Biology

Genetic study finds evidence that we're still evolving

A new genetic study has found evidence of evolution at work in the human genome today
A new genetic study has found evidence of evolution at work in the human genome today
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A new genetic study has found evidence of evolution at work in the human genome today
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A new genetic study has found evidence of evolution at work in the human genome today

"If evolution is real, why aren't we still evolving?" That's one of the main arguments against evolution that you might hear people sling around. Evolution is an extremely gradual process that's all but invisible to the casual observer, but if you know where to look, the evidence shows that it is still happening. We've seen it in the rise of antibiotic-resistant bacteria and in how generations of fish and lizards respond to changing environments. And now a genetic study has found evidence of natural selection at work in the genomes of over 200,000 people.

Evolution works through the basic principle of natural selection. Random mutations often emerge in an animal's genes, and if they turn out to help that individual survive longer, it'll be more likely to procreate and pass on its genes. Eventually, the most beneficial genes will rise to the top and spread throughout a population, while individuals carrying "bad" genes will slowly be weeded out.

Conducted by researchers at Columbia University, a new study analyzed the genomes of 60,000 US citizens of European ancestry, and 150,000 people in Britain. With a sample size of 210,000 people in total, the researchers were able to track how specific mutations rose and fell across generations, which genes impacted survival rates, and roughly which traits were becoming more or less common in the population. Since the UK database didn't have as many genomes from older people, the researchers approximated the results by taking into account the age of death of the participants' parents.

Out of all of the genetic mutations the researchers studied, two in particular stood out as linked to survival rates. Women carrying one or two copies of a gene called ApoE4, which has been associated with Alzheimer's, appear on average to die much younger than those without it, causing a drastic drop-off of the frequency of ApoE4 in women over the age of 70. Meanwhile, the frequency of a mutation in a gene called CHRNA3 (which is linked to heavy smoking) drops off around middle age in men.

The researchers were surprised to find only two mutations to be so directly linked to survival rates, leading them to conclude that perhaps natural selection had already taken care of similar variations.

"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 Molly Przeworski, co-author of the study.

Measuring the evolution of specific physical traits is a tougher process, since dozens or hundreds of individual mutations can play a part in determining the likelihood of each trait. So the team collated sets of mutations that are linked to 42 chosen traits, such as height and body mass index (BMI), and then worked backwards to estimate a person's traits according to their genetics.

Using this method, the team found sets of traits that could be linked to longer or shorter lifespans. People predisposed to high cholesterol, high BMI, heart disease and, to a lesser extent, asthma, were more likely to die younger, while delayed onset of puberty seems to correlate with a longer life. The death rate was three to four percent lower for men and women who started puberty a year later than average, while for women, a one-year childbearing delay lowered that rate by six percent.

It may be fairly subtle, but the researchers point to the study as potential evidence of evolution hard at work in humans today. But environmental factors play a part too, and progress isn't always a straight line forward.

"The environment is constantly changing," says Hakhamenesh Mostafavi, lead author of the study. "A trait associated with a longer lifespan in one population today may no longer be helpful several generations from now or even in other modern day populations."

The research was published in the journal PLOS Biology.

Source: Columbia University

10 comments
vince
We stopped evolving once we no longer depended on forging for food as other animals do. Everyone passes on their genes nowadays regardless of fit and the rest of humanity protects them so even those not fit pass on their genes like the rest of us. Therefore evolution stopped for mankind. If mother nature comes along with a virulent virus we have no protections for and then only a few percent of us survive--then those ancestors are 'evolved'. But that won't happen when science protects us from those nasty viruses and for the most part stops them cold.
KaiserPingo
Yes we do evolve. But the deciding factors are changing, because the numbers of birth are so extremely high. The most succesfulls are not the ones with the most children, and therefore their genes are not gonna matter much. Genetically the most efficient spreading of genes are most likely in the "lower middle groups", where you have a history of many children, having a high survival rate, getting an ok education and materialistically having enough to have a good life. From a geneticcaly point of view, you could argue, that the "almost good enough genes" are actually the most succesfulls.
myale
I agree with Vince - medicine means that where nature would cause things not to survive - we can intervene, so it is no longer survival of the fittest, so bad genes etc are not removed or limited but allowed to remain or even thrive, so evolution as per Darwinism is stopped or massively reduced.
Bob
Our kids are not bigger and heavier because of genetics, it's because they are eating meat containing anabolic steroids and genetically modified foods which are not healthier but more profitable than natural foods. We are already seeing the average lifespan for men beginning to drop. Fewer and fewer people even know how to survive without modern conveniences. Any major catastrophe will have a huge number of casualties. Cave men were a whole lot more capable than we are. If anything, mankind is much weaker and has devolved. Science and technology will make us extinct.
Lardo
"Since the UK database didn't have as many genomes from older people, the researchers approximated the results..." In other words... we "fudged the numbers".
joseph93
Oh people... Factors affect everything and are constantly changing just like the many reasons why you stress out are constantly changing. Environment, diet, risks, location, genes present, etc are all contributing factors that constantly vary and then some. Nothing stops evolving unless its extinct. Genes are manipulated in every way imaginable, and for those who don't study the science, genes are manipulated in every way unimaginable. Common Sense is relative, and science/science theory is not common sense. With that said, this sample size does not seem promising. How was "European ancestry" assessed? There are individuals that are as black as night with a 85% European genome, and White Americans whose DNA has more than 60% Native Amerindian genome. More emphasis on how European ancestry and British origin was assessed and why they were assessed should be observed.
Rusty Harris
Considering some of the videos you see on youtube, I think in some ways, we started to DEvolve, decades ago ;)
ljaques
Please expose these "scientists" who believe that we ever stopped evolving, then reroute them into other jobs where they can -buy-a-clue-. The reason we use rats (and other animals) is that their genetics are sped up compared to ours and we can study things more rapidly. For some "climate scientists", Earth's climate is also evolving, and would have done so without us. Please, people! Science is a methodical process, not a politically driven idea, the latter being something our schools seem to be teaching nowadays. (sigh) Here you go: sci·en·tif·ic meth·od noun " A method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses." Nothing there says "Modify your results until they match your original hypothesis.", which is what appears to be happening today.
Riaanh
@Rusty Harris, well said!
Grunchy
De-evolution is an idea nearly as old as the idea of evolution. In this theory non-advantageous mutations in a protected species (people) have an artificially increased probability of being passed along. These mutations usually have the form of increased chance of developing an illness, but also other weaknesses such as flat feet, asthma, allergies, and elongated eyeballs (nearsightedness). Devo is the de-evolution band, ha ha.