adults lack grammar Steven Pinker, The Language Instinct (or Noam Chomsky s non-political writing)

8 Grammar makes a difference Morris lecture AKC 9 th October 2008 (pidgin English, Nicaraguan sign language v1) Could Morris give an AKC lecture on the 9 th October, If Morris can give an AKC lecture on 9 th October 2008, will he, and should he? Were Morris to give an AKC lecture on 9 th Oct 2008, will its content relate to any other lectures given before or after his?

9 Critical postnatal periods of human development Grammar is complex human behaviour that we possess instinctively, and only reflect upon when using it for artefactual behaviour such as writing It is hard-wired, and has a typical critical period So, what other instinctive, complex human behaviour is hard-wired?

10 Fetal Alcohol Syndrome During pregnancy, there is no safe lower limit of alcohol, no safe period sustained high levels of alcohol intake causes fetal death. Consumption greater than 1 glass of wine per day during pregnancy produces recognizable FAS, 10% lower mental ability and recognizable physical changes. Higher alcohol intake increases the damage to affect personality, social and ethical awareness. Adults lack impulse control and have trouble understanding the consequences of their behaviour. "They break things, and they yell and they scream and they swear, and they're hyper-sexual. Assaults, sure, phones being thrown, lots of property destruction. Around 60% of adults spend time in goal; punishment is ineffective.

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12 Hard-wired moral instincts Frontal cortex above the eyes provides impulse-control, awareness of the consequences of our acts that holds back from extreme behaviour. Awareness of the consequences of our actions, the social implications of cause and effect, is also vital if punishment is to deter, and in normal social interactions.

13 Romanian Orphans Normal human interactions with babies during their first few years are essential for their mental, and hence social and physical, development. Factory-produced babies (US orphanages in the 30 s, Romania under Ceausescu) and neglected babies (mothers are heroin addicts, or FAS affected) lack these interactions and are permanently affected.

14 Romanian Orphans brain activity US-adopted Romanian orphans, age ~8 yr old, show mild neurocognitive impairment, impulsivity, and attention and social deficits. Their brains show abnormally low metabolic activity in several distinct areas (orbital frontal gyrus, the infralimbic prefrontal cortex, amygdala and head of hippocampus, the lateral temporal cortex and the brain stem). The first two regions are near the eyes cortex; the amydala is the source of much emotional behaviour; lateral temporal cortex also contributes to social/moral instincts; and the control settings for alertness, aggression/ depression/anxiety are within the brain stem.

15 Romanian Orphans emotional intelligence difficulty identifying facial expressions of emotion. significant difficulty matching appropriate facial expressions to happy, sad, and fearful scenarios. postinstitutionalized children performed as well as comparison children when asked to identify and match angry facial expressions.

16 Romanian Orphans - stress Postinstitutionalized children showed prolonged elevations in cortisol levels following the mother, but not the stranger, interaction. More severe neglect was associated with the highest basal cortisol levels and the most impaired cortisol regulation following the mother interaction. These results suggest that early social deprivation may contribute to long-term regulatory problems of the stress-responsive system, and that these differences are most evident within the context of ongoing, close interpersonal relationships. Cortisol controls stress responses at multiple levels, from energy regulation to memory.

17 Romanian Orphans - hormones the vasopressin and oxytocin neuropeptide systems, which are critical in the establishment of social bonds and the regulation of emotional behaviors, are affected by early social experience. This is from a readable scientific paper: Proc Natl Acad Sci U S A Nov 22;102 (47): From The Cover: Early experience in humans is associated with changes in neuropeptides critical for regulating social behavior. Alison B Wismer Fries, Toni E Ziegler, Joseph R Kurian, Steve Jacoris, Seth D Pollak

18 Summary Many critical aspects of human development occur postnatally In typical critical periods during which normal social/ environmental interactions must occur If missed, the acquisition of these instinctive ways of reacting to the world cannot be recovered, and have to be learned. Steven Pinker: The Blank Slate. The modern denial of human nature. Allen Lane/Penguin