Are Humans
Still Evolving?
When asked what evolution is,
we may imagine primitive men like Australopithecus evolving into humans or
dinosaurs which are believed to be the ancestors of lizards or crocodiles. Most
of us think of the evolution as a process that happened tens of thousands of
years ago. But this is a misconception we often make. In fact, the evolution is
still working today although the changes don’t appear significantly. Bacteria
are one of the good examples which prove this. Since nylon was invented in
1940s, nylon eating bacteria are nothing but new. The bacterium Pseudomonas can metabolize the nylon due
to the certain enzymes it has. Surprisingly,
however, same thing happened to non-nylon eating bacteria when they were placed
in an environment where nylon was the only available food source(Bocco,
2011). Whenever the experiment was tried, the
bacteria evolved until they could consume nylon. This example shows that most forms
of life can adapt to the change of environment by evolving. Of course, human
being is not an exception. As environment surrounding humans has changed a lot to
that of early humans’, humans would be still evolving. However, as humans are
much more complex life form than bacteria are, humans’ changes appear less
noticeably and progress more slowly. But, in fact, many scientists have found a
number of evidences that humans are still evolving.
At first, to understand this
article better, it would be helpful to take a look at the history of evolution
theory and what 'Natural Selection' is. Many people regard Charles Darwin as a father
of the theory of evolution. He can be called in this way as he systematized
evolution at his book ‘On the Origin of Species’. However, the concept of
evolution is much older. Ancient Greek philosopher Anaximander, believed as a
precursor of the concept of evolution, supposed that mankind naturally
originated from an early animal species. And in 1809, biologist Jean-Baptiste
Lamarck asserted ‘The Theory of Use and Disuse’, insisting that ‘traits of an organism are designed and inherited by
effort, the environment, or by the use and disuse’. However, it was Darwin who
established the concept of modern natural selection and forever changed the
theory of evolution.
In natural selection,
one species’ possibility of survival can be determined by how well adapted it
is to the environment. Natural selection doesn't generate new species. To help
a species adapt better its environment, the process simply changes the genetic
makeup and sends it to next generation. Also, the process can easily be
predicted. If a certain trait which can solve the problem lacks, the species
will develop the missing trait.
Today, many researches
on human evolution are proceeding. In 2007, Researchers of Utah
University discovered that a human evolution has not ceased and it is even accelerating(Siegel,
2007).
"We used a new genomic technology to show that humans are evolving
rapidly, and that the pace of change has accelerated a lot in the last 40,000
years, especially since the end of the Ice Age roughly 10,000 years ago,"says research team leader
Henry Harpending(2007). He says there are implications from the study.
According to Harpending,
the considerable increase in human population over the last 10,000 years has
speeded up the occurrence of evolution. It’s because we are now in new
environments where we need to adapt and more mutations occur due to larger
population. Therefore, thinking evolution has halted because of its
invisibility is obviously a misconception.
Now let’s take a look at
the several evidences that verify the argument. The fact that we can drink milk
proves that people are still evolving. When our ancestors made a living through
hunting-gathering ways, most of humans’ ability to digest lactose shut down
during their childhood. The gene regulated producing enzyme called ‘lactase’
which can digest lactose because human beings’ only available dairy food was
mothers’ milk at that time. However, when they began to domesticate cows, sheep
and goats, people could drink milk gained from those animals. But many new
diseases also began to appear as our eating habits had changed. This problem
was solved by creating genetic mutation which allowed grown up human to digest
lactose. According to experts of Broad Institute of MIT, this mutation is
presumed to appear 7,500 years ago in Europe. People with a genetic mutation
were able to spread their genes, so now more than 95 percent of Northern
European people carry the genetic mutation that can digest milk.
The fact that we are
losing wisdom teeth is other evidence. Most people think of wisdom teeth as an
irritating medical annoyance. Interestingly, however, the reason wisdom teeth
grow much later than other teeth have something to do with evolution. Our
ancestors had much larger jaws than we do. It must have helped them to chew
tougher foods like roots and nuts and tore a meat apart. However, nowadays we
can utilize utensils like forks and knives to cut food. Also, we have plenty of
foods that are much softer and easier to chew. Therefore, jaws of modern humans
became too small to contain all of them. That is why wisdom teeth disrupt the
other when they are coming in. Like an appendix that lost its original function
as we quit eating uncooked food, wisdom teeth have become a trace of our
evolution. In fact, 35 percent of us are already born without wisdom teeth.
Some even have just one, two or three wisdom teeth. It’s no surprise because
evolution tends to eliminate a trait to save on the needless energy expenditure
it takes to develop it when that trait is no longer necessary.
Human
brains are shrinking due to the evolution. According to John Hawks(Choi, 2009),
professor of the University of Wisconsin–Madison,study of human genome has
revealed that hundreds of our genes show evidence of change during the 10,000
years of human evolution. He also mentioned that particularly our brains
are evolving recently. He said that our brains have been shrinking, not
growing, over the last 5,000 years in comparison to archaeological data
discovered in Europe, China and Australia. The average volume of the human
brain has shrunked about 150 cubic centimeters: from 1,350cc to 1,200cc.
Professor Hawks suspected that the shrinkage of human brains is related with
the change of our lifestyle. Unlike in hunter-gather society, we now live in a
huge society. We can rely on others in many parts of our lives and work
together. Therefore, smaller space would be enough for brains to take up. Also,
smaller brains are more efficient as it can be rewired to work faster.
Evolution also made us
stronger to endure diseases. You can see the most obvious evidence in mutation
against malaria.Sickle cell anemia is an example of defense mechanism against
malaria. Actually, sickle cell anemia is a disorder that deforms red blood
cells into sickle shapes. It impairs blood flow and tissues. Surprisingly, this
malady can also prevent the malaria parasite from infecting blood cells. Sickle
cell is best known in Africa, but there is also an India-Pakistan variant that
seems to have evolved very recently. Dr. Ian Barnes(Hullinger, 2012) from the School of
Biological Sciences at Royal Holloway says thatliving in cities has also
produced a genetic variant that allows us to be more resistant to diseases like
tuberculosis and leprosy.
Despite these scientific
bases, some argue that evolution of humanity is now over. Recently Sir David
Attenborough, the famous naturalist, said that humans have stopped physical and
genetic evolution, during an interview with week's Radio Times(Furness, 2013).
His argument seems
plausible at first glance as we have achieved astonishing advancement in
reducing infant mortality and in combating many diseases. However, children’s
survival is not assured as Attenborough said and it is not consistent across
the world. Still, a lot of people cannot have basic healthcare and continue to
die because of diseases and malnutrition. Moreover, even if we do reach the point of “being able
to rear 90-95% of babies that are born”, that will only counter one of the conditions
necessary for natural selection(Katti, 2013).
Attenborough is right in that
natural selection requires variation. It needs some people to prosper more than
others. So the improved survival prospects around the world might have
decreased the potential for natural selection to work in those who are not
threatened by natural tragedies. However, natural selection doesn't really care
about survival. It only helps the emergence of gadgets that can solve the
problems efficiently. Of course, it does help species to survive but what it is
ultimately interested in is sending variations to next generations in order to
increase the effectiveness. Therefore, the argument that our natural selection
has stopped due to our increased survival prospects is flawed.
In fact, humanity has
not abandoned its ability to make genetic variation. The human genome shows
that recent population explosion made more variations within the last 200
generations. Thus, we may be evolving faster than ever before. Among them are
mutations like lactose tolerance, smaller jaws and carrying the sickle-cell
anemia.
Until now, evolution and
civilization was considered as discrete thing. Human developed civilization
after the process of evolution and society kept changing in the civilization
was a universal thought. However, many scientific evidences prove that humans
are still evolving, and our evolution is progressing faster than ever before due
to the rapid development of civilization. Evolution is not a story of hunched
primitive man anymore. It is a story of us. Theory of evolution is still a
primary object of study to biologists and even today ground breaking hypothesis
is ready to emerge. As we have seen how human being has recently adapted to new
surroundings, I believe that we can somewhat predict how we will evolve in the
future. This will not only give enjoyment of imagining future of humanity but
also make us prepare for an upcoming future.
Reference
Bocco,
Diana (2011). Ten Examples of Natural Selection. Retrieved from http://www.discovery.com/tv-shows/curiosity/topics/10-examples-natural-selection.htm
Hullinger,
Jessica (2012). 5 Signs Humans Are Still Evolving. Retrieved from http://mentalfloss.com/article/30795/5-signs-humans-are-still-evolving
Nelson,
Bryan (2012). Projecting Human
Evolution: 5 Traits We Might Possess in the Future. Retrieved from http://www.mnn.com/earth-matters/wilderness-resources/stories/projecting-human-evolution-5-traits-we-might-possess-in
Furness, Hannah (2013). Sir David Attenborough: Humans Have Stopped Evolving.
Retrieved from http://www.telegraph.co.uk/science/evolution/10297124/Sir-David-Attenborough-Humans-have-stopped-evolving.html -
Choi,
Charles Q. (2009). Humans Still Evolving as Our Brains Shrink. Retrieved from http://www.nbcnews.com/id/33916577/ns/technology_and_science-science/t/humans-still-evolving-our-brains-shrink/
Katti,
Madhusudan (2013). Sorry Attenborough, Humans Still Evolve by Natural Selection.
Retrieved from http://www.thehindu.com/sci-tech/sorry-attenborough-humans-still-evolve-by-natural-selection/article5141928.ece
Rickard, Ian
(2013).
Sir David Attenborough Is Wrong – Humans Are Still
Evolving. Retrieved from http://www.theguardian.com/commentisfree/2013/sep/10/david-attenborough-humans-still-evolving
Siegel,
Lee J. (2007). Are Humans Evolving Faster?. Retrieved from http://unews.utah.edu/old/p/120607-1.html
