Zimmer 6-7

by snowcat
In chapter six Zimmer begins by Culvier’s work on mammal’s teeth and how they are important in identifying species of animals. When Harlan brought his Basilosaurus, which was thought to be a giant reptile, to London Owen concluded it was a giant mammal. He was able to make this assertion because the Basilosaurus had the same pattern of teeth seen in marine mammals. Koch on the other hand was an example of scientists losing sight of what is important. He put together a fossil from five different animals called it a sea serpent and named it the Missourium. Fortunately true scientists did discredit him. Although Flower was just speculating, he was able to correctly guess the origin of whales. He said he believed that their ancestors were conventional land mammals and they were not a close relative to seals. Synapsids which were the earliest amniotes to become successful on land became that way largely because they evolved a new way to eat. They changed their jaws, muscles, and teeth so they would be able to slice food it the front of their mouth and chew it in the back. They also gained the ability to chew and breathe at the same time by evolving a nasal passage at the back of the mouth.

He begins talking about Gingerich in chapter seven, a paleontologist who never suspected he would be studying whales. Gingerich had an interest in land mammals and only ended up studying whales because he found Pakicetus, an early whale too extraordinary to ignore. From that time on Gingerich became obsessed with whales. When working on a Basilosaurus fossil Gingerich discovered legs. When a leg was found on a Canadian whale the leg is known as an atavism. Atavisms used to be discarded as freaks of nature by biologists, but it is now known that they are a mechanism by which evolution can occur. They can also be a step back into the past lineage of an organism. Another interesting idea is how tetrapods lose their legs. It might seem like they no longer use their legs and the legs waste away to nothing, this is not the case though. In order to lose their legs they must first elongate their bodies all the while stretching out and changing their organs, and then evolve a way of moving like a snake. It is also a fallacy to believe that an animal gives up a structure just because they have become useless. A fish could not go blind without gaining a new sensory organ, in this case lateral lines.

Zimmer 5

by snowcat
Zimmer begins chapter five by asking how we can trace cetaceans’ ancestors back to land. The cetaceans are divided into two suborders: the mysticetes that have baleen and the odontocetes that have teeth. How dolphins swim has been studied by many scientists. They swim very efficiently and are propelled forward both on their upstroke and downstroke of the tail. Another interesting thing about dolphins is how they maintain their fertility. In theory dolphins should be overheating their gonads because of all the heat generated by swimming, but what actually happens is they reroute their circulation so that the gonads are actually cooled by swimming. It is thought that dolphins might swim by acting like a spring, but this has not been shown to be true conclusively. Blubber acts as evidence in support of the spring movement because it is shown to have a resilience value of 87%. A dolphin’s ability to echolocate is a very important innovation. Cranford wanted to study the anatomy of a dolphin involved in echolocation so he decided to make thin slices of the head and photograph the slices and scan the pictures into a computer which would then give him ability to visualize the structure in 3D. This method was not very useful or successful, but luckily he did a CT scan which turned out to be very useful. He found that the air is pumped by the larynx, through the nasal passage, and past the monkey lips which vibrate as the air passes through them. The air is not passed out through the blowhole though. It is brought back down into the nose so it can be used again. A dolphin’s ears are very different structurally from a land mammal’s ears. A dolphin’s ear is separated from its skull and is surrounded by pockets of foam and air. This prevents the dolphin from being confused about where sounds are originating from. The power of echolocation is amazing. Dolphins are able to tell if a ball is present from over 100 yards away, distinguish between different shapes of objects, and tell the difference between different types of metals. Dolphins are also able to understand commands from humans. If a trained dolphin is told RIGHT HOOP LEFT FRISBEE FETCH the dolphin will get the frisbee that is on its left and bring it to the hoop on its right. This suggests that the dolphins are able to understand abstract representations of things and their relationships to other things.

Zimmer 3-4

by snowcat
Zimmer begins chapter three by asking how do you make a hand. Owen thought that limbs were based on a vertebrate archetype. Darwin on the other hand said that the homology of the limbs was due to the fact they came from a common ancestor. Embryos start off as limbless and the kidneys signal for cells to congregate and form limb buds. The formation of the limb occurs at the apical ectodermal ridge. The tissues are differentiated into cartilage and connective tissue and blood vessels bring bone-generating cells to the tissue. Muscles and tendons attach to the bones and stretch as the bones grow. Finally one of the most important steps occurs; cell death carves out the digits of the hand. Shubin and Alberch showed that there is a homology of growth in limbs and the size of the limb influenced the amount of digits formed. Shubin was able to study a large sample size of rough-skinned newts because of a freak freeze of a California pond. He found that almost a third of the newts had some sort of limb deformity. These variations were almost always attributed to branching limb pattern described by Shubin and Alberch.

Chapter five begins by describing Clack’s research on the development of ears. Nineteenth century embryologists found that the stapes in the human ear corresponds to the hyomandibular in fish. Clack discovered a small stapes in the Acanthostega which showed that the hyomandibular shrunk as tetrapods developed a new form of eating. Cladograms can be used to show how evolution of breathing might have occurred. Lungfish used a double mouth pump, amphibians used the double mouth pump in addition to ribs for exhalation, and amniotes used ribs for inhalation and exhalation. In order for amniotes to be able to come on to land several things needed to happen. Instead of the egg being made of jelly and being susceptible to drying out, it needed membranes. It was also necessary for the amniotes to be able to conserve water through its intestines. Amniotes also needed to evolve grinding teeth and large jaws in order to eat plants, as well as allowing bacteria into its gut to extract as many nutrients as possible from the plants and to break down cellulose. It was also an advantage for these early herbivores to grow large in order to be less threatened by predators. It thought that the amniotic eggs are the reason that terrestrial herbivores were able to evolve, without them they would be stuck in the water.

Carroll 10-11

by snowcat
In chapter 10 Carroll discusses the evolution of humans. Some of the important features we have evolved are bipedalism, our larger brain, speech, and language. In order for us to evolve bipedal locomotion changes had to be made in the vertebral column, pelvis, feet and limb proportions, not one simple change could allow for bipedalism. An important discovery in Tanzania was of two sets of footprints that showed two of our ancestors walking upright. An interesting point about our Neanderthal relatives is that they had a larger brain than us, and for some unexplained reason we survived and they died out. One of the important factors in the evolution of the brain seems to be the neocortex which is much larger in primates than in other mammals. New centers have also evolved, for example in primates there is a region called the ventral premotor area and this is turned on during visually guided movements. Another important region of the brain is Broca’s area which is found in human brains and is important in speech and language. One anatomical feature of Broca’s area is that it is larger on the left hemisphere of the brain; evidence of this asymmetry has also been found in great apes which suggests that the common ancestor of humans and great apes had this asymmetry.

Carroll begins chapter eleven by talking about how Darwin chose to word the concluding paragraph of Origin of the Species and how the words he chose for this book “endless forms most beautiful” remain unchanged throughout the book. Carroll states that Evo Devo is a cornerstone for a more modern synthesis. Many different types of animal forms are created using the same basic toolkit. Also many different organs and structures in various animals use the basic genetic components controlling their formation. He also states how switches are very important in creating large amounts of complexity and diversity. He credits microevolution as the vehicle for macroevolution stating the continuity of the tool kit and structures in many organisms throughout time as evidence. Then Carroll discusses how evolution is much more of a controversy in the US then other countries and how many Americans are clueless about even the most basic principles of biology. He concludes his book by talking about human settlement has often led to the demise of several species of animals. From Van Diemen’s land tiger and the Tasmanian wolf to the dodos of Mauritius human settlement has often decreased the diversity of animals. Carroll concludes by asking if we will do something to stop the loss of diversity.

Book Review

by Gladys
Overall I enjoyed At the Waters Edge much more than I enjoyed Endless Forms. I thought that Zimmers book was a much more interesting read. Since the author presented it as a story, it makes the new fossil discoveries much more exciting. There are characters. We learn little personal facts about the scientist we hear about rather than just names and dates. For me, this makes remembering the names and dates more interesting. I also enjoyed the way the book focused on one category. While it was a broad category, by the end I thought it was all tied together nicely. I especially liked the X analogy. Describing how terrestrial animals were sliding down one side toward the sea, and aquatic creatures were crawling up the other side onto dry land. While smaller aspects of development were discussed in the book, they all related to the topic expressed in the title.
Personally, I did not enjoy Carrolls book as much. I found the level of explaination awkward. I thought for some chapters, there was too much explaination of some very general biological concepts, while in other chapters it seemed assumed the reader was an well educated biologist. I enjoyed much more the personal stories that Carroll put into the book and the data presented that was collected from his own lab. Perhaps this should be a signal to myself that I enjoy storybooks rather than pop-science.

Review of Carroll and Zimmer

by snowcat
Overall I liked both books. Carroll’s book was strong in describing the biology behind development, but at times it was not an easy read. It was definitely written at level where an understanding of basic biology is a must. Although the topics were often complex I feel that he did a good job of trying to make them easier to understand. Since this is a 4000 level course, I believe it is a suitable book for the course even if it is a difficult read at times. Other things I enjoyed about Carroll’s book were the pictures scattered through it as well as the illustrations at the beginning of every chapter. I thought the use of illustrations and quotations at the beginning of every chapter was interesting and was especially appropriate for a book used in a liberal arts college. Zimmer’s book was easier to read with less scientific background necessary to understand most of it. Something that I really enjoyed about this book was how it discussed the people who made different discoveries and what led them down those paths. The history of the various discoveries made them much more interesting as well as creating a much better picture of how science “happens.” This book also used pictures to help to show what various animals might have looked like, this was helpful in allowing you to view an extinct species as more than a latin name. I also felt the cladograms where also very helpful in thinking about the history of a species of animal. In conclusion I think both books were very informative and interesting. They also had very different styles of prose which is nice because it helps you to see the different ways people write about biology.

Chapter 10

by snowcat
Zimmer concludes his book with a chapter discussing macroevolution. He explains although fish and whales both live in the same environment, they have different strategies for doing so. Whales do not swim like fish, but use an adaptation of the mammalian gait in the water. Since whales did not have a fish’s lateral lines to rely on they needed to keep their terrestrial sense organs such as ears in working order. He suggests that the expansion of whales into the ocean was due to the fact that it was a wide open niche. Gould and Eldredge came up with a hypothesis called punctuated equilibrium to describe how macroevolution occurs. This hypothesis says that most adaptations to a species occur as the species is originating, not during its lifetime. It used to be thought that mosasaurs became extinct 65 million years ago without evolving into any new forms. Debraga and Carroll showed that this was not the case. Mosasaurs evolved into amphibious crocodilelike animals over the period of 65 million years. They also found that rate of evolution was slow during the ancestors of mosasaurs increased during their origin and slowed down again after their origin. They also found that the most important adaptations to water occurred long after the mosasaurs became committed to living in the water.

Comparative Review

by AmandaD
Overall I enjoyed reading both At the Water's Edge and Endless Forms Most Beautiful, but Zimmer's book had the kind of delightful details that made the story telling unique. The kinds of metaphors that Zimmer used were playful. In just this last chapter, he compares Hox genes to ancient dictators, microbe genes to business cards, and anatomical changes to a fugue. My favorite quote from the book is: "Think of teeth as furniture: condylarths had plain Mission style, and living ungulates have evolved them into Rococco." Carroll, on the other hand, is not so playful. His metaphors are less accurate are from the kind of mind preoccupied with science, computers, and math. While he did write a nice technical piece, it lacked joy and far transfer.

Plesiosaur bones found in Antarctica

by Esperanza
Scientists reported today that bones from a baby plesiosaur were recovered from an Antarctic island. The researchers said the animal's stomach area was well-preserved, including forked ribs, sometimes into three prongs, and numerous small, rounded stomach stones probably used to help maintain buoyancy or to aid digestion. The new fossil is one of the most complete of its type ever found. The skeleton was found in an area covered with volcanic ash, leading them to speculate that the plesiosaur was killed in an eruption, either by the blast or by ash dumped in the ocean.

Link for squirrel article

by Esperanza
Here's the link for that article

Contraceptive for squirrel

by Esperanza
The gray squirrel, which was introduced to Britain from the US in the 19th century, is now overrunning the countryside, out-breeding and out-eating its smaller British cousin, the red squirrel. The red squirrel only numbers 160,000 in the wild while the gray squirrel is up to 3 million and rising. Scientists are now experimenting with a fertility control agent to try to control the population and allow the indigenous red squirrel to make a comeback. Lethal control is currently the only way they have of controlling the gray squirrel population so an alternative method is favorable to many.

Ch. 10 of Zimmer

by Esperanza
Chapter ten closes the book with a discussion about the macroevolution of whales. Zimmer compares whales to the earliest tetrapods. He considers Acanthostega and Ambulocetus surprisingly alike. They both were ambush hunters living in shallow water. They both had long, flat heads, snapping jaws, short limbs, and powerful tails. The whales and early tetrapods both began with a minor group of animals that were probing around the edges of a new ecosystem and evolved new adaptations for their immediate conditions. These adaptations later turned out to be more exaptations for their continued evolution. They both stumbled into empty terrain and capitalized on it. The whales had the terrain of an ocean robbed of its giant marine reptiles and the early tetrapods had continents without a single vertebrate on them. Scientists argue over whether evolution happened gradually or in great leaps. The most important adaptations that the whales accumulated for water came only after they had committed themselves totally to the sea.

I enjoyed both of the books read for this class. Zimmer’s book was more enjoyable to me though as it was more a history book so it flowed. Carroll’s book was more informative on development as it actually spoke or genes and how they interact. I felt that Zimmer knew how to capture an audience’s attention better or at least an audience that didn’t have a basic understanding of biology already. Carroll’s book needed a background in biology to understand quite a bit of it yet he also explained some things for those who didn’t know biology when they wouldn’t understand the majority of the book anyway. Both books were helpful in understanding developmental biology, however, and I think they are a good addition to the class.

Zimmer ch 10

by dreamingtree
In chapter 10 of “At the Water’s Edge”, Carl Zimmer explores the macroevolution of whales and tetrapods. In less than 15 million years a hoofed land mammal evolved into the whale, and a lobe-fin evolved into a sturdy-limbed, tetrapod with no gills. Both whales and early tetrapod evolution began with animals exploring the edges of a new ecosystem; the costal wetlands of the Devonain or the shores of the shallow, Tethys Sea. New adaptations arose, allowing those animals to better survive in those conditions. Zimmer used the analogy of an X to illustrate the origins of the first tetrapod and whales and their similarities and differences. Mesonychidlike ancestors of the whale are on the top left tip and lobe-fins are at the bottom left tip. Both ancestors evolved along their axis to their current respective habitats. At the middle of the X Acanthostega and Amulocetus crossed paths. They were surprisingly similar; both animals hunted in shallow water, had long flat heads with snapping jaws, short limbs and strong tails. Farther along, the whale Dorudon is similar to the lobe-fin Eusthenopteron. There is also a debate between scientists about whether the evolution of whales and tetrapods occurred gradually or by punctuated equilibrium. It seems that some changes happen rapidly, while others happen more slowly.

Both “At the Water’s Edge” and “Endless Forms Most Beautiful”, were interesting to read. Carroll’s book had an Evo Devo opinion on development and talked mostly about how genes produced animals and they were responsible for their characteristics. Zimmer gave more of a history of the evolution of animals, in particular tetrapods and whales. The books tied into lecture and expanded on the ideas we were learning about, as well as introduce new ideas that helped give a good overall perspective on developmental biology. I learned a lot from both these books. I enjoyed talking about them in class discussion and it was very useful to write a summary each week and read other students’ summaries. I liked Zimmer’s book better since it was more of a story and he is a better writer than Carroll. I knew that whales evolved from a land mammal but it was really interesting to read the entire story. I would recommend keeping these books in class.

Zimmer Ch. 10 and Review of Both Books

by Stealth
In chapter ten of Carl Zimmer’s book, “At the Water’s Edge,” Zimmer takes main concepts of the book that were previously discussed and ties them together. Zimmer also introduces punctuated equilibrium that refers to species changing when they originate and not during the course of their life. We also learn about the mosasaurs which were giant reptiles that are related to some lizards that exist today. The mosasaurs lived in the waters off the coasts and then made a move to come on to land. Over the course of time they evolved to become better adapted to land. Eventually three different families of mosasaurs were formed. From there they lived until on day their kind went extinct. This allowed for the whales to do well in the oceans. This is because when whales did go into the ocean fulltime, they had great reward because nothing else was there except a vast quantity of food waiting to be eaten. Another topic covered in this is macroevolution, which are the large scale changes that occur over time. To demonstrate this, Carl talks about the changes that occurred that allowed whales to become descendants of mesonychids.

When looking at both that we have read this semester side by side, I would have to say that I enjoyed reading both books. Sean B. Carroll’s book, “Endless Forms Most Beautiful” was more like a science text book while Carl Zimmer’s book, “At the Water’s Edge” seemed more like a history book. Carroll’s book did a good job of covering topics associated with Evo Devo by giving good explanations of things like Hox proteins and the development of strips on organisms. Zimmer also did a good job by walking the reader through the evolution of whales and explaining what happened along the way along with giving the reader a better perspective of the transitions made by organisms between land and water. For both books the class discussion definitely helped me make sense of the topics that I did not understand and it was also nice that Myers also add the topics ideas and facts that were not talked about in the books. Both were very well written and very informative and worked well for this class and I would recommend keeping them and using them for the next class.

More Good News for Stem Cells

by Stealth
Here is another interesting article that talks about how some new research in stem cells and how stem cells were able to prevent tumors. Until recently, people had wondered that because stem cells are undifferentiated, they might lead to tumor formation. But a recent study done showed that when both mice and human embryonic stem cells were placed in a microcapsule made of alginate (which is made from seaweed); they actually prevented tumors from forming. They showed this by placing the stem cells (which were in a capsule) into lab animals. At the same time the research group also showed that the differentiating of the stem cells is not stopped by them being encapsulated. All of this was good news for those in Australia, because it helps get rid of some bumps that might be in the way of the new human embryo cloning legislation that just passed very recently in Australia.

The Key to Finding New Cures?

by Stealth
Here is an interesting article that talks about how the genome of a sea urchin is very similar to that of humans and how sea urchins may hold the keys to finding cures for diseases as well as preventing them. Researchers at the Sea Urchin Sequencing Group, have not to long ago, completed the sequencing of the sea urchin genome. They found that the purple sea urchin has 23,300 genes. Of these 23,300 genes, purple sea urchins have 7,000 genes in common with us humans. The really cool thing though is that they share the some of the same genes that are known to be linked to Parkinson’s and Alzheimer’s disease to name a few. Unlike humans, sea urchins only have one type of immune system and that is the one they are born with. This is significant because some sea urchins can live for a very long time and in order to do so they must have a very strong immune system. In fact it is 10 to 20 times larger than humans in terms of genes. With this scientists, hope to find new antibiotics and agents that they can use to fight off viruses

Development Take-Home Exam #3

by PZ Myers

Due 21 December 2006 (or earlier!)

Write a two to three page, single-spaced essay on the questions below that succinctly summarizes your main ideas on the topic. Three pages is an absolute upper limit on the length; these are big questions, but I expect you to exercise discrimination and practice brevity in delivering the answers.

You can and should work on the research with other students, but you must do the actual organization and writing of the essay itself on your own.

Everyone must answer this question:

1. Read this paper:

Sanchez-Soriano N, Prokop A. (2005) The Influence of Pioneer Neurons on a Growing Motor Nerve in Drosophila Requires the Neural Cell Adhesion Molecule Homolog FasciclinII. J Neurosci 25(1):78-87.

Write a summary. Be sure to explain the experiments and their results in sufficient detail that we can understand how the authors come to their conclusions.

Pick two of the following three questions to answer.

2. I talked to you about morphogenesis in complex multi-cellular animals, and the various processes involved in signaling, adhesion, migration, and tissue-level shape changes. Get simpler. Tell me about the morphogenetic events in slime mold aggregation and differentiation, and relate them to the developmental processes in metazoans..

3. The development of commissural pathways is a special case in neurodevelopment. Explain how pathways that cross the midline are set up in vertebrates Tell me all about netrins, robo, slit, and any other molecules you think are important in establishing these pathways, and how they work; also outline the relevant tissue level organization of the CNS—what is the floorplate and roofplate?.

4. Compare and contrast the general principles of the development of plants vs. animals. Explain the effects of cell walls and meristems, and also the similarities and differences of some of the transcription factors involved in patterning (MADS vs. Hox). I want you to write this explanation as if you were preparing the background research for your favorite high school biology teacher (if you didn’t have one, pretend) who is putting together a lesson plan for a lecture on development. In other words, think about how to communicate the idea to high school kids, but write it for someone with some basic knowledge of biology.

ATWE 10

by AmandaD
Chapter ten tied together the major ideas in the book to provide a large scale summary of animal evolution and the mechanisms behind it. The largest tie is in between the metamorphosis of whales and early tetrapods. Both lines began with a small group of animals exploring the borders of a new ecosystem ripe for colonization. The exaptations of lungs in tetrapods and long tails in mesonychids became essential for their survival in a new environment. Stepping back to view the whole process, we see that drastic changes in the environment open up and close routes of life and change. The ability of an organism to adapt to those changes is ruled by their genes and how they develop, in other words animals are “constrained by their history.” To fully understand the transitions groups undergo the history of that group’s branch must be considered. On a similar note, Zimmer brings back the characters from the first chapter of the book, Richard Owen and Charles Darwin, to symmetrically complete it. Transitional fossils build on Darwin’s original ideas to tell the story individual lineages and the overall story of macroevolution.

Bimodality of calcium dependent axon pathfinding

by AmandaD
The growth cone is a motile structure at the tip of the axon that guides axon outgrowth. It can detect the presence of various molecules that will either attract or repel the growing axon. Somehow the receptors in the growth cone activate pathways that result in a change in the local cytoskeleton and adhesive ability of the growth cone. Calcium is an important mediator in this pathway. In this article (link goes to abstract in PubMed), Gomez and Zheng reviewed research on the role of calcium in axon pathfinding. The article explained how calcium signals are bimodal: they seem to stimulate certain processes and inhibit the same processes. It’s interesting that a single simple ion can signal the growth cone to produce opposing motile behaviors. Although calcium influx tends to repulse the growth cone and calcium outflow tends to attract it, it’s not the absolute calcium concentration that really guides the growth cone, it’s the change in local concentration relative to the baseline that affects morphology. Calcium can change the way that the cell responds to a particular factor such as netrin. The chemoattraction of the growth cone to netrin can be reversed to repulsion when certain calcium channels are blocked. Calcium signaling pathways are also involved in the branching pattern of the axon and dendrites. Branching factors work through calcium activated pathways to expand branches while other factors eliminate branches by activating other calcium signals, again bimodal. This can work because a distinct signal is used for each process.

City Birds

by dreamingtree
On the theme of birds, new research has shown that songbirds that live in city areas sing shorter and faster songs than birds that live in rural areas. City birds even adjust the pitch of their songs to be heard over the noise of the city. Ecologists at the Leiden University in the Netherlands analyzed bird songs in rural and urban areas in Europe. They found that the same species of bird will sing songs shorter, faster and higher in pitch in the city than birds of the same species in the forest. Researches hypothesized that the reason for this is that cities are full of low-frequency noises and that by shifting their songs to higher frequencies they make their songs stand out. This research may explain why some species of birds are better adapted for life in a city than others. Here is the link.

Avian Flu

by dreamingtree
Disease ecologists at the Consortium for Conservation Medicine in New York City and other institutions in the U.S. and the U.K. have analyzed the entry of the avian flu into the U.S. They believe if it enters the U.S. it will most likely be from migrating birds coming from Latin America. Unlike the U.S. in the Mexico and Brazil there is no testing or quarantine system for imported poultry, opening up an opportunity for the virus to become established in the Western Hemisphere. The virus has caused 154 human fatalities and scientists worry that if it acquires the ability to be passed easily from human to human it may become a pandemic. More research is needed, however, on poultry and wild birds to accurately predict the spread of the virus. Here is the link.

the man in the moon

by Gladys
NASA scientists have released their plan to have a permenant base on the moon by 2020. The base is set to be fully operational by 2024. NASA researchers are planning to have the base on rim of the Shackleton basin. This location recieves almost full-time sunlight, and also offers access to the "dark side of the moon." This area is considered exciting because of the lack of radio contact. NASA stated that they wont make any final decisions until their lunar recon orbiter comes back, which will not even be launched until next year. NASA plans to take this step by step, until their money runs out. They are currently open to commercial sponsorship. Check it out

Neanderthal Genome

by Gladys
Scientists are currently working on sequencing the Neanderthal genome. The research is taking place at the Max-Planck Institute for Evolutionary Anthropology in Germany. Researchers are hoping that the neanderthal genome will help answer so questions about our own development and evolution. The DNA was extracted from a small fossilized bone and only approximately four grams of the bone are needed for the genome project. The news artical is here

The Condom of the Future?

by snowcat
The Institute for Condom Consultancy is developing a new type of condom. A man inserts his penis into a spray can and with a push of a button the can coats it with a latex condom. The company claims that this condom will be more effective because the condoms will be custom fit for each person. They hope to have this new condom on the market by 2008.

Ch 8 and 9

by Gladys
Chapter 8 in the Zimmer book begins by talking about Frank Fish. Fish was a self proclaimed ecological physiologist/functional morphologist. His main objective was to study how warm-blooded animals adapted to life in the water. He began his research by studying muskrats. By carefully studying their swimming he was able to deduct how other mammals would swim with the body forms they have. Muskrats used their long tail to help propel them through the water. After Fish’s discoveries, Zimmer talks about Hans Thewissen and his hunt for the “middle man.” He was interested in finding the link between whales and terrestrial creatures. To do this he returned to Pakistan to pull out some more fossils. On his second trip he found what he was looking for but unfortunately, he was out of money. He was forced to leave some of his most exciting findings, mainly the leg bones of Ambulocetus, in Pakistan. His mentor Gingerich was finally able to bring the bones back more than a year later. The two men worked on the bones and published at almost the same time.
Chapter 9 in Zimmer begins be talking about the great variety of species that arose after the extinction of the dinosaurs. With the number of fossils the researchers found, it was difficult to age the bones appropriately. They thought the could put them in the right order, but sometimes it is more confusing than that. Zimmer then begins to describe the Dorudon. This was a contemporary of Basilosaurus. They are described as decent swimmers with legs and toes and and small head with a long neck. The evolution of whales into what we recognize today too much longer than it did for the whales to “enter” the water. The evolution of baleen whales is not yet completely understood. Next Zimmer gives a short review about DNA and how it is read into evolution and then writes about human evolution and our relation to primates. He also reminds us not to be too focused on our own evolution, because terrestrial mammals are not necessarily superior.

E. coli Outbreak at Taco Bell

by snowcat
There has been another outbreak of E. coli, this time at three Taco Bell restaurants in New Jersey. E. coli is a generally harmless type of bacteria often found in the feces of humans and animals, but a few strains can cause severe health problems such as abdominal cramps, fever, bloody diarrhea, kidney failure, blindness, paralysis, or even death. On the bright side, for those of us in Morris our only option for americanized mexican food is Taco Johns.

Zimmer 8-9

by snowcat
Chapter eight begins by talking about Frank Fish who studies how mammals swim. One of the big problems swimming mammals need to overcome is how to maintain their body temperature in water. Fish studied muskrats who overcome this problem is a similar way to dolphins. They manage their body temperature by changing to circulation of their blood, in warmer temperatures they dump heat by increasing circulation to the tail, in cooler temperature they shut down circulation to the tail to conserve heat. Then Fish became interested in developing a theory of how mammals swim. The least efficient technique, and the first one he suspects mammals used was the dog paddle. An improvement on the dog paddle is how otters swim. They do not alter their hind legs like in the dog paddle, but move them together; this resembles a terrestrial gallop in motor patterns. All that is needed for the whale to do at this point is grow a larger tail and have blubber in order to swim as efficiently as possible. Thewissen, who was a former student of Gingerich, was not very interested in whales, but ended discovering a whale that walked. This whale, Ambulocetus, resembled a crocodile and along with Gingerich’s Rodhocetus are important in understanding the origin of whales.

Chapter nine begins with discussion of how there were many species of whales that branched off in many directions. An important ancestral whale and one that could possibly have given rise to whales today is the Dorudon atrox. It had a long head attached to a flexible neck and a very long spine. It also had an important vertebra modification that allowed for the whale to generate more thrust per swimming stroke. Although this ancestor gets closer to our idea of a whale, it is still missing echolocation. Michel Milinkovitch used DNA sequencing to try to see how whales are related to each other. One issue he has to address with his version of the whale cladogram is that he suggests that baleen whales lost echolocation capabilities, which he explains by the fact that baleen whales didn’t need echolocation for feeding. Being a geneticist Milinkovitch is biased toward having more trust in a cladogram based on molecular biology than one based on morphology. Luckett, an anatomist and mammalogist believes that the molecular biologists need to think more like anatomists in order to build the best cladogram of the whale family. Zimmer concludes this chapter by talking about the encephalization quotient of various mammals and how it affects the IQ of different mammals.

Photophilia

by AmandaD
There's a lovely science photo library you can visit here. There are floral compositions, nicely rendered proteins, electron micrographs of red blood cells, stars, satellite images of volcanoes, x-rays. It's great.

Ch. 8 & 9 of Zimmer

by Esperanza
Chapter 8 of Zimmer involves the process by which whales went from walking to swimming. Frank Fish wanted to study how a warm-blooded mammal adapted its metabolism to water. He started by studying muskrats and videotaping them swimming in water. He discovered that with their mode of swimming they burned as much energy pound for pound and mile for mile as a human. He then went on to videotape many different mammals swimming. Fish’s theory of swimming development started with the dog paddle which is inefficient but enough for animals just crossing a creek and not living in the water. The next step would be the mode used by otters. The otter swims by pushing both hind limbs back together during a dive while bending its back so the undulation continues into its tail. This continues to push against water as the hind limbs move forward and would normally lose momentum. Fish declared that this was the way the earliest whales must have swum until their tails grew larger and more muscular and their backs became more flexible and loosed from their hips. Hans Thewissen found a skeleton of a whale that dated after Pakicetus but before Basilosaurus. It had forelegs that were short with great flat hands and hind legs that ended in feet shaped like clown shoes. It was a whale that walked and he named it Ambulocetus (walking whale). Not long after that Gingerich found a younger whale that had smaller legs than Ambulocetus that had normal functioning knees unlike Basilosaurus but the spine was no longer fused to the hips so that body resembled half a tail. He called this whale Rodhocetus.

Chapter nine deals with how to classify Archaeocetes, mysticetes, and odontocetes. At first scientists thought they descended from three different terrestrial vertebrates as archaeocetes did not have baleen teeth but theirs were differentiated dental work while more toothed whales have jaws full of identical pegs. A different whale, Aetiocetus, was discovered that resembled a baleen whale structurally in the skull except that it had teeth instead of baleen so it was decided that baleen whales descended from Archaeocetes.

Teen cough medicine abuse on the rise

by Esperanza
The abuse of non-prescription cough medicine by teens is on the rise. A drug found in the cough medicine can produce hallucinogenic effects. Calls for help to California’s poison control rose 50% each year between 1999 and 2004 for reactions to the drug dextromethorphan which is a cough suppressant. Most of the calls involved side effects suffered by youths aged 9 to 17 years.