News from the Columbia Climate School
Brian Kateman
Modern day human evolution is a contentious topic in the scientific and broader community.
While many people conceptualize evolution to be a gradual process, with natural selection blindly tinkering away at genetic and phenotypic diversity across generations, dramatic changes in a species, under certain circumstances, can accelerate rapidly.
Recent studies suggest that Homo sapiens are not exempt from the process and may still be evolving.
Nicholas Wade, an author of two books on recent human evolution and a writer for the Science section of the New York Times, reported yesterday on the most recent known instance of human evolution in response to natural selection.
Using a complete set of data on birth, marriages, and death records on the island of Île aux Coudres, researchers from the University of Quebec at Montreal extracted the histories of women born on the island between 1799 and 1940. The scientists determined in their study that the age at which a woman had her first child decreased on average from 26 to 22 years, resulting in four more children in a lifetime.
Though biologists cannot rely on genetic sequences to discover recent instances of human evolution, they can infer such findings from the health histories and morphology of individuals.
Researchers from the University of Yale examined the vital statistics of over 2,000 postmenopausal women participating in the Framingham Heart Study. Investigators searched for correlations between women’s physical characteristics and the number of offspring they produced. They determined that slightly overweight women tended to produce more children and that these characteristics were in fact passed on genetically.
Drawing upon other examples of recent human evolution, such as defenses against malaria and tolerance to lactose, studies have also shown that hundreds of genes in our genome have changed in the past millennia and the brain may even be shrinking.
Still, countless questions remain: Do you think these studies sufficiently suggest that humans are still evolving? If so, what does the future hold in store for our species?
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The problem with this theory is that it doesnt take into consideration the fact that we homo sapiens have deactivated the most powerful weapon in the arsenal of evolution: Natural Selection.
For any trait to become powerful enough to permeate the whole species it has to convey the individuals that possess it the ability to pass their genes (and the trait) to their offspring in greater sucess and quantity than those who don’t have it. In other words, it must increase the ability to survive. Back in Darwin times, only 50% of humans in England survided to age 21 (an age in which they can reproduce and spread their genes). You could conceive some traits that would move this population to evolve, for instance, resistance to cholera or chicken pox; but now that medical and healthcare practices allow 99% plus of English babies to reach sexual maturity, EVERY TRAIT is passed on. In today’s world there are not real “bad “genetic changes that would resuce your chances of passing your genes. Also, those humans that could be considered to be more “apt” or “fittest” or “successful” in today’s standards are not going to necessarily have more offspring because of that reason. In fact, probably the opposite is true!
So humans will change over time, but not necessarily according to any “improved” model.
Under which circumstances, for instance, would the IQ of H. sapiens increase over time? Evolutionarily speaking, only under conditions in which higher IQ males mated preferably with higher IQ females AND had more children than the average. Is that occurring?
The answer is NO! Probably the opposite is more frequent.
Best regards
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