Author: Carina Storrs
Publication Date: January 20, 2010
Link: http://www.scientificamerican.com/article.cfm?id=early-human-population-size-genetic-diversity
Summary: A series of genetic studies tell that the human
species a million years ago was on the brink of extinction. At the time, the
population did not exceed a mere 55,500. Originally, one might assume the population
would expand, due to fossils showing evidence of immigration across Africa,
Asia, and Europe at the time. But genetic studies show that the population, and
its genetic diversity, actually suffered a great deal. Tests were run on human
genomes to estimate an effective population size, and compare their genetic
diversity with that of the early humans. The effective population of the early
humans researchers had estimated (18,500) shows that their genetic diversity is
between 1.7 and 2.9 times greater than humans today. The effective population
today is about 10,000. Researchers believe the population today is so much
greater due to a “population explosion” 10,000 year ago caused by development
of agriculture. In conclusion, the genetic “bottleneck” that happened one
million years ago was hypothesized to be caused by a catastrophic event, such
as a supervolcano.
Opinion/Reflection: I think it is incredible that the result
of one natural disaster, if large enough, can almost completely annihilate an
entire species. And to think that it was
our species is a little scary in it of itself. Clearly though, it did
not. Thanks to the genetic diversity in
the early humans, and the human population’s ability to restore itself, our
species is able to survive and prosper. As we learned in class, high genetic diversity
within a population is better, because it increased the chances of survival
through changing environmental conditions. Let’s hope our species can maintain
its current level of diversity.
Questions:
1.
What can cause a decline in the genetic
diversity of a population?
2.
What can increase it?
3.
Should we try to control our genetic diversity
(by ways of genetic experimentation, or otherwise)?
5.
What kind of environmental changes could cause a
decline in population, or a struggle to survive?
Opinion/Reflection:
ReplyDeleteI find it to be amazing that, not only did we as a species survive a natural disaster, but were able to make an independent recovery and eventually become the global apex predators. Unlike other species, some of which might just die, we overcame adversity to become the most dangerous animals on the planet. Natural disasters have never proven to destroy human resolve, but usually just strengthen it. Pompeii is one of the earliest instances of this, where the word volcano was formed. The island was mourned, but the lessons taught there were forever burned in our collective memories in way that only humans can. We remember what happens, that, I believe is why we live, even if others die left and right around us.
Response to thoughtful question:
I do not believe that we need to control our genetic diversity, as science shows as commonly accepted fact that genes slowly change in unexpected ways; these changes, as I am sure you all know, are called mutations. Humans have also managed to create materials that are toxic to us because they are harmful to base genetic materials. Materials of specific toxicities might have the capability to alter genes. The most common of these are carcinogens; however there might be other materials that cause different abnormalities and permutations on hereditary traits. My argument is that, either through natural reasons, or by fluke DNA damage, humans will slowly increase their biodiversity, so intentional genetic tampering is an unnecessary and wasteful use of resources.
Opinion/ Reflection:
ReplyDeleteThis article actually has a lot to do with what we learned today in class. We see an example of the "bottleneck effect." The human race started with a larger genetic diversity than we have now, most likely due to a disaster that almost killed off our species. Anyways, I am slightly confused on the significance of "effective population size." So if a species has a larger genetic diversity, then it needs a larger population. Does that mean that if we did not almost go extinct, then the current population would be normal and not "overpopulated?" I also find it amazing how the human race is able to leave the endangered status by itself, compared to other species that require our assistance to repopulate.
Response to a question:
5. What kind of environmental changes could cause a decline in population, or a struggle to survive?
1) Climate change can affect the growth condition of plants, which then translates to the amount of food available.
2) Apocalyptic Scenarios that leave the Earth unlivable by taking out the essentials to life. Some scenarios are: giant meteor, solar flare, nuclear warfare, super volcano, etc.
3) Overuse of resources which then causes a future problem of finding more in the future.
Opinion/ Reflection:
ReplyDeleteThis article as really interesting. I liked how it went in to depth about the bottle neck effect. I never really thought about the bottle neck effect in terms of humans and how we have grown and evolved. To think that thousands of years ago we bottlenecked and the diversity of humans was very low is remarkable. It goes to show just how powerful evolution is because you can see that humans are now so distinctly different. It leads me to wonder just how different we would be if the human race never bottlenecked.
Response to a question:
3. I think it would be beneficial for us to control our biodiversity, but not to expand it. If you think about it, our biodiversity will continue to rise because we are at the top of the food chain. It is awful to think, but things like medicine only hinder the human race from improving. Not the medicine that cures you from a sickness, but medicine that allows you to live with a hereditary conditions that would normally kill you. If doctors keep treating things like this, they will only affect the population longer and with more numbers. For example, if there were to be a bottleneck and all the people with a heart condition were to die out, then the human race would be without heart conditions. The only chance that a person would get heart problems would be if it was a mutation because the couldn't have obtained from their parent. And believe me, I know this is unrealistic, but evolution can't progress if we keep saving the bad traits from dying.
Opinion/Reflection:
ReplyDeleteThis article is a very interesting article. It talks of humans dieing out. I never thought of this possibility that us as the assumed Apex Predator could have died out before our modern civilization. It's weird to think that we might have died out and none of us would be alive at this moment. It's amazing to hear about this story and that back then humans still had a will to survive through even the worst of times as we do now.
Response to a question:
Controlling our genetic diversity would be benificial to our race. However, the way we control it now is not benificial to our race. The way we save those who are dying of a genetic disease is not helpful to us as a race but as an individual. I know not saving someone from death sounds mean and inhuman but the fact is if we save those who have these genetic diseases then we are only hurting our race as a whole.