ri ents ▁can ▁be ▁met abol ized ▁by ▁distinct ▁met abol ic ▁path ways ▁that ▁are ▁effectively ▁inter change able ▁for ▁certain ▁met abol ites ▁even ▁though ▁the ▁total ▁effects ▁of ▁each ▁path way ▁are ▁not ▁identical . ▁In ▁cancer , ▁ther ap ies ▁target ing ▁the ▁E G F ▁re ceptor ▁are ▁th wart ed ▁by ▁the ▁co - activ ation ▁of ▁alternate ▁re ceptor ▁ty ros ine ▁kin ases ▁( RT K ) ▁that ▁have ▁partial ▁functional ▁overlap ▁with ▁the ▁E G F ▁re ceptor ▁( and ▁are ▁therefore ▁deg ener ate ), ▁but ▁are ▁not ▁target ed ▁by ▁the ▁same ▁specific ▁E G F ▁re ceptor ▁in hib itor . ▁Other ▁examples ▁from ▁various ▁levels ▁of ▁bi ological ▁organization ▁can ▁be ▁found ▁in . ▁ ▁Theory ▁▁ ▁Several ▁theoretical ▁develop ments ▁have ▁out lined ▁links ▁between ▁deg ener acy ▁and ▁important ▁bi ological ▁measurements ▁related ▁to ▁robust ness , ▁complexity , ▁and ▁evol v ability . ▁These ▁include : ▁ ▁The oret ical ▁arguments ▁supported ▁by ▁simulations ▁have ▁proposed ▁that ▁deg ener acy ▁can ▁lead ▁to ▁distributed ▁forms ▁of ▁robust ness ▁in ▁protein ▁interaction ▁networks . ▁Those ▁authors ▁suggest ▁that ▁similar ▁phen omena ▁is ▁likely ▁to ▁arise ▁in ▁other ▁bi ological ▁networks ▁and ▁potentially ▁may ▁contribute ▁to ▁the ▁res ili ence ▁of ▁e cos ystem s ▁as ▁well . ▁ ▁Ton oni ▁et ▁al . ▁have ▁found ▁evidence ▁that ▁deg ener acy ▁is ▁in separ able ▁from ▁the ▁existence ▁of ▁hier arch ical ▁complexity ▁in ▁neural ▁populations . ▁They ▁argue