Question

1. Post a paragraph that addresses the following:  
   • How are humans evolving today? Explain.
   • Are humans exempt from natural selection because of the technological nature of our society? Why or why not? Explain.
   • What qualities or characteristics do you predict humans of the future will share because of natural selection? Justify your rationale.

Answer 1

• How are humans evolving today:-

  When we think of human evolution, our minds wander back to the millions of years it took natural selection to produce modern-day man. Recent research suggests that, despite modern technology and industrialization, humans continue to evolve. "It is a common misunderstanding that evolution took place a long time ago, and that to understand ourselves we must look back to the hunter-gatherer days of humans,"

But not only are we still evolving, we're doing so even faster than before. In the last 10,000 years, the pace of our evolution has sped up, creating more mutations in our genes, and more natural selections from those mutations. Here are some clues that show humans are continuing to evolve.

1. HUMANS DRINK MILK.
Historically, the gene that regulated humans' ability to digest lactose shut down as we were weaned off our mothers' breast milk. But when we began domesticating cows, sheep, and goats, being able to drink milk became a nutritionally advantageous quality, and people with the genetic mutation that allowed them to digest lactose were better able to propagate their genes.

The gene was first identified in 2002 in a population of northern Europeans that lived between 6000 and 5000 years ago. The genetic mutation for digesting milk is now carried by more than 95 percent of northern European descendants. In addition, a 2006 study suggests this tolerance for lactose developed again, independently of the European population, 3000 years ago in East Africa.

2. WE'RE LOSING OUR WISDOM TEETH.
Our ancestors had much bigger jaws than we do, which helped them chew a tough diet of roots, nuts, and leaves. And what meat they ate they tore apart with their teeth, all of which led to worn-down chompers that needed replacing. Enter the wisdom teeth: A third set of molars is believed to be the evolutionary answer to accommodate our ancestors' eating habits.

Today, we have utensils to cut our food. Our meals are softer and easier to chew, and our jaws are much smaller, which is why wisdom teeth are often impacted when they come in — there just isn't room for them. Unlike the appendix, wisdom teeth have become vestigial organs. One estimate says 35 percent of the population is born without wisdom teeth, and some say they may disappear altogether.

3. WE'RE RESISTING INFECTIOUS DISEASES.
In 2007, a group of researchers looking for signs of recent evolution identified 1800 genes that have only become prevalent in humans in the last 40,000 years, many of which are devoted to fighting infectious diseases like malaria. More than a dozen new genetic variants for fighting malaria are spreading rapidly among Africans. Another study found that natural selection has favored city-dwellers. Living in cities has produced a genetic variant that allows us to be more resistant to diseases like tuberculosis and leprosy. "This seems to be an elegant example of evolution in action," says Dr. Ian Barnes, an evolutionary biologist at London's Natural History Museum, said in 2010 statement. "It flags up the importance of a very recent aspect of our evolution as a species, the development of cities as a selective force."

4. OUR BRAINS ARE SHRINKING.
While we may like to believe our big brains make us smarter than the rest of the animal world, our brains have actually been shrinking over the last 30,000 years. The average volume of the human brain has decreased from 1500 cubic centimeters to 1350 cubic centimeters, which is an amount equivalent to the size of a tennis ball.

There are several different conclusions as to why this is: One group of researchers suspects our shrinking brains mean we are in fact getting dumber. Historically, brain size decreased as societies became larger and more complex, suggesting that the safety net of modern society negated the correlation between intelligence and survival. But another, more encouraging theory says our brains are shrinking not because we're getting dumber, but because smaller brains are more efficient. This theory suggests that, as they shrink, our brains are being rewired to work faster but take up less room. There's also a theory that smaller brains are an evolutionary advantage because they make us less aggressive beings, allowing us to work together to solve problems, rather than tear each other to shreds.

5. SOME OF US HAVE BLUE EYES.
Originally, we all had brown eyes. But about 10,000 years ago, someone who lived near the Black Sea developed a genetic mutation that turned brown eyes blue. While the reason blue eyes have persisted remains a bit of a mystery, one theory is that they act as a sort of paternity test. “There is strong evolutionary pressure for a man not to invest his paternal resources in another man’s child,” Bruno Laeng, lead author of a 2006 study on the development of blue eyes, told The New York Times. Because it is virtually impossible for two blue-eyed mates to create a brown-eyed baby, our blue-eyed male ancestors may have sought out blue-eyed mates as a way of ensuring fidelity. This would partially explain why, in a recent study, blue-eyed men rated blue-eyed women as more attractive compared to brown-eyed women, whereas females and brown-eyed men expressed no preference.

• Are humans exempt from natural selection because of the technological nature of our society:-We will never be free from natural selection -- it just cannot happen. What will happen is that the selective pressures change (as he pointed out). So now instead of selecting for people that can outrun a predator we are selecting for people that can drive well, or people that are resistant to environmental toxins that we introduce, or people that are able to play the corporate game.

Natural selectioin is not some self-aware entity that can be "foiled" it is simply a term used to describe how and why gene frequencies tend to favor one type of gene over another.

• What qualities or characteristics do you predict humans of the future will share because of natural selection :-

Evolution and natural selection are not the same thing. Evolution is the gradual genetic change of a species over time due to unequal reproduction among members. Natural selection is the phenomenon that rewards certain advantageous traits and punishes others through better or worse survival or reproduction . Natural selection thus is one of several forces that push evolution forward.

Medical science and public health measures have enabled the developed world to escape most natural selection, for the most part, certainly for the past several decades. Most human babies now survive to adulthood in developed countries. Survival is constantly improving and that’s very different than things were throughout the history of life on Earth. In Darwin’s time, for instance, only about 50 percent of British children survived to age 21, so in those days natural selection was certainly operating on humans.

Due to the marginalization of natural selection, futurists often predict that humans will not evolve more in any major way. These include high-profile science figures such as Sir David Attenborough, and even some biologists, such as Professor Steve Jones of University College London, who have said that "evolution is over" for humans, at least in the developed West. Another researcher, Peter Ward, a paleontologist at the University of Washington has written, "I don't think we are going to see any changes - apart from ones we deliberately introduce ourselves, when we start to bio-engineer people, by introducing genes into their bodies, so they live longer or are stronger and healthier."

This idea certainly would be true, were natural selection inserted in place of evolution. Natural selection won’t provide us bigger brains, webbed hands or feet, or improvements in vision or hearing. This is because people who are exceptionally intelligent, have slight webbing in their hands, or have impressive hearing or vision ability end up having the same chance of having children as anyone else. Nearly everyone lives to reproductive age and the decision to have children or not is largely independent of physical health or prowess, and that’s why natural selective forces no longer operate on most of the human population.

But predicting future events entails a great deal of uncertainty. Though not by natural selection, humans may very well evolve dramatically, and this is where the other evolutionary forces come into play. Certain possibilities of our future evolution can be explored, through the careful and creative framing of testable questions relevant to predictions. Imagined functional human adaptations of body parts, for instance, may have corollaries elsewhere in the animal kingdom that scientists may have studied already. Data from current trends in the human population may be relevant to future developments. We’ll consider a handful of directions that human evolution could take.