How hu­mans are still evolv­ing

The Week (US) - - 20 News -

Hu­man evo­lu­tion is of­ten thought of as a process that ended mil­len­nia ago, when our ape-like an­ces­tors mor­phed into Homo sapi­ens. But a new study has found that the process of nat­u­ral se­lec­tion con­tin­ues, grad­u­ally weed­ing out life-short­en­ing traits in mod­ern hu­mans, in­clud­ing genes that pre­dis­pose peo­ple to heart dis­ease, Alzheimer’s, and heavy smok­ing. Ge­neti­cists ex­am­ined the genomes of 210,000 peo­ple of Euro­pean de­scent in search of mu­ta­tions as­so­ci­ated with greater or lesser longevity. Nat­u­ral se­lec­tion—a ba­sic mech­a­nism of Dar­win’s the­ory of evo­lu­tion—is based on the prin­ci­ple that or­gan­isms best suited to their en­vi­ron­ments tend to sur­vive longer, mak­ing it more likely that they’ll pass their genes on to fu­ture gen­er­a­tions.The re­searchers found that the ApoE4 gene linked to Alzheimer’s is be­com­ing less com­mon, par­tic­u­larly among women. A gene mu­ta­tion as­so­ci­ated with a strong ad­dic­tion to cig­a­rette smok­ing in men is also on the de­cline, re­ports. “It may be that men who don’t carry these harm­ful mu­ta­tions can have more chil­dren, or that men and women who live longer can help with their grand­chil­dren, im­prov­ing their chance of sur­vival,” says the study’s co-au­thor, Molly Prze­worski. The anal­y­sis also re­veals that ge­netic vari­ants linked to heart dis­ease, asthma, obe­sity, and high choles­terol all ap­pear less fre­quently in peo­ple who live longer—an in­di­ca­tion that hu­mans may con­tinue to adapt to a con­stantly chang­ing en­vi­ron­ment.

Still climb­ing the lad­der of nat­u­ral se­lec­tion

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