AP Biology class blog for discussing current research in Biology

Tag: Evolution (Page 1 of 2)

Evolution of the Human Gut Microbiome

NIH Image Gallery Image Link

According to an article on Science Daily, Westerners have a very different human gut than hunter-gatherers. Research suggests that Westerners tend to have a less diverse human gut. However, the reason for why is still unclear. Researches from this study have observed two particular groups of people. The hunter-gatherers, known as BaAka pygmies, relied on foods such as fish, fruits, and vegetables. Whereas the group of Westernizers, the Bantu, relied on a market economy. The Bantu grew fruits, other plants and raised goats. They also used antibiotics and therapeutic drugs available.

The results of the study revealed that while the  BaAka and Bantu gut microbes were from similar bacterial species, the abundance of traditional bacterial groups was decreased in the Bantu. When researchers delved into what could have caused the difference between the two groups, they found that diets are the most important driver of microbiome composition in humans.

Another study done by evolutionary biologist, Andrew Moelle, suggests that humans and animals have inherited some bacteria from their ancestors. Moelle studied three types of bacteria living in the feces of wild chimps, bonobos, gorilla and a group of people from Connecticut. He concluded that 2 of the three bacterial trees matched primate relationships. Moelle also expressed how these relationships are getting harder to study due to the effect that industrialization and antibiotics have. They have reduced the diversity of bacteria living in and on humans.  Microbial geneticist, Julia Segre, expressed that humans have been exposed to antibiotics and modern life and as a result, Wild African apes might “still have their ancient gut flora, but the people in Connecticut might not.

A study done by Howard Ochman found that human guts most closely resemble the gut of a gorilla. Like the other researchers, Ochman acknowledges that as a result of modern humans there is a loss of microbial diversity. He also explains how this can be a problem because humans have lost a number of bugs that help digest plant matter. However, humans have gained others that help digest meat.


Beauty is Pain: and naked mole rats have neither

The naked mole rat is the ugly duckling of the rodent family. These small rodents can live up to 32 years, are virtually resistant to cancer, and have evolved to become immune to certain types of pain. Beneath its wrinkled, fleshy surface, the naked mole rat is the closest animal we have to an indestructible species.

A new study published October 11 in Cell Reports offers some reasons behind the rodent’s abilities. Minor evolutionary changes to the amino acids in their pain receptors make the naked mole rat highly insensitive to pain after birth.”We think evolution has selected for this tweak just subtly enough so that the pain signaling becomes non-functional, but not strong enough that it becomes a danger for the animal,” says lead author Gary R. Lewin, a professor at the Max-Delbruck Center for Molecular Medicine in Berlin, Germany.

Much of this is due to the environment and behaviors present in the mole rats life. Naked mole rats often live in large colonies, with up to 300 members. The constant digging of tunnels and over crowding should leave the mole rat in great discomfort, and highly prone to a condition called thermal hyperalgesia. Humans have the same condition, which we generally call heat sensitivity. Imagine entering a hot bathtub with a bad sun burn. When this happens, it’s because sensory receptors on your skin have been chemically “sensitized” by inflammation or high temperatures. Once those receptors are sensitized, even the smallest amount of heat will cause sensory nerves to send signals to the  brain that register this as painful. Naked mole rats lack this reaction.

Through a series of calculated and carefully designed experiments, Lewid and his team were able to pin point what differentiates naked mole rats from all other rodents- a change in their TrkA receptor. They discovered a switch of just one to three amino acid changes on one section of the naked mole rat TrkA receptor that make it less sensitive.

“Even though the naked mole rat’s version of the TrkA receptor is almost identical to that of a mouse or a rat, it has a very significant effect on the animal’s ability to feel pain,” says Lewin. The naked mole rat is built for efficiency. It’s an animal built to survive the toughest of conditions. Evolution has shut down everything that is not necessary in the naked mole rat, including nerve receptors.

In my opinion, the naked mole rat is pretty cool. It has learned to evolve in order to survive. Maybe this trait is why the this species of rodent in particular outlives all of its fellow rodents by over 25 years. My one question would be, “Is the ability to not feel pain always an advantage? Or can this sometimes lead an animal into dangerous situations?” Whatever the answer, the naked mole rat is an evolutionary success.



Evolution: 1, Humans: 0 – HIV Virus has evolved to evade latest gene-editing treatments.

The Human Immunodeficiency Virus (HIV) is notorious for its rapid evolution and elusiveness to our treatments.  Our latest attempt to beat it has been foiled, yet again. As explained in this article, researchers have attempted to eliminate the virus through a genome editing technique called CRISPR-Cas9.  This technique allows scientists to target a specific genetic sequence in a cell to cut, using the Cas9 enzyme and a guiding sequence, and change the function of the gene by inserting corrected/modified sequences.

HIV budding from a Lymphocyte http://

HIV budding from a Lymphocyte
[Picture Source Link]

This highly versatile technique was recently applied to HIV, in an attempt to disable it and prevent further infection from it.  The technique would theoretically delete HIV genetic sequences in an infected cell and prevent further virus production; however, a recent study  shows that the virus evolves rapidly to avoid this treatment.  The fault lies in the fact that the gene-editing technique targets a specific locus on the DNA to modify.  The treatment was successful in destroying HIV genes in that area of the DNA, but the cell’s repair mechanisms allowed the removed HIV genes to be repaired with new sequences.  This means that the new HIV genes will not be targeted by the CRISPR mechanism, because it contains a different marker, and the virus will live long enough to reproduce.  This rapid microevolution demonstrates the power of natural selection: a predator destroys the majority of the population, but those that are adapted to survive the conditions will live long enough to reproduce and pass on its traits! HIV has eluded us once again, but we now know that the gene-editing CRISPR-Cas9 system will work, provided that we don’t miss any HIV loci…

The research looks promising, but will this be our golden ticket?


Original Article: “CRISPR/Cas9 Gene Editing Is Not Good Enough To Beat HIV: What’s Next In Humanity’s Fight Against The Deadly Disease” (Tech Times)

Original Study & Further Reading: “CRISPR/Cas9-Derived Mutations Both Inhibit HIV-1 Replication and Accelerate Viral Escape” (Cell Reports Journal)

Image Source: Wikimedia Commons


Degenerative Evolution?

Myxozoa are tiny parasites that infect fish stock and other aquatic life. Once thought to be unicellular, these multi-celled organisms have recently been analyzed more closely. Containing more than 1300 different species, these highly unusual microorganisms had their DNA sequenced by researchers at the University of Kansas.



Triactinomyxon stage of Myxobolus cerebralis

Myxozoa show many similarities to cnidarians, a phylum that contains jellyfish, corals, and sea anemones. One of the key similarities is the presence of the nematocyst, a weapon or defense mechanism that members of the cnidaria phylum possess. This and other traits were once attributed to convergent evolution. However, this theory was debunked by their gene sequences. On further inspection, these microorganisms are actually tiny jellyfish living on other organisms.

The average cnidarian contains 300 million base pairs. However, Myxozoa have been stripped down to about 20 million base pairs, 15 times less. Despite this reduction in genome size, Myxozoa still contain the genes to express the creation of a nematocyst. These microscopic organisms have one of the smallest animal genomes reported.

The categorization of these organisms is shaking up the foundation of what we can call an “animal.” In the past, animals were classified by whether they had certain genes instrumental in their development such as Hox genes, genes that influence body structure. Myxozoa have no such gene. Since organisms are also classified based on their ancestors, this fumbles the system.

Because of this discovery, scientists are questioning whether this type of backwards evolution from a macro-organism to microorganism is more common than we think. Other microscopic organisms could potentially become “animals” as a result.

This also opens a gate to greater understanding of the organisms in our aquaculture. Many fish are affected by the parasitic nature of Myxozoa.

Next time you eat salmon, notice that you could also unknowingly be eating tiny parasitic jellyfish.

Original Article

The Immaculate Conceptions: Smalltooth Sawfish Experiencing Virgin Births


From Flickr

Chances are you have never heard of the Smalltooth Sawfish, an endangered species most commonly found off the western cost of Florida. These creatures grow to be as long as 25 feet, but their is more that is impressive about these fish than their shockingly large size. Recent studies have shown that around 3% of Smalltooth reproduce asexually, a virgin birth. This is the first hard evidence that birth of parthenogens, offspring born of asexual reproduction, happens in nature. This speaks to the adaptability of life, scientist Demian Chapman, says that it makes sense that endangered species would be the ones most commonly reproducing asexually, “that life finds a way”. This discovery was made when researchers tagged and sampled DNA from around 190 Sawfish, which lead to the discovery of 7 parthenogens.

Scientist hypothesize that during meiosis, sex cells fused together to form offspring. Incredibly, all seven of the parthenogens are fully healthy and functioning, and seem to be viable sexual partners. This “suggests that parthenogens are not a dead end” that this “extreme form of inbreeding” does not lead to any serious defects. Unfortunately, Smalltooth Sawfish are on the verge of extinction due to human interference in their natural habitat. Although the Sawfish are able to reproduce asexually, the occurrence rate is too small to sustain a viable number of Sawfish to save them from extinction, but raising awareness of the issue could be the key to saving these magnificent creatures.


Original Article

Sawfish Extinction

More Examples of Parthenogens in Nature

Smallest Komodo Dragon Out There.

Most everyone knows that Komodo Dragons are the largest lizards on the planet. Surprisingly, humans have only known about these lizards for about 100 years. But thats nothing compared to the newest discovery of a very very small relative of the Komodo dragon. (original article)

These lizards, about the length of a human hand and very skinny, are about as small as the Komodo’s are big. They are even smaller than the pygmy goanna (the short-tailed monitor, V. brevicauda), which, until now, was believed to be the smallest relative of the Komodo Dragon. These new tiny dragons are shorter, thinner, and more boldly colored than the pygmy goanna. It is believed that around the same time chimpanzees and humans begun to separately evolve (between six million and seven million years ago) the pygmy and the newest lizard edition began to evolve separately. Gillenibaumann_01

These little lizards were discovered in Australia, the home of their slightly pygmy goanna larger relatives. Some females can now be seen in the Western Australian Museum in Welshpool. These lizards have yet to be named, but have been nicknamed “Pokey”.

It’s the little discoveries like these that make us realize how much more we still have to learn and discover about our planet. The planet is so vast that in our relatively short period of time here, there is no way we have a full understanding of the creatures we share the earth with!

Proteins Keeping Fishes Alive



Words To Know:

notothenoids: the arctic ice fish

practical application: how organisms adapt through natural selection

superheating: solid is above its melting point but does not actually it to melt at this point


     Fish in Antarctica have been forced to evolve natural antifreeze proteins to stay alive.  These proteins are mainly found in the notothenoid fishes, which are found in freezing temperatures. Arthur DeVries discovered these fish, their ice- binding-proteins and also figured out how they work in the 1960s . The proteins bind to small crystals and also protect cells by binding to their cell membranes. They are anti-freezing proteins that allow fish to survive and adapt to harsh and cold conditions of arctic waters.

Recent Discoveries:

          Paul Cziko, among other researchers in the United States and New Zealand, published in The Proceedings of the National Academy of Sciences that these ‘anti freeze’ proteins’ are also ‘anti melting’. Cziko and his team wanted to understand the antifreeze ability and examined if an anti-freeze protein (that was attached to an ice crystal inside the fish) would melt when the temperature rose. Instead, they found that the ice crystals did not melt. Ice above the melting is point is considered superheated. Cziko’s research basically says that even when it is way past its melting point, the ice (that’s latched on to the protein) still stays frozen inside the fish. These ‘anti-freezing’ proteins are also ‘anti-melting’ proteins that cause ice crystals to accumulate in the fish’s body.

The study shows evolution, not practical application, and this is a typical case of ‘evolutionary trade off’. There are difficulties that get solved, but there’s also a price to pay. Cziko’s research has not indicated any unfavorable effect due to the crystals, but the crystals could potentially block up the blood vessels of the fish and provoke an inflammatory reaction.

Personal Statement: 

      Personally, I really liked the NY Times article. I actually didn’t realize that we had to find additional articles until I re-read the assignment sheet. I found other articles because I was genuinely curious as to how this worked and came about. I was initially attracted to the word ‘protein’ in the article’ title -since it relates to what we are learning in class- but stayed because of the evolutionary aspect. It has always been hard for me to think of evolution as something. It is such a difficult-to-grasp concept since you can’t really see it happening . But, in some way- this made me think that I did see evolution. Instead of making me think of evolution as a concept or theory that I learn at school, it made me think of it as a reality, and as something that actually happens.     

Original Article:

Additional Article:

Additional Article:

The Cambrian Explosion: An Evolutionary Arms Race



About two weeks ago I dropped in on a freshman Biology class on a college visit.  The professor was giving a lecture on something called “The Cambrian Explosion”, something I’d never heard of.  He described the “explosion” as an evolutionary arms race, a period in which the evolutionary process; the diversification of organisms accelerated from 0 to 60 in a “relative blink.”  Needless to say, the lecture piqued my interest, and so I searched the web for some more insight on the curious “explosion.”  I found a great article  from the innovative science blog by Brooke Borel called “The Greatest Animal War”. Borel’s article gave me a better idea of what the Cambrian Explosion was all about.

mouth piece

Pictured is a Cambrian Age fossil of Anomalocaris canadensis from the Burgess Shale Formation.  The fossil preserves the mouthpiece of the organism in great detail, and the mouthpiece itself serves as evidence of useful trait acquired during the Cambrian Explosion.




Above is the grasping claw of the very same Anamolacris canadensis from the Burgess Shale.  The claw is just another evolutionary tool used by the organism to predate and survive.



Scientists interpret the earliest fossil records (which date from about 580 million years ago) as evidence that early organisms were small, simple, and… soft.  The fossil record shows these early life forms to be defenseless and apparently harmless, lacking the “claws, teeth, limbs, or brains” that are characteristic of competitive, modern organisms (organisms that require these features to survive.)  Mysteriously, around roughly 542 million years ago evolution sped up, and so began what Borel describes as a “period of unprecedented one-upmanship.”  Organisms developed all sorts of mechanisms from eyes; to spikes in order compete with their rapidly diversifying and evolving contemporaries.  According to the nautilus article “most of today’s 30 to 40 animal phyla originated in the Cambrian, and have persisted through time with hundreds of variations on a theme.”  Meaning, that the majority of the ancestors of modern organisms all developed in this 54 million year span.

Now where the University Professor and Borel diverged was on the answer to the questions of “what caused this evolutionary arms race? and “Why did it take an extra billion and a half years for the first eukaryotic organisms to arrive?”  The professor was reluctant to commit to any theory that attempted to answer those questions, having to repeat the phrase “well, we just can’t know for sure,” in response to questions throughout the lecture.  Borel however is more definite in her answer, stating “certainly, the environment around the time of the Cambrian encouraged the explosion as well.  Oxygen had accumulated in the oceans after extreme ice ages… with plentiful oxygen, animals could grow large and absorb the air they needed to breathe through their skin.”  The lack of a definitive answer as to why the Cambrian Explosion occurred hardly undermines its significance as an unprecedented explosion of diversity that has never been repeated in Earth’s history.  The mystery shrouding its roots makes it all the more curious and exciting a topic to read about.







Where Does Language Come From?

Somewhere in Britain, there is a family where each member has varied speech difficulties. Some members can’t say words like “hippopotamus”, others have trouble reciting words that begin with the same letter. This family, known as the KE family, was subject to research by Oxford University in the early 2000’s to find that they had a rare gene mutation. The subtle mutation took place in the FOXP2 gene, where only one nucleotide was misplaced. However, this research has opened up the world to the search for the so called “language gene” in our bodies.


There are approximately 6,900 languages in existence today.

For a while, scientists thought that the FOXP2 gene was the “language gene” in our bodies. But further tests show that the gene has much broader capabilities in humans and other animals, such as mice. This evidence suggests that there is no one language gene but instead it relies on a much broader neural support system. With the existence of a language gene being much less concrete, understanding where language originates from becomes much more difficult. A 2010 study by neuroscientist Aldo Faisal showed that what led humans from making stone flakes to axes was a shift in cognitive capacity, not an improvement in physical coordination. Researchers believe that as toolmaking became more common in the world, humans may have acquired the mental capacity for language. Liverpool archaeologist Natalie Uomini says: “A lot of people would say that toolmaking came [before language], I would just say that they co-evolved.” 

Liverpool archeologist Simon Kirby takes a different perspective on the origin of language, arguing that the human brain alone is not enough to explain language and that we must look at the evolution of human culture as well. Through several experiments with fictional languages, Kirby has found that as a language passes from one person to the next, it develops a unique structure and evolves in such a way that participants could guess words that they weren’t even trained to know. This shows that there is a lot more than just brain function in the evolution language. There is a huge social component, and this makes the discovery of language’s origin even messier than originally thought.

The fact that such an integral part of our society is still relatively unknown biologically is fascinating, and many breakthroughs in this topic have been made within the last 5 years. What’s fascinating about the search for language is that it shows that as modern science progresses, we may not find the answer to the question that we asked, but instead find a whole new set of questions that we would never have thought to ask. What do you think about the origin language? Did it come to fruition before or after toolmaking? Leave your thoughts in the comments section below, thanks for reading!




From Fin to Foot

It is widely understood in the scientific community that, at some point, life evolved from aquatic to terrestrial. In that evolution, at some point fish must have evolved into amphibians. The question of this evolutionary jump still remains a mystery, but the discovery of a new fossil has shed new light on the issue, filling in some of the many gaps in this evolutionary story. This new fossil, discovered in Canada was of the Tiktaalik, a proto-amphibian of the Devonian period. Although this species was not necessarily a new find, it was a complete fossil. Prior to the discovery of this specific fossil scientists only had the front half of the Tiktaalik fossil, and as such could only speculate about its back half. The accepted evolutionary story at the time was that front legs developed first as the power behind walking on land, with back legs functioning only as weak supports. However, this new fossil was fully complete and showed a highly developed pair of back legs with a very developed pelvis, quite unlike any found. Although the bones in the fishes back leg were not as complicated as those of modern amphibians, they were far more advanced than the average fish of the time and more advanced than the widely accepted belief of the scientific community had suggested. This Tiktaalik fossil discovered by Dr. Neil Shubin, has fascinated the scientific community, as it is a great example of a creature exhibiting a myriad of evolutionary changes. Although the bone structure development here still favors the fin, there is astounding development in both the fore and hind legs that show that mark this creature as a key link between aquatic and terrestrial life.

This image of the Tiktaalik shows an artists representation of the creature before its powerful hind were discovered

Big Cats of the Past

A snow leopard at the Toronto Zoo The snow leopard is the closest living relative to the Panthera blytheae

In Tibet in 2010  Z. Jack Tseng and Juan Liu travelled to a remote section of the Tibetan Plateau. Whilst there they came across a collection of prehistoric fossils, mostly antelope and other known herbivores, with one notable exception, the skull of a previously undiscovered big cat which they called Panthera blytheae. This skull and the accompanying jawbone fragments belong to what is now, to date, the oldest known big cat. After analysis of its teeth, it has been theorized that this cat would have been quite similar in habitat and hunting style to the modern snow leopard. “In terms of the overall size it would be a little bit smaller than a snow leopard– the size of a clouded leopard and those living cats grow up to around 20kg [44lb],” said Jack Tseng, the discoverer.

Skull of a snow leopard, which is very similar to the skull of the newly found Panthera blytheae

This discovery is quite significant with regards to big cat evolutionary history. Current experts hold that big cats broke from the main felinea subfamily some time around 6.37 million years ago. However, until this find, the oldest big cat fossil was a 3.5 million year old fossil from Tanzania. P. blytheae not only pushes the date back almost two million years, being estimated to have lived between 4.10 and 5.95 million years ago, but also gave weight to the theory that big cats originated first in Asia, not in Africa. Anjali Goswami, a palaeobiologist at University College London said, “This beautiful fossil supports the Asian origin for the group, bringing together molecular, living and fossil data into a unified view of pantherine evolution. It also supports the idea that the Tibetan plateau was, and remains, an important biogeographic region for large mammals and is the center of origin for many important groups. Nailing down the place of origin for pantherines also means that we can better understand the environmental and ecological context in which this group evolved.”

New Prehistoric Fish Discovery to Change How We View Our Evolutionary History?

a reconstruction of Entelognathus Primordialis

Prior to now, it has been accepted as common knowledge that cartilaginous fish predate bony fish in the ancient parts of the evolutionary family tree. As a result, it has been generally assumed that the earliest fish with jaws would have something fairly closely resembling that of a shark, as sharks are accepted to be on of the most ancient of vertebrates. However, the recent discovery of Entelognathus Primordialis in China may cause us to question these long held beliefs and assumptions.


This armored, toothless fish, may be up to 419 Million years old. Making it one of, if not the earliest vertebrate to be discovered to date, and it’s discovery throws a wrench in our image of what our prehistoric ancestors looked like. Entelognathus, rather than being a sleek, sharklike cartilaginous fish, is bony, with many small plates making up it’s skull and jaw. This skeletal template is something found in all land-dwelling vertebrates in modern day, leading scientists to theorize that rather than bony skeletons evolving from cartilaginous ones. it may have happened the other way around. Making our armored ancestors potentially more ancient than sharks’ more scaly predecessors.


We used to be shrews!?!

Ever think where did we come from?  Well, one answer to that could be evolution. While it is not yet a proven fact, it is a theory that shows promise to be true.

Experts on the matter of evolution “recorded 4,500 physical traits for 86 mammalian species, including 40 that are now extinct.”  Using this information in tandem with DNA samples, the experts were able to figure out the probable start of placental mammals.  One of the findings was that the rise of placental mammals came after the dinosaurs had become extinct.  This was an earlier hypothesis that was now confirmed. The death of the Dinosaurs would allow for mammals to fill the top of the food chain where the dinosaurs once stood.  Less competition makes it easier to rise to the top.  Dr. Jonathan Bloch, who works at the Florida museum of Natural history, said “This gives us a new perspective of how major change can influence the history of life, like the extinction of the dinosaurs. This was a major event in Earth’s history that potentially then results in setting the framework for the entire ordinal diversification of mammals, including our own very distant ancestors.”

I think this is incredibly cool how all species could be related to one primal and ancient ancestor.  It shows how we are all linked in some way.

What do you guys think on the matter?


The Purpose of Pruney Fingers

The Finger Phenomenon

After spending a lengthy period in water, you may notice a particular phenomenon occur – wrinkled fingers and toes! A common misconception is that pruney digits are caused by water soaking into our skin, presumably by osmosis. In reality, furrowing in our fingers is caused by constricting blood vessels by the nervous system. But what could be the evolutionary purpose?

One hypothesis in 2011 was that that grooves in wet fingers would allow humans to grip surfaces more easily. Newcastle University researchers in England tested this theory, recording the time it took for subjects to move objects with dry fingers and with wet fingers. Every subject moved objects faster with wet fingers, suggesting that furrowed fingers can better handle moist items – an evolutionary advantage.

However, the study has not revealed how furrows improve grip. Neurobiologist Changizi from Idaho states that there may be other factors for improved grip, such as stickiness or oils. Scientists posit that the furrows may cause friction or increase flexibility. They also put forward a possible disadvantage of having pruney skin: grooves may decrease sensitivity or get caught on things. Further research to come!

What do you think about these theories?


Guts or Glory?

According to Aristotle, what separates man from beasts is his ability to reason. Humans have this luxury because of their large brains, but it comes at a price; guts! Scientists have long imagined that big brains come with an evolutionary cost and up until a recent study, it was all theory.

A Swedish team of researchers, led by Niclas Kolm decided to put this theory, known as the “expensive tissue hypothesis”, to the test. The hypothesis basically states that there is a trade-off between the demands of the brain and the demands of other organs. So, to prove this theory, the team selectively bred common guppies to produce bigger (or smaller) brains. They were able to produce brains that were as much as 9.3 percent larger. The bigger brained fish tended to have smaller guts, as well as produce fewer offspring.

The experiment tested 48 guppies using an underwater arithmetic test to see if the guppies (with large brains) possessed greater cerebral capabilities. It worked! The “smart” fish were more successful at learning and recognizing geometric shapes, that were on a door, in order to get to the food on the other side.

Where these “brainy” fish lost ground, was in the gut division. Males were found to have a 20 precent decrease and females an 8 percent decrease in gut size. Brainier fish(females) were found to produce 19 percent less offspring than the smaller brained fish. This evidence implies that larger brains may be the cause of smaller broods.

Even though the evidence pretty clearly supports the “expensive tissue hypothesis”, Kolm and his team have not completely ruled out the “genetic mechanism for the trade-off”. It is not obvious whether small guts or big brains develop first.

We Need Mosquitoes?!

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

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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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:…/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.


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Crocodiles…They Can Take Down a T-Rex

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

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.

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