Focus-Science and Technology - - DISCOVERIES -

Many of us like noth­ing more than tuck­ing into a fiery chicken madras or lamb bhuna, but the ma­jor­ity of other an­i­mals do their best to avoid hot, spicy foods such as chill­ies – which is pre­cisely why such plants evolved to be hot and spicy in the first place. How­ever, we’re not en­tirely alone: tree shrews (Tu­paia be­lan­geri chi­nen­sis) will also hap­pily chow down on chilli pep­pers when given the chance. Now, an anal­y­sis of their genome by re­searchers at China’s Kun­ming In­sti­tute of Zoology has explained the se­cret of their tol­er­ance.

Spicy foods de­rive most of their heat from a chem­i­cal called cap­saicin. When eaten, cap­saicin trig­gers the ac­ti­va­tion of TRPV1 – a re­cep­tor chan­nel found on the sur­face of painsen­si­tive cells in the tongue and else­where. TRPV1’s reg­u­lar job is to alert an­i­mals to the pres­ence of po­ten­tially harm­ful heat, which is why we ex­pe­ri­ence a burn­ing sen­sa­tion and of­ten start to per­spire when eat­ing spicy foods.

The team be­gan their study of the tree shrew af­ter they were shocked to see cap­tive an­i­mals hap­pily munch­ing on chilli pep­pers. They dis­cov­ered that a sin­gle mu­ta­tion in the shrews’ TRPV1 gene de­creases their re­cep­tors’ sen­si­tiv­ity to cap­saicin. While chilli pep­pers do not grow within the shrews’ nat­u­ral range, a plant called Piper boehme­ri­ae­folium, which con­tains a sub­stance sim­i­lar to cap­saicin called Cap2, does. It’s there­fore be­lieved that shrews with the mu­ta­tion in ques­tion gained an evo­lu­tion­ary ad­van­tage over those with­out, thanks to their ex­panded diet.

A tree shrew heads off in search of some chilli sauce

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