Genetic studies say humans are still evolving: dementia is obese or eliminated by natural selection.

Original title: Genetic Research Says Humans Are Still Evolving: Obesity or Natural Selection
September 9
A large study analyzing the genomes of 210,000 people in the UK and the US has found that a range of diseases are being "eliminated" from the human gene pool through natural selection processes.
Researchers have found that genetic variants associated with Alzheimer's disease and heavy tobacco addiction are less common in people who live longer, suggesting that natural selection processes are phasing out adverse mutations in both countries, the Daily Mail of London reported on September 6.
researchers also found that groups of genetic variants that make people susceptible to heart disease, high cholesterol, obesity or asthma are also less likely to occur in people who live longer, and whose genes are more likely to be passed on to the next generation and spread through the population.
"It's a subtle signal, and we've found genetic evidence that the natural selection process is happening in modern humans," said Joseph Pickerer, an evolutionary geneticist at the New York Genomics Research Center and one of the study's authors. The
revolution has allowed biologists to see for themselves how natural selection actually occurs by mapping the genes of hundreds of thousands of people they can compare.
by tracking the relative "rise and fall" of specific variants over generations, the researchers were able to infer which traits were spreading and which were decaying.
the study, researchers analyzed the genomes of 60,000 European-Americans using data from Kaiser Permante, California, and 150,000 Britons through the British Biomedical Library.
to compensate for the relative lack of data on older people in the UK biomedical library, the researchers used the age at which the participants' parents died as an alternative indicator when exploring the impact of specific mutations on longevity.
two variations with a wide range of influences stand out.
researchers found that the ApoE4 gene associated with Alzheimer's disease appeared less frequently in women over the age of 70, and previous studies have shown that women who carry one or two copies of the gene tend to die earlier than those who do not.
researchers also found a similar downward trend in the frequency with which a variant of the CHRNA3 gene associated with heavy smoking addiction in men appeared in middle-aged and older adults.
when a genetic mutation that provides a survival advantage appears, new beneficial traits evolve. Although it may take a long time to evolve complex traits such as upright walking, evolution itself occurs in every generation as adaptations become more frequent.