However, a phobia is an irrational fear as opposed to a rational fear.By ensuring that their surroundings were free from spiders, arachnophobes would have had a reduced risk of being bitten in ancestral environments, giving them a slight advantage over non-arachnophobes in terms of survival. However, having a disproportionate fear of spiders in comparison to other, potentially dangerous creatures present during Homo sapiens environment of evolutionary adaptiveness may have had drawbacks.In The Handbook of the Emotions (1993), psychologist Arne Öhman studied pairing an unconditioned stimulus with evolutionarily-relevant fear-response neutral stimuli (snakes and spiders) versus evolutionarily-irrelevant fear-response neutral stimuli (mushrooms, flowers, physical representation of polyhedra, firearms, and electrical outlets) on human subjects and found that ophidiophobia (fear of snakes) and arachnophobia required only one pairing to develop a conditioned response while mycophobia, anthophobia, phobias of physical representations of polyhedra, firearms, and electrical outlets required multiple pairings and went extinct without continued conditioning while the conditioned ophidiophobia and arachnophobia were permanent.Psychiatrist Randolph M. Nesse notes that while conditioned fear responses to evolutionarily novel dangerous objects such as electrical outlets is possible, the conditioning is slower because such cues have no prewired connection to fear, noting further that despite the emphasis of the risks of speeding and drunk driving in drivers education, it alone does not provide reliable protection against traffic collisions and that nearly one-quarter of all deaths in 2014 of people aged 15 to 24 in the United States were in traffic collisions.
Lethal arthrogryposis with anterior horn cell disease (LAAHD)  is an autosomal recessive genetic disorder characterized by reduced mobility of the foetus and early death. Presentation
LAAHD resembles LCCS1 disease but the phenotype is milder, with survival beyond 32nd gestational week. However, the foetuses are often stillborn or survive only few minutes. The movements of the foetus during pregnancy are scanty and stiff, often only in upper limbs. The malpositions are distal. The inwards spiral and especially the elbow contractures are less severe than in LCCS1 disease. Some patients have intrauterine long bone fractures. Skeletal muscles are affected and show neurogenic atrophy. The size and shape of spinal cord at different levels are normal but anterior horn motoneurons are diminished in number and degenerated. Molecular genetics
LAAHD disease results from compound heterozygosity of GLE1FinMajor and a missense point mutation in exon 13 (6 cases in 3 families) or a missense mutation in exon 16 ( seven cases in 3 families). One of the latter cases survived 12 weeks, mostly under artificial respiration. Diagnosis
Treatment
Epidemiology
LAAHD is one of approximately 40 Finnish heritage diseases. Families affected by these diseases come from different parts of Finland, and birthplaces of the ancestors of affected individuals do not show geographic clustering. References


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