BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: Evolution (Page 3 of 3)

We Need Mosquitoes?!

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On October 7, 2012

In Student Post

Picture By maureen_sill, Flickr

Yes, in fact, we do need mosquitoes. And not only mosquitoes but all the other types of insects as well. A recent discovery by Anurag Agrawal, the leader of the study and a professor of ecology and evolutionary biology at Cornell University, revealed that insects are hugely important because of the roles they play in the evolution of plants. In Agrawal’s study, in which he observed the interactions of plant-eating moths and evening primroses, the primroses treated with insecticide lost through evolution the traits that protect them from insects.

 

This points to the idea that if plants don’t need to defend themselves against insects, they stop developing the traits required to defend themselves. The real shocker in this discovery, however, was how quickly the primroses adapted to this situation, in just 3-4 generations. Agrawal “was ‘very surprised’ by how quickly this process occurred, and that such surprises, ‘tell us something about the potential speed and complexities of evolution. In addition, experiments like ours that follow evolutionary change in real-time provide definitive evidence of evolution.”
But why are insects important then? Well, it is believed that many plant traits developed solely as a means of defense against insects. Some of these traits are desirable to people, like fruit’s bitter taste. In addition, with farmers trying to breed certain crops to be resistant to pests, this study shows that some genetic trade-offs might make it impossible to get certain traits in pest resistant plants. So bear with those pesky insects, as their relationship with plants is extremely important.

A Woodpecker’s Headache

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On October 6, 2012

In Student Post

Have you ever wondered how a woodpecker can “peck” a tree at twenty times a second without damaging their head? Thinking about it, if you hit your head against a wall, you get a little dizzy.

Photo Credit: DigitalAlan

Does the woodpecker get dizzy? Research shows that with the study of evolution, all of these questions can be answered.

There are a lot of animals in this world that bang their skulls as a living. A woodpecker is one example. Other examples include “antler mammals” such as deer as well as many other birds. Looking at a deer’s skull, for example, one can see that the skull is quite large with a very small area for the brain; deer do not have large brains. Because the brain is surround with small amounts of cerebrospinal fluid in a small area, the brain is not able to rattle around when the deer bucks something. This is one example of how the study of skulls can lead to knowledge about an animal’s lifestyle.

Another animal, such as the gannet, has a skull that has evolved over hundreds of years. The gannet preys on fish in the ocean. While flying one hundred feet over the water, they can spot their prey. When they are ready to dive, they plunge into the water at sixty miles per hour! (That would definitely hurt my head) If we think about survival of the fittest while looking at the gannet’s school, we can see that the skull has an area that is more dense right in the front (the forehead of the bird). With a beak that can move up and down, they can direct the impact of the water right towards this large area. Also, air sacs in front of the skull allow for more protection the skull and the brain. This gives them a huge advantage in the areas where they live.

More studies of skulls can lead to how the animal can adapt to the environment and behave accordingly. Tarsiers, for example, are small creatures living in Southeast Asia. These miniature monkeys have huge eye sockets. Because they live in a “less threating area,” they need to keep an eye out for prey. Also, rabbits have auditory bullae, which allows them to have very acute hearing. This allows them to hear an owl swooping down to catch them. All of these adaptations need a specific skull.

The study of skulls can show what type of an environment an animal is living in. From deer to birds, all animals have different skulls. Survival of the fittest shows that with different adaptations, animals need different skulls. The next time you see a woodpecker, think about how your head would feel in that situation!

 

How Old Are You, Polar Bear?

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On April 30, 2012

In Student Post

 

Some Rights Reserved: http://www.flickr.com/photos/xrayspx/3969642331/sizes/s/in/photostream/

Do you remember where mammals have DNA? (hint- it isn’t just in the nucleus)

Mammal cells have DNA in both their cell nuclei and their mitochondria. While DNA in the nucleus is a combination of both parents, mitochondrial DNA is inherited directly from the mother. (For more information about nuclear DNA and mitochondrial DNA download: www.cbc.ca/fifth/2008-2009/the_girl_in…/dna-definitions.doc)

And what does this have to do with the age of Polar Bears?

Well, according to a recent article in the New York Times, scientists have been surprised to find that polar bears are not so closely related to brown bears as previously thought. For years, scientists thought that the polar bear specie evolved about 150,000 years ago. Adaptations, probably due to natural selection, include white fur and webbed paws – both of which are very helpful in the icy Arctic.

Researchers Axel Jenkle and Frank Haler, of the Biodiversity and Climate Research Center in Frankfurt studied 19 polar bears, 18 brown bears and 7 black bears. After analyzing the nuclear DNA of polar bears, they believe that brown bears and polar bears began taking different evolutionary paths as much as 600,000 years ago.

The old, incorrect, theory was based on mitochondrial DNA. The mitochondrial DNA of polar bears and brown bears are very similar.  Because polar bears live on ice, and there aren’t many fossils saved in the icy arctic, it has been difficult to trace the evolution of these famous white bears.

Now scientists are trying to figure out why the mitochondrial DNA of brown and polar bears is so similar. One hypothesis is that polar bears mated with brown bears during time of global warming or climate changes. There is some evidence of the bottleneck effect, which helps support this theory.

 

Link to main article: http://www.nytimes.com/2012/04/20/science/polar-bears-did-not-descend-from-brown-bears-dna-study-indicates.html?_r=2&ref=science

 

 

Crocodiles…They Can Take Down a T-Rex

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On March 18, 2012

In Student Post

I don’t know about you, but I’ve always wondered what I would do if I was ever being chased by a crocodile. At a young age I learned that you should always run zig zag, because that slows the beast down. Good advice right? Well, what if the crocodile still catches up to you? Don’t say your prayers yet. If your crocodile is relatively small, but just looks like it would have a nasty bite because of the way it’s teeth look, you may be in the clear!

Photo Credit: Ramy Alaa

A recent article explains that the the size, shape, and look of jaws is not an accurate barometer of how hard that particular crocodile will bite. For years, scientists believed that evolution created crocodiles with jaws that are broader so that their bite is also very strong. Reversely, crocodiles with a jaw that looks somewhat delicate would have a low bite force. Now scientists know that teeth and jaws evolve completely separately to that of bite force. In fact, the only variable that affects the bite force a crocodile will have is the size of the animal.

To give some perspective, the average crocodile now has a bite force of approximately 2,000 pounds. In his study, Dr. Erickson discovered that a crocodile alive at the same time of the dinosaurs had a bite force of 23,000 pounds. This bite force is greater than what a T-Rex would have had!

In order to fully test his theory that only size of the animal is related to bite force, Dr. Erickson invented a device that measures the bite force of a crocodile as the animal is crunching down on the metal padded rod. Using this device, Dr. Erickson was able to measure the bite force’s of all 23 species of crocodilians. The results were surprising. Instead of jaw size and shape, the only correlation to bite force came from the size of the animal.

I encourage you to think about an escape plan if you are ever faced with a crocodile. Whether or not their bite force is considered strong or not, most likely it could still severely injure you. I suggest running away, even if the crocodile looks like it’s bite force is less than 1000 pounds. Trust me. What do you think about this recent finding? Common sense? Or did you assume that jaw shape played a part in how hard a crocodile could bite, as well?

from single cell to multi-cellular

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On February 27, 2012

In Student Post

Have you ever wondered how single cellular organism evolved into multicellular organisms? In a recent New York Times article, some scientists decided to see if they could get single cellular organisms to somehow evolve into multicellular ones. The problem that they thought of was that in multicellular organisms there are many cells which die so that the entire organism can live on. Why single cell organisms would group together with other single cell organisms just to die for the new multicellular organism was puzzling.

They designed an experiment where they had yeast in flasks of broth where they were being shaken for a day and then left alone for the yeast to settle. Then a drop of the settled yeast was taken and transferred to a new flask where the yeast could continue to grow. This process was continued and would allow the yeast which had evolved to be the densest and to settle furthest down to be carried to the next flask. after a few weeks the scientists observed that the yeast was falling faster and was becoming cloudy at the bottom. When looked at under the microscope the scientists found that the yeast had evolved into snowflake shaped clumps of hundreds of yeast cells stuck together. These cells were not just unrelated clumps since when separated individually, cells would recreate these snowflake shaped clumps. This property of clusters of single celled organisms to make a multicellular like organism is not special to yeast. Another organism called choanoflagellates is a single celled organism that also exhibits these traits.

One of the more amazing parts about this was that to reproduce, branches of the snowflake clump would break off after growing too large. When looked at closer they found that a section of the cells near the branch commit suicide to separate the branch to allow it to grow into a new clump. Being able to create multicellular organisms that had cells willing to commit suicide for the rest of the organism in a matter of weeks was amazing and could mean that the history of single celled organisms evolving into multicellular ones might not be as complicated as previously thought. Even though this form of natural selection was done in flasks, the natural environment could have preferred multicellular organisms over single cellular organisms for a number of reasons.

Secrets (almost) Revealed about the Evolution of Plants

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On January 11, 2012

In Student Post

Now that we are studying plants in class, and learning about different adaptations and some of the evolution of plants I thought this study would be interesting to look at.

The sequencing of the genome of a plant known as spikemoss, may give scientists a better understanding of how all kinds of plants evolved over the past 500 million years! This is the first sequencing for a non-seed vascular plant. Selaginella has been on this earth for about 200 million years and is a lycophyte

I was surprised that the Selaginella genome has about 22,300 genes and that’s small according professor Jody Banks. Selaginella is the only known plan to not have experienced a polyploidy event and is also missing the genes known in other plants to control flowing and becoming and adult. These genes are unknown in the Selaginella, but the genome would help scientists understand how these plants genes give the plant some unique characteristics and also help understand how Selaginella and other plants are evolutionarily connected.

The genome sequence was compared with others, and researchers identified genes that are present only in vascular and flowering plants. These genes that were identified most likely played important roles in the early evolution of vascular and flowering plants. Many of these genes have unknown functions, but it is likely that those genes that were identified may function in the development of fruits and seeds. Banks said: “[having an idea of what the function of the genes is] gives us ideas. It’s an important piece of the puzzle in understanding how plants evolved.” Also there are metabolic genes that evolved independently in Selaginella and flowering plant, which means Selaginella, could be a huge resource for new pharmaceuticals. The Selaginella is defiantly an interesting and great plant to study.

Photo Credit:http://www.flickr.com/photos/ki/195802378/

Sharks prove evolution; hybrid shark.

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On January 11, 2012

In Student Post

Photo taken by "warrenski"

Sharks are just adding to their long list of impressive abilities. They are amazingly immune and can help cure cancer, they can be a cyclopes, and now they are proving evolution.

The world’s first hybrid shark has been discovered in Austrian waters. The shark is a cross of an Australian Blacktip shark and a Common Blacktip shark. Common Blacktip sharks are found in the Atlantic Ocean. This discovery displays the animals fight for existence; overfishing and pollution have reduced shark populations in general all over the globe. The adaptation of this new hybrid allows the animal to survive in cooler water temperatures, previously intolerant for species. Scientist believe the sharks are “adapting to cope” with global warming and changing water temperatures.  This adaptation and creation of a hybrid creature is evolution. This discovery proves that evolution is no longer a theory but is happening right now.

The new hybrid species has many generations under it’s belt, displaying its ability to reproduce. The species will have to be further studied before comparing their life to that of their parents. This discovery also opens the door to the discovery of other species crossbreeding or evolving as well.

Photo of Common Blacktip Shark: http://www.flickr.com/photos/warrenski/6503846891/

 

 

Love Hormone: From Maternal Love to Romantic Attachment to Basic Survival Need

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On January 10, 2012

In Student Post

Photo Credit: Roberto Pagani

Introduction

The hormone oxytocin, known as the Love Hormone and sometimes the Cuddle Hormone, is responsible for a plethora of emotional and nervous responses in our bodies. It is a hormone exclusively found in mammals. It causes maternal bonds to form between mothers and their children along with romantic bonds to form between monogamous pairs. Oxytocin controls many social responses that aid bonding and even cause us to feel sympathy. Oxytocin is also known for its ability to cause subjects to feel content, reduce anxiety, and feel calm and secure around one’s mate. The presence of oxytocin is a basic survival adaptation for mammals because it causes them to trust members outside the family unit and therefore permits mating to occur among unrelated members of the same species, thus creating a healthier, more diverse gene pool.

Maternal Love

It’s not surprising that oxytocin is only present in mammals. After all, it controls the release of milk to the nipples during lactation, helps dilate the cervix and trigger labor, and aids formation of bonds between members of species that are vital to the survival of many mammals. One particular bond that oxytocin helps initially form is that between mother

Under Creative Commons Licensing

and offspring. However, one study found that oxytocin levels are higher when first creating a maternal bond than once the bond has been made, therefore oxytocin begins the maternal behavior in the mother, but does not solely maintain it. Researchers have also found that the higher level of oxytocin in mothers during pregnancy, the stronger the bond between mother and child will be once the baby is born and the more maternal the mother will act towards the baby.

Romantic Attachment

Oxytocin is also responsible for causing romantic attachment to form between a monogamous pair. Oxytocin is the cause of the anxiety a person feels when they have been separated from the one they love or, more specifically, have been monogamously paired with. When a monogamous pair is with each other, oxytocin is released. This release causes them to feel content, happier, relaxed, and trusting: basic components of “feeling in love”. However, when the pair is separated for a prolonged period of time, separation anxiety kicks in because the oxytocin which was keeping stress levels low before is no longer being release. Large amounts of oxytocin are released during sexual intercourse and orgasm, hence its name “the love hormone”. Therefore, habitual sexual intercourse between a monogamous pair works to strengthen the romantic bond and causes heightened separation anxiety.

Mammalian Evolutionary Benefits of Oxytocin

The presence of oxytocin is a basic survival adaptation for mammals because it causes stress levels to fall and trust levels to rise, thus it creates the proper conditions for bonding between non-family members or in other words, strangers who they’re instinctually wired to avoid. The social bonding between non-family members aided and maintained by oxytocin is the psychological strategy which enables humans to override our neophobia and to mate with and create a strong, life-long bond with a complete stranger. Mating with non-family members is fundamental to a species survival because it creates a healthier, more diverse gene pool. On top of social bonding that leads to mating, the maternal instincts and maternal bonds are increased by higher levels of oxytocin. The presence of oxytocin in mother is vital for mammalian survival because they have evolved to care for our young and provide them with milk and protection until they are old enough to fend for themselves. Without the oxytocin present during labor, mammals wouldn’t have maternal instincts when offspring is born, the dilation of the cervix would become impaired, milk would not be let down to the nipples during lactation (so there would be no lactation), and mothers wouldn’t have the strong bonds or urges to care for their young.

 

My Opinion and Conclusion

We know that oxytocin causes romantic bonds to form between monogamous humans and causes us to feel sympathy, but what about animals? The “Love Hormone” is known to form maternal bonds between rat mothers and their young and even helps rats form life long monogamous mating bonds. Is it possible that if oxytocin forms bonds and causes sympathy in humans and also causes pair bonding between animals that it could also cause animals such as rats to feel sympathy? Evidence of this would be groundbreaking because it would prove that animals are capable of feeling emotions previously thought to be solely possessed by humans.

 

For More:

http://www.biomedcentral.com/1745-0179/content/2/1/28#B14

http://jn.physiology.org/content/94/1/327.long

http://www.springerlink.com/content/m761t10000r382q5/

http://www.annualreviews.org/doi/abs/10.1146/annurev.neuro.27.070203.144148?url_ver=Z39.88-2003&rfr_dat=cr_pub%3Dpubmed&rfr_id=ori%3Arid%3Acrossref.org&journalCode=neuro

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953948/?tool=pmcentrez

 

 

 

 

 

Guppy Love!

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On December 4, 2011

In Student Post

Tiger Guppy (domesticated)- CC licensed photo by Leonard Paguia

Guppies (those small, colorful freshwater fish that everyone loves to keep in their fish tanks) have been evolving in the wild for more than 500,000 years, yet one feature has remained constant over all that time. Research conducted by UCLA Biologists has shown that the orange spot found on the wild male guppy has remained not simply the same color, but the same hue of orange since near the beginning of this fish’s existence. The reason for all this effort? That particular shade of orange is the one that female guppies prefer. What is so fascinating about this to biologists is that it proves that evolution is not simply an organisms adaptations to be better suited to its environment.

The two pigments that, when combined, allow a male to have an orange-colored spot are carotenoids (taken in by the guppies through food) and drosopterins (synthesized by the guppies). A higher percentage of carotenoids would make a guppy’s spot appear more yellow, and a higher percentage of drosopterins would make the spot appear more red.

Now one would think that, in order to conserve energy and be able to function more efficiently, a male guppy that had an abundance of carotenoids in its diet would not waste energy on synthesizing drosopterins as it would not need them to have a brightly colored spot. Conversely, one would think that in order to maintain a bright and noticeable spot, a guppy that did not have a lot of carotenoids in its diet would synthesize more drosopterins. However, this is not the case.

As the type and availability of food for male guppies has varied as a result of both time and location (guppies are native to both trinidad and venezuela) they have evolved to match the levels of carotenoids and drosopterins to produce that orange that the females are so attracted to, even if it comes at a high energy cost, or the spot must be more dull to produce the correct shade.

Although we all understand that reproduction is the ultimate goal of all organisms, what these guppies have done over the past half a million years is still not evolution in the way that many of us think about it. What has happened with a great many organisms is that they adapt in ways that make it more easy for them to survive and then these traits become attractive to the opposite sex because their presence indicates that that individual will produce offspring that will also be better suited for its environment. Here, however, male guppies have striven to remain attractive to their mates even when this comes at a high energy cost for many. As a result, the females have not had to change their taste in mates, and the males have been forced to continue playing to their preferences, or risk not reproducing.

Can you think of any other organisms that have adapted to be attractive to mates even when it made them less suited for their environment?

For further reading on the actual experiment conducted by UCLA biologists click here

 

Are Canadians Genetically Superior?

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On October 25, 2011

In Student Post

Photo by Anirudh Koul Flickr

I mean they do have Ryan Reynolds,  Rachel McAdams, Ryan Gosling, Ellen Paige, that tall guy from Glee, and Beiber. Well, maybe Bieber doesn’t isn’t a testiment to Canadian superiority, but recent studies have found certain signs of rapid genetic changes among the recent residents of a small Canadian town,  Ile aux Coudres, in the last 140 years. These changes include the average age of first maternity dropping from 26 to 22, resulting in larger families which are advantageous in rural areas.

Now while some may argue that this is merely an effect of the rural culture, anthropologist and geneticist, Emmanuel Milot says “Culture shapes the selection pressures acting on the age at first birth and the reproductive history of women in this population [therefore,] the cultural context was favoring the selection of some genes.” With the help of the Catholic Church’s detailed record keeping, Milot and his team were able to identify this trend as one attributed to genetic rather than environmental changes.

This study supports the school of thought that humans are still evolving and examines microevolution over the course of just a few generations.  Other studies show that certain human populations in different regions are evolving differently still today. A classic example of this regional evolution is the Mongoloid Race‘s decreased amount of sweat glands and small eyes. These are regional adaptations meant to be advantageous against the cold, snowy environment in which they live. Less sweat glands means more water conserved and less sweat released in order to avoid having it freeze on their skin, thus avoiding dehydration and hypothermia. Smaller eyes are beneficial because they help keep the sun’s glare from the snow at a minimum. These are all examples of ancient regional evolutions, similar to the current day changes occurring in some small Canadian villages.

It is definitely exciting to think that we are still evolving and adapting to our environment. It is a testament to the human race’s ability to change and adapt which has led us as far as we are today. Have you noticed any recent changes in your region’s population? Do you see any growing genetic trends in today’s youth?

 

For More:

http://www.wired.com/wiredscience/2009/03/genetic-signatures-of-recent-human-evolution-continued/

http://news.softpedia.com/news/9-Things-You-Did-not-Know-About-Chinese-and-Mongoloid-Race-66420.shtml

http://www.wired.com/wiredscience/2011/10/recent-human-evolution/

http://www.human-evol.cam.ac.uk/Members/Lahr/pubs/YPA-98-41.pdf

Dear Darwin: What Makes Ryan Reynolds “Sexy”?

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On October 17, 2011

In Student Post

Photo Credit: Paco Paco Flickr

Now we all know that a big jaw, prominent brow, and bulging muscles are conventionally thought of as attractive features in a man and that large breasts, an hour-glass figure, and big eyes are attractive in women, but have you ever wondered why?

Well the answer lies in an unexpected place: science. According to the Evolutionary Theory of Attraction, what men and women  perceive to be attractive is actually based on adaptational behaviors that traditionally helped survival. Studies show that women look for masculine features such as a defined jaw, prominent brow, and muscular build because these often to reflect physiological and behavioral traits such as strength, aggression, virility, and a strong immune system, which would be advantageous to pass on to offspring and would mean that the man can provide and protect his family.

So while women’s attraction is rooted in a man’s ability to provide for his family, men on the put more emphasis on signs of fertility and youth. The hour-glass figure: large breasts and “child-bearing” hips, and youthful features such as plump lips, a hip-to-waist ratio of 0.7, a face with a high forehead, good skin, and big eyes are signs to men that the prospective mate is fertile and young. Such features helped ensure the male that his genes would be passed on to his offspring. Other factors such as symmetry, especially facial symmetry, is attractive because it means that there are strong genetics at work according to researchers and experts.

Recent studies show that when a woman chooses a mate, often times she must subconsciously choose between a macho man and his more wimpy counterpart depending on her situation. While the macho man has preferential genes to pass on to offspring, these traits often mean tendency to abandon, hostility, and promiscuity. The less masculine man is more likely to provide the stability, love, and care for a family. In fact, according to expert, Dr. DeBruine’s study, a woman’s environment greatly plays into her attraction between these two types of men. In her study on women in countries with poor health standards, women preferred men with more masculine features more than those who lived in more stable and healthy societies. This is a classic example of natural selection because the women look for healthier genes often associated with masculine, macho attractive men.

So that is why we find movie stars like Angelina Jolie, Brad Bitt, and Ryan Reynolds are attractive: evolutionary adaptations meant to help ensure our survival and the successful passing on of genes to offspring. Do you agree with this theory of attraction? And which category would you put yourselves in ladies, those who go after Mr. Sensitive or those who go after Mr. Dangerous?

 

For more on this go to:

http://www.cnn.com/HEALTH/blogs/paging.dr.gupta/2007/10/evolution-of-attraction.html

http://ezinearticles.com/?Male-Female-Attraction—Evolutionary-Theory&id=2236366

http://wilderdom.com/personality/L7-2EvolutionPersonality.html

http://www.economist.com/node/17672806

http://antimisandry.com/chit-chat-main/sociobiological-theories-attraction-11277.html

http://webspace.ship.edu/cgboer/sociobiology.html

History through Hair

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On October 5, 2011

In Student Post

We all know that DNA makes up who we are and what our bodies are like. But scientists have been trying to do new things with genes and specifically what the sequences of a gene can tell us about our history. DNA becomes mixed when people from different places migrate around the world and reproduce with other people. Because of this, human DNA has become very similar around the world with certain traits being associated with certain areas of the world, but an over all diffusion of most traits.

But recently scientists have found a people who have some how managed to stay isolated for thousands of years. In a recent article in The New York Times, the scientists were finally able to get a lock of hair from one of these Australian Aborigines. When scientists sequenced a lock of hair from an Australian Aborigine, they found that it had “no evidence of European admixture and estimate contamination levels to be below .5%.” This means that the Aborigine’s DNA hasn’t been influenced by any other people around the world since they migrated from Africa to Australia about 50,000 years ago. For these people to have kept themselves isolated for so long is amazing, but it also means that these people’s DNA is one of the closest to links to the human race’s ancestors.

These scientists have tried to use their knowledge about human DNA to figure out how the earliest people migrated from place to place through history. This is limited because DNA has a very random component of what genes get passed on. Also scientists look for mutations which have developed in one group of people that isn’t present in another group of people to see when these people could have diverged in migration in history. This is only a guess becuase mutations are random and so is their frequency. When trying to estimate when things could have happened by using the differences in the number of mutations in DNA, scientists have to make guesses that span around ten thousand years depending on how far back they go.

Scientists have been studying DNA for a very long time. There have been many different ways people have thought of using DNA, some which seem like crazy science fiction such as the movie GATTACA which uses the idea of controlling every bit of a person’s DNA to make them perfect. Then there are the other ones which people might never have thought possible but which are now well known such as cloning an animal by implanting DNA from one animal into another animal’s egg cell. How far can people go with cloning and other DNA research? What other uses does DNA provide?

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