common members order contains nearly species insect parasites living externally warm hosts include species bird bats diseases live hairs feathers host feed skin debris pierce host skin feed blood usually spend life single host eggs known hairs feathers eggs hatch times fully grown process takes weeks humans host species head body body smallest known insect model organism subject research human society middle ages appear songs novels wake commonly feature psychiatric disorder early subjects appearing book classification order clearly grouping united members number derived features including warm combination abdominal form single ventral nerve junction order traditionally divided recent classifications suggest recognized occurring mammals exclusively parasites elephants family mammals primitive widespread birds live south american australian mammals nearly species identified parasitic birds mammals present continent habitats host animals birds occupy found carry species genera description small insects ranging length narrow heads oval flattened bodies compound eyes reduced size absent antennae short segments mouth parts retractable head adapted piercing pump start gut powered muscles attached inside cuticle head consist toothed set arranged cylinder inside canal food canal segments fused abdominal segments separate single large tip legs flattened slightly larger ranging length similar form head wider species compound eyes adapted antennae segments slender club shaped legs short robust terminated claws specific single species host evolved usually coloured match fur feathers host biology divided groups obtain feeding body host feeding skin fragments feathers hair debris found host body found specific types animals cases particular body animals known host different species typical mammals birds example humans different species inhabit hair generally survive long removed host species house bacteria bodies assist insect deprived die host dies use ride fly attempt find new host color varies pale dark gray feeding blood considerably darker female usually common males species young developing eggs egg commonly called attach eggs hosts hair specialized hair bond difficult specialized products inhabiting birds simply leave eggs parts body inaccessible interior feather shafts living eggs tend pale whitish dead eggs born miniature versions adult known young times reaching final adult form usually month hatching ecology average number host tends higher large bodied bird species small ones distribution bird individuals live birds birds relatively free pattern pronounced territorial colonial social bird species host organisms dive water feed aquatic prey harbor fewer taxa bird taxa capable stronger defense stronger cell immune response larger harbor taxa reductions size host populations cause long lasting reduction taxonomic example birds introduced new_zealand host fewer species europe sex balanced social hosts female biased social hosts presumably stronger isolation living separate birds case extinction species results extinction host specific host switching random event rarely likely successful occurred evolutionary time scales successfully accomplished reduce host life heavy little effect host habit dust bathing domestic probably attempt birds rid transmit diseases parasites individuals spend life cycle single host able transfer new host reduce effect plumage heavily infested birds lose heat disadvantage context sexual rivalry human body time smallest insect known transmit certain diseases human head closely related simple life history small pair ideal model organisms study molecular mechanisms transmission cases borne fever transmitted locals reported italy interaction humans humans host different kinds head body controlled subject significant dna research 2000s led discoveries human evolution species human belong genera head body human head body genus share common ancestor genus share common ancestor phylogenetic analysis reed sister taxa words genera descended common ancestor age divergence common ancestor estimated million years ago matches age predicted divergence parasites rely hosts host parasite events likely example genetic evidence suggests human ancestors acquired approximately million years ago unlike genus divergence match age host divergence likely occurred million years ago reed propose species host switch million years ago difficult determine parasite host switch occurred evolutionary history explanation containing fewest evolutionary changes additionally dna differences head body provide evidence humans clothing years ago leaving africa human head body occupy distinct ecological zones head live feed body live clothing feed body body require clothing survive divergence head body common ancestor provides estimate date introduction clothing human evolutionary history mitochondrial human species body head fragmented number seven million years ago analysis mitochondrial dna human body hair reveals greater genetic diversity existed african non african human shed light human migratory patterns pre history dominating theory human migration africa hypothesis genetic diversity time occur relatively constant rate genetic diversity african human hosts existed africa modern history associated human society history middle ages essentially death archbishop_of_canterbury recorded boiled like water burst alternate laughing treatment pork lead book descriptions minute bodies glasses observations inquiries illustrated human drawn seen early microscope satirical description new world called men investigating nature trying weigh air like real scientist harvard medical researcher wrote book rats history showing body head transmit humans despite modern view body transmit disease soldiers trenches world war suffered severely carried germans boasted effective control suffered badly second world war eastern especially grim jews concentration camps nazi regime psychiatric disorder patients express persistent fear animals imagining continually infested complaining false belief live organisms present skin literature folklore book character infested bats song southern tribe story love eggs sealed basket woven mother gives instructing open reaches home hearing voices coming opens basket people world human beings pour directions irish songwriter wrote popular song house song contains lines went stairs light sure minutes fight bugs collected march stomach formed great arch recorded double dedicated poem inspired witnessing lady church ugly saint dare set fit fine lady seek dinner poor body mentioned biblical plague visited frogs flies palace fill intrusion filled land recorded scottish bed repay shakespeare compares brother ask care
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