<prompt> Fingqa isihloko: Wake wazibuza yini ukuthi kungani siba mpunga noma ukuthi kungani izintshebe zabesilisa eziningi zinombala obomvu, obomvu? Noma kungani izinwele eziyigolide zomntwana omncane zivame ukunyamalala ngaphambi kokuba abe neminyaka eyishumi ubudala? Lapha, isazi esivelele, uRodney Sinclair, uProfesa Wezifo Zesikhumba esibhedlela i-Epworth naseNyuvesi yaseMelbourne, uchaza isayensi yombala wezinwele - nokuthi kungani abanye bethu beqalekisiwe ngokuba nokumpunga okuningi kunabanye... Yini enquma umbala wezinwele? Umbala wezinwele ukhiqizwa amangqamuzana aziwa ngokuthi ama-melanocyte, athuthela ekhanda lapho izinwele ziqala ukukhula esibelethweni. Ama-melanocyte akhiqiza i-pigment ehlanganiswa nemicu yezinwele ekhulayo ukuze ikhiqize izinwele ezinemibala ehlukahlukene ngokumangalisayo. Umbala wezinwele uncike ebukhoneni nasezibalweni zamaqembu amabili ama-melanin: ama-eumelanin ama-pigment ansundu namnyama nama-pheomelanin ama-pigment abomvu namthubi. Nakuba ukuhlukahluka kwesilinganiso salezi zinhlayiya kungadala inqwaba yemibala nama-tone, ngokuvamile izingane ezikanye nazo zinombala wezinwele ofana kakhulu. UProfesa Sinclair uthi izici zofuzo zibonakala zibalulekile ekunqumeni ukuthi siba mpunga nini, kunendlela yethu yokuphila. Iningi lethu litholaamabala alo okuqala lapho seliba neminyaka engu - 30 ubudala, ngokuvamile emathuneni, bese kamuva, entanyeni. Ukuthi umbala wezinwele uhluka kanjani ngokwendawo yomzimba. Ngokwesibonelo, ama-eyelashes amnyama kakhulu ngoba anamazinga aphezulu e-eumalanin. Izinwele ze-scalp zivame ukuba mhlophe kunezinwele ze-pubic, ezivame ukuba nombala obomvu, ngenxa yokuba khona kwe-phaeomelanin pigment. Umbala obomvu uvamile nasezinweleni ezisezansi kwezingalo nasezinweleni zesilevu, ngisho nakubantu abanezinwele ezinsundu kakhulu ekhanda. Ama - hormone anjengama - hormone ashukumisa i - melanocyte angenza izinwele ezikhanyayo zibe mnyama, njengoba kunjalo ngamazinga aphakeme e - estrogen ne - progesterone, akhiqizwa ngesikhathi sokukhulelwa. Imithi ethile, njengaleyo evimbela umalaleveva ingenza izinwele zibe mhlophe, kuyilapho eminye imithi yokulwa nesifo sokuwa ingenza zibe mnyama. Kungani ngokuvamile izingane eziyizimpunga ziba mnyama? Izingane ezimpunga zivame ukubona izinwele zazo ziba mnyama lapho zineminyaka eyisikhombisa noma ngaphezulu...  <response>: URodney Sinclair unguprofesa wezifo zesikhumba eNyuvesi yaseMelbourne. Ithi lapho sesineminyaka engu-50, ingxenye yethu isilahlekelwe umbala ezingxenyeni ezingu-50 zenwele. Uthi ukuba mpunga ngaphambi kwesikhathi kungase kube uphawu lwe-anemia noma isifo se-thyroid. Futhi ngokuvamile izinwele ezisesikhaleni zilula kunezinwele ze-pubic, ezivame ukubazibomvu kancane. 